TGFβ1 impairs the transcriptomic response to contraction in myotubes from women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is characterised by a hormonal imbalance affecting the reproductive and metabolic health of reproductive-aged women. Exercise is often recommended as a first-line therapy for women with PCOS to help improve their overall health however, women with PCOS are resistant to the metabolic benefits of exercise training. Here, we aimed to gain insight into the mechanisms responsible for such resistance to exercise in PCOS. We employed an in vitro approach with electrical pulse stimulation (EPS) of cultured skeletal muscle cells to explore whether muscle cells from women with PCOS have an altered gene expression signature in response to muscle contraction. Following EPS, 4,719 genes were differentially expressed (FDR < 0.05) in myotubes from women with PCOS compared to only 173 in healthy control women. Both groups included genes involved in skeletal muscle contraction. We also determined the effect of two transforming growth factor-beta ligands that are elevated in plasma of women with PCOS, the transforming growth factor beta-1 (TGFβ1) and the anti-müllerian hormone (AMH), alone and on the EPS-induced response. While AMH (30 ng/ml) had no effect, TGFβ1 (5 ng/ml) induced the expression of extracellular matrix genes and impaired the exercise-like gene expression signature in myotubes from women with and without PCOS in response to EPS by interfering with key processes related to muscle contraction, calcium transport and actin filament. Collectively, our findings suggest that while the fundamental gene expression responses of skeletal muscle to contraction is intact in PCOS, elevated circulating factors like TGFβ1 may be responsible for the impaired adaptation to exercise intervention in women with PCOS. Primary myotube cultures were established from skeletal muscle biopsies (vastus lateralis) obtained from six overweight insulin resistant PCOS women (PCOS) and six healthy lean control women (CTRL), all aged between 18-40 years old. Myotubes were treated with TGFB1 (5ng/ml) or AMH (30ng/ml), and also with and without EPS (11.5 V, 2 ms, 1Hz). RNA-seq analysis was performed with primary myotubes from five women with PCOS and five healthy women (an additional myotube sample for the healthy women was included for the non-treated condition only).