Angiotensin IV upregulates the activity of protein phosphatase 1α in Neura-2A cells

The peptide angiotensin IV(Ang IV)is a derivative of angiotensin II.While insulin regulated amino peptidase(IRAP)has been proposed as a potential receptor for Ang IV,the signalling pathways of Ang IV through IRAP remain elusive.We applied high-resolution mass spectrometry to perform a systemic quantitative phosphoproteome of Neura-2A(N2A)cells treated with and without Ang IV us-ing sta ble-isotope labeling by amino acids in cell culture(SILAC),and identifi ed a reduction in the phosphorylation of a major Ser/Thr protein phosphorylase 1(PP1)upon Ang IV treatment.In addition,spinophilin(spn),a PP1 reg-ulatory protein that plays important functions in the neural system,was expressed at higher levels.Immunoblotting revealed decreased phosphorylation of p70S6 kinase(p70S6K)and the major cell cycle modulator retinoblas-toma protein(pRB).These changes are consistent with an observed decrease in cell proliferation.Taken together,our study suggests that Ang IV functions via regulating the activity of PP1.