title: Expression levels of the BAK1 and BCL2 genes highlight the role of apoptosis in age-related hearing impairment.
abstract: Age-related hearing impairment (ARHI) is a progressive and a common sensory disorder in the elderly and will become an increasingly important clinical problem given the growing elderly population. Apoptosis of cochlear cells is an important factor in animal models of ARHI. As these cells cannot regenerate, their loss leads to irreversible hearing impairment. Identification of molecular mechanisms can facilitate disease prevention and effective treatment. In this study, we compared the expression of the genes BAK1 and BCL2 as two arms of the intrinsic apoptosis pathway between patients with ARHI and healthy subjects. ARHI and healthy subjects were selected after an ear nose throat examination, otoscopic investigation, and pure tone audiometry. RNA was extracted from peripheral blood samples, and relative gene expression levels were measured using quantitative real-time polymerase chain reaction. BAK1 and the BAK1/BCL2 ratio were statistically significantly upregulated in the ARHI subjects. The BAK1/BCL2 ratio was positively correlated with the results of the audiometric tests. Our results indicate that BAK-mediated apoptosis may be a core mechanism in the progression of ARHI in humans, similar to finding in animal models. Moreover, the gene expression changes in peripheral blood samples could be used as a rapid and simple biomarker for early detection of ARHI.
authors.affiliation: ENT and Head & Neck Research Center and Department, Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Biochemistry Department, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Masoumeh
authors.initials: M
authors.lastname: Falah
authors.affiliation: Cellular and Molecular Research Center, Biochemistry Department, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Najafi
authors.affiliation: Department of Medical Genetics, National Institute for Genetic Engineering and Biotechnology, Tehran, Iran.
authors.forename: Massoud
authors.initials: M
authors.lastname: Houshmand
authors.affiliation: ENT and Head & Neck Research Center and Department, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Farhadi
mesh_terms: D000368:Aged; D017209:Apoptosis / Q000235:genetics* / Q000502:physiology; D001299:Audiometry; D015415:Biomarkers; D003051:Cochlea / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011304:Presbycusis / Q000097:blood / Q000235:genetics* / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000097:blood; D060888:Real-Time Polymerase Chain Reaction; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000096:biosynthesis* / Q000097:blood
chemical_list: C494772:BAK1 protein, human; C000595707:BCL2 protein, human; D015415:Biomarkers; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein
keywords: age-related hearing impairment (ARHI); biomarker; presbycusis; treatment