The role of Xenopus dickkopf1 in prechordal plate specification and neural patterning

Development ◽  
2000 ◽  
Vol 127 (22) ◽  
pp. 4981-4992 ◽  
Author(s):  
O. Kazanskaya ◽  
A. Glinka ◽  
C. Niehrs
Keyword(s):  
Target Genes ◽  
Loss Of Function ◽  
Dorsoventral Patterning ◽  
Gastrula Stage ◽  
Neural Patterning ◽  
Prechordal Plate ◽  
Wnt Inhibitor ◽  
The Central Nervous System ◽  
Wnt Inhibitors

Dickkopf1 (dkk1) encodes a secreted WNT inhibitor expressed in Spemann's organizer, which has been implicated in head induction in Xenopus. Here we have analyzed the role of dkk1 in endomesoderm specification and neural patterning by gain- and loss-of-function approaches. We find that dkk1, unlike other WNT inhibitors, is able to induce functional prechordal plate, which explains its ability to induce secondary heads with bilateral eyes. This may be due to differential WNT inhibition since dkk1, unlike frzb, inhibits Wnt3a signalling. Injection of inhibitory antiDkk1 antibodies reveals that dkk1 is not only sufficient but also required for prechordal plate formation but not for notochord formation. In the neural plate dkk1 is required for anteroposterior and dorsoventral patterning between mes- and telencephalon, where dkk1 promotes anterior and ventral fates. Both the requirement of anterior explants for dkk1 function and their ability to respond to dkk1 terminate at late gastrula stage. Xenopus embryos posteriorized with bFGF, BMP4 and Smads are rescued by dkk1. dkk1 does not interfere with the ability of bFGF to induce its immediate early target gene Xbra, indicating that its effect is indirect. In contrast, there is cross-talk between BMP and WNT signalling, since induction of BMP target genes is sensitive to WNT inhibitors until the early gastrula stage. Embryos treated with retinoic acid (RA) are not rescued by dkk1 and RA affects the central nervous system (CNS) more posterior than dkk1, suggesting that WNTs and retinoids may act to pattern anterior and posterior CNS, respectively, during gastrulation.

scholarly journals Insights Into the Role of CSF1R in the Central Nervous System and Neurological Disorders

2021 ◽  
Vol 13 ◽  
Author(s):  
Banglian Hu ◽  
Shengshun Duan ◽  
Ziwei Wang ◽  
Xin Li ◽  
Yuhang Zhou ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Neurological Disorders ◽  
Neurological Diseases ◽  
Colony Stimulating Factor ◽  
Loss Of Function ◽  
Axonal Spheroids ◽  
The Central Nervous System ◽  
Stimulating Factor

The colony-stimulating factor 1 receptor (CSF1R) is a key tyrosine kinase transmembrane receptor modulating microglial homeostasis, neurogenesis, and neuronal survival in the central nervous system (CNS). CSF1R, which can be proteolytically cleaved into a soluble ectodomain and an intracellular protein fragment, supports the survival of myeloid cells upon activation by two ligands, colony stimulating factor 1 and interleukin 34. CSF1R loss-of-function mutations are the major cause of adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) and its dysfunction has also been implicated in other neurodegenerative disorders including Alzheimer’s disease (AD). Here, we review the physiological functions of CSF1R in the CNS and its pathological effects in neurological disorders including ALSP, AD, frontotemporal dementia and multiple sclerosis. Understanding the pathophysiology of CSF1R is critical for developing targeted therapies for related neurological diseases.

scholarly journals Developmental timing of CCM2 loss influences cerebral cavernous malformations in mice

2011 ◽  
Vol 208 (9) ◽  
pp. 1835-1847 ◽  
Author(s):  
Gwénola Boulday ◽  
Noemi Rudini ◽  
Luigi Maddaluno ◽  
Anne Blécon ◽  
Minh Arnould ◽  
...  
Keyword(s):  
Autosomal Dominant ◽  
Vascular Malformations ◽  
Vascular Lesions ◽  
Developmental Timing ◽  
Cerebral Cavernous Malformations ◽  
Loss Of Function ◽  
Cavernous Malformations ◽  
The Central Nervous System ◽  
Dominant Condition

Cerebral cavernous malformations (CCM) are vascular malformations of the central nervous system (CNS) that lead to cerebral hemorrhages. Familial CCM occurs as an autosomal dominant condition caused by loss-of-function mutations in one of the three CCM genes. Constitutive or tissue-specific ablation of any of the Ccm genes in mice previously established the crucial role of Ccm gene expression in endothelial cells for proper angiogenesis. However, embryonic lethality precluded the development of relevant CCM mouse models. Here, we show that endothelial-specific Ccm2 deletion at postnatal day 1 (P1) in mice results in vascular lesions mimicking human CCM lesions. Consistent with CCM1/3 involvement in the same human disease, deletion of Ccm1/3 at P1 in mice results in similar CCM lesions. The lesions are located in the cerebellum and the retina, two organs undergoing intense postnatal angiogenesis. Despite a pan-endothelial Ccm2 deletion, CCM lesions are restricted to the venous bed. Notably, the consequences of Ccm2 loss depend on the developmental timing of Ccm2 ablation. This work provides a highly penetrant and relevant CCM mouse model.

scholarly journals The age-regulated zinc finger factor ZNF367 is a new modulator of embryonic neurogenesis

2018 ◽  
Author(s):  
Valentina Naef ◽  
Sara Monticelli ◽  
Debora Corsinovi ◽  
Maria Teresa Mazzetto ◽  
Alessandro Cellerino ◽  
...  
Keyword(s):  
Population Aging ◽  
Candidate Gene Approach ◽  
Loss Of Function ◽  
Neuronal Function ◽  
Embryonic Neurogenesis ◽  
Age Related ◽  
The Central Nervous System ◽  
Brain Age ◽  
Global Population

AbstractGlobal population aging is one of the major social and economic challenges of contemporary society. During aging the progressive decline in physiological functions has serious consequences for all organs including brain. The age-related incidence of neurodegenerative diseases coincides with the sharp decline of the amount and functionality of adult neural stem cells. Recently, we identified a short list of brain age-regulated genes by means of next-generation sequencing. Among them znf367 codes for a transcription factor that represents a central node in gene coregulation networks during aging but its function, in the central nervous system (CNS), is completely unknown. As proof of concept we analyzed the role of znf367 during neurogenesis. By means of a gene loss of function approach limited to the CNS, we suggested that znf367 might act as a key controller of the neuroblasts cell cycle, particularly in the progression of mitosis and spindle check-point. Using a candidate gene approach, based on a weighted-gene co-expression network analysis, we suggested possible targets of znf367 such as fancd2 and ska3. The age-related decline of znf367 well correlated with its role during embryonic neurogenesis opening new lines of investigation to improved maintenance and even repair of neuronal function.

scholarly journals Inhibition of a transcriptional repressor rescues hearing in a splicing factor–deficient mouse

2020 ◽  
Vol 3 (12) ◽  
pp. e202000841
Author(s):  
Yoko Nakano ◽  
Susan Wiechert ◽  
Bernd Fritzsch ◽  
Botond Bánfi
Keyword(s):  
Alternative Splicing ◽  
Target Genes ◽  
Transcriptional Repressor ◽  
Dominant Negative ◽  
Splicing Factor ◽  
Loss Of Function ◽  
Transgenic Expression ◽  
Mechanosensory Hair Cells

In mechanosensory hair cells (HCs) of the ear, the transcriptional repressor REST is continuously inactivated by alternative splicing of its pre-mRNA. This mechanism of REST inactivation is crucial for hearing in humans and mice. Rest is one of many pre-mRNAs whose alternative splicing is regulated by the splicing factor SRRM4; Srrm4 loss-of-function mutation in mice (Srrm4bv/bv) causes deafness, balance defects, and degeneration of all HC types other than the outer HCs (OHCs). The specific splicing alterations that drive HC degeneration in Srrm4bv/bv mice are unknown, and the mechanism underlying SRRM4-independent survival of OHCs is undefined. Here, we show that transgenic expression of a dominant-negative REST fragment in Srrm4bv/bv mice is sufficient for long-term rescue of hearing, balancing, HCs, alternative splicing of Rest, and expression of REST target genes including the Srrm4 paralog Srrm3. We also show that in HCs, SRRM3 regulates many of the same exons as SRRM4; OHCs are unique among HCs in that they transiently down-regulate Rest transcription as they mature to express Srrm3 independently of SRRM4; and simultaneous SRRM4–SRRM3 deficiency causes complete HC loss by preventing inactivation of REST in all HCs. Thus, our data reveal that REST inactivation is the primary and essential role of SRRM4 in the ear, and that OHCs differ from other HCs in the SRRM4-independent expression of the functionally SRRM4-like splicing factor SRRM3.

Formation of neuroblasts in the embryonic central nervous system of Drosophila melanogaster is controlled by SoxNeuro

Development ◽  
2002 ◽  
Vol 129 (18) ◽  
pp. 4193-4203 ◽  
Author(s):  
Marita Buescher ◽  
Fook Sion Hing ◽  
William Chia
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Transcription Factors ◽  
Neural Progenitor Cells ◽  
Loss Of Function ◽  
Dorsoventral Patterning ◽  
Sox Proteins ◽  
The Central Nervous System ◽  
Modulation Of Gene Expression ◽  
Determining Factor

Sox proteins form a family of HMG-box transcription factors related to the mammalian testis determining factor SRY. Sox-mediated modulation of gene expression plays an important role in various developmental contexts. Drosophila SoxNeuro, a putative ortholog of the vertebrate Sox1, Sox2 and Sox3 proteins, is one of the earliest transcription factors to be expressed pan-neuroectodermally. We demonstrate that SoxNeuro is essential for the formation of the neural progenitor cells in central nervous system. We show that loss of function mutations of SoxNeuro are associated with a spatially restricted hypoplasia: neuroblast formation is severely affected in the lateral and intermediate regions of the central nervous system, whereas ventral neuroblast formation is almost normal. We present evidence that a requirement for SoxNeuro in ventral neuroblast formation is masked by a functional redundancy with Dichaete, a second Sox protein whose expression partially overlaps that of SoxNeuro. Genetic interactions of SoxNeuro and the dorsoventral patterning genes ventral nerve chord defective and intermediate neuroblasts defective underlie ventral and intermediate neuroblast formation. Finally, the expression of the Achaete-Scute gene complex suggests that SoxNeuro acts upstream and in parallel with the proneural genes.

Gsh2 and Pax6 play complementary roles in dorsoventral patterning of the mammalian telencephalon

Development ◽  
2001 ◽  
Vol 128 (2) ◽  
pp. 193-205 ◽  
Author(s):  
K. Yun ◽  
S. Potter ◽  
J.L. Rubenstein
Keyword(s):  
Transcription Factors ◽  
Molecular Markers ◽  
Dorsoventral Patterning ◽  
Embryonic Mouse ◽  
Lateral Ganglionic Eminence ◽  
Multiple Regions ◽  
Early Expression ◽  
The Central Nervous System ◽  
Functional Alleles

The telencephalon has two major subdivisions, the pallium and subpallium. The pallium, which primarily consists of glutamatergic cortical structures, expresses dorsal molecular markers, whereas the subpallium, which primarily consists of the GABAergic basal ganglia, expresses ventral molecular markers. Here, we present evidence that the progenitor and postmitotic cells flanking the pallial/subpallial boundary (PSB) in the embryonic mouse can be subdivided into multiple regions that express unique combinations of transcription factors. The domains that immediately flank the PSB are the ventral pallium (VP) and the dorsal lateral ganglionic eminence (dLGE). The early expression of the Pax6 and Gsh2 homeobox transcription factors overlaps in the region of the dLGE. Analyses of mice that lack functional alleles of either Gsh2 or Pax6 demonstrate that these genes have complementary roles in patterning the primordia flanking the PSB. In the Gsh2 mutants, the dLGE is respecified into a VP-like structure, whereas in the Pax6 mutants the VP is respecified into a dLGE-like structure. The role of Pax6 in dorsalizing the telencephalon is similar to its role in the spinal cord, supporting the hypothesis that some dorsoventral patterning mechanisms are used at all axial levels of the central nervous system.

scholarly journals Importin α7 deficiency causes infertility in male mice by disrupting spermatogenesis

Development ◽  
2021 ◽  
Author(s):  
Na Liu ◽  
Fatimunnisa Qadri ◽  
Hauke Busch ◽  
Stefanie Huegel ◽  
Gabin Sihn ◽  
...  
Keyword(s):  
Sertoli Cells ◽  
Male Fertility ◽  
Target Genes ◽  
Cell Function ◽  
Expression Patterns ◽  
Male Mice ◽  
Loss Of Function ◽  
Altered Expression ◽  
Importin Α

Spermatogenesis is driven by an ordered series of events, which rely on trafficking of specific proteins between nucleus and cytoplasm. The importin α family of proteins mediates movement of specific cargo proteins when bound to importin β. Importin α genes have distinct expression patterns in mouse testis, implying they may have unique roles during mammalian spermatogenesis. Here we use a loss-of-function approach to specifically determine the role of importin α7 in spermatogenesis and male fertility. We show that ablation of importin α7 in male mice leads to infertility and has multiple cumulative effects on both germ cells and Sertoli cells. Importin α7-deficient mice exhibit an impaired Sertoli cell function, including loss of Sertoli cells and a compromised nuclear localization of the androgen receptor. Furthermore, our data demonstrate devastating defects in spermiogenesis including incomplete sperm maturation and massive loss of sperms that are accompanied by disturbed histone-protamine-exchange, differential localization of the transcriptional regulator Brwd1 and altered expression of Rfx2 target genes. Our work uncovers the essential role of importin α7 in spermatogenesis and hence in male fertility.

scholarly journals MIR822 modulates monosporic female gametogenesis through an ARGONAUTE9-dependent pathway in Arabidopsis thaliana

2021 ◽  
Author(s):  
ANDREA TOVAR AGUILAR ◽  
Daniel GRIMANELLI ◽  
Gerardo Acosta Garcia ◽  
Jean Philippe Vielle Calzada ◽  
Jesus Agustin Badillo-Corona ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Flowering Plants ◽  
Loss Of Function ◽  
Genes Encoding ◽  
Functional Megaspore ◽  
Dependent Pathway ◽  
Female Gametogenesis

In the ovule of flowering plants, the establishment of the haploid generation occurs when a somatic cell differentiates into a Megaspore Mother Cell (MMC) and initiates meiosis. As most flowering plants, Arabidopsis thaliana undergoes a monosporic type of gametogenesis; three meiotically derived cells degenerate without further division, and a single one, the functional megaspore (FM), divides mitotically to form the female gametophyte. In Arabidopsis, the ARGONAUTE4 clade proteins are involved in the control of megasporogenesis. In particular, mutations in ARGONAUTE9 (AGO9) lead to the ectopic differentiation of gametic precursors that can give rise female gametophytes. However, the genetic basis and molecular mechanisms that control monosporic gametogenesis remain largely unknown. Here, we show that Arabidopsis plants carrying loss-of-function mutations in the AGO9-interacting miR822a give rise to extranumerary surviving megaspores that acquire a FM identity and divide without giving rise to differentiated female gametophytes. The overexpression of three miR822a target genes encoding Cysteine/Histidine-Rich C1 domain proteins (DC1) phenocopy mir822a plants. The miR822a targets are overexpressed in ago9 mutant ovules, confirming that miR822a acts through an AGO9-dependent pathway to negatively regulate DC1 domain proteins. Our results identify a new role of miRNAs in the most prevalent form of female gametogenesis in flowering plants

scholarly journals The functional landscape of patient derived RNF43 mutations predicts Wnt inhibitor sensitivity

2020 ◽  
Author(s):  
Jia Yu ◽  
Permeen Akhtar Bt Mohamed Yuso ◽  
Pamela Goh ◽  
Nathan Harmston ◽  
David M. Epstein ◽  
...  
Keyword(s):  
Cell Surface ◽  
Genome Editing ◽  
Response To Therapy ◽  
Missense Mutations ◽  
Loss Of Function ◽  
Multiple Cancers ◽  
Wnt Inhibitor ◽  
Reporter Assays ◽  
Wnt Inhibitors

AbstractA subset of Wnt-addicted cancers are sensitive to targeted therapies that block Wnt secretion or receptor engagement. RNF43 loss-of-function mutations that increase cell surface Wnt receptor abundance cause sensitivity to Wnt inhibitors. However, it is not clear which of the clinically identified RNF43 mutations affect its function in vivo. We assayed 90 missense and 45 truncating RNF43 mutations found in human cancers, using a combination of cell-based reporter assays, genome editing, flow cytometry and immunofluorescence microscopy. Patent-derived xenograft (PDX) models with C-terminal truncating RNF43 mutations were tested for Wnt inhibitor sensitivity. We find that five common germline variants of RNF43 have wild-type activity. The majority of cancer-associated missense mutations in the RING and PA domains are either loss of function or hyperactivating. Hyperactivating mutants appear to function through formation of inactive dimers with endogenous RNF43 and/or ZNRF3. C-terminal truncation mutants including the common G659fs mutant, have discordant behavior in in vitro versus in vivo assays. PDXs and cell lines with C-terminal truncations show increased cell surface FZD, Wnt/β-catenin signaling and are responsive to PORCN inhibition in vivo, providing clear evidence of RNF43 loss of function. In conclusion, RNF43 nonsense and frameshift mutations, including those in the C-terminal domain, and specific missense mutations in RING and PA are loss of function and predict response to upstream Wnt inhibitors in microsatellite stable cancers. This study expands the landscape of actionable RNF43 mutations, potentially extending the benefit of these therapies to additional patients.Statement of SignificanceLoss of function RNF43 mutations, first described in pancreatic cancers, drive progression of multiple cancers by increasing cellular sensitivity to Wnt ligands. These cancers are therefore uniquely sensitive to agents such as PORCN inhibitors that block Wnt production. As the PORCN inhibitors and other upstream inhibitors advance into clinical trials it is important to identify the right patients to treat with these upstream Wnt inhibitors. Hence a detailed map of mutations that are actionable is required.Here we systematically examined a spectrum of 135 patient-derived RNF43 mutations from multiple cancers. Using cell-based reporter assays, genome editing and patient-derived xenografts, we identify rules to guide patient selection. MSS cancers with either truncating mutations anywhere in the gene, including C-terminal truncations around the G659 position, or point mutations in well-defined functional domains, are likely to have RNF43 loss of function and hence a response to therapy.

scholarly journals Importin α7 deficiency causes infertility in male mice by disrupting spermatogenesis

2020 ◽  
Author(s):  
Na Liu ◽  
Fatimunnisa Qadri ◽  
Hauke Busch ◽  
Stefanie Huegel ◽  
Gabin Sihn ◽  
...  
Keyword(s):  
Sertoli Cells ◽  
Male Fertility ◽  
Target Genes ◽  
Cell Function ◽  
Expression Patterns ◽  
Male Mice ◽  
Loss Of Function ◽  
Altered Expression ◽  
Importin Α

AbstractSpermatogenesis is driven by an ordered series of events, which rely on trafficking of specific proteins between nucleus and cytoplasm. The importin α family of proteins mediates movement of specific cargo proteins when bound to importin β. Importin α genes have distinct expression patterns in mouse testis, implying they may have unique roles during mammalian spermatogenesis. Here we use a loss-of-function approach to specifically determine the role of importin α7 in spermatogenesis and male fertility. We show that ablation of importin α7 in male mice leads to infertility and has multiple cumulative effects on both germ cells and Sertoli cells. Importin α7-deficient mice exhibit an impaired Sertoli cell function, including loss of Sertoli cells and a compromised nuclear transport of the androgen receptor. Furthermore, our data demonstrate devastating defects in spermiogenesis that are accompanied by disturbed histone-protamine-exchange, absence of the transcriptional regulator Brwd1 and altered expression of Rfx2 target genes, resulting in incomplete sperm maturation and massive loss of sperms. Our work uncovers the essential role of importin α7 in spermatogenesis and hence in male fertility.

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