TY - JOUR
T1 - Spatiotemporally controlled overexpression of cyclin D1 triggers generation of supernumerary cells in the postnatal mouse inner ear
AU - Tarang, Shikha
AU - Pyakurel, Umesh
AU - Weston, Michael D.
AU - Vijayakumar, Sarath
AU - Jones, Timothy
AU - Wagner, Kay Uwe
AU - Rocha-Sanchez, Sonia M.
N1 - Funding Information:
Technical support for luciferase imaging was provided by Drs. Kazuhito Sakamoto and Qian Zhang (UNMC). The microscopic confocal systems were made available by the UNMC Advanced Microscopy Core facility and Nebraska Center for Cell Biology (NCCB) at Creighton University. Mouse lines used in the study were maintained at Creighton University's Animal Resource Facility. This work received past support through an NIH/NCRR 5P20RR018788-NIH/NIGMS 8P20GM103471 COBRE grant (Shelley D. Smith, PI) and NIH/ORIP R21OD019745-01A1 (S.M.R.-S.).
Funding Information:
Technical support for luciferase imaging was provided by Drs. Kazuhito Sakamoto and Qian Zhang (UNMC). The microscopic confocal systems were made available by the UNMC Advanced Microscopy Core facility and Nebraska Center for Cell Biology (NCCB) at Creighton University. Mouse lines used in the study were maintained at Creighton University’s Animal Resource Facility. This work received past support through an NIH/ NCRR 5P20RR018788 -NIH/ NIGMS 8P20GM103471 COBRE grant (Shelley D. Smith, PI) and NIH/ORIP R21OD019745-01A1 (S.M.R.-S.).
Publisher Copyright:
© 2020 Elsevier B.V.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/5
Y1 - 2020/5
N2 - The retinoblastoma family of pocket proteins (pRBs), composed of Rb1, p107, and p130 are negative regulators of cell-cycle progression. The deletion of any individual pRB in the auditory system triggers hair cells’ (HCs) and supporting cells’ (SCs) proliferation to different extents. Nevertheless, accessing their combined role in the inner ear through conditional or complete knockout methods is limited by the early mortality of the triple knockout. In quiescent cells, hyperphosphorylation and inactivation of the pRBs are maintained through the activity of the Cyclin-D1-cdk4/6 complex. Cyclin D1 (CycD1) is expressed in the embryonic and neonatal inner ear. In the mature organ of Corti (OC), CycD1 expression is significantly downregulated, paralleling the OC mitotic quiescence. Earlier studies showed that CycD1 overexpression leads to cell-cycle reactivation in cultures of inner ear explants. Here, we characterize a Cre-activated, Doxycycline (Dox)-controlled, conditional CycD1 overexpression model, which when bred to a tetracycline-controlled transcriptional activator and the Atoh1-cre mouse lines, allow for transient CycD1 overexpression and pRBs’ downregulation in the inner ear in a reversible fashion. Analyses of postnatal mice's inner ears at various time points revealed the presence of supernumerary cells throughout the length of the cochlea and in the vestibular end-organs. Notably, most supernumerary cells were observed in the inner hair cells’ (IHCs) region, expressed myosin VIIa (M7a), and showed no signs of apoptosis at any of the time points analyzed. Auditory and vestibular phenotypes were similar between the different genotypes and treatment groups. The fact that no significant differences were observed in auditory and vestibular function supports the notion that the supernumerary cells detected in the adult mice cochlea and macular end-organs may not impair auditory functions.
AB - The retinoblastoma family of pocket proteins (pRBs), composed of Rb1, p107, and p130 are negative regulators of cell-cycle progression. The deletion of any individual pRB in the auditory system triggers hair cells’ (HCs) and supporting cells’ (SCs) proliferation to different extents. Nevertheless, accessing their combined role in the inner ear through conditional or complete knockout methods is limited by the early mortality of the triple knockout. In quiescent cells, hyperphosphorylation and inactivation of the pRBs are maintained through the activity of the Cyclin-D1-cdk4/6 complex. Cyclin D1 (CycD1) is expressed in the embryonic and neonatal inner ear. In the mature organ of Corti (OC), CycD1 expression is significantly downregulated, paralleling the OC mitotic quiescence. Earlier studies showed that CycD1 overexpression leads to cell-cycle reactivation in cultures of inner ear explants. Here, we characterize a Cre-activated, Doxycycline (Dox)-controlled, conditional CycD1 overexpression model, which when bred to a tetracycline-controlled transcriptional activator and the Atoh1-cre mouse lines, allow for transient CycD1 overexpression and pRBs’ downregulation in the inner ear in a reversible fashion. Analyses of postnatal mice's inner ears at various time points revealed the presence of supernumerary cells throughout the length of the cochlea and in the vestibular end-organs. Notably, most supernumerary cells were observed in the inner hair cells’ (IHCs) region, expressed myosin VIIa (M7a), and showed no signs of apoptosis at any of the time points analyzed. Auditory and vestibular phenotypes were similar between the different genotypes and treatment groups. The fact that no significant differences were observed in auditory and vestibular function supports the notion that the supernumerary cells detected in the adult mice cochlea and macular end-organs may not impair auditory functions.
UR - http://www.scopus.com/inward/record.url?scp=85082521347&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85082521347&partnerID=8YFLogxK
U2 - 10.1016/j.heares.2020.107951
DO - 10.1016/j.heares.2020.107951
M3 - Article
C2 - 32244147
AN - SCOPUS:85082521347
VL - 390
JO - Hearing Research
JF - Hearing Research
SN - 0378-5955
M1 - 107951
ER -