Deleting the ribosomal prolyl hydroxylase OGFOD1 protects mice against diet-induced obesity and insulin resistance.

Type 2 diabetes predisposes patients to heart disease, which is the primary cause of death across the globe. Type 2 diabetes often accompanies obesity and is defined by insulin resistance and abnormal glucose handling. Insulin resistance impairs glucose uptake and results in hyperglycemia, which damages tissues such as kidneys, liver, and heart. 2-oxoglutarate (2-OG)- and iron-dependent oxygenases (2-OGDOs), a family of enzymes regulating various aspects of cellular physiology, have been studied for their role in obesity and diet-induced insulin resistance. However, nothing is known of the 2-OGDO family member 2-oxoglutarate and iron-dependent prolyl hydroxylase domain containing protein 1 (OGFOD1) in this setting. OGFOD1 deletion leads to protection in cardiac ischemia-reperfusion injury and cardiac hypertrophy, which are two cardiac events that can lead to heart failure. Considering the remarkable correlation between heart disease and diabetes, the cardioprotection observed in OGFOD1-knockout mice led us to challenge these knockouts with high-fat diet. Wildtype mice fed a high-fat diet developed diet-induced obesity, insulin resistance, and glucose intolerance, but OGFOD1 knockout mice fed this same diet were resistant to diet-induced obesity and insulin resistance. These results support OGFOD1 down-regulation as a strategy for preventing obesity and insulin handling defects.

OGFOD1 modulates the transcriptional and proteomic landscapes to alter isoproterenol-induced hypertrophy susceptibility.

Cardiac hypertrophy is associated with increased translation. However, little is known of the mechanisms that regulate translation in hypertrophy. Members of the 2-oxoglutarate-dependent dioxygenase family regulate several aspects of gene expression, including translation. An important member of this family is OGFOD1. Here, we show OGFOD1 accumulates in failing human hearts. Upon OGFOD1 deletion, murine hearts showed transcriptomic and proteomic changes, with only 21 proteins and mRNAs (0.6%) changing in the same direction. Additionally, OGFOD1-KO mice were protected from induced hypertrophy, supporting a role for OGFOD1 in the cardiac response to chronic stress.

Ogfod1 deletion increases cardiac beta-alanine levels and protects mice against ischaemia- reperfusion injury.

AIMS: Prolyl hydroxylation is a post-translational modification that regulates protein stability, turnover, and activity. The proteins that catalyze prolyl hydroxylation belong to the 2-oxoglutarate- and iron-dependent oxygenase family of proteins. 2-oxoglutarate- and iron-dependent oxygenase domain-containing protein 1 (Ogfod1), which hydroxylates a proline in ribosomal protein s23 is a newly described member of this family. The aims of this study were to investigate roles for Ogfod1 in the heart, and in the heart's response to stress. METHODS AND RESULTS: We isolated hearts from wild-type (WT) and Ogfod1 knockout (KO) mice and performed quantitative proteomics using tandem mass Tag labelling coupled to liquid chromatography and tandem mass spectrometry (LC-MS/MS) to identify protein changes. Ingenuity pathway analysis identified 'Urate Biosynthesis/Inosine 5'-phosphate Degradation' and 'Purine Nucleotides Degradation II (Aerobic)' as the most significantly enriched pathways. We performed metabolomics analysis and found that both purine and pyrimidine pathways were altered with the purine nucleotide inosine 5'-monophosphate showing a 3.5-fold enrichment in KO hearts (P = 0.011) and the pyrimidine catabolism product beta-alanine showing a 1.7-fold enrichment in KO hearts (P = 0.014). As changes in these pathways have been shown to contribute to cardioprotection, we subjected isolated perfused hearts to ischaemia and reperfusion (I/R). KO hearts showed a 41.4% decrease in infarct size and a 34% improvement in cardiac function compared to WT hearts. This protection was also evident in an in vivo I/R model. Additionally, our data show that treating isolated perfused WT hearts with carnosine, a metabolite of beta-alanine, improved protection in the context of I/R injury, whereas treating KO hearts with carnosine had no impact on recovery of function or infarct size. CONCLUSIONS: Taken together, these data show that Ogfod1 deletion alters the myocardial proteome and metabolome to confer protection against I/R injury.

High Frequency of Ovarian Cyst Development in Vhl2B/+;Snf5+/- Mice.

The new paradigm of mutations in chromatin-modifying genes as driver events in the development of cancers has proved challenging to resolve the complex influences over disease phenotypes. In particular, impaired activities of members of the SWI/SNF chromatin remodeling complex have appeared in an increasing variety of tumors. Mutations in SNF5, a member of this ubiquitously expressed complex, arise in almost all cases of malignant rhabdoid tumor in the absence of additional genetic alterations. Therefore, we studied how activation of additional oncogenic pathways might shift the phenotype of disease driven by SNF5 loss. With the use of a genetically engineered mouse model, we examined the effects of a hypomorphic Vhl2B allele on disease phenotype, with a modest up-regulation of the hypoxia response pathway. Snf5+/-;Vhl2B/+ mice did not demonstrate a substantial difference in overall survival or a change in malignant rhabdoid tumor development. However, a high percentage of female mice showed complex hemorrhagic ovarian cysts, a phenotype rarely found in either parental mouse strain. These lesions also showed mosaic expression of SNF5 by immunohistochemistry. Therefore, our studies implicate that modest changes in angiogenic regulation interact with perturbations of SWI/SNF complex activity to modulate disease phenotypes.

A Gro/TLE-NuRD corepressor complex facilitates Tbx20-dependent transcriptional repression.

The cardiac transcription factor Tbx20 has a critical role in the proper morphogenetic development of the vertebrate heart, and its misregulation has been implicated in human congenital heart disease. Although it is established that Tbx20 exerts its function in the embryonic heart through positive and negative regulation of distinct gene programs, it is unclear how Tbx20 mediates proper transcriptional regulation of its target genes. Here, using a combinatorial proteomic and bioinformatic approach, we present the first characterization of Tbx20 transcriptional protein complexes. We have systematically investigated Tbx20 protein-protein interactions by immunoaffinity purification of tagged Tbx20 followed by proteomic analysis using GeLC-MS/MS, gene ontology classification, and functional network analysis. We demonstrate that Tbx20 is associated with a chromatin remodeling network composed of TLE/Groucho corepressors, members of the Nucleosome Remodeling and Deacetylase (NuRD) complex, the chromatin remodeling ATPases RUVBL1/RUVBL2, and the T-box repressor Tbx18. We determined that the interaction with TLE corepressors is mediated via an eh1 binding motif in Tbx20. Moreover, we demonstrated that ablation of this motif results in a failure to properly assemble the repression network and disrupts Tbx20 function in vivo. Importantly, we validated Tbx20-TLE interactions in the mouse embryonic heart, and identified developmental genes regulated by Tbx20-TLE binding, thereby confirming a primary role for a Tbx20-TLE repressor complex in embryonic heart development. Together, these studies suggest a model in which Tbx20 associates with a Gro/TLE-NuRD repressor complex to prevent inappropriate gene activation within the forming heart.