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Shiying Shao, Yun Gao, Bing Xie, Fei Xie, Sai Kiang Lim and GuoDong Li

Shortage of cadaveric pancreata and requirement of immune suppression are two major obstacles in transplantation therapy of type 1 diabetes. Here, we investigate whether i.p. transplantation of alginate-encapsulated insulin-producing cells from the embryo-derived mouse embryo progenitor-derived insulin-producing-1 (MEPI-1) line could lower hyperglycemia in immune-competent, allogeneic diabetic mice. Within days after transplantation, hyperglycemia was reversed followed by about 2.5 months of normo- to moderate hypoglycemia before relapsing. Mice transplanted with unencapsulated MEPI cells relapsed within 2 weeks. Removal of the transplanted capsules by washing of the peritoneal cavity caused an immediate relapse of hyperglycemia that could be reversed with a second transplantation. The removed capsules had fibrotic overgrowth but remained permeable to 70 kDa dextrans and displayed glucose-stimulated insulin secretion. Following transplantation, the number of cells in capsules increased initially, before decreasing to below the starting cell number at 75 days. Histological examination showed that beyond day 40 post-transplantation, encapsulated cell clusters exhibited proliferating cells with a necrotic core. Blood glucose, insulin levels, and oral glucose tolerance test in the transplanted animals correlated directly with the number of viable cells remaining in the capsules. Our study demonstrated that encapsulation could effectively protect MEPI cells from the host immune system without compromising their ability to correct hyperglycemia in immune-competent diabetic mice for 2.5 months, thereby providing proof that immunoisolation of expansible but immune-incompatible stem cell-derived surrogate β-cells by encapsulation is a viable diabetes therapy.

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Jie Liu, Fei Gao, Yue-Fang Liu, Hai-Ting Dou, Jia-Qi Yan, Zong-Min Fan and Zeng-Ming Yang

Embryo implantation and decidualization are key steps for successful reproduction. Although numerous factors have been identified to be involved in embryo implantation and decidualization, the mechanisms underlying these processes are still unclear. Based on our preliminary data, Prss56, a trypsin-like serine protease, is strongly expressed at implantation site in mouse uterus. However, the expression, regulation and function of Prss56 during early pregnancy are still unknown. In mouse uterus, Prss56 is strongly expressed in the subluminal stromal cells at implantation site on day 5 of pregnancy compared to inter-implantation site. Under delayed implantation, Prss56 expression is undetected. After delayed implantation is activated by estrogen, Prss56 is obviously induced at implantation site. Under artificial decidualization, Prss56 signal is seen at the primary decidual zone at the initial stage of artificial decidualization. When stromal cells are induced for in vitro decidualization, Prss56 expression is significantly elevated. Dtprp expression under in vitro decidualization is suppressed by Prss56 siRNA. In cultured stromal cells, HB-EGF markedly stimulates Prss56 expression through EGFR/ERK pathway. Based on promoter analysis, we also showed that Egr2 is involved in Prss56 regulation by HB-EGF. Collectively, Prss56 expression at implantation site is modulated by HB-EGF/EGFR/ERK signaling pathway and involved in mouse decidualization.

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Xiaoyi Ma, Fei Gao, Qi Chen, Xiuping Xuan, Ying Wang, Hongjun Deng, Fengying Yang and Li Yuan

The angiotensin-converting enzyme 2 (ACE2)/angiotensin 1–7 (A1–7)/MAS axis and glutamate decarboxylase 67 (GAD67)/gamma-aminobutyric acid (GABA) signal both exist in the islet and play important roles in regulating blood glucose metabolism. It has been reported that the activation of ACE2 in the brain increases GABA expression to improve biological effects; however, it is unclear whether there is functional correlation between the ACE2/A1–7/MAS axis and GAD67/GABA signal in the islet. In this study, we showed that the ACE2/A1–7/MAS and GABA signaling systems decreased in the islet of different metabolic stress models. In ACE2-knockout mice, we found that GAD67 and GABA expression decreased significantly, which was reversed by exogenous administration of A1–7. Furthermore, A1–7 mediated PDX1 and AKT activation was inhibited by allylglycine (a specific GAD67 inhibitor) in MIN6 cells. Moreover, giving A1–7 and GABA could significantly reduce beta-cell dedifferentiation and improved glucose metabolism during metabolic stress in vivo and in vitro. In conclusion, our study reveals that the ACE2/A1–7/MAS axis improves beta-cell function through regulating GAD67/GABA signal in beta cells and that up-regulating the ACE2/A1–7/MAS axis and GABA signals delays the development of obesity-induced diabetes.

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Wang-Yang Xu, Yan Shen, Houbao Zhu, Junhui Gao, Chen Zhang, Lingyun Tang, Shun-Yuan Lu, Chun-Ling Shen, Hong-Xin Zhang, Ziwei Li, Peng Meng, Ying-Han Wan, Jian Fei and Zhu-Gang Wang

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.