The elusive MAESTRO gene: Its human reproductive tissue-specific expression pattern

The encoded transcript of the Maestro—Male-specific Transcription in the developing Reproductive Organs (MRO) gene exhibits sexual dimorphic expression during murine gonadal development. The gene has no homology to any known gene and its expression pattern, protein function or structure are still unknown. Previously, studying gene expression in human ovarian cumulus cells, we found increased expression of MRO in lean-type Polycystic Ovarian Syndrome (PCOS) subjects, as compared to controls. In this study, we examined the MRO splice variants and protein expression pattern in various human tissues and cells. We found a differential expression pattern of the MRO 5’-UTR region in luteinized granulosa-cumulus cells and in testicular tissues as compared to non-gonadal tissues. Our study also shows a punctate nuclear expression pattern and disperse cytoplasmic expression pattern of the MRO protein in human granulosa-cumulus cells and in testicular germ cells, which was later validated by western blotting. The tentative and unique features of the protein hampered our efforts to gain more insight about this elusive protein. A better understanding of the tissue-specific MRO isoforms expression patterns and the unique structure of the protein may provide important insights into the function of this gene and possibly to the pathophysiology of PCOS.