Regulation of GTP cyclohydrolase I by alternative splicing in mononuclear cells.
GTP cyclohydrolase I (GCH, EC 3.5.4.16) regulates the level of tetrahydrobiopterin and in turn the activities of nitric oxide synthase and aromatic amino acid hydroxylases. Type II GCH mRNA, an alternatively spliced species abundant in blood cells, encodes a truncated and nonfunctional protein. When we stimulate peripheral blood mononuclear cells by PHA, the transcription of full-length GCH mRNA increased, but that of type II mRNA decreased transiently. We further demonstrated that the type II cDNA exerted a dominant-negative effect on the wild-type cDNA, similar to the effect of some GCH mutants. Therefore, type II mRNA may regulate GCH and then contribute to the regulation of NO production by BH4-dependent iNOS in mononuclear cells. Selection of the splicing sites may be coupled with transcriptional activation of the GCH gene.
Hwu
Wuh-Liang
WL
Department of Pediatrics and Medical Genetics, National Taiwan University Hospital and National Taiwan University, College of Medicine, Taipei, Taiwan ROC.
Yeh
Hui-Ying
HY
Fang
Shu-Wen
SW
Chiang
Hao-Sen
HS
Chiou
Yu-Wei
YW
Lee
Yu-May
YM
D017398:Alternative Splicing; D015153:Blotting, Western; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006136:GTP Cyclohydrolase / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D005799:Genes, Dominant; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D012333:RNA, Messenger; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D006136:GTP Cyclohydrolase