Biology subjects

Davidson, G.

Publications and source records attributed to Davidson, G..

21 records · Page 2Linked to original sources

bioRxiv2020

The TFIID subunit Taf4 is required for pancreatic beta cell function and identity.

We selectively inactivated the Taf4 subunit of general transcription factor TFIID in adult murine pancreatic beta cells (BCs). Taf4 inactivation rapidly diminishes expression of critical genes involved in BC function leading to increased glycaemia, lowered plasma insulin levels, defective glucose-stimulated insulin secretion and in the longer term reduced BC mass through apoptosis of a subpopulation of BCs. Nevertheless, glycaemia and blood insulin levels are stabilised after 11 weeks with mutant animals showing long term survival. Bulk RNA-seq and ATAC-seq together with single cell RNA-seq on isolated Langerhans islets show that Taf4 loss leads to a remodelling of chromatin accessibility and gene expression not only in targeted BCs, but also alpha and delta cells. One week after Taf4-loss, cells with mixed BC, alpha and/or delta cell identities were observed as well as a BC population trans-differentiating into alpha-like cells. Computational analysis defines how known critical BC and alpha cell determinants may act in combination with additional transcription factors and the NuRF chromatin remodelling complex to promote BC trans-differentiation.

cell biology↗

bioRxiv2019

Diet-induced changes to host gut microbiota are linked to foraging innovation in a wild bird.

The microbial community in the gut is influenced by environmental factors, especially diet, which can moderate host behaviour through the microbiome-gut-brain axis. However, the ecological relevance of microbiome-mediated behavioural plasticity in wild animals is unknown. We presented wild-caught great tits (Parus major) with a problem-solving task and showed that performance was weakly associated with variation in the gut microbiome. We then manipulated the gut microbiome by feeding birds one of two diets that differed in their relative levels of fat, protein and fibre content: an insect diet (low content), or a seed diet (high content). Microbial communities were less diverse among individuals given the insect compared to those on the seed diet. Individuals were less likely to problem-solve after being given the insect diet, and the same microbiota metrics that were altered as a consequence of diet were also those that correlated with variation in problem solving performance. Although the effect on problem-solving behaviour could have been caused by motivational or nutritional differences between our treatments, our results nevertheless raise the possibility that dietary induced changes in the gut microbiota could be an important mechanism underlying individual behavioural plasticity in wild populations.

ecology↗

bioRxiv2019

CHD4 regulates PADI1 and PADI3 expression linking pyruvate kinase M2 citrullination to glycolysis and proliferation.

CHD3 and CHD4 are mutually exclusive ATPase subunits of the Nucleosome Remodelling and Deacetylation (NuRD) complex that regulates gene expression. CHD4 is essential for growth of multiple patient derived melanoma xenografts and for breast cancer. Here we show that CHD4 regulates expression of PADI1 (Protein Arginine Deiminase 1) and PADI3 in multiple cancer cell types modulating citrullination of three arginines of the allosterically-regulated glycolytic enzyme pyruvate kinase M2 (PKM2). Citrullination reprograms cross-talk between PKM2 ligands lowering its sensitivity to the inhibitors Tryptophan, Alanine and Phenylalanine and promoting activation by Serine. Citrullination thus bypasses normal physiological regulation by low Serine levels to promote excessive glycolysis defining a novel pathway regulating proliferation of melanoma and other cancer cells. We provide unique insight as to how conversion of arginines to citrulline impacts key interactions within PKM2 that act in concert to reprogram its activity as an additional mechanism regulating this important enzyme.

cancer biology↗