Mitochondrial AR overactivation coupled with uterine decidual mitochondrial defects in PCOS-associated pregnancy loss

Nuclear androgen receptor (AR) dysregulation characterizes polycystic ovary syndrome (PCOS) pathophysiology and contributes to mitochondrial dysfunction-related adverse pregnancy outcomes. However, ARs also localize to mitochondria in many cell types, and mitochondrial dysfunction is implicated in the underlying pathogenesis of PCOS. In this study, human endometrial decidual basalis tissues and rat gravid uterine tissues were collected, and subcellular fractionation, western blot, quantitative real-time polymerase chain reaction (qPCR), electron microscopy, and enzyme-linked immunosorbent assay (ELISA) were conducted. PCOS patients with early pregnancy exhibited increased expression of AR mRNA and mitochondrial AR protein in decidual basalis. Similar alterations of AR levels were also observed in gravid uterus of 5α-dihydrotestosterone (DHT) + insulin-exposed pregnant rats with fetal loss. In both PCOS patients and DHT + insulin-exposed pregnant rats, uterine mitochondria displayed disorganized cristae along with decreased uterine mitochondrial DNA (mtDNA) content and reduced expression of mitochondrial morphogenesis (mito-morphosis) genes (sorting and assembly machinery component 50 (SAMM50), coiled-coil helix coiled-coil helix domain-containing protein 3 (CHCHD3), and dynamin-related protein 1 (DRP1)) and total adenosine triphosphate (ATP) levels. In addition, there was dysregulated expression of mitochondrial fusion and fission, biogenesis, mitophagy, and mitochondrial ribosome protein gene. In DHT + insulin-exposed pregnant rats, treatment with flutamide prevented fetal loss and partially rescued mitochondrial morphological abnormalities in uterine decidual stromal cells. In addition, flutamide normalized uterine Ar mRNA and mitochondrial AR protein expression; inner membrane mitochondrial protein (Immt), ras homolog enriched in brain protein (Rheb), and Mrp7 mRNA expression; and the Parkin:PTEM-induced putative kinase 1 (Pink1) ratio and restored total nicotinamide adenine dinucleotide (NAD) and ATP contents. Collectively, this work identifies mitochondrial AR in the uterus and implicates hyperandrogenism-induced, AR-dependent mitochondrial dysfunction in decidual stromal cells as a key mechanism underlying pregnancy loss in PCOS.