EP300 (p300) mediated histone butyrylation is critical for adipogenesis
ObjectiveThe master epigenetic enzyme EP300 (p300) besides having lysine acetyltransferase activity can also catalyse other acylation modifications (propionylation, butyrylation, crotonylation etc.), the physiological implications of which are yet to be established fully. We hypothesized that p300 catalysed histone butyrylation may have a causal relationship with adipogenesis and the consequent obesity. MethodsHistone butyrylation pattern was investigated in 3T3L1 cells upon adipogenesis by immunoblotting and chromatin immunoprecipitation experiments. A small molecule modulator that could specifically inhibit p300 catalysed butyrylation without affecting its canonical acetyltransferase activity was screened from a series of compounds and then administered in differentiating 3T3L1 adipocytes as well as high fat diet-induced and genetically obese mice to validate the importance of butyrylation in adipogenesis. ResultsHistone butyrylation was increased upon adipogenesis both globally and locally in the promoters of pro-adipogenic genes along with an upregulation in the expression of acyl CoA generating enzyme Acss2, knockdown of which led to reduced butyrylation. Treatment of differentiating 3T3L1 cells with the p300 specific butyrylation inhibitor LTK-14A led to abrogation of adipogenesis with reduced expression of pro-adipogenic genes and inhibition of H4K5 butyrylation. LTK-14A administration could also attenuate weight gain in both mice models of obesity by preventing adipocyte hypertrophy via H4K5 butyrylation inhibition. ConclusionOur results indicate that p300 catalysed histone butyrylation may have a causal relationship with the process of adipogenesis. Site specific inhibition of butyrylation could lead to adipogenesis repression and hence this epigenetic modification could be targeted for obesity treatment. HighlightsO_LIHistone butyrylation has been established as a new epigenetic signature in the context of adipogenesis. C_LIO_LITo the best of our knowledge, this is the first report of a selective inhibitor of p300 catalysed histone acylation (butyrylation) without affecting its canonical acetyltransferase activity. C_LIO_LISpecific inhibition of H4K5 butyrylation could be a possible mechanism for inhibiting adipogenesis and hepatic steatosis leading to better control of obesity. C_LIO_LILTK-14A class of molecule could be developed as anti-obesity therapeutics. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=195 HEIGHT=200 SRC="FIGDIR/small/454641v3_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@1f29b35org.highwire.dtl.DTLVardef@abc5fcorg.highwire.dtl.DTLVardef@1534388org.highwire.dtl.DTLVardef@176d706_HPS_FORMAT_FIGEXP M_FIG Proposed model for the role of p300-mediated histone butyrylation in adipogenesis: In pre-adipocytes, there exists a basal level of histone acetylation while butyrylation is present to a much lesser extent owing to low stoichiometric levels of butyryl CoA. Induction of adipogenesis causes a simultaneous upregulation of histone acetylation and butyrylation marks leading to increased rate of adipogenesis and concomitant transcriptional activation of pro-adipogeneic genes. Onset of obesity in mice, either due to excess energy intake through high fat diet consumption or increased de novo synthesis of fatty acids due to leptin receptor gene mutation leading to hyperphagic behavior, is accompanied by adipocyte hyperplasia and hypertrophy. Both the organs of adipose tissue and liver were found to have enhanced levels of H4K5 butyrylation during obesity. LTK-14A, a butyrylation specific inhibitor could efficiently prevent the processes of adipogenesis and adipocyte hypertrophy due to inhibition of H4K5 butyrylation in these organs. Thus the compound could attenuate weight gain by selective inhibition of butyrylation without affecting acetylation, thereby highlighting the importance of histone butyrylation in adipogenesis and obesity. C_FIG