<i>DDX3Y</i>, a Male-Specific Region of Y Chromosome Gene, May Modulate Neuronal Differentiation

Although it is apparent that chromosome complement mediates sexually dimorphic expression patterns of some proteins that lead to functional differences, there has been insufficient evidence following the manipulation of the male-specific region of the Y chromosome (MSY) gene expression during neural development. In this study, we profiled the expression of 23 MSY genes and 15 of their X-linked homologues during neural cell differentiation of NTERA-2 human embryonal carcinoma cell line (NT2) cells in three different developmental stages using qRT-PCR, Western blotting, and immunofluorescence. The expression level of 12 Y-linked genes significantly increased over neural differentiation, including <i>RBMY1</i>, <i>EIF1AY</i>, <i>DDX3Y</i>, <i>HSFY1</i>, <i>BPY2</i>,<i> PCDH11Y</i>, <i>UTY</i>, <i>RPS4Y1</i>, <i>USP9Y</i>, <i>SRY</i>, <i>PRY</i>, and <i>ZFY</i>. We showed that siRNA-mediated knockdown of DDX3Y, a DEAD box RNA helicase enzyme, in neural progenitor cells impaired cell cycle progression and increased apoptosis, consequently interrupting differentiation. Label-free quantitative shotgun proteomics based on a spectral counting approach was then used to characterize the proteomic profile of the cells after <i>DDX3Y</i> knockdown. Among 917 reproducibly identified proteins detected, 71 proteins were differentially expressed following <i>DDX3Y</i> siRNA treatment compared with mock treated cells. Functional grouping indicated that these proteins were involved in cell cycle, RNA splicing, and apoptosis, among other biological functions. Our results suggest that MSY genes may play an important role in neural differentiation and demonstrate that <i>DDX3Y</i> could play a multifunctional role in neural cell development, probably in a sexually dimorphic manner.