CD38 deficiency suppresses adipogenesis and lipogenesis in adipose tissues through activating Sirt1/PPARγ signaling pathway.

It has been recently reported that CD38 was highly expressed in adipose tissues from obese people and CD38-deficient mice were resistant to high-fat diet (HFD)-induced obesity. However, the role of CD38 in the regulation of adipogenesis and lipogenesis is unknown. In this study, to explore the roles of CD38 in adipogenesis and lipogenesis in vivo and in vitro, obesity models were generated with male CD38-/- and WT mice fed with HFD. The adipocyte differentiations were induced with MEFs from WT and CD38-/- mice, 3T3-L1 and C3H10T1/2 cells in vitro. The lipid accumulations and the alternations of CD38 and the genes involved in adipogenesis and lipogenesis were determined with the adipose tissues from the HFD-fed mice or the MEFs, 3T3-L1 and C3H10T1/2 cells during induction of adipocyte differentiation. The results showed that CD38-/- male mice were significantly resistant to HFD-induced obesity. CD38 expressions in adipocytes were significantly increased in WT mice fed with HFD, and the similar results were obtained from WT MEFs, 3T3-L1 and C3H10T1/2 during induction of adipocyte differentiation. The expressions of PPARγ, AP2 and C/EBPα were markedly attenuated in adipocytes from HFD-fed CD38-/- mice and CD38-/- MEFs at late stage of adipocyte differentiation. Moreover, the expressions of SREBP1 and FASN were also significantly decreased in CD38-/- MEFs. Finally, the CD38 deficiency-mediated activations of Sirt1 signalling were up-regulated or down-regulated by resveratrol and nicotinamide, respectively. These results suggest that CD38 deficiency impairs adipogenesis and lipogenesis through activating Sirt1/PPARγ-FASN signalling pathway during the development of obesity.

Dihydroergotamine ameliorates liver fibrosis by targeting transforming growth factor ß type II receptor.

BACKGROUND: The transforming growth factor ß (TGFß) signaling pathway plays a crucial role in the development of liver fibrosis by activating TGFß type II receptor (TGFßR2), followed by the recruitment of TGFßR1 finally triggering downstream signaling pathway. AIM: To find drugs targeting TGFßR2 that inhibit TGFßR1/TGFßR2 complex formation, theoretically inhibit TGFß signaling pathway, and thereby ameliorate liver fibrosis. METHODS: Food and Drug Administration-approved drugs were screened for binding affinity with TGFßR2 by virtual molecular docking. We identified 6 candidates and further explored their potential by Cell Counting Kit-8 (CCK-8) cell cytotoxic experiment to validate toxicity and titrated the best cellular working concentrations. Next, we further demonstrated the detailed molecular working mechanisms using mutagenesis analysis. Finally, we used a mouse model to investigate its potential anti-liver fibrosis effect. RESULTS: We identified 6 drug candidates. Among these 6 drugs, dihydroergotamine (DHE) shows great ability in reducing fibrotic gene expressions such as collagen, p-SMAD3, and α-SMA in TGFß induced cellular model of liver fibrosis in LX-2 cells. Furthermore, we demonstrated that DHE binds to TGFßR2. Moreover, mutation of Leu27, Phe30, Thr51, Ser52, Ile53, and Glu55 of TGFßR2 disrupted the binding of TGFßR2 with DHE. In addition, DHE significantly improved liver fibrosis, as evidenced by Masson's trichrome staining of liver sections. This is further supported by the width and the velocity of the portal vein, and serum markers of liver function. In line with those observations, DHE also decreased macrophages infiltration and extracellular matrix deposition in the liver. CONCLUSION: DHE alleviates liver fibrosis by binding to TGFßR2 thereby suppressing TGFß signaling pathway. We show here that as far as drug repurposing, DHE has great potential to treat liver fibrosis.

ACE2 pathway regulates thermogenesis and energy metabolism.

Identification of key regulators of energy homeostasis holds important therapeutic promise for metabolic disorders, such as obesity and diabetes. ACE2 cleaves angiotensin II (Ang II) to generate Ang-(1-7) which acts mainly through the Mas1 receptor. Here, we identify ACE2 pathway as a critical regulator in the maintenance of thermogenesis and energy expenditure. We found that ACE2 is highly expressed in brown adipose tissue (BAT) and that cold stimulation increases ACE2 and Ang-(1-7) levels in BAT and serum. Ace2 knockout mice (Ace2-/y) and Mas1 knockout mice (Mas1-/-) displayed impaired thermogenesis. Mice transplanted with brown adipose tissue from Mas1-/- display metabolic abnormalities consistent with those seen in the Ace2 and Mas1 knockout mice. In contrast, impaired thermogenesis of Leprdb/db obese diabetic mice and high-fat diet-induced obese mice were ameliorated by overexpression of Ace2 or continuous infusion of Ang-(1-7). Activation of ACE2 pathway was associated with improvement of metabolic parameters, including blood glucose, lipids, and energy expenditure in multiple animal models. Consistently, ACE2 pathway remarkably enhanced the browning of white adipose tissue. Mechanistically, we showed that ACE2 pathway activated Akt/FoxO1 and PKA pathway, leading to induction of UCP1 and activation of mitochondrial function. Our data propose that adaptive thermogenesis requires regulation of ACE2 pathway and highlight novel potential therapeutic targets for the treatment of metabolic disorders.

Population genomics reveals that natural variation in PRDM16 contributes to cold tolerance in domestic cattle.

Environmental temperature serves as a major driver of adaptive changes in wild organisms. To discover the mechanisms underpinning cold tolerance in domestic animals, we sequenced the genomes of 28 cattle from warm and cold areas across China. By characterizing the population structure and demographic history, we identified two genetic clusters, i.e., northern and southern groups, as well as a common historic population peak at 30 kilo years ago. Genomic scan of cold-tolerant breeds determined potential candidate genes in the thermogenesis-related pathways that were under selection. Specifically, functional analysis identified a substitution of PRDM16 (p.P779L) in northern cattle, which maintains brown adipocyte formation by boosting thermogenesis-related gene expression, indicating a vital role of this gene in cold tolerance. These findings provide a basis for genetic variation in domestic cattle shaped by environmental temperature and highlight the role of reverse mutation in livestock species.

Secretion of inhibin during the estrous cycle in the female Asian elephant (Elephas maximus).

To define the source of circulating inhibin in female Asian elephants, the immunolocalizations of the inhibin α, ß(A) and ß(B) subunits, 3ß-hydroxysteroid dehydrogenase (3ß-HSD), aromatase cytochrome P450 (P450arom) and cytochrome 17α-hydroxylase P450 (P450 c17) were investigated. Concentrations of immunoreactive (ir-) inhibin, progesterone and follicle-stimulating hormone (FSH) during the estrous cycle were measured by radioimmunoassay. Inhibin immunoreactivity in follicular fluid and homogenate of corpora lutea was also measured. Immunolocalizations of inhibin subunits, 3ß-HSD, P450arom and P450c17 were detected in the granulosa cells of antral follicles and luteal cells. The follicular fluid contained high levels of ir-inhibin and bioactive inhibin. The homogenate of corpora lutea also contained ir-inhibin. Serum ir-inhibin remained at low levels during the early non-luteal phase, began to increase from the late non-luteal phase and continued to increase during the early luteal phase. Serum ir-inhibin showed maximal levels in the middle of the luteal phase and gradually decreased to baseline three weeks prior to progesterone decline. The serum ir-inhibin levels were positively correlated with progesterone throughout the estrous cycle. On the other hand, ir-inhibin was negatively correlated with FSH during the late non-luteal and early luteal phases. These findings strongly suggest that the corpus luteum is one of the sources of inhibin as well as granulosa cells in the Asian elephant.

Effects of hypothyroidism on gonadal function after transition of short day photoperiod in male golden hamsters (Mesocricetus auratus).

Thyroid hormones permit the annual reproductive transition of seasonal breeders. Although, precise function of thyroid hormones in seasonal breeding is not well understood. In the present study, we examined effects of hypothyroidism on the hypothalamus-pituitary-gonadal axis in adult male golden hamsters after transition of the short-day photoperiod (SD; 8 h light: 16 h dark) condition. We confirmed that hypothyroid, which had been induced by administration of thiouracil in drinking water for 4 weeks, did not have direct effects on testes in male hamsters under the long-day photoperiod. Plasma concentrations of free T3 and T4 decreased 15 weeks after transition of SD condition. Plasma concentrations of testosterone in the hypothyroid group decreased earlier than in the control group after the transition from LD to SD. In animals treated with testosterone after castration, plasma concentrations of LH in the hypothyroid group decreased earlier than in the control group after the transition of SD. On the other hand, pituitary response to GnRH for LH release did not change in castrated hamsters as a result of hypothyroidism. These results suggest that thyroid hormones act the hypothalamus and might be required to maintain GnRH secretion in male golden hamsters.