Human DENND1A.V2 Drives Cyp17a1 Expression and Androgen Production in Mouse Ovaries and Adrenals

The DENND1A locus is associated with polycystic ovary syndrome (PCOS), a disorder characterized by androgen excess. Theca cells from ovaries of PCOS women have elevated levels of a DENND1A splice variant (DENND1A.V2). Forced expression of this variant in normal theca cells increases androgen biosynthesis and CYP17A1 expression, whereas knockdown of the transcript in PCOS theca cells reduced androgen production and CYP17A1 mRNA. We attempted to create a murine model of PCOS by expressing hDENND1A.V2 using standard transgenic approaches. There is no DENND1A.V2 protein equivalent in mice, and the murine Dennd1a gene is essential for viability since Dennd1a knockout mice are embryonically lethal, suggesting that Dennd1a is developmentally critical. Three different hDENND1A.V2 transgenic mice lines were created using CMV, Lhcgr, and TetOn promoters. The hDENND1A.V2 mice expressed hDENND1A.V2 transcripts. While hDENND1A.V2 protein was not detectable by Western blot analyses, appropriate hDENND1A.V2 immunohistochemical staining was observed. Corresponding Cyp17a1 mRNA levels were elevated in ovaries and adrenals of CMV transgenic mice, as were plasma steroid production by theca interstitial cells isolated from transgenic ovaries. Even though the impact of robust hDENND1A.V2 expression could not be characterized, our findings are consistent with the notion that elevated hDENND1A.V2 has a role in the hyperandrogenemia of PCOS.