Author(s)

Sonia M. Rocha-Sanchez, Laura R. Scheetz, Sabrina Siddiqi, Michael W. Weston, Lynette M. Smith, Kate Dempsey, Hesham Ali, JoAnn McGee, Edward J. Walsh

College of Information Science and Technology, University of Nebraska at Omaha, Omaha, USA.
College of Public Health, University of Nebraska Medical Center, Omaha, USA.
Department of Oral Biology, Creighton University School of Dentistry, Omaha, USA.
Developmental Auditory Physiology Laboratory, Boys Town National Research Hospital, Omaha, USA.

Loss of postnatal mammalian auditory hair cells (HCs) is irreversible. Earlier studies have highlighted the importance of the Retinoblastoma family of proteins (pRBs) (i.e., Rb1, Rbl1/p107, and Rbl2/p130) in the auditory cells’ proliferation and emphasized our lack of information on their specific roles in the auditory system. We have previously demonstrated that lack of Rbl2/p130 moderately affects HCs’ and supporting cells’ (SCs) proliferation. Here, we present evidence supporting multiple roles for Rbl1/p107 inthe developing and mature mouse organ of Corti (OC). Like other pRBs, Rbl1/p107 is expressed in the OC, particularly in the Hensen’s and Deiters’ cells. Moreover, Rbl1/p107 impacts maturation and postmitotic quiescence of HCs and SCs, as evidenced by enhanced numbers of these cells and the presence of dividing cells in the postnatal Rbl1/p107^－/－OC. These findings were further supported by microarray and bioinformatics analyses, suggesting downregulation of several bHLH molecules, as well as activation of the Notch/Hes/Hey signaling pathway in homozygous Rbl1/p107 mutant mice. Physiological assessments and detection of ectopic HC marker expression in postnatal spiral ganglion neurons (SGNs) provided evidence for incomplete cell maturation and differentiation in Rbl1/p107^﹣/﹣OC. Collectively, the present study highlights an important role for Rbl1/p107 inOC cell differentiation and maturation, which is distinct from other pRBs.

Rbl1/p107; Inner Ear; Proliferation; Differentiation; Hair Cells; Supporting Cells

Rocha-Sanchez, S. , Scheetz, L. , Siddiqi, S. , Weston, M. , Smith, L. , Dempsey, K. , Ali, H. , McGee, J. and Walsh, E. (2013) Lack of Rbl1/p107 Effects on Cell Proliferation and Maturation in the Inner Ear. Journal of Behavioral and Brain Science, 3, 534-555. doi: 10.4236/jbbs.2013.37056.