Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_24_библиотеки_им_акад_М_И_Перельмана
.pdf
138
CPe
Hindbrai
https://t.me/medicina_free
K. J. Millen
abc
MB
n
Fig. 20.1 Overview of progenitor zones and the cell migrations that
build the mature cerebellum. (a) Sagittal section of the developing midbrain and hindbrain showing that the cerebellum (CB) is derived from
the dorsal region anterior hindbrain inuenced by signaling factors
from the mid-hindbrain junction isthmic organizer (IsO) and the dorsal
roof plate (rp). (b) A composite of embryonic developmental processes
during embryogenesis. The VZ gives rise to all cerebellar GABAergic
neurons and interneurons. The RL gives rise to the three major glutamatergic neuronal subtypes that populate the cerebellum. Initially, cerebellar nuclei projection neurons migrate from the rhombic lip into the
Nuclear Transitory Zone (NTZ) over the anlage as the rostral migratory
stream. As embryonic development proceeds, granule cell progenitors
(GCPs) next migrate out of the RL and migrate tangentially under the
of cerebellar anlage rotate and fuse on the dorsal mid-line to
form the cerebellar vermis. Neurogenesis in the RL rst gen-
PONS
4
CB
th
V
Midbrain
IsO
rp
NTZ
EGL
VZ
RG
UBC
VZ
RL
RP/CPe
pial surface to establish the EGL of the developing cerebellum. The RL
also gives rise to unipolar brush cells (UBC) later in development, that
migrate into the cerebellar anlage. (c) The EGL is composed of two
sublayers: a proliferating external zone and an inner differentiating
zone. EGL proliferation is largely driven by the mitogen sonic hedgehog (SHH) secreted from Purkinje cells which have formed the Purkinje
layer (PL) under the EGL. (d) The proliferation of GCPs in the EGL is
responsible for the dramatic size increase of the post-natal mouse cerebellum. As granule neurons exit the cell cycle, they exit the EGL,
migrating radially inward to settle below the developing Purkinje cell
layer to form the internal granule layer (IGL), resulting in (e) the nal
laminar arrangement of the mature cerebellum. [Modied and reused
with permission from (Haldipur and Millen 2019)]
post-conception (dpc) and the EGL differentiation is complete within the second post-natal year (Haldipur etal. 2019).
erates glutamatergic neurons of the cerebellar nuclei which
migrate in a rostral migratory stream over the top of the
anlage to settle into a Nuclear Transitory Zone (NTZ) just
20.2 Mouse Cerebellar Developmental
posterior of the mid/hindbrain junction. This is followed by
the generation of granule cell progenitors (GCPs) that also
migrate over the anlage and under the pial surface, to form an
external granule layer (EGL). In the EGL, GCPs undergo
multiple rounds of cell division to generate large numbers of
differentiating granule neurons which causes the cerebellum
to dramatically grow in size and foliate. Differentiating granule neurons exit the EGL and migrate inwards into the cerebellar anlage on radial Bergmann glial bers whose end feet
are anchored at the pial surface. As granule neurons migrate
inwards, they trail a T-shaped axon whose parallel bers
form the molecular layer of the mature cerebellar cortex,
while granule cell soma settle in the internal granule layer
(IGL) under the Purkinje cells, which are now thinned into a
monolayer from the previously multi-layered Purkinje cell
plate.
Notably, cerebellar development is an extended process.
It is initiated at around the time of neural tube closure when
the cerebellar territory is specied and continues through
post-natal stages when the EGL is nally depleted as the last
granule neurons differentiate and migrate inwards to form
the IGL, followed by the completion of gliogenesis and circuit maturation. In mice, cerebellar development extends
from embryonic day (e) 9.0 through postnatal day (P) 21. In
humans the cerebellar territory is dened prior to 30 days
Our understanding of the developmental events that build
and maintain the mature cerebellum described above, are the
result of decades of research built on the extremely strong
foundation of genetics, particularly mouse genetics. Mice
with ataxia, a hallmark of cerebellar dysfunction, are relatively easy to spot in large colonies of mice. Hence over the
last ~100years of mouse genetics, many spontaneous mutant
mice were described, with names including reeler, weaver,
leaner and tippy reecting their obvious motor phenotypes.
Extensive analyses identied the developmental steps that
went awry, using histological methods in combination complemented by cell-type specic markers dened from early
in situ, immunohistochemistry and early genome-wide
screens expression screens. The availability of the mouse
genome sequence enhanced positional cloning of the causative genes.
Building on the rich resource of spontaneous mutants, the
eld of cerebellar developmental genetics has rapidly progressed from the 1990s to the present, primarily due to the
rapid maturation of genome engineering and molecular
genetic technologies. Many mutant mouse strains have been
generated for genes expressed in the developing cerebellum,
EGL
PL
SHH
CPe
d
EGL
ML
PL
IGL
e
WM
ML
Genetics: fromPhenotypes toGenes
andBack Again
PL
IGL
20 The Genetic Programs Behind Cerebellar Development
https://t.me/medicina_free
139
with many causing developmental disruptions that have further informed our understanding of the genetic programs
driving cerebellar development. Genome engineering technology has also provided additional tools to probe cerebellar
development and function. For example, this has included
the permanent labelling of transient progenitors and all of
their descendants to dene progenitor lineages (Hoshino
etal. 2005; Machold and Fishell 2005; Wang etal. 2005). It
has enabled exquisite uorescent tagging to dissect complex
cell biological processes such as granule cell migration (Ong
et al. 2020). Cell electrical activity can be disrupted in
dened populations to probe neuronal activity functions during development and behaviour in vivo (Lindeman et al.
2021). As another example, the development of long-range
circuitry between the cerebellum and cerebral cortex contributing to autism related behaviors has been studied through
the ablation of specic populations of Purkinje cells (Kelly
etal. 2020).
Given the extensive foundation of cerebellar developmental knowledge based on developmental genetic analyses and
the highly ordered laminar structure of the mature cerebellum, a key observation is that the nal cerebellar form often
predicts the underlying developmental abnormalities. As discussed later, this can be important for the study of human
cerebellar developmental disorders, where developmental
data is almost always unavailable. To demonstrate this concept, I will show that the primary developmental defects
underlying the dysmorphology of the Lurcher mouse mutant
are readily deduced simply based on the nal adult
morphology.
The Lurcher mutation was rst isolated in 1954 as a spon-
taneously occurring autosomal dominant mutation. The adult
cerebellum of these animals is small and devoid of virtually
all cerebellar Purkinje cells and moderately diminished gran-
ule cell numbers (Vogel etal. 2007) (Fig.20.2). Yet the cer-
ebellum is reasonably foliated and even retains somewhat
normal lamination. Simply by examining the gross histology
of the adult cerebellum, in the context of decades of cerebellar developmental research, we can conclude that embryonic
cerebellar patterning of VZ and RL proliferative zones likely
proceeded normally, despite the signicant losses of two
major neuronal subclasses in adults. Patterning of foliation
in large part depends on the correct patterning of Purkinje
cells, hence Purkinje cells must have been born and assumed
their correct regional identity by birth. Once patterned, foliation is driven by post-natal EGL proliferation which in turn
depends on secreted mitogens (SHH) from the underlying
Purkinje cells during post-natal stages. Hence, Purkinje cells
were present during these early post-natal stages. The presence of an adult molecular layer and (diminished) IGL, signies that GNP proliferation in the EGL occurred, followed
by inward migration of differentiating granule neurons along
ordered Bergmann glial bers which occur from P4 through
P15. Further, ordered Bergmann glial bers require Purkinje
cells for maintenance. Based on these observations, we can
conclude that Lurcher mice had Purkinje cells through most
of the development and even through early post-natal stages,
Purkinje cells supported foliation and some granule cell proliferation and some differentiation. We would therefore predict based exclusively on the adult histology, that the Lurcher
Fig. 20.2 The Lurcher cerebellum. Sagittal section of control (left) and Lurcher (right) mutant adult cerebellar vermis, highlighting the severe
hypoplasia and dysmorphology of the Lurcher cerebellum scale bar is 1mm. [Modied and reused with permission from (Vogel etal. 2007)]
140
https://t.me/medicina_free
K. J. Millen
mutation primarily impacts Purkinje cells during the end of
the rst postnatal week. Indeed, extensive detailed histology
and chimera studies did conclude this. Further, positional
cloning demonstrated that the Lurcher locus encodes a gain
of function in the glutamate ionotropic receptor delta type
subunit 2, Grid2 (Zuo etal. 1997), preferentially expressed
in post-natal Purkinje cells. The Lurcher Grid2 mutation
triggers post-natal Purkinje cell death via a combination of
aberrant autophagy and excitotoxicity (Vogel etal. 2007).
There are a multitude of lessons to be learned from mutant
mice with either spontaneous or engineered mutations that
cause structural cerebellar malformations. As discussed in
the next section, these lessons are also relevant to the emerging biology from the study of human cerebellar developmental disorders.
1. Since cerebellar morphology is stereotypical and estab-
lished by key developmental programs which are spatially and temporally distinct, structural abnormalities
that result are readily identied and can provide clues
regarding their developmental pathogenesis.
2. Cerebellar development is orchestrated by complex
developmental interdependencies. Each neuronal class
does not develop in isolation but rather depends on both
direct cell–cell contacts and a multitude of short- and
long-range molecular signals.
3. Cerebellar malformation can result from derailed devel-
opment due to aberrant gene function, and/or developmental degeneration. Further, even adult cerebellar
atrophy may have underlying cerebellar developmental
abnormalities that increase the risk for degeneration later
in life (Serra etal. 2006).
4. Few if any genes that cause cerebellar developmental dis-
orders have restricted expression or function to the developing cerebellum. For example Grid2 is expressed in
other CNS regions, including in the cerebral cortex
(www.allenbrainatlas.org) and loss and gain of function
mutations in GRID2 in humans are associated with cerebellar ataxias which can also include intellectual disability and even epilepsy, likely implicating other brain
regions in the pathogenesis (www.omim.org).
20.3 Human Cerebellar Developmental
Disorders andHuman Cerebellar
Development
Human cerebellar malformations have been recognized for
more than 100 years, based on post-mortem examinations
(Haldipur etal. 2019). However, advances in brain imaging
studies have allowed the recognition of many additional cerebellar structural malformations classied based on key
imaging features (Fig.20.3). Some of these include highly
specic pathognomonic imaging features which distinguish
them from all other malformations such as the Molar Tooth
Sign, complex midbrain and cerebellar peduncle malformation seen in patients with Joubert syndrome. Other imaging
other features are much less specic such as cerebellar hypoplasia. In combination with imaging advances, human
genetic analyses together with detailed clinical phenotyping
has allowed the stratication of patient populations and the
identication of a multitude of genes that contribute to
human cerebellar developmental disorders. This has also led
to the growing recognition that cerebellar developmental
decits are often a part of broader neurodevelopmental disorders, intellectual disability syndromes with previously
overlooked cerebellar developmental pathology (Aldinger
and Doherty 2016; Aldinger etal. 2019).
As in the mouse, in humans, disruption of critical cerebellar developmental programs including neurogenesis, proliferation and neuronal migration have important consequences
on the cerebellar outcome. Mouse models have been essential to dene developmental pathogenesis once human genetics have identied causative genes. There is some overlap in
genes previously described as mouse cerebellar malformation genes as causative genes for human cerebellar malformation phenotypes. For example, Wnt1 loss of function has
long been known to cause a dramatic anterior cerebellar
foliation defect in mice. This notable phenotype is caused by
the loss of Wnt1 function as a morphogen at the midhindbrain junction during early neural tube stages. Loss of
Wnt1 signaling leads to loss of the anterior cerebellar territory at the anterior of the hindbrain and hence aberrant patterning of anterior foliation (McMahon and Bradley 1990;
Thomas etal. 1991). Wnt1 null mutant mice die at birth due
to other hindbrain defects that affect breathing and suckling.
Hypomorphic mutants survive as adults, with less severe patterning defects, and are ataxic. Notably, human patients with
WNT1 loss of function mutations present with variable cerebellar hypoplasia and other associated hindbrain (and other)
abnormalities reminiscent of Wnt1 mouse mutant phenotype
(Aldinger et al. 2016). However, these cerebellar ndings
were not the reason that these patients came to attention.
WNT1 loss of function in humans was rst associated with
severe osteogenesis imperfecta (Marini etal. 2014) and retrospectively cerebellar and other brain abnormalities were
described. Bone development has not been a major focus of
mouse models, although defects have been reported
(Vollersen etal. 2021). Ascertainment bias in both mouse
and humans directed the initial studies of the rst roles studied for this gene in each species.
Ascertainment bias has had many consequences regarding the genes studied for their roles in directing cerebellar
development. Another prominent example is FOXC1. Human
genetic analysis of Dandy–Walker malformation, an imaging
diagnosis involving inferior-predominant cerebellar hypo-
20 The Genetic Programs Behind Cerebellar Development
https://t.me/medicina_free
141
Fig. 20.3 Magnetic resonance images (MRI) showing sagittal views
of the cerebellar vermis from a subset of human cerebellar malformations. The image of a patient with cerebellar vermis hypoplasia (CVH)
shows decreased vermis size that does not reach the obex, the narrowing of the fourth ventricle in the caudal medulla (white line), as occurs
in normal subjects. In addition to vermis hypoplasia, subjects with
Dandy–Walker malformation (DWM) also exhibit an increased posterior fossa size and an upward rotation of the vermis. The parasagittal
image of a patient with Joubert syndrome shows vermis hypoplasia and
plasia and an enlarged fourth ventricle with an elongated
posterior tail (Fig. 20.3), identied haploinsufciency of
FOXC1 as a rare cause of this malformation (Aldinger etal.
2009). Both FOXC1 human haploinsufciency and increased
gene dosage had previously been shown to cause anterior
chamber defects of the eye (Nishimura etal. 2001) and have
since been shown to also cause cerebral small-vessel disease
and stroke (French et al. 2014). Until there was a link to
human cerebellar malformation, the focus on mouse Foxc1
models was limited to cardiovascular and somite phenotypes
(Kume et al. 2001). Yet once it was clear that Foxc1 was
required for cerebellar development, detailed mouse developmental analyses showed that Foxc1 is required in the
developing mesenchyme adjacent to the cerebellar anlage.
This mesenchyme will differentiate into the pia, dura, bone
and dermis of the posterior fossa. Yet long before this differentiation happens, the Foxc1 transcription factor directs
an elongated superior cerebellar peduncle (white arrowhead). The plane
of this off-midline image is designated with a dotted white line in the
corresponding axial image. The “molar tooth” malformation of Joubert
syndrome and related disorders can be seen in the axial MRI as elongated cerebellar peduncles (white arrowhead) and deepened interpeduncular fossa (black arrow) compared with a normal subject (N;
inset). Subjects with pontocerebellar hypoplasia (PCH) exhibit both
decreased vermis size and pontine hypoplasia (arrows). Cb cerebellum,
PF posterior fossa [Reused with permission from (Sajan etal. 2010)]
transcription of Sdf1a– a morphogen secreted by these mesenchymal cells, that is received by the adjacent radial glia
and other cells in the developing cerebellum to drive the proliferation of progenitors and direct neuronal migration
(Haldipur etal. 2014, 2017). It is doubtful that the role of
Foxc1 in cerebellar development would have been a focus of
mouse studies without human genetic studies. Yet, the synergistic human and mouse studies revealed essential new
insights into normal cerebellar developmental mechanisms
and the pathogenesis of human cerebellar developmental
disorders.
Another lesson learned from cerebellar developmental disorders in humans that were not initially apparent from mouse
studies has been the importance of vascular and environmental
injuries as causes of cerebellar developmental disorders.
Indeed, a recent genetic analysis of a large cohort of cerebellar
malformation cases demonstrated that among the two-thirds
142
https://t.me/medicina_free
K. J. Millen
of individuals in the study who did not receive a molecular
diagnosis, one-half had evidence of a prenatal injury (Aldinger
et al. 2019). There is evidence that two stages of cerebellar
development are particularly vulnerable to injury.
The rst stage of cerebellar development that is susceptible to vascular injury is an early epoch from roughly 8–13
post-conception weeks (pcw). A striking recent discovery is
that the human rhombic lip, unlike the rodent, or even nonhuman primate (macaque) rhombic lip is very complex with
both molecular and structure sub-compartmentation.
Uniquely, the human is composed of a ventricular and subventricular zone, which are bisected by a rich vascular bed.
From 8–13 pcw, the human RL is a long fragile ribbon-like
structure that is extremely fragile (Haldipur et al. 2019).
Growing evidence suggests that vascular disruptions of this
early, fragile RL may be associated with at least some cases
of Dandy–Walker malformation (Haldipur et al. 2021).
Problematically, the data is and likely will forever remain
correlative. Imaging data is only for development around
17–19 pcw, when standard clinical screening studies are conducted. Yet even at this stage, prior to extensive elaboration
of the developing cerebellar structure, cerebellar morphological abnormalities can be apparent in imaging studies and
occasionally they are show evidence of vascular injury due to
hemosiderin deposits. Since cerebellar outcome (at all stages
of development) predicts prior developmental disruptions, a
careful histological analysis of mid-gestation pathology
clearly implicates earlier developmental disruptions of the
rhombic lip, some of which likely involved vascular insult.
The second stage of cerebellar development that is vulnerable to insult is the third trimester. From 28–41 pcw, normal
human cerebellar volume increases in size by 177%
(Limperopoulos etal. 2005). This size increase is driven by
the explosive proliferation of GCPs in the EGL and differentiation of granule neurons additionally contributing to the
growth of the molecular layer and IGL.In humans, 80% of all
neurons of the entire CNS are granule neurons and there are
~5000 granule neurons for every Purkinje neuron (Haldipur
etal. 2019). Although numerous genes have been shown to
underlie EGL decits in human cerebellar hypoplasia
(Aldinger and Doherty 2016; Aldinger etal. 2019), prematurity alone is a huge risk factor for cerebellar hypoplasia.
Further cerebellar hypoplasia is one of the most common
complications in preterm infants associated with poor neurodevelopmental outcome, even in the absence of supratentorial
injury (Limperopoulos etal. 2007). Causes are the complicated interplay of a variety of factors including cerebellar
hemorrhage, glucocorticoid and opioid exposure, undernutrition, infection, inammation and hypoxia–ischemia, which
themselves are likely inuenced by genetic risk factors
(Aldinger et al. 2019; Gano and Barkovich 2019). Recent
studies have clearly shown that the development of cerebellar
circuitry, both within the cerebellum and between the cerebel-
lum and other brain regions, especially the cerebral cortex,
are compromised when prematurity disrupts cerebellar granule cell development is compromised (Sathyanesan et al.
2019; van der Heijden etal. 2021). These studies remind us
that major neurodevelopmental disorders such as intellectual
disability, autism spectrum disorder, attention-decit hyperactivity disorder, and beyond have potential links to abnormal
cerebellar development that should not be discounted.
20.4 The Current Age ofTranscriptomics
and Epigenomics
Historically, dening the genetic programs that drive cerebellar development and cerebellar disorders has almost
exclusively relied on analysis and inuence of single genes.
Early in situ, immunohistochemistry, and early genome-
wide bulk transcriptomic studies, including SAGE and
related technologies allowed us to begin to link gene expression to development. They also allowed the development of
powerful tools to manipulate gene expression in model
organisms, particularly the mouse. Notably, bulk transcriptome analyses provide data on the genes with the highest
expression in the largest number of cells. Bulk analyses however dilute signals from rare cell types unless cell populations are isolated (Heiman etal. 2014), yet enrichment can
be difcult with rare populations.
Within the last 5years, there has been a seismic shift in
cerebellar molecular genetics towards genome wide transcriptomic and epigenomic analyses at the single cell level.
This is providing unprecedented new insight into the genetic
programs that drive cerebellar development and cerebellar
disorders. Multiple single-cell datasets that describe the transcriptome of the adult and developing mouse and human cerebellum, and less familiar model organisms including the
chicken and opossum (Aldinger et al. 2021; Carter et al.
2018; Kebschull et al. 2020; Lake et al. 2018; Rosenberg
et al. 2018; Sarropoulos et al. 2021; Vladoiu et al. 2019;
Wizeman etal. 2019). The advent of single-cell transcriptomic analyses is revolutionizing our ability to dene gene
expression proles of rare transient progenitor populations
and also has revealed previously unrecognized heterogeneity
of neuronal populations including Purkinje cells, cerebellar
nuclei neurons and unipolar brush cells. Epigenomic studies
from bulk tissue and cell populations demonstrated that
chromatin remodeling is an essential feature of cerebellar
development, particularly during histogenesis and the establishment of circuits (Zhu et al. 2016). Now single cell
ATACseq analyses in combination with single-cell transcriptomics are revealing master regulatory programs orchestrating suites of genes driving differentiation and these studies
are beginning to address the evolutionary dynamics that
underlie species differences.
20 The Genetic Programs Behind Cerebellar Development
https://t.me/medicina_free
143
20.5 New Models andFuture Perspectives
Modern molecular biological technologies are driving current progress in our understanding of the genetic programs
behind cerebellar development in a multitude of species.
However, beyond rodent (mostly mice) and chicken models,
we have limited access to cerebellar developmental tissue,
including humans. We are further restricted in our abilities to
manipulate development to test genetic hypotheses beyond
mouse for both ethical and practical reasons. CRISPR technology can enable genetic manipulation in non-traditional
models, but these experiments are essentially impractical.
Non-human primate and other mammalian models, including pigs and sheep, are not widely available. Hence it is
imperative to develop invitro models of cerebellar development to both model species-specic developmental programs, especially human, and to model human disease
pathogenesis. Both 2D and 3D (organoid) cerebellar neuron
differentiation protocols from human induced pluripotent
stem cells (iPSCs) and human embryonic stem (hES) cells
are under development (Behesti etal. 2021; Buchholz etal.
2020; Hua etal. 2021; Nayler etal. 2021; Silva etal. 2021).
The recent availability of native human developmental cerebellar transcriptomic data will enable the identication of
human-relevant signaling programs to more accurately direct
the differentiation of all neuronal types. As this technology
matures, there are two important hurdles that will have to be
overcome. Normal cerebellar development and circuitry
depend on the establishment of normal cerebellar lamination. Thus, the establishment of laminar cultures should be a
priority. Further, given the extended time scale (years) of
normal human cerebellar development, it will likely be a
challenge to achieve complete neuronal maturation in culture. Identication of the mechanisms regulating developmental time is a nascent eld of research. Recently, increases
in protein stability in humans vs mouse have been shown to
contribute to the lengthening of fundamental human biochemical and developmental biological processes (Rayon
and Briscoe 2021). It remains unknown how these can be
globally regulated to speed up time invitro.
Historical studies of mouse cerebellar mutants marked the
beginning of the eld of cerebellar developmental neurogenetics. The eld has dramatically matured in the last 30years
with genome engineering advances in mice and dramatic
evolution of molecular biological technologies. Vast amounts
of morphological and phenotypic data describing altered cerebellar development are available, complemented by enormous amounts of detailed transcriptomic and genomic data.
A challenge will be to integrate all of the data to enrich our
understanding of the genetic programs behind cerebellar
development and cerebellar disorders.
Acknowledgements This work was supported by NIH R37NS095733
Javits Neuroscience Award to KJM. Apologies to all authors whose
work could not be fully cited due to reference limits.
References
Aldinger KA, Doherty D (2016) The genetics of cerebellar malforma-
tions. Semin Fetal Neonatal Med 21:321–332
Aldinger KA, Lehmann OJ, Hudgins L, Chizhikov VV, Bassuk AG,
Ades LC, Krantz ID, Dobyns WB, Millen KJ (2009) FOXC1 is
required for normal cerebellar development and is a major contributor to chromosome 6p25.3 Dandy–Walker malformation. Nat Genet
41:1037–1042
Aldinger KA, Mendelsohn NJ, Chung BH, Zhang W, Cohn DH,
Fernandez B, Alkuraya FS, Dobyns WB, Curry CJ (2016) Variable
brain phenotype primarily affects the brainstem and cerebellum in
patients with osteogenesis imperfecta caused by recessive WNT1
mutations. J Med Genet 53:427–430
Aldinger KA, Timms AE, Thomson Z, Mirzaa GM, Bennett JT,
Rosenberg AB, Roco CM, Hirano M, Abidi F, Haldipur P et al
(2019) Redening the etiologic landscape of cerebellar malformations. Am J Hum Genet 105:606–615
Aldinger KA, Thomson Z, Phelps IG, Haldipur P, Deng M, Timms
AE, Hirano M, Santpere G, Roco C, Rosenberg AB etal (2021)
Spatial and cell type transcriptional landscape of human cerebellar
development. Nat Neurosci 24:1163–1175. https://doi.org/10.1038/
s41593- 021- 00872- y
Behesti H, Kocabas A, Buchholz DE, Carroll TS, Hatten ME (2021)
Altered temporal sequence of transcriptional regulators in the generation of human cerebellar granule cells. Elife 10:e67074. https://
doi.org/10.7554/eLife.67074
Buchholz DE, Carroll TS, Kocabas A, Zhu X, Behesti H, Faust PL,
Stalbow L, Fang Y, Hatten ME (2020) Novel genetic features of
human and mouse Purkinje cell differentiation dened by comparative transcriptomics. Proc Natl Acad Sci U S A 117:15085–15095
Carter RA, Bihannic L, Rosencrance C, Hadley JL, Tong Y, Phoenix
TN, Natarajan S, Easton J, Northcott PA, Gawad C (2018) A singlecell transcriptional atlas of the developing murine cerebellum. Curr
Biol 28:2910–2920
Chizhikov V, Millen KJ (2020) Chapter 16: Neurogenesis in the
cerebellum. In: Rubenstein J, Rakic P, Chen B, Kwan K (eds)
Comprehensive developmental neuroscience. Academic Press,
London
French CR, Seshadri S, Destefano AL, Fornage M, Arnold CR, Gage
PJ, Skarie JM, Dobyns WB, Millen KJ, Liu T etal (2014) Mutation
of FOXC1 and PITX2 induces cerebral small-vessel disease. J Clin
Invest 124:4877–4881
Gano D, Barkovich AJ (2019) Cerebellar hypoplasia of prematurity:
causes and consequences. Handb Clin Neurol 162:201–216
Haldipur P, Millen KJ (2019) What cerebellar malformations tell us
about cerebellar development. Neurosci Lett 688:14–25
Haldipur P, Gillies GS, Janson OK, Chizhikov VV, Mithal DS, Miller
RJ, Millen KJ (2014) Foxc1 dependent mesenchymal signalling
drives embryonic cerebellar growth. Elife 3:e03962. https://doi.
org/10.7554/eLife.03962
Haldipur P, Dang D, Aldinger KA, Janson OK, Guimiot F, Adle-
Biasette H, Dobyns WB, Siebert JR, Russo R, Millen KJ (2017)
Phenotypic outcomes in mouse and human Foxc1 dependent
Dandy–Walker cerebellar malformation suggest shared mechanisms. Elife 6:e20898. https://doi.org/10.7554/eLife.20898
Haldipur P, Aldinger KA, Bernardo S, Deng M, Timms AE, Overman
LM, Winter C, Lisgo SN, Razavi F, Silvestri E et al (2019)
144
https://t.me/medicina_free
K. J. Millen
Spatiotemporal expansion of primary progenitor zones in the devel-
oping human cerebellum. Science 366:454–460
Haldipur P, Bernardo S, Aldinger KA, Sivakumar T, Millman J, Sjoboen
AH, Dang D, Dubocanin D, Deng M, Timms AE et al (2021)
Evidence of disrupted rhombic lip development in the pathogenesis
of Dandy–Walker malformation. Acta Neuropathol 142:761–776
Heiman M, Kulicke R, Fenster RJ, Greengard P, Heintz N (2014) Cell
type-specic mRNA purication by translating ribosome afnity
purication (TRAP). Nat Protoc 9:1282–1291
Hoshino M, Nakamura S, Mori K, Kawauchi T, Terao M, Nishimura
YV, Fukuda A, Fuse T, Matsuo N, Sone M etal (2005) Ptf1a, a
bHLH transcriptional gene, denes GABAergic neuronal fates in
cerebellum. Neuron 47:201–213
Hua TT, Bejoy J, Song L, Wang Z, Zeng Z, Zhou Y, Li Y, Sang QA
(2021) Cerebellar differentiation from human stem cells through
retinoid, Wnt, and sonic hedgehog pathways. Tissue Eng Part A
27:881–893
Kebschull JM, Richman EB, Ringach N, Friedmann D, Albarran E,
Kolluru SS, Jones RC, Allen WE, Wang Y, Cho SW etal (2020)
Cerebellar nuclei evolved by repeatedly duplicating a conserved
cell-type set. Science 370(6523):eabd5059. https://doi.org/10.1126/
science.abd5059
Kelly E, Meng F, Fujita H, Morgado F, Kazemi Y, Rice LC, Ren C,
Escamilla CO, Gibson JM, Sajadi S et al (2020) Regulation of
autism-relevant behaviors by cerebellar-prefrontal cortical circuits.
Nat Neurosci 23:1102–1110
Kume T, Jiang H, Topczewska JM, Hogan BL (2001) The murine
winged helix transcription factors, Foxc1 and Foxc2, are both
required for cardiovascular development and somitogenesis. Genes
Dev 15:2470–2482
Lake BB, Chen S, Sos BC, Fan J, Kaeser GE, Yung YC, Duong TE,
Gao D, Chun J, Kharchenko PV etal (2018) Integrative single-cell
analysis of transcriptional and epigenetic states in the human adult
brain. Nat Biotechnol 36:70–80
Leto K, Arancillo M, Becker EB, Buffo A, Chiang C, Ding B, Dobyns
WB, Dusart I, Haldipur P, Hatten ME etal (2016) Consensus paper:
cerebellar development. Cerebellum 15:789–828
Limperopoulos C, Soul JS, Gauvreau K, Huppi PS, Wareld SK,
Bassan H, Robertson RL, Volpe JJ, du Plessis AJ (2005) Late ges-
tation cerebellar growth is rapid and impeded by premature birth.
Pediatrics 115:688–695
Limperopoulos C, Bassan H, Gauvreau K, Robertson RL Jr, Sullivan
NR, Benson CB, Avery L, Stewart J, Soul JS, Ringer SA etal (2007)
Does cerebellar injury in premature infants contribute to the high
prevalence of long-term cognitive, learning, and behavioral disabil-
ity in survivors? Pediatrics 120:584–593
Lindeman S, Hong S, Kros L, Mejias JF, Romano V, Oostenveld
R, Negrello M, Bosman LWJ, De Zeeuw CI (2021) Cerebellar
Purkinje cells can differentially modulate coherence between sen-
sory and motor cortex depending on region and behavior. Proc
Natl Acad Sci U S A 118:e2015292118. https://doi.org/10.1073/
pnas.2015292118
Low AYT, Goldstein N, Gaunt JR, Huang KP, Zainolabidin N, Yip
AKK, Carty JRE, Choi JY, Miller AM, Ho HST et al (2021)
Reverse-translational identication of a cerebellar satiation net-
work. Nature 600:269–273
Lowenstein ED, Cui K, Hernandez-Miranda LR (2022) Regulation
of early cerebellar development. FEBS J 2022:16426. https://doi.
org/10.1111/febs.16426
Machold R, Fishell G (2005) Math1 is expressed in temporally dis-
crete pools of cerebellar rhombic-lip neural progenitors. Neuron
48:17–24
Marek S, Siegel JS, Gordon EM, Raut RV, Gratton C, Newbold DJ,
Ortega M, Laumann TO, Adeyemo B, Miller DB etal (2018) Spatial
and temporal organization of the individual human cerebellum.
Neuron 100:977–993
Marini JC, Reich A, Smith SM (2014) Osteogenesis imperfecta due to
mutations in non-collagenous genes: lessons in the biology of bone
formation. Curr Opin Pediatr 26:500–507
McMahon AP, Bradley A (1990) The Wnt-1 (int-1) proto-oncogene is
required for development of a large region of the mouse brain. Cell
62:1073–1085
Metoki A, Wang Y, Olson IR (2022) The social cerebellum: a large-
scale investigation of functional and structural specicity and connectivity. Cereb Cortex 32:987–1003
Nayler S, Agarwal D, Curion F, Bowden R, Becker EBE (2021) High-
resolution transcriptional landscape of xeno-free human induced
pluripotent stem cell-derived cerebellar organoids. Sci Rep 11:12959
Nishimura DY, Searby CC, Alward WL, Walton D, Craig JE, Mackey
DA, Kawase K, Kanis AB, Patil SR, Stone EM etal (2001) A spectrum of FOXC1 mutations suggests gene dosage as a mechanism
for developmental defects of the anterior chamber of the eye. Am J
Hum Genet 68:364–372
Ong T, Trivedi N, Wakeeld R, Frase S, Solecki DJ (2020) Siah2
integrates mitogenic and extracellular matrix signals linking neuronal progenitor ciliogenesis with germinal zone occupancy. Nat
Commun 11:5312
Rayon T, Briscoe J (2021) Cross-species comparisons and invitro mod-
els to study tempo in development and homeostasis. Interface Focus
11:20200069
Rosenberg AB, Roco CM, Muscat RA, Kuchina A, Sample P, Yao Z,
Graybuck LT, Peeler DJ, Mukherjee S, Chen W etal (2018) Singlecell proling of the developing mouse brain and spinal cord with
split-pool barcoding. Science 360:176–182
Sajan SA, Waimey KE, Millen KJ (2010) Novel approaches to studying
the genetic basis of cerebellar development. Cerebellum 9:272–283
Sarropoulos I, Sepp M, Fromel R, Leiss K, Trost N, Leushkin E,
Okonechnikov K, Joshi P, Giere P, Kutscher LM et al (2021)
Developmental and evolutionary dynamics of cis-regulatory elements in mouse cerebellar cells. Science 373:eabg4696. https://doi.
org/10.1126/science.abg4696
Sathyanesan A, Zhou J, Scadi J, Heck DH, Sillitoe RV, Gallo V (2019)
Emerging connections between cerebellar development, behaviour
and complex brain disorders. Nat Rev Neurosci 20:298–313
Schmahmann JD (2019) The cerebellum and cognition. Neurosci Lett
688:62–75
Serra HG, Duvick L, Zu T, Carlson K, Stevens S, Jorgensen N, Lysholm
A, Burright E, Zoghbi HY, Clark HB et al (2006) RORalphamediated Purkinje cell development determines disease severity in
adult SCA1 mice. Cell 127:697–708
Silva TP, Sousa-Luis R, Fernandes TG, Bekman EP, Rodrigues CAV,
Vaz SH, Moreira LM, Hashimura Y, Jung S, Lee B et al (2021)
Transcriptome proling of human pluripotent stem cell-derived cerebellar organoids reveals faster commitment under dynamic conditions. Biotechnol Bioeng 118:2781–2803
Thomas KR, Musci TS, Neumann PE, Capecchi MR (1991) Swaying
is a mutant allele of the proto-oncogene Wnt-1. Cell 67:969–976
van der Heijden ME, Lackey EP, Perez R, Isleyen FS, Brown AM,
Donofrio SG, Lin T, Zoghbi HY, Sillitoe RV (2021) Maturation of
Purkinje cell ring properties relies on neurogenesis of excitatory
neurons. Elife 10:e68045. https://doi.org/10.7554/eLife.68045
Vladoiu MC, El-Hamamy I, Donovan LK, Farooq H, Holgado BL,
Sundaravadanam Y, Ramaswamy V, Hendrikse LD, Kumar S, Mack
SC et al (2019) Childhood cerebellar tumours mirror conserved
fetal transcriptional programs. Nature 572:67–73
Vogel MW, Caston J, Yuzaki M, Mariani J (2007) The Lurcher mouse:
fresh insights from an old mutant. Brain Res 1140:4–18
Vollersen N, Zhao W, Rolvien T, Lange F, Schmidt FN, Sonntag S,
Shmerling D, von Kroge S, Stockhausen KE, Sharaf A etal (2021)
The WNT1(G177C) mutation specically affects skeletal integrity
in a mouse model of osteogenesis imperfecta type XV.Bone Res
9:48
20 The Genetic Programs Behind Cerebellar Development
https://t.me/medicina_free
145
Wang VY, Rose MF, Zoghbi HY (2005) Math1 expression redenes
the rhombic lip derivatives and reveals novel lineages within the
brainstem and cerebellum. Neuron 48:31–43
Wizeman JW, Guo Q, Wilion EM, Li JY (2019) Specication of diverse
cell types during early neurogenesis of the mouse cerebellum. Elife
8:e42388. https://doi.org/10.7554/eLife.42388
Zhu X, Girardo D, Govek EE, John K, Mellen M, Tamayo P, Mesirov
JP, Hatten ME (2016) Role of Tet1/3 genes and chromatin remodeling genes in cerebellar circuit formation. Neuron 89:100–112
Zuo J, De Jager PL, Takahashi KA, Jiang W, Linden DJ, Heintz N
(1997) Neurodegeneration in Lurcher mice caused by mutation in
delta2 glutamate receptor gene. Nature 388:769–773
Part IV
https://t.me/medicina_free
Cerebellar Circuits: Biochemistry, Neurotransmitters
and Neuromodulation
Granule Cells andParallel Fibers
https://t.me/medicina_free
EgidioD’Angelo
21
Abstract
The granule cells (GrCs) are the smallest and most numer-
ous neurons of the brain and constitute the main elements
of the granular layer of the cerebellum. The GrCs are
essential for cerebellar functioning (Galliano et al. Cell
Rep 3:1239–1251, 2013) by determining a complex spa-
tiotemporal reconguration of incoming signals (Casali
etal. Commun Biol 3(1):635, 2020). GrC functioning is
based on some specic properties (D’Angelo Cerebellar
granule cell. In: Handbook of the cerebellum and cerebel-
lar disorders, Springer, Berlin, 765–791, 2013):
1. GrCs have a special structure and connectivity pattern
allowing fast combinatorial processing.
2. GrCs are connected to mossy bers (MFs) and Golgi
cells (GoCs) in glomeruli allowing neurotransmitter
spillover and crosstalk.
3. GrCs are silent at rest and respond with spike bursts to
MF activity by exploiting specic ionic channel
properties.
4. GrCs are at the core of a complex NMDA- and NOdependent system that regulates long-term synaptic
plasticity in MFs and parallel bers (PFs).
5. GrCs have a peculiar postnatal development determining their connectivity with MFs and Purkinje cells
(PCs) (see Chaps. 13, 15, 17, 18).
Keywords
Granule cells · Parallel bers · Cerebellum
E. D’Angelo (*)
Department of Brain and Behavioral Sciences, University of Pavia,
Pavia, Italy
Department of Physiology, University of Pavia, Pavia, Italy
Brain Connectivity Center, IRCCS Mondino, Pavia, Italy
e-mail: dangelo@unipv.it; egidiougo.dangelo@unipv.it
21.1 Granule Cell Structure
andElectroresponsiveness
GrCs are composed of a small soma emitting four short
unbranched dendrites on average and receive excitatory
inputs from MFs and inhibitory inputs from GoCs (Eccles
et al. 1967). GrCs are excitatory and transmit their output
through the ascending axon (AA) that then bifurcates into
the parallel bers (PF). The AA contacts GoCs on their basal
dendrites and PCs on their terminal dendritic branchings,
while the PF contacts both GoCs, PCs and molecular layer
interneurons (MLIs) in the molecular layer (Fig. 21.1;
Mapelli etal. 2014; Masoli and D’Angelo 2017).
GrCs express ionic channels conferring specic electroresponsive properties (D’Angelo etal. 2001). Nav1.6 have the
highest concentration in the axon initial segment (AIS),
where action potentials are initiated and are located along the
axon but are almost absent from soma (Goldfarb etal. 2007).
In the AIS, broblast growth factor homologous factor (FHF)
regulates Nav1.6 channel inactivation and spike bursting,
while in the axon FHF is missing favoring high-delity
action potential conduction (Dover etal. 2016). The Nav1.6
sodium channels, in addition to the transient component generating the spike upstroke, produce a persistent current,
which amplies theta-frequency oscillations and resonance.
Moreover, Nav1.6 channels produce a resurgent current reinforcing burst generation. The Ca2+ channels are of the high
voltage-activated type: in the soma, N-type Ca2+ channels are
activated during the action potential upstroke and regulate a
BK Ca2+-dependent K+ current, while in the synaptic terminals, P/Q and R type Ca2+ channels regulate neurotransmitter
release (Galliano etal. 2013). A-type K+ channels regulate
spike initiation and M-type K+ channels determine oscillations and resonance. Finally, GIRK type K+ channels control
GrC resting membrane potential and input conductance.
These properties have been incorporated into realistic models (D’Angelo et al. 2001) demonstrating that GrCs are
indeed designed to rapidly respond to incoming MF inputs
with short spike bursts raising up to about 300Hz. The spikes
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023
D. L. Gruol et al. (eds.), Essentials of Cerebellum and Cerebellar Disorders, https://doi.org/10.1007/978-3-031-15070-8_21
149
Соседние файлы в папке Библиотека им академика М.И. Перельмана