Papadaki, H. | bioRxiv Science

bioRxiv2022

Glucagon-like peptide-1 receptor in the human hypothalamus is associated with body mass index and colocalizes with the anorexigenic neuropeptide nucleobindin-2/nesfatin-1.

IntroductionGlucagon-like peptide-1 (GLP-1) anorexigenic and anti-obesogenic effects are centrally mediated. Data on animals emphasize the importance of neuronal GLP-1 receptor (GLP-1R) for feeding suppression, although it is unclear whether astrocytes participate in the transduction of anorectic GLP-1R-dependent signals. In humans, the brain circuitry underlying these effects remains insufficiently investigated. GLP-1R neuroanatomic localization in human hypothalamus, a brain region with a pivotal role in energy homeostasis regulation, is essential in order to improve our understanding of GLP-1 signaling pathways and central metabolic functions. The present study aimed to explore GLP-1R protein expression in human hypothalamus and its correlation with body mass index (BMI). MethodsSections of hypothalamus from 28 autopsy cases, 11 with normal weight (BMI < 25 Kg/m2) and 17 with non-normal weight (BMI [≥] 25 Kg/m2), were examined using immunohistochemistry and double immunofluorescence labeling. ResultsProminent GLP-1R immunoexpression was detected in neurons of several hypothalamic nuclei, including paraventricular, supraoptic, and infundibular nuclei, lateral hypothalamic area (LH), and basal forebrain nuclei. Interestingly, in LH, GLP-1R protein expression was significantly decreased in individuals with BMI [≥] 25 Kg/m2, compared with normal weight counterparts (p=0.03). Furthermore, GLP-1R was moderately and negatively correlated ({tau}b=-0.347, p=0.024) with BMI levels only in the LH. GLP-1R extensively colocalized with the anorexigenic and anti-obesogenic neuropeptide nucleobindin-2/nesfatin-1, but not with the astrocytic marker glial fibrillary acidic protein (GFAP). ConclusionThese data suggest a potential role for GLP-1R in the regulation of energy balance in human hypothalamus, possibly through interactions with nesfatin-1. In LH, an appetite- and reward-related brain region, reduced GLP-1R immunoexpression may contribute to dysregulation of homeostatic and/or hedonic feeding behavior. GLP-1R colocalization with nesfatin-1 in the basal forebrain, a cognition-related brain area, might give impetus towards elucidating additional central actions of GLP-1R.

neuroscience↗

bioRxiv2020

KRAS signalling in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) arises from mesothelial cells lining the pleural cavity of asbestos-exposed individuals and rapidly leads to the development of pleural effusion and death. MPM harbours loss-of-function mutations in genes like BAP1, NF2, CDKN2A, and TP53, but isolated deletion of these genes alone in mice does not cause MPM and mouse models of the disease are sparse. Here we show that a significant proportion of human MPM harbour point mutations and copy number alterations in the KRAS proto-oncogene. These mutations are likely pathogenic, since ectopic expression of mutant KRASG12D in the pleural mesothelium of conditional mice causes MPM. Murine MPM cell lines derived from these tumours carry the initiating KRASG12D lesions, secondary Bap1 alterations, and human MPM-like gene expression profiles. Moreover, they are transplantable and actionable by KRAS inhibition. Our results indicate that KRAS mutations likely play an important and underestimated role in MPM, which warrants further exploration.

physiology↗