title: Angiotensin-(1-7)/mas inhibits apoptosis in alveolar epithelial cells through upregulation of MAP kinase phosphatase-2.
abstract: Earlier work from this laboratory showed that autocrine generation of angiotensin II and c-Jun-NH2-terminal kinase phosphorylation (p-JNK) are both required events in alveolar epithelial cell (AEC) apoptosis. Although earlier data showed that angiotensin-(1-7) [ANG-(1-7)] protects against AEC apoptosis, the pathways by which ANG-(1-7)/mas activation prevent JNK phosphorylation and apoptosis are poorly understood. Therefore, in the current study, it was theorized that ANG-(1-7) activates a mitogen-activated protein kinase phosphatase (MKP) and thereby reduces JNK phosphorylation to inhibit apoptosis and promote cell survival. This hypothesis was evaluated in the human A549 and mouse MLE12 AEC lines and primary cultures of human AECs. Cells were transfected with small-interfering RNAs, antisense oligonucleotides, or inhibitors specific for MKP-2 or mas, and were then assayed for phospho-JNK, caspase-9, loss of mitochondrial membrane potential, and nuclear fragmentation. Silencing of MKP-2 significantly prevented the blockade of all apoptotic markers by ANG-(1-7). Knockdown or blockade of mas receptor by antisense oligonucleotides or by the receptor antagonist A779, respectively, caused significant decreases in MKP-2, and simultaneously increased the apoptotic markers of caspase-9 activation and nuclear fragmentation. These data show that the ANG-(1-7)/mas pathway constitutively prevents JNK phosphorylation and apoptosis of AECs by maintaining activation of the JNK-selective phosphatase MKP-2, and further demonstrate the critical role of the ANG-(1-7) receptor mas in AEC survival.
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan; and.
authors.forename: Indiwari
authors.initials: I
authors.lastname: Gopallawa
authors.affiliation: Department of Physiology, Michigan State University, East Lansing, Michigan uhal@msu.edu.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Uhal
mesh_terms: D056809:Alveolar Epithelial Cells / Q000378:metabolism; D000803:Angiotensin I / Q000378:metabolism*; D017209:Apoptosis / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects*; D054637:Dual-Specificity Phosphatases / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D054639:Mitogen-Activated Protein Kinase Phosphatases / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D010766:Phosphorylation; D011650:Pulmonary Alveoli / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology
chemical_list: D010446:Peptide Fragments; D000803:Angiotensin I; D048031:JNK Mitogen-Activated Protein Kinases; D054639:Mitogen-Activated Protein Kinase Phosphatases; C490583:DUSP4 protein, human; D054637:Dual-Specificity Phosphatases; C118790:angiotensin I (1-7)
keywords: angiotensin peptides; c-Jun-NH2-terminal kinase phosphorylation; mitogen-activated protein kinase phosphatase; type II pneumocyte