Biology subjects

Alahmad, A.

Publications and source records attributed to Alahmad, A..

2 recordsLinked to original sources

bioRxiv2019

Papillary renal cell carcinomas rewire glutathione metabolism and are deficient in anabolic glucose synthesis

Papillary renal cell carcinoma (pRCC) is a malignant kidney cancer with a prevalence of 7-20% of all renal tumors. Proteome and metabolome profiles of 19 pRCC and patient-matched healthy kidney controls were used to elucidate the regulation of metabolic pathways and the underlying molecular mechanisms. Glutathione (GSH), a main reactive oxygen species (ROS) scavenger, was highly increased and can be regarded as a new hallmark in this malignancy. Isotope tracing of pRCC derived cell lines revealed an increased de novo synthesis rate of GSH, based on glutamine consumption. Furthermore, rewiring of the main pathways involved in ATP and glucose synthesis was observed at the protein level. In contrast, transcripts encoding for the respiratory chain were not regulated, which prompts for non-genetic profiling. The molecular characteristics of pRCC are increased GSH synthesis to cope with ROS stress, deficient anabolic glucose synthesis, and compromised oxidative phosphorylation, which could potentially be exploited in innovative anti-cancer strategies.\n\nSIGNIFICANCE STATEMENTWe applied proteome- and metabolome profiling to elucidate molecular features in malign papillary renal cell carcinomas. By this characterization, a reprogramming of the main metabolic pathways, such as gluconeogenesis and fatty acid- and amino acid metabolism were identified. The proteins involved in the respiratory chain and the corresponding enzymatic activities were strongly reduced in pRCC, showing an anti-correlation compared with the transcriptome. Similar to renal oncocytomas, the ROS scavenger glutathione was identified as a hallmark in pRCC. Our results suggest that impaired metabolism and dysfunctional mitochondria determine the fate of pRCC. Furthermore, we propose that the specific regulation of the mitochondrial respiratory chain can differentiate highly similar malignant pRCCs from benign renal oncocytomas.

cancer biology↗

bioRxiv2018

Mutations in ELAC2 associated with hypertrophic cardiomyopathy impair mitochondrial tRNA 3’-end processing

Dysfunction of mitochondrial gene expression, caused by mutations in either the mitochondrial or nuclear genomes, is associated with a diverse group of human disorders characterized by impaired mitochondrial respiration. Within this group, an increasing number of mutations have been identified in nuclear genes involved in mitochondrial RNA metabolism. For instance, pathogenic mutations have been identified in the genes encoding enzymes involved in the precursor transcript processing, including ELAC2. The ELAC2 gene codes for the mitochondrial RNase Z, which is responsible for endonucleolytic cleavage of the 3 ends of mitochondrial pre-tRNAs. Here, we report the identification of sixteen novel ELAC2 variants in individuals presenting with mitochondrial respiratory chain deficiency, hypertrophic cardiomyopathy and lactic acidosis. We provided further evidence for the pathogenicity of the three previously reported variants by studying the RNase Z activity in an in vitro system and applied this recombinant system to investigate all novel missense variants, confirming the pathogenic role of these new ELAC2 mutations. We also modelled the residues affected by missense mutation in solved RNase Z structures, providing insight into enzyme structure and function. Finally, we show that primary fibroblasts from the individuals with novel ELAC2 variants have elevated levels of unprocessed mitochondrial RNA precursors. Our study thus broadly confirms the correlation of ELAC2 variants with severe infantile-onset forms of hypertrophic cardiomyopathy and mitochondrial respiratory chain dysfunction. One rare missense variant associated with the occurrence of prostate cancer (p.Arg781His) impairs the mitochondrial RNase Z activity of ELAC2, possibly indicating a functional link between tumorigenesis and mitochondrial RNA metabolism.

genetics↗