Modulation Of Neprilysin Gene And Protein Expression By 5-HT_2C Receptor In Human Glioma Cell Line U251

Alzheimer disease(AD)is a chronic progressive neurodegenerative disorder of the central nervous system. Amyloid plaques, which are largely composed of amyloid-βprotein(Aβ), are considered to be the primary cause of the disease. Neprilysin(NEP), a member of zinc metallopeptidase family, has recently been focused in pharmacological research. Besides cleaving peptide signaling molecules in cardiovascular, inflammatory and immune system such as atrial natriuretic peptide, bradykinin, tachykinin, substance P and enkephalin, it has been proved to be a principal enzyme capable of degrading extracellular Aβin the brain. Since the results of cell and animal experiments suggested that stimulation of serotonin receptor subtype 5-HT2C can increase secretion of soluble amyloid precursor protein(sAPPα)and reduce accumulation of Aβpeptide both in vitro and in vivo, it is not known whether activation of 5-HT2C receptor can also affect NEP expression.Thus, we investigated NEP expression in human glioma cell Line U251. U251 was incubated with different concentrations of m-CPP(5-HT2C receptor agonist)or RS 102221(5-HT2C receptor antagonist)for different time. RT-PCR was used to measure the mRNA level of neprilysin and western blot was used to analyse the protein level of neprilysin. Compared with the control group, a significant concentration-dependent increase in NEP mRNA level was observed after treated with m-CPP range from 10-8~10-5mol/L. On the contrary, RS 102221 caused NEP mRNA concentration-dependent reduction. Relative levels of neprilysin protein generally paralleled those of the mRNA. These results suggest that activation of 5-HT2C receptor can increase NEP expression in human glioma cell line U251, which might be of value in the exploration of etiology of and therapy of AD.