Cloning, expression, and functional characterization of human cyclooxygenase-1 splicing variants: evidence for intron 1 retention.
J Pharmacol Exp Ther
; 315(3): 1298-305, 2005 Dec.
Article
em En
| MEDLINE
| ID: mdl-16141368
ABSTRACT
Recently, a splicing variant of cyclooxygenase (COX)-1, arising via the retention of its intron 1, was identified in canine. It was called COX-3 and was reported to be differentially sensitive to inhibition by various nonsteroidal anti-inflammatory drugs (NSAIDs) as well as acetaminophen (Chandrasekharan et al., 2002). However, the existence of an orthologous splicing variant in human tissues has been questioned due to a reading frame shift and premature termination. In this study, we first confirmed the existence of intron 1-retained COX-1 in certain human tissues at both the mRNA and protein levels. Molecular biology studies revealed that three distinct COX-1 splicing variants exist in human tissues. The most prevalent of these variants, called COX-1b1, arises via retention of the entire 94 base pair (bp) of intron 1, leading to a shift in the reading frame and termination at bp 249. However, the other two variant types, called COX-1b2 and COX-1b3, retain entire intron 1, but they are missing a nucleotide in one of two different positions, thereby encoding predicted full-length and likely COX-active proteins. Functional studies revealed that the COX-1b2 is able to catalyze the synthesis of prostaglandin F2alpha from arachidonic acid with Km and Vmax values of 0.54 microM and 3.07 pmol/mg/min, respectively. However, no significant differential selectivity for inhibition by selected NSAIDs was observed. Accordingly, we conclude that intron 1-retained human COX-1 is not likely to be the therapeutic target of acetaminophen or a candidate of COX-3.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Íntrons
/
Expressão Gênica
/
Splicing de RNA
/
Clonagem Molecular
/
Ciclo-Oxigenase 1
Limite:
Animals
/
Humans
Idioma:
En
Revista:
J Pharmacol Exp Ther
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Estados Unidos