Roles of homeobox and bHLH genes in specification of a retinal cell type

Previous analysis of mutant mice has revealed that the bHLH genes Mash1 and Math3, and the homeobox gene Chx10 are essential for generation of bipolar cells, the interneurons present in the inner nuclear layer of the retina. Thus, a combination of the bHLH and homeobox genes should be important for bipolar cell genesis, but the exact functions of each gene remain largely unknown. We have found that in Mash1-Math3 double-mutant retina, which exhibits a complete loss of bipolar cells, Chx10 expression did not disappear but remained in Muller glial cells, suggesting that Chx10 expression per se is compatible with gliogenesis. In agreement with this, misexpression of Chx10 alone with retrovirus in the retinal explant cultures induced generation of the inner nuclear layer cells, including Muller glia, but few of them were mature bipolar cells. Misexpression of Mash1 or Math3 alone did not promote bipolar cell genesis either, but inhibited Muller gliogenesis. In contrast, misexpression of Mash1 or Math3 together with Chx10 increased the population of mature bipolar cells and decreased that of Muller glia. Thus, the homeobox gene provides the inner nuclear layer-specific identity while the bHLH genes regulate the neuronal versus glial fate determination, and these two classes of genes together specify the bipolar cell fate. Moreover, Mash1 and Math3 promoted the bipolar cell fate, but not the other inner nuclear layer-specific neuronal subtypes in the presence of Chx10, raising the possibility that the bHLH genes may be involved in neuronal subtype specification, in addition to simply making the neuronal versus glial fate choice.

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Misexpression of basic helix-loop-helix genes in the murine cerebral cortex affects cell fate choices and neuronal survival

Development ◽

10.1242/dev.127.14.3021 ◽

2000 ◽

Vol 127 (14) ◽

pp. 3021-3030 ◽

Cited By ~ 5

Author(s):

L. Cai ◽

E.M. Morrow ◽

C.L. Cepko

Keyword(s):

Cerebral Cortex ◽

Cell Fate ◽

Neuronal Survival ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

Bhlh Genes ◽

Infected Cells ◽

Glial Fate

To investigate the role(s) of basic helix-loop-helix genes (bHLH) genes in the developing murine cerebral cortex, Mash1, Math2, Math3, Neurogenin1 (Ngn1), Ngn2, NeuroD, NeuroD2 and Id1 were transduced in vivo into the embryonic and postnatal cerebral cortex using retrovirus vectors. The morphology and location of infected cells were analyzed at postnatal stages. The data indicate that a subset of bHLH genes are capable of regulating the choice of neuronal versus glial fate and that, when misexpressed, they can be deleterious to the survival of differentiating neurons, but not glia.

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Transgenic expression of the proneural transcription factor Ascl1 in Müller glia stimulates retinal regeneration in young mice

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1510595112 ◽

2015 ◽

Vol 112 (44) ◽

pp. 13717-13722 ◽

Cited By ~ 120

Author(s):

Yumi Ueki ◽

Matthew S. Wilken ◽

Kristen E. Cox ◽

Laura Chipman ◽

Nikolas Jorstad ◽

...

Keyword(s):

Transcription Factor ◽

Bipolar Cells ◽

Muller Glia ◽

Müller Glia ◽

Retinal Regeneration ◽

Transgenic Expression ◽

Retinal Injury ◽

Young Mice

Müller glial cells are the source of retinal regeneration in fish and birds; although this process is efficient in fish, it is less so in birds and very limited in mammals. It has been proposed that factors necessary for providing neurogenic competence to Müller glia in fish and birds after retinal injury are not expressed in mammals. One such factor, the proneural transcription factor Ascl1, is necessary for retinal regeneration in fish but is not expressed after retinal damage in mice. We previously reported that forced expression of Ascl1 in vitro reprograms Müller glia to a neurogenic state. We now test whether forced expression of Ascl1 in mouse Müller glia in vivo stimulates their capacity for retinal regeneration. We find that transgenic expression of Ascl1 in adult Müller glia in undamaged retina does not overtly affect their phenotype; however, when the retina is damaged, the Ascl1-expressing glia initiate a response that resembles the early stages of retinal regeneration in zebrafish. The reaction to injury is even more pronounced in Müller glia in young mice, where the Ascl1-expressing Müller glia give rise to amacrine and bipolar cells and photoreceptors. DNaseI-seq analysis of the retina and Müller glia shows progressive reduction in accessibility of progenitor gene cis-regulatory regions consistent with the reduction in their reprogramming. These results show that at least one of the differences between mammal and fish Müller glia that bears on their difference in regenerative potential is the proneural transcription factor Ascl1.

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Functional Roles of Otx2 Transcription Factor in Postnatal Mouse Retinal Development

Molecular and Cellular Biology ◽

10.1128/mcb.01209-07 ◽

2007 ◽

Vol 27 (23) ◽

pp. 8318-8329 ◽

Cited By ~ 112

Author(s):

Chieko Koike ◽

Akihiro Nishida ◽

Shinji Ueno ◽

Hiromitsu Saito ◽

Rikako Sanuki ◽

...

Keyword(s):

Cell Fate ◽

Bipolar Cell ◽

Functional Role ◽

Retinal Development ◽

Terminal Differentiation ◽

Cell Development ◽

Bipolar Cells ◽

Conditional Knockout ◽

Retinal Bipolar Cells

ABSTRACT We previously reported that Otx2 is essential for photoreceptor cell fate determination; however, the functional role of Otx2 in postnatal retinal development is still unclear although it has been reported to be expressed in retinal bipolar cells and photoreceptors at postnatal stages. In this study, we first examined the roles of Otx2 in the terminal differentiation of photoreceptors by analyzing Otx2; Crx double-knockout mice. In Otx2 +/−; Crx −/− retinas, photoreceptor degeneration and downregulation of photoreceptor-specific genes were much more prominent than in Crx −/− retinas, suggesting that Otx2 has a role in the terminal differentiation of the photoreceptors. Moreover, bipolar cells decreased in the Otx2 +/−; Crx −/− retina, suggesting that Otx2 is also involved in retinal bipolar-cell development. To further investigate the role of Otx2 in bipolar-cell development, we generated a postnatal bipolar-cell-specific Otx2 conditional-knockout mouse line. Immunohistochemical analysis of this line showed that the expression of protein kinase C, a marker of mature bipolar cells, was significantly downregulated in the retina. Electroretinograms revealed that the electrophysiological function of retinal bipolar cells was impaired as a result of Otx2 ablation. These data suggest that Otx2 plays a functional role in the maturation of retinal photoreceptor and bipolar cells.

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Develop an efficient and specific AAV-based labeling system for Muller glia in mice

10.1101/2021.12.10.472182 ◽

2021 ◽

Author(s):

Yanxia Gao ◽

Kailun Fang ◽

Zixiang Yan ◽

Haiwei Zhang ◽

Guannan Geng ◽

...

Keyword(s):

Cell Fate ◽

Vision Loss ◽

Hepatitis Virus ◽

Regulatory Element ◽

Amacrine Cells ◽

Muller Glia ◽

Müller Glia ◽

Reporter System ◽

Cell Degeneration ◽

Labeling System

AbstractCell degeneration in the retina leads to several ocular diseases and vision loss. Considerable research efforts focus on reprogramming Muller glia (MG) into functional cells to rescue vision as a promising therapeutic strategy, although whether MG can convert into functional amacrine cells, bipolar cells, retinal ganglia cells (RGCs), rods or cones in mammals remains controversial. The broad applicability of tracking MG differentiation thus presents a need for improved labeling efficiency and specificity. Here, we compared AAV-based labeling strategies with conventional lineage-tracking by crossing transgenic mouse lines. We found that reporter expression was weak and not MG-specific in mGFAP-Cre transgenic mice. Different AAV serotypes showed a range of efficiency and specificity in labeling MG, leading us to optimize a human GFAP-Cre reporter system packaged in the AAV9 serotype with the WPRE (WPRE, woodchuck hepatitis virus post-transcriptional regulatory element) removed. The hGFAP-Cre-ΔWPRE reporter could label 20-73.8% MGs, with non-specific RGC labeling rates ranging from 0-0.08% at doses of 1 × 108 to 1010 vector genomes (vg) per eye, an approximate 40-fold reduction compared with the AAV9-hGFAP-Cre-WPRE labeling system. The AAV9-hGFAP-Cre-ΔWPRE system thus represents a highly efficient and specific labeling system for Muller glia, providing a valuable tool for tracking cell fate in vivo.

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Math3 and NeuroD regulate amacrine cell fate specification in the retina

Development ◽

10.1242/dev.129.4.831 ◽

2002 ◽

Vol 129 (4) ◽

pp. 831-842 ◽

Cited By ~ 8

Author(s):

Tomoyuki Inoue ◽

Masato Hojo ◽

Yasumasa Bessho ◽

Yasuo Tano ◽

Jacqueline E. Lee ◽

...

Keyword(s):

Cell Fate ◽

Double Mutant ◽

Amacrine Cell ◽

Homeobox Gene ◽

Amacrine Cells ◽

Cell Fates ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

Normal Number ◽

Cell Genesis

The basic helix-loop-helix genes Math3 and NeuroD are expressed by differentiating amacrine cells, retinal interneurons. Previous studies have demonstrated that a normal number of amacrine cells is generated in mice lacking either Math3 or NeuroD. We have found that, in Math3-NeuroD double-mutant retina, amacrine cells are completely missing, while ganglion and Müller glial cells are increased in number. In the double-mutant retina, the cells that would normally differentiate into amacrine cells did not die but adopted the ganglion and glial cell fates. Misexpression studies using the developing retinal explant cultures showed that, although Math3 and NeuroD alone only promoted rod genesis, they significantly increased the population of amacrine cells when the homeobox gene Pax6 or Six3 was co-expressed. These results indicate that Math3 and NeuroD are essential, but not sufficient, for amacrine cell genesis, and that co-expression of the basic helix-loop-helix and homeobox genes is required for specification of the correct neuronal subtype.

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Faculty Opinions recommendation of Müller glia cells regulate Notch signaling and retinal angiogenesis via the generation of 19,20-dihydroxydocosapentaenoic acid.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718245184.793490808 ◽

2014 ◽

Author(s):

William A Muller

Keyword(s):

Notch Signaling ◽

Muller Glia ◽

Müller Glia ◽

Glia Cells ◽

Retinal Angiogenesis

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Faculty Opinions recommendation of Stimulation of functional neuronal regeneration from Müller glia in adult mice.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.727841108.793535182 ◽

2017 ◽

Author(s):

Jun Takahashi

Keyword(s):

Muller Glia ◽

Neuronal Regeneration ◽

Müller Glia ◽

Adult Mice ◽

Stimulation Of

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Development in the Mammalian Auditory System Depends on Transcription Factors

International Journal of Molecular Sciences ◽

10.3390/ijms22084189 ◽

2021 ◽

Vol 22 (8) ◽

pp. 4189

Author(s):

Karen L. Elliott ◽

Gabriela Pavlínková ◽

Victor V. Chizhikov ◽

Ebenezer N. Yamoah ◽

Bernd Fritzsch

Keyword(s):

Transcription Factors ◽

Cell Fate ◽

Auditory System ◽

Hair Cells ◽

System Development ◽

Neuronal Cell ◽

Spiral Ganglion Neuron ◽

Cochlear Hair Cells ◽

Cochlear Nuclei ◽

Bhlh Genes

We review the molecular basis of several transcription factors (Eya1, Sox2), including the three related genes coding basic helix–loop–helix (bHLH; see abbreviations) proteins (Neurog1, Neurod1, Atoh1) during the development of spiral ganglia, cochlear nuclei, and cochlear hair cells. Neuronal development requires Neurog1, followed by its downstream target Neurod1, to cross-regulate Atoh1 expression. In contrast, hair cells and cochlear nuclei critically depend on Atoh1 and require Neurod1 expression for interactions with Atoh1. Upregulation of Atoh1 following Neurod1 loss changes some vestibular neurons’ fate into “hair cells”, highlighting the significant interplay between the bHLH genes. Further work showed that replacing Atoh1 by Neurog1 rescues some hair cells from complete absence observed in Atoh1 null mutants, suggesting that bHLH genes can partially replace one another. The inhibition of Atoh1 by Neurod1 is essential for proper neuronal cell fate, and in the absence of Neurod1, Atoh1 is upregulated, resulting in the formation of “intraganglionic” HCs. Additional genes, such as Eya1/Six1, Sox2, Pax2, Gata3, Fgfr2b, Foxg1, and Lmx1a/b, play a role in the auditory system. Finally, both Lmx1a and Lmx1b genes are essential for the cochlear organ of Corti, spiral ganglion neuron, and cochlear nuclei formation. We integrate the mammalian auditory system development to provide comprehensive insights beyond the limited perception driven by singular investigations of cochlear neurons, cochlear hair cells, and cochlear nuclei. A detailed analysis of gene expression is needed to understand better how upstream regulators facilitate gene interactions and mammalian auditory system development.

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