Biology subjects

De Pinto, V.

Publications and source records attributed to De Pinto, V..

2 recordsLinked to original sources

bioRxiv2020

The secret of VDAC isoforms is in their gene regulation? Characterization of human VDAC genes expression profile, promoter activity, and transcriptional regulators.

BackgroundVDACs (Voltage-Dependent Anion-selective Channels) are pore-forming proteins of the outer mitochondrial membrane, whose permeability is primarily due to their presence. In higher eukaryotes three isoforms raised during the evolution: they have the same exon-intron organization and the proteins show the same channel-forming activity. We provide a comprehensive analysis of the three human VDAC genes (VDAC1-3), their expression profiles, promoter activity, and potential transcriptional regulators. ResultsVDAC isoforms are broadly but also specifically expressed in various human tissues at different levels with a predominance of VDAC1 and VDAC2 over VDAC3. However, RNA-seq CAGE approach revealed a higher level of transcription activation of VDAC3 gene. We experimentally confirmed this information by reporter assay of VDACs promoter activity. Transcription Factor Binding Sites (TFBSs) distribution in the promoters was investigated. The main regulators common to the three VDAC genes were identified as E2FF, NRF1, KLFS, EBOX transcription factors family members. All of them are involved in cell cycle and growth, proliferation, differentiation, apoptosis, and metabolism. More transcription factors specific for each isoform gene were identified, supporting the results in the literature, indicating a general role of VDAC1, as actor of apoptosis for VDAC2, and the involvement in sex determination and development of VDAC3. ConclusionsFor the first time, we propose a comparative analysis of human VDAC promoters to investigate their specific biological functions. Bioinformatics and experimental results confirm the essential role of VDAC protein family in mitochondrial functionality. Moreover, insights about a specialized function and different regulation mechanisms arise for the three isoforms genes.

molecular biology↗

bioRxiv2020

NRF-1 and HIF-1α modulate activity of human VDAC1 gene promoter during starvation and hypoxia in HeLa cells

VDAC (Voltage Dependent Anion Channel) is a family of pore forming protein located in the outer mitochondrial membrane. Its channel property ensures metabolites exchange between mitochondria and the rest of the cell resulting in metabolism and bioenergetics regulation, and in cell death and life switch. VDAC1 is the best characterized and most abundant isoform, and is involved in many pathologies, as cancer or neurodegenerative diseases. However, little information is available about its gene expression regulation in normal and/or pathological conditions. In this work, we explored VDAC1 gene expression regulation in normal conditions and in the contest of metabolic and energetic mitochondrial dysfunction and cell stress. The most active area of the putative promoter region was characterized in terms of transcription factors responsive elements both by bioinformatic studies and promoter activity experiments. In particular, we found a predominant presence of NRF-1 together with other transcription factors binding sites, involved in cell growth, proliferation, development and we studied their prevalence in gene activity. Furthermore, upon depletion of nutrients or controlled hypoxia, as reported in various pathologies, we found that VDAC1 transcripts levels were significantly increased in a time related manner. VDAC1 promoter activity was also validated by gene reporter assays. According to PCR real-time data, it was confirmed that VDAC1 promoter activity is further stimulated when are exposed to stress. A bioinformatic survey suggested NRF-1 e HIF-1 as the most active TFBS. Their validation was obtained by mutagenesis and overexpression experiments. In conclusion, we demonstrated experimentally the involvement of both NRF-1 and HIF-1 in the regulation of VDAC1 promoter activation at basal level and in cell stress conditions.

molecular biology↗