Search

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. [ABSTRACT FROM AUTHOR]

Hypoxia-inducible factor-1 (HIF-1) is important in cellular hypoxia responses. The crucial role for the von Hippel-Lindau (VHL) tumour suppressor gene product pVHL in HIF-1 regulation is demonstrated. The interaction between HIF-1 and pVHL may be iron dependent and required for the oxygen-dependent degradation of HIF alpha-subunits. HIF-1 activation may thus underlie the angiogenic phenotype of VHL tumours.

Introduction: The type 1 insulin-like growth factor receptor (IGF1R) mediates many key aspects of the malignant phenotype. Clear cell renal cell carcinoma (CC-RCC) is a highly chemoresistant tumour that is characterised by frequent inactivating mutation of the von Hippel-Lindau (VHL) gene. In CC-RCC cells, IGF1R protein levels were not affected by hypoxia, but were higher in cells harbouring inactivating VHL mutations than in isogenic cells expressing wild-type (WT) VHL. Steady-state IGF1R mRNA and IGF1R promoter activity were significantly lower in CC-RCC cells expressing WT VHL compared with parental cells, consistent with a transcriptional effect. VHL was shown to sequester Sp1 and HuR to suppress IGF1R expression at the level of transcription and mRNA stability. This represents a new, non-HIF-dependent role for VHL. IGF1R mRNA levels were found to be significantly higher in biopsies of CC-RCC than benign kidney, confirming the clinical relevance of these findings. Methods: We proceeded to test the hypothesis that IGF1R upregulation contributes to the survival and chemoresistance of CC-RCC cells. Results: IGF1R depletion using sequence-specific IGF1R siRNA was found to block survival of CC-RCC cells expressing either mutant (MT) or WT VHL. Moreover, IGF1R gene silencing was found to induce sensitisation to 5-fluorouracil (5-FU) in CC-RCC cells expressing MT but not WT VHL, supporting the hypothesis that the IGF1R upregulation that follows VHL inactivation contributes to chemoresistance. IGF1R knockdown also sensitised MT VHL CC-RCC cells to etoposide, zoledronate and rapamycin but not to cisplatin. Conclusions: These findings suggest that anti-IGF1R strategies may be of therapeutic benefit in advanced CC-RCC patients. [ABSTRACT FROM AUTHOR]

Human prolyl hydroxylases are involved in the modification of transcription factors, procollagen, and ribosomal proteins, and are current medicinal chemistry targets. To date, there are few reports on inhibitors selective for the different types of prolyl hydroxylases. We report a structurally informed template-based strategy for the development of inhibitors selective for the human ribosomal prolyl hydroxylase OGFOD1. These inhibitors did not target the other human oxygenases tested, including the structurally similar hypoxia-inducible transcription factor prolyl hydroxylase, PHD2., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Hypoxia-inducible factor (HIF) is the major transcriptional regulator of cellular responses to hypoxia. The two principal HIF-α isoforms, HIF-1α and HIF-2α, are progressively stabilized in response to hypoxia and form heterodimers with HIF-1β to activate a broad range of transcriptional responses. Here, we report on the pan-genomic distribution of isoform-specific HIF binding in response to hypoxia of varying severity and duration, and in response to genetic ablation of each HIF-α isoform. Our findings reveal that, despite an identical consensus recognition sequence in DNA, each HIF heterodimer loads progressively at a distinct repertoire of cell-type-specific sites across the genome, with little evidence of redistribution under any of the conditions examined. Marked biases towards promoter-proximal binding of HIF-1 and promoter-distant binding of HIF-2 were observed under all conditions and were consistent in multiple cell type. The findings imply that each HIF isoform has an inherent property that determines its binding distribution across the genome, which might be exploited to therapeutically target the specific transcriptional output of each isoform independently., (© 2018 The Authors. Published under the terms of the CC BY 4.0 license.)