Leukocyte antigen-related protein tyrosine phosphatase negatively regulates hydrogen peroxide-induced vascular smooth muscle cell apoptosis.
Reactive oxygen species (ROS) have been implicated in vascular smooth muscle cell (VSMC) apoptosis, a hallmark of advanced atherosclerotic lesions. Transient oxidation and inactivation of protein-tyrosine phosphatases play a critical role in cellular response to ROS production. However, the function of leukocyte antigen-related (LAR) protein-tyrosine phosphatase in ROS signaling is not known. To determine the expression of LAR in ROS-induced apoptosis, we investigated hydrogen peroxide-induced cell death and signaling in aortic VSMCs from wild-type and LAR(-/-) mice. Histone-associated DNA fragmentation and caspase-3/7 activity were significantly enhanced, mitochondrial membrane integrity was compromised, and cell viability was significantly decreased following H(2)O(2) treatment in LAR(-/-) VSMCs compared with wild-type cells. Stronger and sustained increase in autophosphorylation and activity of Fyn, an Src family tyrosine kinase, was observed in LAR(-/-) cells compared with wild-type cells following H(2)O(2) treatment. LAR binds to activated Fyn in H(2)O(2)-treated VSMCs, and recombinant LAR dephosphorylates phosphorylated-Fyn in vitro. In addition, LAR deficiency enhanced H(2)O(2)-induced phosphorylation of Janus kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), and p38 mitogen-activated protein kinase (MAPK). PP2, a Fyn-specific inhibitor, blocked JAK2, STAT3, and p38 MAPK activation and significantly attenuated apoptosis induced by H(2)O(2). AG490, a JAK2-specific inhibitor, significantly attenuated H(2)O(2)-induced apoptosis, and blocked H(2)O(2)-induced activation of STAT3, but not p38 MAPK in both wild-type and LAR(-/-) VSMCs. Attenuation of Fyn expression by short hairpin RNA significantly decreased H(2)O(2)-induced downstream signaling and apoptosis in VSMCs. Together, these data indicate that LAR regulates Fyn/JAK2/STAT3 and Fyn/p38 MAPK pathways involved in ROS-induced apoptosis.
Department of Medicine, Carolina Cardiovascular Biology Center, University of North Carolina, Chapel Hill, North Carolina 27599-7126, USA.
Juxiang
J
Li
Xi-Lin
XL
Niu
Nageswara R
NR
Madamanchi
D000818:Animals; D017209:Apoptosis; D053938:DNA Fragmentation; D053614:Janus Kinase 2 / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000473:pathology*; D051076:Proto-Oncogene Proteins c-fyn / Q000378:metabolism; D017382:Reactive Oxygen Species; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
D017382:Reactive Oxygen Species; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; C064626:Ltk protein, mouse; D020794:Receptor Protein-Tyrosine Kinases; C494960:Fyn protein, mouse; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases; D048051:p38 Mitogen-Activated Protein Kinases