Urocortin (UCN), a newly identified, 40-amino-acid, corticotropin-releasing hormone (CRH) structurally related peptide, has been demonstrated to be expressed in the central nervous system and many peripheral tissues of rats and man. This study aimed to investigate the expression profile of UCN in rat lung and the effect of UCN on lung vascular permeability. The expression of UCN mRNA was detected by reverse transcriptase PCR (RT–PCR). UCN peptide was measured by immunohistochemistry and Western blot analysis. We found that both UCN mRNA and peptide were obviously expressed in rat lung. Immunohistochemistry results showed that UCN peptide is mainly expressed in bronchial epithelium mucosa and alveolar epithelium. We also found that rats receiving inhalation aerosol of UCN had a significant elevation of lung vascular permeability compared with rats receiving vehicle and ovalbumin (OVA) by the Evans blue (EB) technique. UCN aerosol inhalation resulted in obvious pulmonary congestion and edema observed under light microscope by hematoxylin and eosin (HE) staining. The nonselective peptide CRH receptor antagonist astressin markedly reduced lung vascular permeability triggered by UCN. Enhanced pulmonary vascular permeability induced by UCN was markedly inhibited by pretreatment with the mast-cell stabilizer cromolyn and histamine-1 (H1) receptor antagonist azelastine respectively, but not by the leukotriene receptor antagonist montelukast. In summary, in the present study, we demonstrated for the first time that UCN is expressed in rat lung and contributes to an increase in lung vascular permeability through activation of CRH receptors. Mast cells and histamine may be involved in this effect of UCN. Peripherally produced UCN in lung may act as an autocrine and paracrine proinflammatory factor.
Yuqing Wu, Yinyan Xu, Hong Zhou, Jin Tao, and Shengnan Li
Yan Wang, Mengqi Zhang, Zhikun Huan, Shanshan Shao, Xiujuan Zhang, Dehuan Kong, and Jin Xu
Previous studies suggest that postmenopausal osteoarthritis is linked to a decrease in estrogen levels. However, whether follicle-stimulating hormone (FSH), the upstream hormone of estrogen, affects cartilage destruction and thus contributes to the onset of osteoarthritis has never been explored. To evaluate the potential involvement of FSH in joint degeneration and to identify the molecular mechanisms through which FSH influences chondrocytes, mouse cartilage chondrocytes and the ATDC5 chondrocyte cell line were treated with FSH and inhibitors of intracellular signaling pathways. We observed that FSH induces chondrocyte dedifferentiation by decreasing type II collagen (Coll-II) synthesis. Chondrocyte cytoskeleton reorganization was also observed after FSH treatment. The FSH-induced decrease in Coll-II was rescued by ERK-1/2 inhibition but aggravated by p38 inhibition. In addition, knocking down the FSH receptor (Fshr) by using Fshr siRNA abolished chondrocyte dedifferentiation, as indicated by the increased expression of Coll-II. Inhibition of the protein Gαi by pertussis toxin (PTX) also restored FSH-inhibited Coll-II, suggesting that Gαi is downstream of FSHR in chondrocyte dedifferentiation. FSHβ antibody blockade prevented cartilage destruction and cell loss in mice. Moreover, decreased Coll-II staining due to the progression of aging could be rescued by blocking FSH. Thus, we suggest that high circulating FSH, independent of estrogen, is an important regulator in chondrocyte dedifferentiation and cartilage destruction.
Xin-gang Yao, Xin Xu, Gai-hong Wang, Min Lei, Ling-ling Quan, Yan-hua Cheng, Ping Wan, Jin-pei Zhou, Jing Chen, Li-hong Hu, and Xu Shen
Impaired glucose-stimulated insulin secretion (GSIS) and increasing β-cell death are two typical dysfunctions of pancreatic β-cells in individuals that are destined to develop type 2 diabetes, and improvement of β-cell function through GSIS enhancement and/or inhibition of β-cell death is a promising strategy for anti-diabetic therapy. In this study, we discovered that the small molecule, N-(2-benzoylphenyl)-5-bromo-2-thiophenecarboxamide (BBT), was effective in both potentiating GSIS and protecting β-cells from cytokine- or streptozotocin (STZ)-induced cell death. Results of further studies revealed that cAMP/PKA and long-lasting (L-type) voltage-dependent Ca2 + channel/CaMK2 pathways were involved in the action of BBT against GSIS, and that the cAMP/PKA pathway was essential for the protective action of BBT on β-cells. An assay using the model of type 2 diabetic mice induced by high-fat diet combined with STZ (STZ/HFD) demonstrated that BBT administration efficiently restored β-cell functions as indicated by the increased plasma insulin level and decrease in the β-cell loss induced by STZ/HFD. Moreover, the results indicated that BBT treatment decreased fasting blood glucose and HbA1c and improved oral glucose tolerance further highlighting the potential of BBT in anti-hyperglycemia research.
Jin-Wen Xu, Naomi Yasui, Katsumi Ikeda, Wei-Jun Pan, June Watanabe, Masahide Shiotani, Atsushi Yanaihara, Tomohiro Miki, and Yukio Yamori
Isoflavones have attracted much attention due to their association with health benefits; however, comprehensive understanding of the beneficial impacts of isoflavones on uterine biology at the molecular level remains unexplored. In the present study, our data showed that isoflavones aglycones AglyMax, genistein, and equol, but not daidzein, within the range of plasma concentration, displayed bioavailability in regulating the secretion of leukemia inhibitory factor (LIF) and transforming growth factor β (TGF-β) in Ishikawa cells, which was blocked by an estrogen receptor antagonist ICI 182 780, mitogen-activated protein kinase kinase (MEK)1/2 inhibitor PD98059, and p38 mitogen-activated protein kinase inhibitor SB203580. We also found that AglyMax and genistein increased in cyclic AMP release and the expression of glycodelin protein in Ishikawa cells assayed using western blot and immunochemical staining. The MEK1/2 inhibitor PD98059 and the protein kinase A inhibitor H89, but not SB203580, attenuated this glycoprotein expression. Moreover, isoflavone aglycones AglyMax stimulated LIF, and TGF-β secretion, and glycodelin expression in separate primary endometrial epithelial cells in the follicular phase or luteal phase from healthy subject donors. Overall, our findings suggest that isoflavones may alter the uterine expression of estrogen-responsive genes.
Junhong Chen, Jing Sun, Michelle E Doscas, Jin Ye, Ashley J Williamson, Yanchun Li, Yi Li, Richard A Prinz, and Xiulong Xu
p70 S6 kinase (S6K1) is a serine/threonine kinase that phosphorylates the insulin receptor substrate-1 (IRS-1) at serine 1101 and desensitizes insulin receptor signaling. S6K1 hyperactivation due to overnutrition leads to hyperglycemia and type 2 diabetes. Our recent study showed that A77 1726, the active metabolite of the anti-rheumatoid arthritis (RA) drug leflunomide, is an inhibitor of S6K1. Whether leflunomide can control hyperglycemia and sensitize the insulin receptor has not been tested. Here we report that A77 1726 increased AKTS473/T308 and S6K1T389 phosphorylation but decreased S6S235/236 and IRS-1S1101 phosphorylation in 3T3-L1 adipocytes, C2C12 and L6 myotubes. A77 1726 increased insulin receptor tyrosine phosphorylation and binding of the p85 subunit of the PI-3 kinase to IRS-1. A77 1726 enhanced insulin-stimulated glucose uptake in L6 myotubes and 3T3-L1 adipocytes, and enhanced insulin-stimulated glucose transporter type 4 (GLUT4) translocation to the plasma membrane of L6 cells. Finally, we investigated the anti-hyperglycemic effect of leflunomide on ob/ob and high-fat diet (HFD)-induced diabetes mouse models. Leflunomide treatment normalized blood glucose levels and overcame insulin resistance in glucose and insulin tolerance tests in ob/ob and HFD-fed mice but had no effect on mice fed a normal chow diet (NCD). Leflunomide treatment increased AKTS473/T308 phosphorylation in the fat and muscle of ob/ob mice but not in normal mice. Our results suggest that leflunomide sensitizes the insulin receptor by inhibiting S6K1 activity in vitro, and that leflunomide could be potentially useful for treating patients with both RA and diabetes.
Jian-Ting Ke, Mi Li, Shi-Qing Xu, Wen-Jian Zhang, Yong-Wei Jiang, Lan-yun Cheng, Li Chen, Jin-Ning Lou, and Wei Wu
The efficacy of gliquidone for the treatment of diabetic nephropathy was investigated by implanting micro-osmotic pumps containing gliquidone into the abdominal cavities of Goto-Kakizaki (GK) rats with diabetic nephropathy. Blood glucose, 24 h urinary protein, and 24 h urinary albumin levels were measured weekly. After 4 weeks of gliquidone therapy, pathological changes in the glomerular basement membrane (GBM) were examined using an electron microscope. Real-time PCR, western blotting, and immunohistochemistry were employed to detect glomerular expression of receptors for advanced glycation end products (RAGE) (AGER), protein kinase C β (PKCβ), and protein kinase A (PKA) as well as tubular expression of the albumin reabsorption-associated proteins: megalin and cubilin. Human proximal tubular epithelial cells (HK-2 cells) were used to analyze the effects of gliquidone and advanced glycation end products (AGEs) on the expression of megalin and cubilin and on the absorption of albumin. Gliquidone lowered blood glucose, 24 h urinary protein, and 24 h urinary albumin levels in GK rats with diabetic nephropathy. The level of plasma C-peptide increased markedly and GBM and podocyte lesions improved dramatically after gliquidone treatment. Glomerular expression of RAGE and PKCβ decreased after gliquidone treatment, while PKA expression increased. AGEs markedly suppressed the expression of megalin and cubulin and the absorption of albumin in HK-2 cells in vitro, whereas the expression of megalin and cubilin and the absorption of albumin were all increased in these cells after gliquidone treatment. In conclusion, gliquidone treatment effectively reduced urinary protein in GK rats with diabetic nephropathy by improving glomerular lesions and promoting tubular reabsorption.
Shibin Ding, Ying Fan, Nana Zhao, Huiqin Yang, Xiaolei Ye, Dongliang He, Xin Jin, Jian Liu, Chong Tian, Hongyu Li, Shunqing Xu, and Chenjiang Ying
Epidemiological findings on the association between bisphenol A (BPA, 2,2-bis-(4-hydroxyphenyl)propane) exposure and type 2 diabetes mellitus (T2DM) are paradoxical. In animal studies, BPA has been shown to disrupt pancreatic function and blood glucose homeostasis even at a reference ‘safe’ level during perinatal period. In this study, we explored the effects of long-term paternal exposure to a ‘safe’ level of BPA on parents themselves and their offspring. Adult male genitor rats fed with either standard chow diet (STD) or high-fat diet (HFD) were treated respectively with either vehicle or BPA (50 μg/kg per day) for 35 weeks. The male rats treated with vehicle or BPA for 21 weeks were then used as sires, and the adult female rats were fed with STD during the gestation and lactation. Offspring rats were weaned on postnatal day 21 and fed with STD in later life. Metabolic parameters were recorded on the adult male rats and their adult offspring. BPA exposure disrupted glucose homeostasis and pancreatic function, and HFD aggravated these adverse effects. However, BPA exposure did not alter body weight, body fat percentage, or serum lipid. In addition, the paternal BPA exposure did not cause adverse reproductive consequence or metabolic disorder in the adult offspring. Our findings indicate that chronic exposure to a predicted ‘safe’ dose of BPA contributes to glucose metabolic disorders, and that HFD aggravates these adverse effects in paternal rats.