S12-03 The cytolinker Pigs is a target and a negative regulator of Notch signalling during epithelial somatic cell differentiation in the Drosophila ovary

Hair cell fate determination in the inner ear has been shown to be controlled by specific genes. Recent loss-of-function and gain-of-function experiments have demonstrated that Math1, a mouse homolog of the Drosophila gene atonal, is essential for the production of hair cells. To identify genes that may interact with Math1 and inhibit hair cell differentiation, we have focused on Hes1, a mammalian hairy and enhancer of split homolog, which is a negative regulator of neurogenesis. We report here that targeted deletion of Hes1 leads to formation of supernumerary hair cells in the cochlea and utricle of the inner ear. RT-PCR analysis shows that Hes1 is expressed in inner ear during hair cell differentiation and its expression is maintained in adulthood. In situ hybridization with late embryonic inner ear tissue reveals that Hes1 is expressed in supporting cells, but not hair cells, of the vestibular sensory epithelium. In the cochlea, Hes1 is selectively expressed in the greater epithelial ridge and lesser epithelial ridge regions which are adjacent to inner and outer hair cells. Co-transfection experiments in postnatal rat explant cultures show that overexpression of Hes1 prevents hair cell differentiation induced by Math1. Therefore Hes1 can negatively regulate hair cell differentiation by antagonizing Math1. These results suggest that a balance between Math1 and negative regulators such as Hes1 is crucial for the production of an appropriate number of inner ear hair cells.

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Sufu regulation of Hedgehog signaling in P19 cells is required for proper glial cell differentiation

10.1101/2021.08.24.457497 ◽

2021 ◽

Author(s):

Danielle M. Spice ◽

Joshua Dierolf ◽

Gregory M. Kelly

Keyword(s):

Retinoic Acid ◽

Cell Differentiation ◽

Glial Cell ◽

Neural Differentiation ◽

Hedgehog Signaling ◽

Target Genes ◽

Cell Model ◽

Ectopic Expression ◽

Negative Regulator ◽

Embryonal Carcinoma Cell

AbstractHedgehog signaling is essential for vertebrate development, however, less is known about the negative regulators that influence this pathway during the differentiation of cell fates. Using the mouse P19 embryonal carcinoma cell model, Suppressor of Fused (SUFU), a negative regulator of the Hedgehog pathway, was investigated during retinoic acid-induced neural differentiation. We found Hedgehog signaling was activated in the early phase of neural differentiation and became inactive during terminal differentiation of neurons and astrocytes. SUFU, which regulates signaling at the level of GLI, remained relatively unchanged during the differentiation process, however SUFU loss through CRISPIR-Cas9 gene editing resulted in decreased cell proliferation and ectopic expression of Hedgehog target genes. Interestingly, SUFU-deficient cells were unable to differentiate in the absence of retinoic acid, but when differentiated in its presence they showed delayed and decreased astrocyte differentiation; neuron differentiation did not appear to be affected. Retinoic acid-induced differentiation also caused ectopic activation of Hh target genes in SUFU-deficient cells and while the absence of the GLI3 transcriptional inhibitor suggested the pathway was active, no full-length GLI3 was detected even though the message encoding Gli3 was present. Thus, the study would indicate the proper timing and proportion of glial cell differentiation requires SUFU, and its normal regulation of GLI3 to maintain Hh signaling in an inactive state.

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Delta-Notch signalling and the patterning of sensory cell differentiation in the zebrafish ear: evidence from the mind bomb mutant

Development ◽

10.1242/dev.125.23.4637 ◽

1998 ◽

Vol 125 (23) ◽

pp. 4637-4644 ◽

Cited By ~ 22

Author(s):

C. Haddon ◽

Y.J. Jiang ◽

L. Smithers ◽

J. Lewis

Keyword(s):

Cell Differentiation ◽

Lateral Inhibition ◽

Hair Cells ◽

Sensory Cell ◽

Cell Types ◽

Notch Signalling ◽

Supporting Cells ◽

Fine Grained ◽

Mechanosensory Hair Cells ◽

The Mind

Mechanosensory hair cells in the sensory patches of the vertebrate ear are interspersed among supporting cells, forming a fine-grained pattern of alternating cell types. Analogies with Drosophila mechanosensory bristle development suggest that this pattern could be generated through lateral inhibition mediated by Notch signalling. In the zebrafish ear rudiment, homologues of Notch are widely expressed, while the Delta homologues deltaA, deltaB and deltaD, coding for Notch ligands, are expressed in small numbers of cells in regions where hair cells are soon to differentiate. This suggests that the delta-expressing cells are nascent hair cells, in agreement with findings for Delta1 in the chick. According to the lateral inhibition hypothesis, the nascent hair cells, by expressing Delta protein, would inhibit their neighbours from becoming hair cells, forcing them to be supporting cells instead. The zebrafish mind bomb mutant has abnormalities in the central nervous system, somites, and elsewhere, diagnostic of a failure of Delta-Notch signalling: in the CNS, it shows a neurogenic phenotype accompanied by misregulated delta gene expression. Similar misregulation of delta; genes is seen in the ear, along with misregulation of a Serrate homologue, serrateB, coding for an alternative Notch ligand. Most dramatically, the sensory patches in the mind bomb ear consist solely of hair cells, which are produced in great excess and prematurely; at 36 hours post fertilization, there are more than ten times as many as normal, while supporting cells are absent. A twofold increase is seen in the number of otic neurons also. The findings are strong evidence that lateral inhibition mediated by Delta-Notch signalling controls the pattern of sensory cell differentiation in the ear.

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Abnormal Meiosis Initiation in Germ Cell Caused by Aberrant Differentiation of Gonad Somatic Cell

Oxidative Medicine and Cellular Longevity ◽

10.1155/2019/8030697 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8

Author(s):

Min Chen ◽

Suren Chen ◽

Jingjing Zhou ◽

Fangfang Dong ◽

...

Keyword(s):

Cell Differentiation ◽

Germ Cell ◽

Somatic Cell ◽

Germ Cells ◽

Somatic Cells ◽

Ectopic Expression ◽

Genital Ridge ◽

Male And Female ◽

Germ Cell Differentiation ◽

Exact Function

The interaction between germ cell and somatic cell plays important roles in germ cell development. However, the exact function of gonad somatic cell in germ cell differentiation is unclear. In the present study, the function of gonad somatic cell in germ cell meiosis was examined by using mouse models with aberrant somatic cell differentiation. In Wt1R394W/R394W mice, the genital ridge is absent due to the apoptosis of coelomic epithelial cells. Interestingly, in both male and female Wt1R394W/R394W germ cells, STRA8 was detected at E12.5 and the scattered SYCP3 foci were observed at E13.5 which was consistent with control females. In Wt1-/flox; Cre-ERTM mice, Wt1 was inactivated by the injection of tamoxifen at E9.5 and the differentiation of Sertoli and granulosa cells was completely blocked. We found that most germ cells were located outside of genital ridge after Wt1 inactivation. STRA8, SYCP3, and γH2AX proteins were detected in germ cells of both male and female Wt1-/flox; Cre-ERTM gonads, whereas no thread-like SYCP3 signal was observed. Our study demonstrates that aberrant development of gonad somatic cells leads to ectopic expression of meiosis-associated genes in germ cells, but meiosis was arrested before prophase I. These results suggest that the proper differentiation of gonad somatic cells is essential for germ cell meiosis.

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The cytolinker Pigs is a direct target and a negative regulator of Notch signalling

Development ◽

10.1242/dev.043224 ◽

2010 ◽

Vol 137 (6) ◽

pp. 913-922 ◽

Cited By ~ 15

Author(s):

M. K. Pines ◽

B. E. Housden ◽

F. Bernard ◽

S. J. Bray ◽

K. Roper

Keyword(s):

Notch Signalling ◽

Negative Regulator ◽

Direct Target

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Tissue-specific DNA demethylation is required for proper B-cell differentiation and function

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1604365113 ◽

2016 ◽

Vol 113 (18) ◽

pp. 5018-5023 ◽

Cited By ~ 51

Author(s):

Shari Orlanski ◽

Verena Labi ◽

Yitzhak Reizel ◽

Adam Spiro ◽

Michal Lichtenstein ◽

...

Keyword(s):

Cell Differentiation ◽

B Cell ◽

Somatic Cell ◽

Cell Development ◽

Dna Demethylation ◽

Conditional Knockout ◽

B Cell Differentiation ◽

Ample Evidence ◽

Tissue Specific ◽

And Function

There is ample evidence that somatic cell differentiation during development is accompanied by extensive DNA demethylation of specific sites that vary between cell types. Although the mechanism of this process has not yet been elucidated, it is likely to involve the conversion of 5mC to 5hmC by Tet enzymes. We show that a Tet2/Tet3 conditional knockout at early stages of B-cell development largely prevents lineage-specific programmed demethylation events. This lack of demethylation affects the expression of nearby B-cell lineage genes by impairing enhancer activity, thus causing defects in B-cell differentiation and function. Thus, tissue-specific DNA demethylation appears to be necessary for proper somatic cell development in vivo.

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