A model for mammalian cochlear hair cell differentiation in vitro: effects of retinoic acid on cytoskeletal proteins and potassium conductances

Barhl1, a mouse homologous gene of Drosophila BarH class homeobox genes, is highly expressed within the inner ear and crucial for the long-term maintenance of auditory hair cells that mediate hearing and balance, yet little is known about the molecular events underlying Barhl1 regulation and function in hair cells. In this study, through data mining and in vitro report assay, we firstly identified Barhl1 as a direct target gene of Atoh1 and one E-box (E3) in Barhl1 3’ enhancer is crucial for Atoh1-mediated Barhl1 activation. Then we generated a mouse embryonic stem cell (mESC) line carrying disruptions on this E3 site E-box (CAGCTG) using CRISPR/Cas9 technology and this E3 mutated mESC line is further subjected to an efficient stepwise hair cell differentiation strategy in vitro. Disruptions on this E3 site caused dramatic loss of Barhl1 expression and significantly reduced the number of induced hair cell-like cells, while no affections on the differentiation toward early primitive ectoderm-like cells and otic progenitors. Finally, through RNA-seq profiling and gene ontology (GO) enrichment analysis, we found that this E3 box was indispensable for Barhl1 expression to maintain hair cell development and normal functions. We also compared the transcriptional profiles of induced cells from CDS mutated and E3 mutated mESCs, respectively, and got very consistent results except the Barhl1 transcript itself. These observations indicated that Atoh1-mediated Barhl1 expression could have important roles during auditory hair cell development. In brief, our findings delineate the detail molecular mechanism of Barhl1 expression regulation in auditory hair cell differentiation.

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Faculty Opinions recommendation of Hedgehog signaling regulates prosensory cell properties during the basal-to-apical wave of hair cell differentiation in the mammalian cochlea.

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

10.3410/f.718075777.793482639 ◽

2013 ◽

Author(s):

Andy Groves

Keyword(s):

Cell Differentiation ◽

Hair Cell ◽

Hedgehog Signaling ◽

Hair Cell Differentiation

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HIC1 Represses Atoh1 Transcription and Hair Cell Differentiation in the Cochlea

Stem Cell Reports ◽

10.1016/j.stemcr.2021.02.022 ◽

2021 ◽

Vol 16 (4) ◽

pp. 797-809

Author(s):

Dunia Abdul-Aziz ◽

Nicolai Hathiramani ◽

Lauren Phung ◽

Vittoria Sykopetrites ◽

Albert S.B. Edge

Keyword(s):

Cell Differentiation ◽

Hair Cell ◽

Hair Cell Differentiation

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Hes1 is a negative regulator of inner ear hair cell differentiation

Development ◽

10.1242/dev.127.21.4551 ◽

2000 ◽

Vol 127 (21) ◽

pp. 4551-4560 ◽

Cited By ~ 5

Author(s):

J.L. Zheng ◽

J. Shou ◽

F. Guillemot ◽

R. Kageyama ◽

W.Q. Gao

Keyword(s):

Cell Differentiation ◽

Hair Cell ◽

Inner Ear ◽

Cell Fate ◽

Hair Cells ◽

Outer Hair Cells ◽

Negative Regulator ◽

Pcr Analysis ◽

Loss Of Function ◽

Hair Cell Differentiation

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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A counter gradient of Activin A and follistatin instructs the timing of hair cell differentiation in the murine cochlea

eLife ◽

10.7554/elife.47613 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 3

Author(s):

Meenakshi Prajapati-DiNubila ◽

Ana Benito-Gonzalez ◽

Erin Jennifer Golden ◽

Shuran Zhang ◽

Angelika Doetzlhofer

Keyword(s):

Cell Differentiation ◽

Hair Cell ◽

Hair Cells ◽

Activin A ◽

Sensory Epithelium ◽

Outer Hair Cells ◽

Longitudinal Gradient ◽

Hair Cell Differentiation ◽

Local Gradient ◽

Molecular Signals

The mammalian auditory sensory epithelium has one of the most stereotyped cellular patterns known in vertebrates. Mechano-sensory hair cells are arranged in precise rows, with one row of inner and three rows of outer hair cells spanning the length of the spiral-shaped sensory epithelium. Aiding such precise cellular patterning, differentiation of the auditory sensory epithelium is precisely timed and follows a steep longitudinal gradient. The molecular signals that promote auditory sensory differentiation and instruct its graded pattern are largely unknown. Here, we identify Activin A and its antagonist follistatin as key regulators of hair cell differentiation and show, using mouse genetic approaches, that a local gradient of Activin A signaling within the auditory sensory epithelium times the longitudinal gradient of hair cell differentiation. Furthermore, we provide evidence that Activin-type signaling regulates a radial gradient of terminal mitosis within the auditory sensory epithelium, which constitutes a novel mechanism for limiting the number of inner hair cells being produced.

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Modulation of spontaneous B-cell differentiation in macroglobulinemia by retinoic acid

Blood ◽

10.1182/blood.v83.8.2206.2206 ◽

1994 ◽

Vol 83 (8) ◽

pp. 2206-2210 ◽

Cited By ~ 6

Author(s):

Y Levy ◽

S Labaume ◽

MC Gendron ◽

JC Brouet

Keyword(s):

Retinoic Acid ◽

Cell Differentiation ◽

B Cells ◽

B Cell ◽

Plasma Cells ◽

B Cell Differentiation ◽

Trans Retinoic Acid ◽

All Trans Retinoic Acid ◽

Culture Supernatants

Abstract We previously showed that clonal blood B cells from patients with macroglobulinemia spontaneously differentiate in vitro to plasma cells. This process is dependent on an interleukin (IL)-6 autocrine pathway. We investigate here whether all-trans-retinoic acid (RA) interferes with B-cell differentiation either in patients with IgM gammapathy of undetermined significance (MGUS) or Waldenstrom's macroglobulinemia (WM). RA at a concentration of 10(-5) to 10(-8) mol/L inhibited by 50% to 80% the in vitro differentiation of purified B cells from four of five patients with MGUS and from one of five patients with WM as assessed by the IgM content of day 7 culture supernatants. We next determined whether this effect could be related to an inhibition of IL- 6 secretion by cultured B cells and/or a downregulation of the IL-6 receptor (IL-6R), which was constitutively expressed on patients' blood B cells. A 50% to 100% (mean, 80%) inhibition of IL-6 production was found in seven of 10 patients (five with MGUS and two with WM). The IL- 6R was no more detectable on cells from patients with MGUS after 2 days of treatment with RA and slightly downregulated in patients with WM. It was of interest that B cells susceptible to the action of RA belonged mostly to patients with IgM MGUS, which reinforces our previous data showing distinct requirements for IL-6-dependent differentiation of blood B cells from patients with VM or IgM MGUS.

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