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

Abstract

The <i>DENND1A</i> 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 <i>DENND1A</i> splice variant (DENND1A.V2). Forced expression of this variant in normal theca cells increases androgen biosynthesis and <i>CYP17A1</i> expression, whereas knockdown of the transcript in PCOS theca cells reduced androgen production and <i>CYP17A1</i> 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 <i>Dennd1a</i> gene is essential for viability since <i>Dennd1a</i> knockout mice are embryonically lethal, suggesting that <i>Dennd1a</i> is developmentally critical. Three different hDENND1A.V2 transgenic mice lines were created using CMV, <i>Lhcgr</i>, 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 <i>Cyp17a1</i> 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.