Effects of nitric oxide synthase deficiency on a disintegrin and metalloproteinase domain-containing protein 12 expression in mouse brain samples

Abstract

Abstract.A d isi nt eg r i n a nd met a l loprot ei nase domain-containing protein 12 (ADAM12) belongs to the ADAM family of transmembrane proteins. Via proteolysis, cell adhesion, cell-cell fusion, cell-matrix interaction and membrane protein shedding, ADAM proteins are involved in normal brain development, and also in cancer genesis and progression, and in inflammation. Therefore, neurobiological research focusing on this protein is increasing. Nitric oxide (NO), which is endogenously produced by NO synthases (NOS), is associated with glial tumors. However, knock-out of NOS produces only limited antitumor effects. The present study analyzed the expression of ADAM12 in the cortex and hippocampus of C57/BL6 wild-type mice, and endothelial NOS-, neuronal NOS-(nNOS) or inducible NOS (iNOS)-deficient ( -/-) mice, at different stages of development. Expression of ADAM12 was quantified using immunoblot analysis of cortical and hippocampal tissue samples from fetal, neonatal (5 days postnatal), adult (12 weeks old) or >1 year old mice. Using reverse transcription-quantitative polymerase chain reaction, ADAM12 expression was analyzed in cultured N9, OLN93, C6 and PC12 cells, representing the four main cell types in the brain, following NOS inhibition. ADAM12 expression was low in all mouse genotypes and regions of the brain, and in fetal and neonatal mice, an increase in expression was observed with increasing age. The highest levels of expression were observed in the cortex of adult mice, iNOS -/-mice of >1 year and wild-type mice, and in the hippocampus of adult and iNOS -/-mice of >1 year. By contrast, ADAM12 expression was lowest in adult nNOS -/-mice. Inhibition of NOS using N ω -Nitro-L-arginine methyl ester hydrochloride, induced ADAM12 mRNA expression in N9 and PC12 cell lines. Inhibition of NOS using L-N 6 -(1-Iminoethyl)lysine dihydrochloride, induced ADAM12 mRNA expression in N9 and C6 cell lines. No change in ADAM12 expression was observed in OLN93 cells following NOS inhibition. ADAM12 expression in mouse hippocampus and cortex samples demonstrated considerable variation during development, with a marked increase observed in adult and >1 year old mice, compared with that in fetal and neonatal mice. IntroductionNitric oxide (NO) is an important signaling molecule found in animals, including humans. Reduced NO production is associated with important cardiovascular risk factors, such as hyperlipidemia (1,2), diabetes, hypertension, smoking, atherosclerosis and aging (3). The bioavailability of NO in cells and tissues decreases with age. This may be a result of a decrease in the expression of the constitutive isoforms [endothelial nitric oxide synthase (eNOS) and neuronal NOS (nNOS)], with age (4). Inducible NOS (iNOS)-mediated NO formation has been shown to affect longevity. In mice, iNOS overexpression may lead to increased mortality, which is associated with cardiac hypertrophy and sudden cardiac death as a result of bradyarrhythmias (5). iNOS expression is typically not observed in the brains of young (1-3...

A Disintegrin and Metalloproteinase (ADAM) Family: Their Significance in Malignant Tumors of the Central Nervous System (CNS)

“…[63,64] A disintegrin and metalloproteinase-12 (ADAM12) is a cell-surface glycoprotein containing metalloprotease, disintegrin, cysteine-rich and EGF-like domains which possess cell-binding and metalloprotease properties. ADAM12 is able to release of the extracellular parts of membrane-bound proteins, including glycoprotein non-metastatic melanoma protein B and basigin, heparin-binding-EGF, insulin-like growth factor 2-binding proteins 3 and 5, and oxytocinase [65][66][67][68]. It is reported that ADAM12 is predominantly localized in white and gray matter oligodendrocytes of rat and human CNS.…”