Adipose tissue is a highly active endocrine organ secreting a variety of signaling molecules called adipokines. Leptin and resistin are two adipokines critically involved in metabolic homeostasis. Nevertheless, the secretory pathways of these adipokines and their interplays are poorly elucidated. In this work, we have comparatively studied several key aspects of leptin and resistin secretion from 3T3-L1 adipocytes. It was found that leptin and resistin molecules are compartmentalized into different secretory vesicles. The trafficking of leptin and resistin vesicles, and the secretion of leptin and resistin are oppositely regulated by insulin/glycolytic substrates and cAMP/protein kinase A. Interestingly, these two adipokines adversely influence each other on secretion and vesicle trafficking. Finally, we demonstrated that both leptin and resistin secretion are Ca^{2 +} dependent.

Benign and malignant thyroid nodules are more prevalent in females than in males. Experimental data suggest that the proliferative effect of oestrogen rather than polymorphisms is responsible for this gender difference. This study analysed whether both differentiated thyroid cells and thyroid stem and progenitor cells are targets of oestrogen action. In thyroid stem/progenitor cells derived from nodular goitres, the ability of 17β-oestradiol (E₂) to induce the formation of thyrospheres and the expression of oestrogen receptors (ERs) and the effect of E₂ on the growth and expression of markers of stem cells and thyroid differentiation (TSH receptor, thyroperoxidase, thyroglobulin and sodium iodide symporter (NIS)) were analysed. E₂ induced thyrosphere formation, albeit to a lower extent than other growth factors. Thyroid stem and progenitor cells expressed ERα (ESR1) and ERβ (ESR2) with eight times higher expression levels of ER α mRNA compared with the differentiated thyrocytes. E₂ was a potent stimulator of the growth of thyroid stem/progenitor cells. In contrast, TSH-induced differentiation of progenitor cells, in particular, the expression of NIS, was significantly inhibited by E₂. In conclusion, oestrogen stimulated the growth and simultaneously inhibited the differentiation of thyroid nodule-derived stem/progenitor cells. From these data and based on the concept of cellular heterogeneity, we hypothesize a supportive role of oestrogen in the propagation of thyroid stem/progenitor cells leading to the selection of a progeny of growth-prone cells with a decreased differentiation. These cells may be the origin of hypofunctioning or non-functioning thyroid nodules in females.

Previous research on the role of insulin has focused on metabolism. This study investigated the effect of insulin on angiogenesis in endometrial decidualization. High insulin-treated mouse model was constructed by subcutaneous injection of insulin. Venous blood glucose, serum insulin, P4, E2, FSH and LH levels in the pregnant mice were detected by ELISA. Decidual markers, angiogenesis factors and decidual vascular network were detected during decidualization in the pregnant mouse model and an artificially induced decidualization mouse model. Tube formation ability and angiogenesis factors expression were also detected in high insulin-treated HUVECS cells. To confirm whether autophagy participates in hyperinsulinemia-impaired decidual angiogenesis, autophagy was detected in vivo and in vitro. During decidualization, in the condition of high insulin, serum insulin and blood glucose were significantly higher, while ovarian steroid hormones were also disordered (P < 0.05), decidual markers BMP2 and PRL were significantly lower (P < 0.05). Uterine CD34 staining showed that the size of the vascular sinus was significantly smaller than that in control. Endometrial VEGFA was significantly decreased after treatment with high insulin in vivo and in vitro (P < 0.05), whereas ANG-1 and TIE2 expression was significantly increased (P < 0.05). In addition, aberrant expression of autophagy markers revealed that autophagy participates in endometrial angiogenesis during decidualization (P < 0.05). After treatment with the autophagy inhibitor 3-MA in HUVEC, the originally damaged cell tube formation ability and VEGFA expression were repaired. This study suggests that endometrial angiogenesis during decidualization was impaired by hyperinsulinemia in early pregnant mice.

It is proved that epidermal growth factor (EGF)-like factors mediate gonadotropin-induced rodent oocyte maturation via EGF receptor (EGFR). However, the detail kinetics and signal pathway between FSH and EGF/EGFR is not clear in large animals. In the present study, we investigated the roles of EGFR and protein kinase C (PKC) in FSH-induced porcine oocyte meiotic resumption. Porcine cumulus–oocyte complexes were cultured in NCSU37 medium containing 10% porcine follicular fluid and germinal vesicle breakdown (meiotic resumption) was detected after different treatments. The results showed that EGF-like factor amphiregulin (AR) and EGFR mRNA were expressed in porcine cumulus cells, but not oocytes. FSH significantly induced AR mRNA expression with maximum at 4 h and activated EGFR phosphorylation at 8 h. AR (1–100 ng/ml) dose-dependently induced meiosis resumption of porcine oocyte. The specific EGFR inhibitor, AG1478, but not AG43 (the inactive analog of AG1478), completely blocked FSH, EGF, and AR-induced oocyte meiotic resumption; the inhibitory effect of AG1478 on FSH action gradually decreased when the inhibitor was added at 6 h or later and disappeared when it was added at 11 h; EGF reversed the inhibitory effect on FSH when AG1478 was added within 6 h. FSH triggered porcine oocyte meiotic resumption (at 20 h) later than that of EGF and AR (at 18 h). All these results supported that endogenously produced EGFR activator(s), possibly AR (maximum at 4 h) and EGFR activation (began at 6 h and finished within 11 h), in cumulus cells is necessary for FSH-induced porcine oocyte meiotic resumption (began at 18 h). Furthermore, PKC activator PMA mimicked but PKC inhibitor chelerythrine chloride inhibited FSH action, and AG1478 also suppressed PMA-induced porcine oocyte meiotic resumption. These data together suggested that EGFR activation, by PKC signal pathway, participates in FSH-induced porcine oocyte meiotic resumption.

The study was designed to investigate the possible mechanisms of hepatic microRNAs (miRs) in regulating local thyroid hormone (TH) action and ultimately different propensities to high-fat diet (HFD)-induced obesity. When obesity-prone (OP) and obesity-resistant (OR) mice were fed HFD for 7 weeks, OP mice showed apparent hepatic steatosis, with significantly higher body weight and lower hepatic TH receptor b (TRb) expression and type 1 deiodinase (DIO1) activity than OR mice. Next-generation sequencing technology revealed that 13 miRs in liver were dysregulated between the two phenotypes, of which 8 miRs were predicted to target on Dio1 or TRb. When mice were fed for 17 weeks, OR mice had mild hepatic steatosis and increased Dio1 and TRb expression than OP mice, with downregulation of T3 target genes (including Srebp1c, Acc1, Scd1 and Fasn) and upregulation of Cpt1α, Atp5c1, Cox7c and Cyp7a1. A stem-loop qRT-PCR analysis confirmed that the levels of miR-383, miR-34a and miR-146b were inversely correlated with those of DIO1 or TRb. Down-regulated expression of miR-383 or miR-146b by miR-383 inhibitor (anti-miR-383) or miR-146b inhibitor (anti-miR-146b) in free fatty acid-treated primary mouse hepatocytes led to increased DIO1 and TRb expressions, respectively, and subsequently decreased cellular lipid accumulation, while miR-34a inhibitor (anti-miR-34a) transfection had on effects on TRb expression. Luciferase reporter assay illustrated that miR-146b could directly target TRb 3′untranslated region (3′UTR). These findings suggested that miR-383 and miR-146b might play critical roles in different propensities to diet-induced obesity via targeting on Dio1 and TRb, respectively.

Obesity and type 2 diabetes (T2D) are both complicated endocrine disorders resulting from an interaction between multiple predisposing genes and environmental triggers, while diet and exercise have key influence on metabolic disorders. Previous reports demonstrated that 2-aminoadipic acid (2-AAA), an intermediate metabolite of lysine metabolism, could modulate insulin secretion and predict T2D, suggesting the role of 2-AAA in glycolipid metabolism. Here, we showed that treatment of diet-induced obesity (DIO) mice with 2-AAA significantly reduced body weight, decreased fat accumulation and lowered fasting glucose. Furthermore, Dhtkd1^−/− mice, in which the substrate of DHTKD1 2-AAA increased to a significant high level, were resistant to DIO and obesity-related insulin resistance. Further study showed that 2-AAA induced higher energy expenditure due to increased adipocyte thermogenesis via upregulating PGC1α and UCP1 mediated by β3AR activation, and stimulated lipolysis depending on enhanced expression of hormone-sensitive lipase (HSL) through activating β3AR signaling. Moreover, 2-AAA could alleviate the diabetic symptoms of db/db mice. Our data showed that 2-AAA played an important role in regulating glycolipid metabolism independent of diet and exercise, implying that improving the level of 2-AAA in vivo could be developed as a strategy in the treatment of obesity or diabetes.