Experimental & Molecular Medicine is an open access journal that publishes the highest quality articles in translational research and biomedical studies.

Sex steroids influence the maintenance and growth of muscles. Decline in androgens, estrogens and progesterone by aging leads to the loss of muscular function and mass, sarcopenia. These steroid hormones can interact with different signaling pathways through their receptors. To date, sex steroid hormone receptors and their exact roles are not completely defined in skeletal and smooth muscles. Although numerous studies focused on the effects of sex steroid hormones on different types of cells, still many unexplained molecular mechanisms in both skeletal and smooth muscle cells remain to be investigated. In this paper, many different molecular mechanisms that are activated or inhibited by sex steroids and those that influence the growth, proliferation, and differentiation of skeletal and smooth muscle cells are reviewed. Also, the similarities of cellular and molecular pathways of androgens, estrogens and progesterone in both skeletal and smooth muscle cells are highlighted. The reviewed signaling pathways and participating molecules can be targeted in the future development of novel therapeutics.

Do microRNAs (miRNAs) in granulosa cells (GCs) affect oocyte maturation during ovarian follicle development? Sophisticated regulation by miRNAs in ovarian GCs may improve oocyte maturation efficiency during ovarian follicle development. The meiotic competence of oocytes depends on the follicle's potential to undergo appropriate maturation and is an important factor in infertility therapies such as IVF. The exact function of the GCs during follicular development remains unknown. After in vitro maturation (IVM) and ovulation induction of isolated ovarian pre-antral follicles from 12-day-old female C57BL6 mice (n = 40), miRNA expression in the GCs was compared according to the maturity of the oocyte (metaphase I (MI) versus metaphase II (MII)). The miRNAs, which showed notable different expression, were modulated by transfection during IVM of follicles. miRNA expression and candidate target gene expression in GCs of isolated murine ovarian pre-antral follicles were evaluated by real-time PCR after IVM. miR mimics and -inhibitors for selected miRNAs were transfected into the in vitro-maturated follicles, and ovulation, oocyte maturation and fertilization rates were compared. Candidate target gene expressions in GC were evaluated by quantitative PCR and immunohistochemistry using confocal microscopy. The relative expression of mmu-let-7b (0.78 ± 0.10, P = 0.016), mmu-let-7c (0.78 ± 0.12, P = 0.029), mmu-miR-27a (0.57 ± 0.18, P = 0.016) and mmu-miR-322 (0.59 ± 0.14, P = 0.008) was significantly lower in the GCs of follicles containing MII oocytes compared with those of MI oocytes. Transfection with a mmu-miR-27a-mimic sequence decreased the oocyte maturation rate compared with that for the control (9.4 versus 18.9%, P = 0.042), and transfection with mmu-let-7c-, mmu-miR-27a- and mmu-miR-322-inhibitor sequences increased the oocyte maturation rate by 1.5- to 2.0-folds compared with that for the control (40.6, 31.6, and 30.5%versus 18.9%, P < 0.001, P = 0.013, P = 0.021, respectively). The expression of IGFBP-2 was higher in GCs of MII than in the GCs of MI, and higher in miR-inhibitor transfection groups than in miR-mimic transfection groups and controls. An in vitro model was used in lieu of an in vivo model because of the ease of performing miRNA transfection in cell culture. However, studies have shown similarities and differences in in vivo versus in vitro cultured follicles. The findings of the present study need to be confirmed using in vivo maturation models and extended to evaluate developmental competence. Our findings suggest that sophisticated miRNA regulation in GCs may improve oocyte maturation efficiency during ovarian follicle development. This work was supported by a grant from the Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (A111539). None of the authors has any conflicts of interest to declare.

To investigate the relationship between polycystic ovary syndrome (PCOS) and type 2 diabetes mellitus (T2DM) in Korean women. Longitudinal case-control study. Not applicable. PCOS patients aged 15 to 44 years (n = 1,136) and control individuals (n = 5,675), matched 1:5 by age group, income, and region of residence. Not applicable. The occurrence of T2DM. In the PCOS and control groups, 15.7% and 14.4%, respectively, were obese (body mass index ≥25 kg/m2). The incidence rate of T2DM was 15.84/1,000 and 5.80/1,000 person-years in the PCOS and control groups, respectively. The unadjusted hazard ratio (HR) of T2DM in women with PCOS was 2.6-fold higher than that in control individuals. Women with PCOS still had a higher HR of T2DM than did control individuals after adjustment for body mass index, family history of T2DM, physical exercise level, and total cholesterol. PCOS was significantly associated with T2DM in women both with and without obesity. PCOS is independently associated with an increased incidence of T2DM in both obese and nonobese women. Screening for T2DM should be considered for both obese and nonobese women with PCOS in Korea.