Palmitic acid induces ß-cell ferroptosis by activating ceramide signaling pathway.

Individuals with type 2 diabetes mellitus frequently display heightened levels of palmitic acid (PA) in their serum, which may lead to ß-cell damage. The involvement of ferroptosis, a form of oxidative cell death in lipotoxic ß-cell injury remains uncertain. Here, we have shown that PA induces intracellular lipid peroxidation, increases intracellular Fe2+ content and decreases intracellular glutathione peroxidase 4 (GPX4) expression. Furthermore, PA causes distinct changes in pancreatic islets and INS-1 cells, such as mitochondrial atrophy and increased membrane density. Furthermore, the presence of the ferroptosis inhibitor has a significant mitigating effect on PA-induced ß-cell damage. Mechanistically, PA increased ceramide content and c-Jun N-terminal kinase (JNK) phosphorylation. The ceramide synthase inhibitor effectively attenuated PA-induced ß-cell damage and GPX4/Fe2+ abnormalities, while inhibiting JNK phosphorylation. Additionally, the JNK inhibitor SP600125 improved PA-induced cell damage. In conclusion, by promoting ceramide synthesis, PA inhibited GPX4 expression and increased intracellular Fe2+ to induce ß-cell ferroptosis. Moreover, JNK may be a downstream mechanism of ceramide-triggered lipotoxic ferroptosis in ß-cells.

A Bat-Derived Putative Cross-Family Recombinant Coronavirus with a Reovirus Gene.

The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002 and Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 has generated enormous interest in the biodiversity, genomics and cross-species transmission potential of coronaviruses, especially those from bats, the second most speciose order of mammals. Herein, we identified a novel coronavirus, provisionally designated Rousettus bat coronavirus GCCDC1 (Ro-BatCoV GCCDC1), in the rectal swab samples of Rousettus leschenaulti bats by using pan-coronavirus RT-PCR and next-generation sequencing. Although the virus is similar to Rousettus bat coronavirus HKU9 (Ro-BatCoV HKU9) in genome characteristics, it is sufficiently distinct to be classified as a new species according to the criteria defined by the International Committee of Taxonomy of Viruses (ICTV). More striking was that Ro-BatCoV GCCDC1 contained a unique gene integrated into the 3'-end of the genome that has no homologs in any known coronavirus, but which sequence and phylogeny analyses indicated most likely originated from the p10 gene of a bat orthoreovirus. Subgenomic mRNA and cellular-level observations demonstrated that the p10 gene is functional and induces the formation of cell syncytia. Therefore, here we report a putative heterologous inter-family recombination event between a single-stranded, positive-sense RNA virus and a double-stranded segmented RNA virus, providing insights into the fundamental mechanisms of viral evolution.

Neutral ceramidase activity inhibition is involved in palmitate-induced apoptosis in INS-1 cells.

Neutral ceramidase (NCDase) is a class of ceramidases, a key enzyme in ceramide degradation. Recently, it was observed that NCDase activity was suppressed by saturated fatty acids to increase ceramide content in rat muscle. However, little is known about its changes in activity and roles in palmitate (Palm)-induced lipotoxicity in pancreatic ß cells. Here, we demonstrated that Palm treatment significantly down-regulated NCDase activity, mRNA and protein levels in rat INS-1 cells. In addition, Palm caused a significant accumulation of ceramide, while SPH level remained unchanged, suggesting that inhibition of NCDase activity led to no change of SPH level after treatment with Palm for 24 h. Furthermore, NCDase overexpression significantly reduced Palm-induced apoptosis in INS-1 cells. Conversely, NCDase siRNA knockdown markedly exacerbated Palm-induced apoptosis. In conclusion, Palm treatment suppressed the activity of NCDase and down-regulated its mRNA and protein expression. Furthermore, NCDase inhibition was involved in Palm-induced apoptosis by blocking ceramide degradation in INS-1 cells.

The prevalence, awareness, management and influencing factors of diabetes in middle-aged and elderly in China, evidence from the CHARLS in 2015.

Diabetes seriously affects the health of middle-aged and elderly. What we can do is to suppress the progression and avoid complications of diabetes. The aim of this study was to evaluate the prevalence, management and influencing factors in middle-aged and elderly diabetics. The data used in our study came from the follow-up survey (2015) of China Health and Retirement Longitudinal Study. After all the questionnaire data of participants was acquired, the first screening step was conducted and the participants without blood glucose or glycosylated hemoglobin test results were excluded. In the second screening step, participants without self-reported diabetes, age <45 were excluded. After data screening, STATA 16.0 software (StataCorp, USA) was used to conduct statistical analysis. Multiple logistics regression was used to analyze the influencing factors of diabetes in middle-aged and elderly. After data screening, A total of 9738 participants were enrolled in the survey of the China Health and Retirement Longitudinal Study in 2015, including diabetes 1965 and control 7773. The prevalence of diabetes in age >60 (22.20%) was significantly higher than that in age 45 to 60 (16.60%). Age, residence, physical activity, drinking, smoking and body mass index were key influencing factors according to the results of logistics regression. 46.92% diabetics were diagnosed in hospital, 22.14% were diagnosed by community medical care. 1298 among 1965 diabetes patients had standardized medication to control blood glucose, the rate was only 66.01%. The awareness rate of diabetes was only 28.75%, and the monitoring, treatment and accepting medical advice rates were 68.32%, 66.01% and 56.99% separately. The follow-up rate of diabetes was only 14.16%. Diabetes is widely prevalent in the middle-aged and elderly with the prevalence of 16.60% in the participants with age 45 to 60. The rate of self-rated diabetics underestimated the true prevalence of diabetes. Age, residence, physical activity, drinking, smoking and body mass index are key influencing factors to diabetes. Although a national diabetes health management model has been established, the awareness of diabetes was only 28.75%. Standardized diabetes registration and regular follow up should also be strictly implemented.

Low-grade elevation of palmitate and lipopolysaccharide synergistically induced ß-cell damage via inhibition of neutral ceramidase.

High concentrations of free fatty acids (FFAs) or lipopolysaccharide (LPS) could lead to ß-cell apoptosis and dysfunction, while low-grade elevation of FFAs or LPS, which are more common in people with type 2 diabetes mellitus (T2DM) or obesity, have no obvious toxic effect on ß-cells. Palmitate is a component closely related to metabolic disorders in FFAs. Recent studies have found that low-grade elevation of palmitate and LPS synergistically affects the sphingolipid signaling pathway by activating Toll-like receptor 4 (TLR4) and further enhances the expression of inflammatory cytokines in immune cells. Previous studies demonstrated that sphingolipids also played an important role in the occurrence and development of T2DM. This study aimed to investigate the synergistic effects of low-grade elevation of palmitate and LPS on viability, apoptosis and insulin secretion in the rat pancreatic ß-cell line INS-1 or islets and the role of sphingolipids in this process. We showed that low-grade elevation of palmitate or LPS alone did not affect the viability, apoptosis, glucose-stimulated insulin secretion (GSIS) or intracellular insulin content of INS-1 cells or islets, while the combination of the two synergistically inhibited cell viability, induced apoptosis and decreased basal insulin secretion in INS-1 cells or islets. Treatment with palmitate and LPS markedly upregulated TLR4 protein expression and downregulated neutral ceramidase (NCDase) activity and protein expression. Additionally, low-grade elevation of palmitate and LPS synergistically induced a significant increase in ceramide and a decrease in sphingosine-1-phosphate. Blocking TLR4 signaling or overexpressing NCDase remarkably attenuated INS-1 cell injury induced by the combination of palmitate and LPS. However, inhibition of ceramide synthase did not ameliorate injury induced by palmitate and LPS. Overall, we show for the first time that low-grade elevation of palmitate and LPS synergistically induced ß-cell damage by activating TLR4 signaling, inhibiting NCDase activity, and further modulating sphingolipid metabolism, which was different from a high concentration of palmitate-induced ß-cell injury by promoting ceramide synthesis.