title: Functional promoter polymorphisms direct the expression of cystathionine gamma-lyase gene in mouse models of essential hypertension.
abstract: Despite the well-known role of cystathionine γ-lyase (Cth) in cardiovascular pathophysiology, transcriptional regulation of Cth remains incompletely understood. Sequencing of the Cth promoter region in mouse models of genetic/essential hypertension (viz. Blood Pressure High [BPH], Blood Pressure Low [BPL] and Blood Pressure Normal [BPN] mice) identified several genetic variations. Transient transfections of BPH/BPL-Cth promoter-reporter plasmids into various cell types revealed higher promoter activity of BPL-Cth than that of BPH-Cth. Corroboratively, endogenous Cth mRNA levels in kidney and liver tissues were also elevated in BPL mice. Computational analysis of the polymorphic Cth promoter region predicted differential binding affinity of c-Rel, HOXA3 and IRF1 with BPL/BPH-Cth promoter domains. Over-expression of c-Rel/HOXA3/IRF1 modulated BPL/BPH-Cth promoter activities in a consistent manner. Gel shift assays using BPH/BPL-Cth-promoter oligonucleotides with/without binding sites for c-Rel/HOXA3/IRF1 displayed formation of specific complexes with c-Rel/HOXA3/IRF1; addition of antibodies to reaction mixtures resulted in supershifts/inhibition of Cth promoter-transcription factor complexes. Furthermore, chromatin immunoprecipitation (ChIP) assays proved differential binding of c-Rel, HOXA3 and IRF1 with the polymorphic promoter region of BPL/BPH-Cth. Tumor necrosis factor-α (TNF-α) reduced the activities of BPL/BPH-Cth promoters to different extents that were further declined by ectopic expression of IRF1; on the other hand, siRNA-mediated down-regulation of IRF1 rescued the TNF-α-mediated suppression of the BPL/BPH-Cth promoter activities. In corroboration, ChIP analysis revealed enhanced binding of IRF1 with BPH/BPL-Cth promoter following TNF-α treatment. BPL/BPH-Cth promoter activity was diminished upon exposure of hepatocytes and cardiomyoblasts to ischemia-like pathological condition due to reduced binding of c-Rel with BPL/BPH-Cth-promoter. Taken together, this study reveals the molecular basis for the differential expression of Cth in mouse models of essential hypertension under basal and pathophysiological conditions.
authors.affiliation: Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Vinayak
authors.initials: V
authors.lastname: Gupta
authors.affiliation: Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Piyushkumar R
authors.initials: PR
authors.lastname: Kapopara
authors.affiliation: Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Abrar A
authors.initials: AA
authors.lastname: Khan
authors.affiliation: Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Arige
authors.affiliation: Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Subramanian
authors.affiliation: Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Parshuram J
authors.initials: PJ
authors.lastname: Sonawane
authors.affiliation: Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Binu K
authors.initials: BK
authors.lastname: Sasi
authors.affiliation: Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India. Electronic address: nmahapatra@iitm.ac.in.
authors.forename: Nitish R
authors.initials: NR
authors.lastname: Mahapatra
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001794:Blood Pressure; D002874:Chromosome Mapping; D019295:Computational Biology / Q000379:methods; D003542:Cystathionine gamma-Lyase / Q000235:genetics*; D004195:Disease Models, Animal; D000075222:Essential Hypertension; D005786:Gene Expression Regulation; D023281:Genomics / Q000379:methods; D006973:Hypertension / Q000235:genetics* / Q000503:physiopathology*; D051379:Mice; D059372:Nucleotide Motifs; D009928:Organ Specificity / Q000235:genetics; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D040641:Quantitative Trait Loci; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D003542:Cystathionine gamma-Lyase
keywords: Cystathionine γ-lyase promoter; Gene regulation; Ischemia; Transcription factor; Tumor necrosis factor-α