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Shengyi Sun, Elissa W P Wong, Michelle W M Li, Will M Lee, and C Yan Cheng

During spermatogenesis, spermiation takes place at the adluminal edge of the seminiferous epithelium at stage VIII of the epithelial cycle during which fully developed spermatids (i.e. spermatozoa) detach from the epithelium in adult rat testes. This event coincides with the migration of preleptotene/leptotene spermatocytes across the blood–testis barrier from the basal to the apical (or adluminal) compartment. At stage XIV of the epithelial cycle, Pachytene spermatocytes (diploid, 2n) differentiate into diplotene spermatocytes (tetraploid, 4n) in the apical compartment of the epithelium, which begin meiosis I to be followed by meiosis II to form spermatids (haploid, 1n) at stage XIV of the epithelial cycle. These spermatids, in turn, undergo extensive morphological changes and traverse the seminiferous epithelium until they differentiate into elongated spermatids. Thus, there are extensive changes at the Sertoli–Sertoli and Sertoli–germ cell interface via protein ‘coupling’ and ‘uncoupling’ between cell adhesion protein complexes, as well as changes in interactions between integral membrane proteins and their peripheral adaptors, regulatory protein kinases and phosphatases, and the cytoskeletal proteins. These precisely coordinated protein–protein interactions affect cell adhesion and cell movement. In this review, we focus on the 14-3-3 protein family, whose members have different binding partners in the seminiferous epithelium. Recent studies have illustrated that 14-3-3 affects protein–protein interactions in the seminiferous epithelium, and regulates cell adhesion possibly via its effects on intracellular protein trafficking and cell-polarity proteins. This review provides a summary on the latest findings regarding the role of 14-3-3 family of proteins and their potential implications on spermatogenesis. We also highlight research areas that deserve attentions by investigators.

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Jinyu Ma, Yuejun Wang, Jie Ding, Shouping Zhang, Yinuo Yang, and Cheng Sun

Several histone deacetylase (HDAC) inhibitors have been shown to play beneficial roles in treating obesity and its related metabolic syndromes. However, the underlying mechanisms are still not understood well. In this study, we examined the potential roles of SAHA, a potent inhibitor of HDACs, on energy expenditure and explored the molecular mechanism involved. Our data showed that SAHA induces less lipid accumulation and smaller lipid droplets in cultured adipocytes. In vivo studies showing SAHA reduces body weight gain and increases core temperature in lean and obese mice. Furthermore, SAHA accelerates blood glucose disposal, improves insulin sensitivity and attenuates fatty liver in obese animals. Transcriptome sequencing found that a group of zinc finger proteins (Zfps) was up-regulated by SAHA. Functional studies showed that the knockdown of Zfp691 or Zfp719 largely abolishes SAHA-induced Ucp1 expression in adipocytes. ChIP assay showed that SAHA stimulates histone H3 acetylation at Zfp719 promoter. Luciferase reporter analysis revealed that Zfp719 activates Ucp1 promoter. As a consequence, forced expression of Zfp719 increases Ucp1 expression and promotes lipid catabolism in adipocytes. Taken together, our data indicate that by stimulating axis of ZFPs-UCP1, SAHA induces white fat browning and energy consumption, which makes it a potential drug for treating obesity and related metabolic dysfunctions.

Free access

Hong Ma, Jin Yuan, Jinyu Ma, Jie Ding, Weiwei Lin, Xinlei Wang, Mingliang Zhang, Yi Sun, Runze Wu, Chun Liu, Cheng Sun, and Yunjuan Gu

Bone morphogenetic protein 7 (BMP7), a member of the transforming growth factor-β (TGF-β) family, plays pivotal roles in energy expenditure. However, whether and how BMP7 regulates hepatic insulin sensitivity is still poorly understood. Here, we show that hepatic BMP7 expression is reduced in high-fat diet (HFD)-induced diabetic mice and palmitate (PA)-induced insulin-resistant HepG2 and AML12 cells. BMP7 improves insulin signaling pathway in insulin resistant hepatocytes. On the contrary, knockdown of BMP7 further impairs insulin signal transduction in PA-treated cells. Increased expression of BMP7 by adenovirus expressing BMP7 improves hyperglycemia, insulin sensitivity and insulin signal transduction. Furthermore, BMP7 inhibits mitogen-activated protein kinases (MAPKs) in both the liver of obese mice and PA-treated cells. In addition, inhibition of MAPKs recapitulates the effects of BMP7 on insulin signal transduction in cultured hepatocytes treated with PA. Activation of p38 MAPK abolishes the BMP7-mediated upregulation of insulin signal transduction both in vitro and in vivo. Together, our results show that hepatic BMP7 has a novel function in regulating insulin sensitivity through inhibition of MAPKs, thus providing new insights into treating insulin resistance-related disorders such as type 2 diabetes.

Free access

Dong-Xu Han, Chang-Jiang Wang, Xu-Lei Sun, Jian-Bo Liu, Hao Jiang, Yan Gao, Cheng-Zhen Chen, Bao Yuan, and Jia-Bao Zhang

Circular RNAs (circRNAs) are a new class of RNA that have a stable structure characterized by covalently closed circular molecules and are involved in invasive pituitary adenomas and recurrent clinically nonfunctioning pituitary adenomas. However, information on circRNAs in the normal pituitary, especially in rats, is limited. In this study, we identified 4123 circRNAs in the immature (D15) and mature (D120) rat anterior pituitary using the Illumina platform, and 32 differentially expressed circRNAs were found. A total of 150 Gene Ontology terms were significantly enriched, and 16 KEGG pathways were found to contain differentially expressed genes. Moreover, we randomly selected eight highly expressed circRNAs and detected their relative expression levels in the mature and immature rat pituitary by qPCR. In addition, we predicted 90 interactions between 53 circRNAs and 57 miRNAs using miRanda. Notably, circ_0000964 and circ_0001303 are potential miRNA sponges that may regulate the Fshb gene. The expression profile of circRNAs in the immature and mature rat anterior pituitary may provide more information about the roles of circRNAs in the development and reproduction in mammals.

Open access

Shisan Xu, Fangjing Xie, Li Tian, Samane Fallah, Fatemeh Babaei, Sinai H C Manno, Francis A M Manno III, Lina Zhu, Kin Fung Wong, Yimin Liang, Rajkumar Ramalingam, Lei Sun, Xin Wang, Robert Plumb, Lee Gethings, Yun Wah Lam, and Shuk Han Cheng

Sexual differences have been observed in the onset and prognosis of human cardiovascular diseases, but the underlying mechanisms are not clear. Here, we found that zebrafish heart regeneration is faster in females, can be accelerated by estrogen and is suppressed by the estrogen-antagonist tamoxifen. Injuries to the zebrafish heart, but not other tissues, increased plasma estrogen levels and the expression of estrogen receptors, especially esr2a. The resulting endocrine disruption induces the expression of the female-specific protein vitellogenin in male zebrafish. Transcriptomic analyses suggested heart injuries triggered pronounced immune and inflammatory responses in females. These responses, previously shown to elicit heart regeneration, could be enhanced by estrogen treatment in males and reduced by tamoxifen in females. Furthermore, a prior exposure to estrogen preconditioned the zebrafish heart for an accelerated regeneration. Altogether, this study reveals that heart regeneration is modulated by an estrogen-inducible inflammatory response to cardiac injury. These findings elucidate a previously unknown layer of control in zebrafish heart regeneration and provide a new model system for the study of sexual differences in human cardiac repair.