2-subunit gene: role of histone deacetylases

Zhang, Wenzheng, and Bruce C. Kone. NFB inhibits transcription of the H -K -ATPase 2-subunit gene: role of histone deacetylases. Am J Physiol Renal Physiol 283: F904–F911, 2002. First published July 9, 2002; 10.1152/ ajprenal.00156.2002.—The H -K -ATPase 2 (HK 2) gene plays a central role in potassium homeostasis, yet little is known about its transcriptional control. We recently demonstrated that the proximal promoter confers basal transcriptional activity in mouse inner medullary collecting duct 3 cells. We sought to determine whether the B DNA binding element at 104 to 94 influences basal HK 2 gene transcription in these cells. Recombinant NFB p50 footprinted the region 116/ 94 in vitro. Gel shift and supershift analysis revealed NFB p50and p65-containing DNA-protein complexes in nuclear extracts of mouse inner medullary collecting duct 3 cells. A promoter-luciferase construct with a mutated 104/ 94 NFB element exhibited higher activity than the wild-type promoter in transfection assays. Overexpression of NFB p50, p65, or their combination transrepressed the HK 2 promoter. The histone deacetylase (HDAC) inhibitor trichostatin A partially reversed NFBmediated trans-repression of the HK 2 promoter. HDAC6 overexpression inhibited HK 2 promoter activity, and HDAC6 coimmunoprecipitated with NFB p50 and p65. These results suggest that HDAC6, recruited to the DNA protein complex, acts with NFB to suppress HK 2 transcription and identify NFB p50 and p65 as novel binding partners for HDAC6.