Spatiotemporal expression of CWC27 spliceosome-associated protein (CWC27) in the developing mouse inner ear.

CWC27 is a member of cyclophilin-type peptidyl-prolyl cis-trans isomerase family and takes part in the pre-mRNA splicing. The mutation of its gene, Cwc27, has been verified to be related to cancer, craniofacial and skeletal anomalies, retinal degeneration, and hearing loss. However, expression pattern of Cwc27 in the development of inner ear has not been fully understood. In this study, we studied the spatiotemporal expression of Cwc27 mRNA and CWC27 protein in the mouse inner ear from embryonic day (E) 9 to postnatal 0-day by in situ hybridization and immunohistochemistry staining, respectively. The expression level of Cwc27 was analyzed by quantitative reverse transcription polymerase chain reaction. We found that Cwc27 was expressed early in the otocyst at E9. At E13, Cwc27 was expressed in the cochlear duct, spiral ganglion area, and vestibular organ. The expression level of Cwc27 mRNA reached its maximum level at E13. From E14 onward, Cwc27 was expressed in the sensory epithelium in the cochlear duct and spiral ganglion area. From E18 onward, the distribution of CWC27 protein became more limited to the organ of Corti. Our study revealed Cwc27 might play an important part on promoting the development of developing inner ear.