Myocyte enhancer factor 2B is involved in the inducible expression of NOX1/NADPH oxidase, a vascular superoxide-producing enzyme.
NADPH oxidase is a major source of the superoxide produced in cardiovascular tissues. Expression of NOX1, a catalytic subunit of NADPH oxidase, is induced by various vasoactive factors, including angiotensin II, prostaglandin (PG) F(2alpha) and platelet-derived growth factor (PDGF). To clarify the molecular basis of this transcriptional activation, we delineated the promoter region of the NOX1 gene. RT-PCR and 5'-rapid amplification of cDNA ends-based analyses revealed a novel 5'-terminal exon of the rat NOX1 gene located approximately 28 kb upstream of the exon containing the start codon. Both PGF(2alpha) and PDGF enhanced the transcriptional activity of the - 3.6 kb 5'-flanking region of the NOX1 gene in A7r5 cells, a rat vascular smooth muscle cell line. A PGF(2alpha)-response element was located between -146 and -125 in the 5'-flanking region containing a consensus binding site for myocyte enhancer factor 2 (MEF2), to which binding of MEF2 was augmented by PGF(2alpha). Gene silencing of MEF2B by RNA interference significantly suppressed the expression of NOX1, while silencing of activating transcription factor (ATF)-1, previously implicated in up-regulation of NOX1, abolished the PGF(2alpha)- or PDGF-induced expression of MEF2B. These results indicate that superoxide production in vascular smooth muscle cells is regulated by the ATF-1-MEF2B cascade by induction of the expression of the NOX1 gene.
Katsuyama
Masato
M
Department of Pharmacology, Kyoto Prefectural University of Medicine, Japan.
Ozgur Cevik
Muhammer
M
Arakawa
Noriaki
N
Kakehi
Tomoko
T
Nishinaka
Toru
T
Iwata
Kazumi
K
Ibi
Masakazu
M
Matsuno
Kuniharu
K
Yabe-Nishimura
Chihiro
C
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001808:Blood Vessels / Q000201:enzymology*; D002460:Cell Line; D017931:DNA Primers; D018076:DNA, Complementary; D015237:Dinoprost / Q000502:physiology; D024202:Electrophoretic Mobility Shift Assay; D004790:Enzyme Induction; D020868:Gene Silencing; D064326:MEF2 Transcription Factors; D008969:Molecular Sequence Data; D018006:Myogenic Regulatory Factors / Q000502:physiology*; D009247:NADH, NADPH Oxidoreductases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D000074624:NADPH Oxidase 1; D010982:Platelet-Derived Growth Factor / Q000502:physiology; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D013481:Superoxides / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology