POSVP21, a major secretory androgen-dependent protein from sand rat seminal vesicles, identified as a transgelin

The seminal vesicles of adult sand rat contain a major secretory protein band （MW 21 kDa） designated as Psammomys obesus seminal vesicles protein of 21 kDa （POSVP21）. This protein is abundant in secretions, regulated by androgens and also present in the vaginal plug. POSVP21 accounts for over 22.3% of soluble proteins from homogenate during the breeding season, 13.3% during the middle season and 5.3% during the hormonal regression season. It is absent during the non-breeding season. POSVP21 is localized in the cytoplasm of epithelial cells and in secretory products in the lumen. It presents an immunological homology with two epididymal proteins with the same molecular weight and a high degree of homology with transgelin from rat （Rattus norvegicus）.

The novel long noncoding RNA LOC283070 is involved in the transition of LNCaP cells into androgen-independent cells via its interaction with PHB2

We sought to investigate the underlying mechanism of action of the long noncoding RNA （IncRNA） LOC283070 in the development of androgen independence in prostate cancer. The interactions between LOC283070 and target proteins were investigated by RNA pull-down and RNA-binding protein immunoprecipitation （RIP） assays. Subceilular fractionation and quantitative reverse transcription-polymerase chain reaction （qRT-PCR） were used to detect the subcellular localization of LOC283070. Western blotting was performed to detect the expression of prohibitin 2 （PHB2）. Luciferase activity assays were performed to evaluate the effects of LOC283070 and PHB2 on the androgen receptor （AR） signaling pathway. A methyl thiazolyl tetrazolium （MTT） assay and a growth curve assay were used to test cell viability. Flow cytometry was performed to analyze cell cycles. A transwell assay was employed to test cell migration. We identified PHB2 as an interaction partner of LOC283070 in the pull-down and RIP experiments. Furthermore, we confirmed that the enrichment of L0C283070 with PHB2 in androgen-independent LNCaP （LNCaP-AI） cells was much greater than that in LNCaP cells. Moreover, the expression of PHB2 was not significantly different between the two cell lines, and the expression of LOC283070 in the nuclei of the LNCaP-AI cells was significantly greater than that in the LNCaP cells. In vitro data revealed that PHB2 overexpression significantly inhibited AR activity and cell proliferation and migration and induced accumulation of prostate cancer cells in GO/G1 phase. Moreover, the overexpression of LOC283070 fully abrogated the effects of PHB2 overexpression. In conclusion, we found that LOC283070 can bind to PHB2 located in the nucleus and inhibit its effect, and this is one of the mechanisms by which LOC283070 is involved in the transition of LNCaP cells into androgen-independent cells.