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Biological Activities of a New Crotamine-like Peptide from Crotalus oreganus helleri on C2C12 and CHO Cell Lines, and Ultrastructural Changes on Motor Endplate and Striated Muscle

Salazar  et al., Toxicon. 2020.

https://pubmed.ncbi.nlm.nih.gov/33065200/

Crotamine and crotamine-like peptides are non-enzymatic polypeptides found in high concentration in the Crotalus genus venom. Helleramine was isolated and purified from the venom of the rattlesnake, Crotalus oreganus helleri. Purified helleramine increased intracellular Ca2+ in Chinese Hamster Ovary (CHO) cell line, inhibited cell viability of C2C12 (immortalized skeletal myoblast) and promoted early apoptosis and cell death. Skeletal muscle harvested from mice 24 hours after helleramine injection showed contracted myofibrils and profound vacuolization, with loss of plasmatic and basal membrane integrity. The effects of helleramine provide evidence of myotoxic activities of crotamine-like peptides and their possible role in crotalid envenoming. Supported by ORIP (P40OD010960).

Lipocalin-2 Is an Anorexigenic Signal in Primates

Petropoulou et al., eLife. 2020.

https://doi.org/10.7554/eLife.58949

The hormone lipocalin-2 (LCN2) suppresses food intake in mice. Researchers demonstrated that LCN2 increases after a meal and reduces hunger in people with normal weight or overweight, but not in obese individuals. The researchers also showed that LCN2 crosses the blood-brain barrier and binds to the hypothalamus in vervet monkeys. LCN2 was found to bind to the hypothalamus in human, baboon, and rhesus macaque brain sections. When injected into vervets, LCN2 suppressed food intake and lowered body weight without toxic effects in short-term experiments. These findings lay the groundwork to investigate whether LCN2 might be a useful treatment for obesity. Supported by ORIP (P40OD010965), NCATS, NIDDK, NIA, and NHLBI.

Fructose Stimulated De Novo Lipogenesis Is Promoted by Inflammation

Jelena  et al., Nature Metabolism. 2020.

https://pubmed.ncbi.nlm.nih.gov/32839596

Non-alcoholic fatty liver disease (NAFD) affects 30% of adult Americans. While NAFD starts as simple steatosis with little liver damage, its severe manifestation as non-alcoholic steatohepatitis (NASH) is a leading cause of liver failure, cirrhosis, and cancer. Fructose consumption is proposed to increase the risk of hepatosteatosis and NASH. Excessive intake of fructose causes barrier deterioration and low-grade endotoxemia. Using a mouse model, the study examined the mechanism of how fructose triggers these alterations and their roles in hepatosteatosis and NASH pathogenesis. The results demonstrated that microbiota-derived Toll-like receptor (TLR) agonists promote hepatosteatosis without affecting fructose-1-phosphate (F1P) and cytosolic acetyl-CoA. Activation of mucosal-regenerative gp130 signaling, administration of the YAP-induced matricellular protein CCN1 or expression of the antimicrobial peptide Reg3b (beta) counteract fructose-induced barrier deterioration, which depends on endoplasmic-reticulum stress and subsequent endotoxemia. Endotoxin engages TLR4 to trigger TNF production by liver macrophages, thereby inducing lipogenic enzymes that convert F1P and acetyl-CoA to fatty acid in both mouse and human hepatocytes. The finding may be of relevance to several common liver diseases and metabolic disorders. Supported by ORIP (S10OD020025), NCI, NIEHS, NIDDK, NIAID, and NIAAA.