Project description:As ambush-hunting predators that consume large prey after long intervals of fasting, Burmese pythons evolved with unique adaptations for regulating organ structure and function. Among these is cardiac hypertrophy that develops within three days following a meal (1, 2), which we previously showed was initiated by circulating growth factors (3). Post-prandial cardiac hypertrophy in pythons also rapidly regresses with subsequent fasting (2); however, the molecular mechanisms that regulate the dynamic cardiac remodeling in pythons during digestion are largely unknown. In this study, we employed a multi-omics approach coupled with targeted molecular analyses to examine remodeling of the python ventricular transcriptome and proteome throughout digestion. We found that forkhead box protein O1 (FoxO1) signaling was suppressed prior to hypertrophy development and then activated with regression, which coincided with decreased and then increased expression, respectively, of FoxO1 transcriptional targets involved in protein degradation. To define the molecular mechanistic role of FoxO1 in hypertrophy regression, we used cultured mammalian cardiomyocytes treated with post-fed python plasma. Hypertrophy regression both in pythons and in vitro coincided with activation of FoxO1-dependent autophagy; however, introduction of a FoxO1-specific inhibitor prevented both regression of cell size and autophagy activation. Finally, to determine if FoxO1 activation could induce regression, we generated an adenovirus expressing a constitutively active FoxO1. FoxO1 activation was sufficient to prevent and reverse post-fed plasma-induced hypertrophy, which was partially prevented by autophagy inhibition. Our results indicate that modulation of FoxO1 activity contributes to the dynamic ventricular remodeling in post-prandial Burmese pythons.
Project description:As ambush-hunting predators that consume large prey after long intervals of fasting, Burmese pythons evolved with unique adaptations for regulating organ structure and function. Among these is cardiac hypertrophy that develops within three days following a meal (1, 2), which we previously showed was initiated by circulating growth factors (3). Post-prandial cardiac hypertrophy in pythons also rapidly regresses with subsequent fasting (2); however, the molecular mechanisms that regulate the dynamic cardiac remodeling in pythons during digestion are largely unknown. In this study, we employed a multi-omics approach coupled with targeted molecular analyses to examine remodeling of the python ventricular transcriptome and proteome throughout digestion. We found that forkhead box protein O1 (FoxO1) signaling was suppressed prior to hypertrophy development and then activated with regression, which coincided with decreased and then increased expression, respectively, of FoxO1 transcriptional targets involved in protein degradation. To define the molecular mechanistic role of FoxO1 in hypertrophy regression, we used cultured mammalian cardiomyocytes treated with post-fed python plasma. Hypertrophy regression both in pythons and in vitro coincided with activation of FoxO1-dependent autophagy; however, introduction of a FoxO1-specific inhibitor prevented both regression of cell size and autophagy activation. Finally, to determine if FoxO1 activation could induce regression, we generated an adenovirus expressing a constitutively active FoxO1. FoxO1 activation was sufficient to prevent and reverse post-fed plasma-induced hypertrophy, which was partially prevented by autophagy inhibition. Our results indicate that modulation of FoxO1 activity contributes to the dynamic ventricular remodeling in post-prandial Burmese pythons.
Project description:We report an ex vivo kinome-wide RNAi screen in Drosophila aimed to identify cell signaling genes that facilitate trxG to counteract PcG mediated repression. From the list of trxG candidates, Ballchen (BALL), a histone kinase, known to phosphorylate histone H2A at threonine 119 (H2AT119p), was characterized as a trxG regulator. BALL co-localizes with Trithorax on chromatin and depletion of BALL results in increased H2AK118 ubiquitination, a histone mark central to PcG mediated gene silencing. Moreover, analysis of genome-wide binding profile of BALL shows an overlap with 85% known binding sites of TRX across the genome. Both BALL and TRX are highly enriched at actively transcribed genes, which also correlate with presence of H3K4me3 and H3K27ac. We propose that BALL mediated signal positively contributes to the maintenance of gene activation by trxG by counteracting the repressive effect of PcG.
Project description:Background: Exceptional and extreme feeding behaviour makes the Burmese python (Python bivittatus) an interesting model to study physiological remodelling and metabolic adaptation in response to refeeding after prolonged starvation. In this study, we used transcriptome sequencing of five visceral organs during fasting as well as 24h and 48h after ingestion of a large meal to unravel the postprandial changes in Burmese pythons. We first used the pooled data to perform a de novo assembly of the transcriptome and supplemented this with a proteomic survey of enzymes in the plasma and gastric fluid. Results: We constructed a high-quality transcriptome with 34,423 transcripts of which 19,713 (57%) were annotated. Among highly expressed genes (FPKM>100 in one tissue) we found the transition from fasting to digestion was associated with differential expression of 43 genes in the heart, 206 genes in the liver, 114 genes in the stomach, 89 genes in the pancreas and 158 genes in the intestine. We interrogated the function of these genes to test previous hypotheses on the response to feeding. We also used the transcriptome to identify 314 secreted proteins in the gastric fluid of the python Conclusions: Digestion was associated with an upregulation of genes related to metabolic processes, and translational changes therefore appears to support the postprandial rise in metabolism. We identify stomach-related proteins from a digesting individual and demonstrate that the sensitivity of modern LC-MS/MS equipment allows the identification of gastric juice proteins that are present during digestion.