Regulation of neuronal nitric oxide synthase through alternative transcripts

JE Brenman, H Xia, DS Chao, SM Black… - Developmental …, 1997 - karger.com
JE Brenman, H Xia, DS Chao, SM Black, DS Bredt
Developmental neuroscience, 1997karger.com
Nitric oxide (NO) participates in diverse physiological processes ranging from
neurotransmission to muscle relaxation. Neuronal-derived NO can be either beneficial or
detrimental depending on the cellular context. Neuronal NO synthase (nNOS) must therefore
be tightly regulated. One level of regulation involves synthesis of numerous nNOS mRNA
transcripts. At least six distinct molecular species of nNOS mRNA are expressed in a tissue
and developmentally-regulated manner. Alternative splicing allows the creation of nNOS …
Abstract
Nitric oxide (NO) participates in diverse physiological processes ranging from neurotransmission to muscle relaxation. Neuronal-derived NO can be either beneficial or detrimental depending on the cellular context. Neuronal NO synthase (nNOS) must therefore be tightly regulated. One level of regulation involves synthesis of numerous nNOS mRNA transcripts. At least six distinct molecular species of nNOS mRNA are expressed in a tissue and developmentally-regulated manner. Alternative splicing allows the creation of nNOS proteins differing in both enzymatic characteristics and structural features. As one example, we find that there are nNOS mRNAs lacking exon 2. One isoform, nNOSβ, retains full enzymatic activity but lacks a major protein-protein interaction domain (PDZ domain) responsible for targeting nNOS to synaptic membranes. This alternative splicing produces a mislocalized but fully active protein which may be relevant to certain pathologies. As evidence of this, we find that many human brain tumors express an alternatively spliced form of nNOS that co-migrates with nNOSβ, and lacks exon 2. Finally, we also find a 2.5-kb testis-specific nNOS mRNA corresponding to the C-terminal reductase domain of nNOS whose function is unclear.
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