title: A novel signaling pathway of ADP-ribosyl cyclase activation by angiotensin II in adult rat cardiomyocytes.
abstract: ADP-ribosyl cyclase (ADPR-cyclase) produces a Ca(2+)-mobilizing second messenger, cADP-ribose (cADPR), from NAD(+). In this study, we investigated the molecular basis of ADPR-cyclase activation in the ANG II signaling pathway and cellular responses in adult rat cardiomyocytes. The results showed that ANG II generated biphasic intracellular Ca(2+) concentration increases that include a rapid transient Ca(2+) elevation via inositol trisphosphate (IP(3)) receptor and sustained Ca(2+) rise via the activation of L-type Ca(2+) channel and opening of ryanodine receptor. ANG II-induced sustained Ca(2+) rise was blocked by a cADPR antagonistic analog, 8-bromo-cADPR, indicating that sustained Ca(2+) rise is mediated by cADPR. Supporting the notion, ADPR-cyclase activity and cADPR production by ANG II were increased in a time-dependent manner. Application of pharmacological inhibitors and immunological analyses revealed that cADPR formation was activated by sequential activation of Src, phosphatidylinositol 3-kinase (PI 3-kinase)/protein kinase B (Akt), phospholipase C (PLC)-gamma1, and IP(3)-mediated Ca(2+) signal. Inhibitors of these signaling molecules not only completely abolished the ANG II-induced Ca(2+) signals but also inhibited cADPR formation. Application of the cADPR antagonist and inhibitors of upstream signaling molecules of ADPR-cyclase inhibited ANG II-stimulated hypertrophic responses, which include nuclear translocation of Ca(2+)/calcineurin-dependent nuclear factor of activated T cells 3, protein expression of transforming growth factor-beta1, and incorporation of [(3)H]leucine in cardiomyocytes. Taken together, these findings suggest that activation of ADPR-cyclase by ANG II entails a novel signaling pathway involving sequential activation of Src, PI 3-kinase/Akt, and PLC-gamma1/IP(3) and that the activation of ADPR-cyclase can lead to cardiac hypertrophy.
authors.affiliation: Dept. of Biochemistry, Chonbuk National Univ. Medical School, Keum-am dong, Jeonju, 561-182, Republic of Korea.
authors.forename: Rukhsana
authors.initials: R
authors.lastname: Gul
authors.forename: Seon-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Kwang-Hyun
authors.initials: KH
authors.lastname: Park
authors.forename: Byung-Ju
authors.initials: BJ
authors.lastname: Kim
authors.forename: Se-Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Mie-Jae
authors.initials: MJ
authors.lastname: Im
authors.forename: Uh-Hyun
authors.initials: UH
authors.lastname: Kim
mesh_terms: D036541:ADP-ribosyl Cyclase / Q000378:metabolism*; D051997:ADP-ribosyl Cyclase 1 / Q000235:genetics / Q000378:metabolism; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D002478:Cells, Cultured; D036563:Cyclic ADP-Ribose / Q000378:metabolism*; D004789:Enzyme Activation; D006984:Hypertrophy; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D050778:NFATC Transcription Factors / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051966:Phospholipase C gamma / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D020746:Calcium Channels, L-Type; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008562:Membrane Glycoproteins; D050778:NFATC Transcription Factors; D044140:Receptor, Angiotensin, Type 1; D019837:Ryanodine Receptor Calcium Release Channel; D053773:Transforming Growth Factor beta1; D000804:Angiotensin II; D036563:Cyclic ADP-Ribose; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D051966:Phospholipase C gamma; D036541:ADP-ribosyl Cyclase; C498155:Cd38 protein, mouse; D051997:ADP-ribosyl Cyclase 1