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Expression of Calbindin-D protein in wild-type and weaver cerebellum. Calbindin-D expression in wild-type animals at (A) P15, (C) P22 and (E) P28, showing the maturation of the Purkinje cell dendritic trees. Expression in weaver cerebellum at (B) P15, (D) P22 and (F) P28 showing the poorly developed dendritic tree. Note that expression of Calbindin-D protein is maintained at P22 and P28.
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Wnt genes encode secreted proteins implicated in cell fate changes during development. To define specific cell populations in which Wnt genes act, we have examined Wnt expression in the cerebellum. This part of the brain has a relatively simple structure and contains well-characterized cell populations. We found that Wnt-3 is expressed during devel...
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... 1990;Wuenschell and Tobin, 1988), a Purkinje cell marker present in the somata and dendrites Wassef et al., 1985). Calbindin-D expression was examined in sections adjacent to those used for the analysis of Wnt-3 and En-2 expression. At P15, Calbindin-D expression was observed in the Purkinje cell body and dendrites of wild-type and weaver animals (Fig. 4A,B). At P22, Calbindin expression was detected in the almost mature Purkinje cells of the wild-type cerebellum (Fig. 4C). In the weaver cerebellum, Calbindin-D is also expressed in Purkinje cell body and dendrites (Fig. 4D), although a disorganized Purkinje cell layer is evident and the dendritic tree is less developed (compare Fig. 4C,D). ...
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... expression was examined in sections adjacent to those used for the analysis of Wnt-3 and En-2 expression. At P15, Calbindin-D expression was observed in the Purkinje cell body and dendrites of wild-type and weaver animals (Fig. 4A,B). At P22, Calbindin expression was detected in the almost mature Purkinje cells of the wild-type cerebellum (Fig. 4C). In the weaver cerebellum, Calbindin-D is also expressed in Purkinje cell body and dendrites (Fig. 4D), although a disorganized Purkinje cell layer is evident and the dendritic tree is less developed (compare Fig. 4C,D). At P28, expression of Calbindin-D reveals the mature dendritic tree of the wild-type Purkinje cells (Fig. 4E). In ...
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... At P15, Calbindin-D expression was observed in the Purkinje cell body and dendrites of wild-type and weaver animals (Fig. 4A,B). At P22, Calbindin expression was detected in the almost mature Purkinje cells of the wild-type cerebellum (Fig. 4C). In the weaver cerebellum, Calbindin-D is also expressed in Purkinje cell body and dendrites (Fig. 4D), although a disorganized Purkinje cell layer is evident and the dendritic tree is less developed (compare Fig. 4C,D). At P28, expression of Calbindin-D reveals the mature dendritic tree of the wild-type Purkinje cells (Fig. 4E). In the weaver cere- bellum, Calbindin-D is expressed in the cell body and dendrites, although a poorly ...
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... animals (Fig. 4A,B). At P22, Calbindin expression was detected in the almost mature Purkinje cells of the wild-type cerebellum (Fig. 4C). In the weaver cerebellum, Calbindin-D is also expressed in Purkinje cell body and dendrites (Fig. 4D), although a disorganized Purkinje cell layer is evident and the dendritic tree is less developed (compare Fig. 4C,D). At P28, expression of Calbindin-D reveals the mature dendritic tree of the wild-type Purkinje cells (Fig. 4E). In the weaver cere- bellum, Calbindin-D is expressed in the cell body and dendrites, although a poorly developed dendritic tree is evident (compare Fig. 4E,F). Thus, Purkinje cells from weaver mutant cerebellum are not ...
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... cerebellum (Fig. 4C). In the weaver cerebellum, Calbindin-D is also expressed in Purkinje cell body and dendrites (Fig. 4D), although a disorganized Purkinje cell layer is evident and the dendritic tree is less developed (compare Fig. 4C,D). At P28, expression of Calbindin-D reveals the mature dendritic tree of the wild-type Purkinje cells (Fig. 4E). In the weaver cere- bellum, Calbindin-D is expressed in the cell body and dendrites, although a poorly developed dendritic tree is evident (compare Fig. 4E,F). Thus, Purkinje cells from weaver mutant cerebellum are not degenerated at P22 and P28, showing that the decreased expression of Wnt-3 is not due to cell ...
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... cell layer is evident and the dendritic tree is less developed (compare Fig. 4C,D). At P28, expression of Calbindin-D reveals the mature dendritic tree of the wild-type Purkinje cells (Fig. 4E). In the weaver cere- bellum, Calbindin-D is expressed in the cell body and dendrites, although a poorly developed dendritic tree is evident (compare Fig. 4E,F). Thus, Purkinje cells from weaver mutant cerebellum are not degenerated at P22 and P28, showing that the decreased expression of Wnt-3 is not due to cell ...
Citations
... Prenatal alcohol exposure has been shown in previous studies to disrupt Wnt signaling pathway and has been a determinant of FASD 106,107 . In the central nervous system, Wnt signaling is known to modulate neuronal proliferation, migration, adhesion, differentiation, and axon outgrowth [108][109][110][111][112] . FASD have also been linked to abnormal neuronal plasticity responsible for normal wiring of the brain and involved in learning and memory 113 . ...
Nicotine and alcohol are two of the most commonly used and abused recreational drugs, are often used simultaneously, and have been linked to significant health hazards. Furthermore, patients diagnosed with dependence on one drug are highly likely to be dependent on the other. Several studies have shown the effects of each drug independently on gene expression within many brain regions, including the ventral tegmental area (VTA). Dopaminergic (DA) neurons of the dopamine reward pathway originate from the VTA, which is believed to be central to the mechanism of addiction and drug reinforcement. Using a well-established rat model for both nicotine and alcohol perinatal exposure, we investigated miRNA and mRNA expression of dopaminergic (DA) neurons of the VTA in rat pups following perinatal alcohol and joint nicotine-alcohol exposure. Microarray analysis was then used to profile the differential expression of both miRNAs and mRNAs from DA neurons of each treatment group to further explore the altered genes and related biological pathways modulated. Predicted and validated miRNA-gene target pairs were analyzed to further understand the roles of miRNAs within these networks following each treatment, along with their post transcription regulation points affecting gene expression throughout development. This study suggested that glutamatergic synapse and axon guidance pathways were specifically enriched and many miRNAs and genes were significantly altered following alcohol or nicotine-alcohol perinatal exposure when compared to saline control. These results provide more detailed insight into the cell proliferation, neuronal migration, neuronal axon guidance during the infancy in rats in response to perinatal alcohol/ or nicotine-alcohol exposure.
... Wnt1 is transiently expressed in the cerebellum of zebrafish [29] (Fig. 5) and mouse [31] and its mutations in humans result in hypoplasia of the cerebellar vermis [30], indicating that Wnt signaling is a potential mechanism underlying the pathology of arl13b mutant zebrafish and humans. Besides wnt1, other wnt genes have also been detected in the cerebellum, such as wnt3, wnt7a and wnt10b [37], which might be involved in early cerebellar development [3,38,39]. Further study is required to investigate whether they are also regulated by Arl13b. ...
Joubert syndrome is characterized by unique malformation of the cerebellar vermis. More than thirty Joubert syndrome genes have been identified, including ARL13B. However, its role in cerebellar development remains unexplored. We found that knockdown or knockout of arl13b impaired balance and locomotion in zebrafish larvae. Granule cells were selectively reduced in the corpus cerebelli, a structure homologous to the mammalian vermis. Purkinje cell progenitors were also selectively disturbed dorsomedially. The expression of atoh1 and ptf1, proneural genes of granule and Purkinje cells, respectively, were selectively down-regulated along the dorsal midline of the cerebellum. Moreover, wnt1, which is transiently expressed early in cerebellar development, was selectively reduced. Intriguingly, activating Wnt signaling partially rescued the granule cell defects in arl13b mutants. These findings suggested that Arl13b is necessary for the early development of cerebellar granule and Purkinje cells. The arl13b-deficient zebrafish can serve as a model organism for studying Joubert syndrome.
... Cerebella of BTBR mouse displayed hypotrophic Purkinje neurons at an early developmental period. The abnormal development of granule cells could ultimately regulate the growth of PCs (Salinas et al., 1994;Shimada et al., 1998;Sadakata et al., 2004), and we inferred that the disrupted patterning of Purkinje cells may be secondary to abnormal GC development. We cannot ignore the fact that PCs are the sole efferent neurons in cerebellum which connect to the outer brain and participate in more complicated neural activity. ...
Motor control and learning impairments are common complications in individuals with autism spectrum disorder (ASD). Abnormal cerebellar development during critical phases may disrupt these motor functions and lead to autistic motor dysfunction. However, the underlying mechanisms behind these impairments are not clear. Here, we utilized BTBR T⁺ Itprtf/J (BTBR) mice, an animal model of autism, to investigate the involvement of abnormal cerebellar development in motor performance. We found BTBR mice exhibited severe dystonia-like behavior and motor coordination or motor learning impairments. The onset of these abnormal movements coincided with the increased proliferation of granule neurons and enhanced foliation, and Purkinje cells displayed morphological hypotrophy with increased dendritic spine formation but suppressed maturation. The migration of granule neurons seemed unaffected. Transcriptional analyses confirmed the differential expression of genes involved in abnormal neurogenesis and revealed TRPC as a critical regulator in proliferation and synaptic formation. Taken together, these findings indicate that abnormal cerebellar development is closely related to dystonia-like behavior and motor dysfunction of BTBR mice and that TRPC may be a novel risk gene for ASD that may participate in the pathological process of autistic movement disorders.
... BTBR mouse cerebellum exhibited hypotrophic Purkinje neurons at an early developmental period. The abnormal development of granule cells could ultimately regulate the growth of PCs (53)(54)(55), and we inferred that the disrupted patterning of Purkinje cells may be secondary to abnormal GC development. We cannot ignore the fact that PCs are the sole efferent neurons in cerebellum that connect to the outer brain and participate in more complicated neural activity. ...
Background: Motor control and learning impairments are common complications in autistic individuals. Abnormal cerebellar development during critical phases may disrupt these motor functions and lead to the development of autistic motor dysfunction. However, the underlying mechanisms behind these impairments are not clear.
Methods: Dystonic behavior was elicited using tail suspension. Motor control and learning were detected by means of the grid hang test, ladder rung walking, accelerating rotarod, and open field locomotion. Cerebellar development was morphometrically and histologically detected during critical phases. RNA sequencing was used to compare differential gene expression to provide an in-depth interpretation of molecular mechanisms.
Results: BTBR mice, as a model of autism, exhibited severe dystonic behavior and motor coordination or motor learning impairments. The onset of these abnormal movements coincided with the increased proliferation of granule neurons and enhanced foliation, and Purkinje cells exhibited morphological hypotrophy with increased dendritic spine formation but suppressed maturation. The migration of granule neurons seemed unaffected. Transcriptional analyses confirmed the differential expression of genes involved in abnormal neurogenesis and revealed TRPC6 as a critical regulator in proliferation and synaptic formation.
Conclusion: These findings indicate that abnormal cerebellar development is closely related to dystonia and motor dysfunction of BTBR mice and that TRPC6 may be a novel risk gene for ASD that may participate in the pathological process of autistic movement disorders.
... The canonical Wnt pathway also guides synaptogenesis [155][156][157]: WNT-7a promotes axonal remodeling by inhibiting the activity of the GSK3 kinase. Indeed, microtubule-associated proteins Tau, MAP-1B, and MAP-2 (microtubules stabilizer) are direct GSK3 substrates. ...
Cells have developed numerous adaptation mechanisms to external cues by controlling signaling-pathway activity, both qualitatively and quantitatively. The Wnt/β-catenin pathway is a highly conserved signaling pathway involved in many biological processes, including cell proliferation, differentiation, somatic cell reprogramming, development, and cancer. The activity of the Wnt/β-catenin pathway and the temporal dynamics of its effector β-catenin are tightly controlled by complex regulations. The latter encompass feedback loops within the pathway (e.g., a negative feedback loop involving Axin2, a β-catenin transcriptional target) and crosstalk interactions with other signaling pathways. Here, we provide a review shedding light on the coupling between Wnt/β-catenin activation levels and fluctuations across processes and cellular systems; in particular, we focus on development, in vitro pluripotency maintenance, and cancer. Possible mechanisms originating Wnt/β-catenin dynamic behaviors and consequently driving different cellular responses are also reviewed, and new avenues for future research are suggested.
... The granular cells (representing about half the number of total neurons in the brain) migrate after birth from the external granular layer (EGL) to enter the molecular layer and finally reach their final destination. Among the cellular pathways involved in postnatal cerebellum development, the Wnt pathway plays a critical role in regulating cellular growth and differentiation, allowing synapse formation and axon guidance [15,16]. Wnt ligands are recognized by their cell surface receptors and through several cytoplasmic components, notably glycogen synthase kinase-3β (GSK3β), signal to β-catenin, which enters the nucleus and coactivates transcription of target genes to regulate cell fate decision. ...
... Wnt-3a expression is more specific to Purkinje cells. It increases postnatally as granular cells start to make contacts with Purkinje cells and are restricted to these cells in the adult mouse [16]. ...
Gestational methyl donor (especially B9 and B12 vitamins) deficiency is involved in birth defects and brain development retardation. The underlying molecular mechanisms that are dysregulated still remain poorly understood, in particular in the cerebellum. As evidenced from previous data, females are more affected than males. In this study, we therefore took advantage of a validated rat nutritional model and performed a microarray analysis on female progeny cerebellum, in order to identify which genes and molecular pathways were disrupted in response to methyl donor deficiency. We found that cerebellum development is altered in female pups, with a decrease of the granular cell layer thickness at postnatal day 21. Furthermore, we investigated the involvement of the Wnt signaling pathway, a major molecular pathway involved in neuronal development and later on in synaptic assembly and neurotransmission processes. We found that Wnt canonical pathway was disrupted following early methyl donor deficiency and that neuronal targets were selectively enriched in the downregulated genes. These results could explain the structural brain defects previously observed and highlighted new genes and a new molecular pathway affected by nutritional methyl donor deprivation.
... of Wnt3, a specific inhibitor of Shh-induced neuronal mitogenesis, whose production depends on the maturation status of PC (Salinas et al., 1994). The postnatal up-regulation of cerebellar Wnt3 expression critically decreases EGL neuronal precursor's growth, upon inhibition of Shh-mediated signaling through a non-canonical Wnt3-frizzled pathway (Anne et al., 2013;Salinas et al., 1994). ...
... of Wnt3, a specific inhibitor of Shh-induced neuronal mitogenesis, whose production depends on the maturation status of PC (Salinas et al., 1994). The postnatal up-regulation of cerebellar Wnt3 expression critically decreases EGL neuronal precursor's growth, upon inhibition of Shh-mediated signaling through a non-canonical Wnt3-frizzled pathway (Anne et al., 2013;Salinas et al., 1994). Therefore in the Gpr37l1 −/− ;Ptch1 +/− double mutant pups the absence of Gpr37l1 can cause a precocious surge in cerebellar Shh signaling, as well as Wnt3mediated anti-proliferative effects, including the reported down-regulation of the Gli2 transcription factor (Anne et al., 2013), with consequent, earlier down-regulation of Shh-induced, GCP mitogenesis and of tumorigenesis-susceptible, focal hyperproliferation. ...
... Although it is one of the first discernible structures of the brain, its mature organization is often not achieved until several months after birth [66]. This long developmental period provides several opportunities for insult, ranging from affecting migration of Purkinje neurons via the Reelin signaling pathway [67] or granular neuron migration via the Dcc/netrin pathway [68] to later pathways in development affecting Purkinje neuron synapse formation via Wnt3 signaling [69]. ...
Cerebellar abiotrophy (CA) is a neurodegenerative disorder affecting the cerebellum and occurs in multiple species. Although CA is well researched in humans and mice, domestic species such as the dog, cat, sheep, cow, and horse receive little recognition. This may be due to few studies addressing the mechanism of CA in these species. However, valuable information can still be extracted from these cases. A review of the clinicohistologic phenotype of CA in these species and determining the various etiologies of CA may aid in determining conserved and required pathways necessary for proper cerebellar development and function. This review outlines research approaches of studies of CA in domestic species, compared to the approaches used in mice, with the objective of comparing CA in domestic species while identifying areas for further research efforts.
... For example, BMP signaling inhibits GCP proliferation in vitro and induces differentiation by proteasome-mediated degradation of Math1, a transcription factor active in proliferating GCPs, and this signaling is disrupted in mouse models of medulloblastoma [174]. Wnt3, which is expressed in developing and adult Purkinje cells [175], also suppresses GCP proliferation and inhibits medulloblastoma growth, and does so by inhibiting transcriptional responsivity to both Shh and Math1 [176]. Interestingly, Wnt3 expression in Purkinje cells increases postnatally and is lost in mutants lacking GCs, implying that Wnt3 expression depends on interactions between GCs and Purkinje cells [175]. ...
... Wnt3, which is expressed in developing and adult Purkinje cells [175], also suppresses GCP proliferation and inhibits medulloblastoma growth, and does so by inhibiting transcriptional responsivity to both Shh and Math1 [176]. Interestingly, Wnt3 expression in Purkinje cells increases postnatally and is lost in mutants lacking GCs, implying that Wnt3 expression depends on interactions between GCs and Purkinje cells [175]. Finally, proNT3 promotes differentiation by inhibiting Shh-induced proliferation following activation of the pan-neurotrophin receptor p75 [177]. ...
Brain function requires precise neural circuit assembly during development. Establishing a functional circuit involves multiple coordinated steps ranging from neural cell fate specification to proper matching between pre- and post-synaptic partners. How neuronal lineage and birth timing influence wiring specificity remains an open question. Recent findings suggest that the relationships between lineage, birth timing, and wiring specificity vary in different neuronal circuits. In this review, we summarize our current understanding of the cellular, molecular, and developmental mechanisms linking neuronal lineage and birth timing to wiring specificity in a few specific systems in Drosophila and mice, and review different methods employed to explore these mechanisms.
... This has allowed the developmental roles of Dkk1 and its role in postnatal bone regulation to be teased apart by modulating Wnt3 signalling during embryonic development. Wnt3 expression is retained in a number of tissues including the brain [29], however, Wnt3 ?/animals showed no obvious neurological defects in our study or effects in any other tissues that discernibly impacted on animal health or welfare. ...
Wnt antagonist Dkk1 is a negative regulator of bone formation and Dkk1+/− heterozygous mice display a high bone mass phenotype. Complete loss of Dkk1 function disrupts embryonic head development. Homozygous Dkk1−/− mice that were heterozygous for Wnt3 loss of function mutation (termed Dkk1 KO) are viable and allowed studying the effects of homozygous inactivation of Dkk1 on bone formation. Dkk1 KO mice showed a high bone mass phenotype exceeding that of heterozygous mice as well as a high incidence of polydactyly and kinky tails. Whole body bone density was increased in the Dkk1 KO mice as shown by longitudinal dual-energy X-ray absorptiometry. MicroCT analysis of the distal femur revealed up to 3-fold increases in trabecular bone volume and up to 2-fold increases in the vertebrae, compared to wild type controls. Cortical bone was increased in both the tibiae and vertebrae, which correlated with increased strength in tibial 4-point bending and vertebral compression tests. Dynamic histomorphometry identified increased bone formation as the mechanism underlying the high bone mass phenotype in Dkk1 KO mice, with no changes in bone resorption. Mice featuring only Wnt3 heterozygosity showed no evident bone phenotype. Our findings highlight a critical role for Dkk1 in the regulation of bone formation and a gene dose-dependent response to loss of DKK1 function. Targeting Dkk1 to enhance bone formation offers therapeutic potential for osteoporosis.
