Hinze, Y. | Search bioRxiv

bioRxiv2021

P2Y6 receptor signaling in natural killer cells impairs insulin sensitivity in obesity

Natural killer (NK) cells contribute to the development of obesity-associated insulin resistance and have previously been shown to up-regulate the expression of the P2Y purinoreceptor 6 (P2Y6R) upon high fat diet (HFD)-induced obesity. Here, we reveal that NK cell-specific inactivation of the P2Y6R gene improves insulin sensitivity in obese mice and reduces the expression of chemokines in adipose tissue infiltrating NK-cells. Obese mice lacking P2Y6R specifically in NK cells exhibited a reduction in adipose tissue inflammation, exhibited improved insulin-stimulated suppression of lipolysis in adipose tissue and a reduction in hepatic glucose production, leading to an overall improvement of systemic insulin sensitivity. In contrast, myeloid lineage specific P2Y6R inactivation does not affect energy or glucose homeostasis in obesity. Collectively, we show that P2Y6R signaling in NK cells contributes to the development of obesity-associated insulin resistance and thus might be a future target for the treatment of obesity-associated insulin resistance and type 2 diabetes.

immunology↗

bioRxiv2020

Deregulated mito-nuclear communication alters chromatin plasticity and differentiation potential of mesenchymal stem cells upon ageing

Ageing is accompanied by a general decline in the function of many cellular pathways, with metabolic alterations, epigenetic modifications, and stem cell exhaustion representing three important hallmarks of the ageing process. However, whether these pathways are causally or functionally related at a molecular level remains poorly understood. Here, we use bone marrow-derived mesenchymal stem cells (MSCs) isolated from young and old mice to address how age-dependent changes in metabolism and epigenetics are linked and how they impact on the ageing transcriptome and differentiation potential. Given that MSCs maintain specific age-associated properties even under prolonged culture conditions, such as the age-dependent decrease in osteogenic differentiation, they are an excellent model to investigate in vitro the connection of ageing hallmarks on a mechanistic level. In this study, we demonstrate that upon ageing, osteogenic potential of MSCs declines as a consequence of deregulated mito-nuclear communication, mediated by decreased levels of the citrate carrier (CiC). Age-dependent down-regulation of CiC results in acetyl-CoA trapping within mitochondria, hypo-acetylation of histones and chromatin compaction. Together, these changes lead to an altered transcriptional output and are responsible for the reduced differentiation capacity into osteoblasts. Strikingly, short-term supplementation of aged cells with acetate, an exogenous source for cytosolic acetyl-CoA production, rescues not only the age-associated reduction of histone acetylation, but also the osteogenesis defect, representing a potential target for in vitro MSC rejuvenation.

cell biology↗