Clinically,
hypoxia is a major risk factor for
long QT syndrome (LQTS), which is associated with many diseases, such as
myocardial ischemia. LQTS can be caused by the deficiency of hERG, a
potassium ion channel that plays a key role in cardiac repolarization. Modifications such as acetylation of
histones or non-
histone proteins can affect the
protein expression. In the present study, we explored the mechanism underlying
hypoxia-induced LQTS and a potential reversal strategy. Experiments were performed under
hypoxia to determine transcriptional and post-transcriptional expression changes. We used real-time PCR,
chromatin immunoprecipitation assay, and western blotting to determine the
histones acetylation in the hERG gene and the mechanism. Molecular docking, western blotting, IP, and patch -clamp assay were performed to determine the acetylation and ubiquitination levels of hERG
protein and the mechanism. hERG
mRNA and
protein expression were found to decrease under
hypoxia. The
histone deacetylation level increased under
hypoxia at both H3K27 and H4 of the hERG gene. HDAC1 and HDAC2 are the key
enzymes for the mechanism. HDAC6 directly interacts with hERG. The acetylation level of hERG decreased and the ubiquitination level of hERG increased under
hypoxia. The inhibitors of HDAC1, HDAC2, and HDAC6 could reverse the reduction of hERG
mRNA and hERG
protein expression under
hypoxia. In conclusion, deacetylation of hERG gene-associated
histones and hERG
protein might be the mechanisms for LQTS in patients with
hypoxia, and the inhibition of HDAC1, HDAC2, and HDAC6 might be a promising reversal strategy for reducing hERG expression under different pathological conditions.