tailieunhanh - Báo cáo khoa học: Transcription of mammalian cytochrome c oxidase subunit IV-2 is controlled by a novel conserved oxygen responsive element

Subunit 4 of cytochromecoxidase (CcO) is a nuclear-encoded regulatory subunit of the terminal complex of the mitochondrial electron transport chain. We have recently discovered an isoform of CcO 4 (CcO4-2) which is specific to lung and trachea, and is induced after birth. The role of CcO as the major cellular oxygen consumer, and the lung-specific expression of CcO4-2, led us to investigate CcO4-2gene regulation. | ỊFEBS Journal Transcription of mammalian cytochrome c oxidase subunit IV-2 is controlled by a novel conserved oxygen responsive element Maik Huttemann Icksoo Lee Jenney Liu and Lawrence I. Grossman Molecular Medicine and Genetics Wayne State University Schoolof Medicine Detroit MI USA Keywords electron transport chain hypoxia isoform lung mitochondria Correspondence L. Grossman or M. Huttemann Molecular Medicine and Genetics Wayne State University Schoolof Medicine 540 E. Canfield Ave. Detroit MI 48201 USA Fax 1 313 5775218 Tel 1 313 5775326 or 1 3135779150 E-mail mhuttema@ Database CcO4-2 promoter sequences including exon I have been submitted to the GenBank data library under the accession numbers AY219183 human AY219183 cow AY219183 rat and AY219183 mouse Received 18 July 2007 revised 30 August 2007 accepted 5 September 2007 Subunit 4 of cytochrome c oxidase CcO is a nuclear-encoded regulatory subunit of the terminal complex of the mitochondrial electron transport chain. We have recently discovered an isoform of CcO 4 CcO4-2 which is specific to lung and trachea and is induced after birth. The role of CcO as the major cellular oxygen consumer and the lung-specific expression of CcO4-2 led us to investigate CcO4-2 gene regulation. We cloned the CcO4-2 promoter regions of cow rat and mouse and compared them with the human promoter. Promoter activity is localized within a 118-bp proximal region of the human promoter and is stimulated by hypoxia reaching a maximum threefold under 4 oxygen compared with normoxia. CcO4-2 oxygen responsiveness was assigned by mutagenesis to a novel promoter element 5 -GGACGTTCCCACG-3 that lies within a 24-bp region that is 79 conserved in all four species. This element is able to bind protein and competition experiments revealed that within the element the four core bases 5 -TCNCA-3 are obligatory for transcription factor binding. CcO isolated from lung showed a increased maximal turnover .