Central involvement of Rho family GTPases in TNF-alpha-mediated bovine pulmonary endothelial cell apoptosis.
In our recent studies, we defined a critical role for increased levels of myosin light chain (MLC) phosphorylation, a regulatory event in the interaction between actin and myosin in TNF-alpha-induced pulmonary endothelial cell actomyosin rearrangement and apoptosis. The Rho GTPase effector, Rho kinase is an important signaling effector governing levels of MLC phosphorylation which contributes to plasma membrane blebbing in several models of apoptosis. In this study, we directly assessed the role of Rho kinase in TNF-alpha-induced endothelial cell microfilament rearrangement and apoptosis. Inhibition of RhoA GTPase activity by the overexpression of dominant negative RhoA attenuates TNF-alpha-triggered stress fiber formation, consistent with Rho activation as a key event in TNF-alpha-induced cytoskeletal rearrangement. Furthermore, pharmacologic inhibition of Rho kinase as well as dominant negative RhoA overexpression dramatically reduced TNF-alpha-induced bovine endothelial apoptosis reflected by nucleosomal fragmentation as well as caspase 7, 3, and 8 activation. These results indicate that Rho kinase-dependent cytoskeletal rearrangement is critical for early apoptotic events, possibly in the assembly of the death-inducing signaling complex leading to initiator and effector caspase activation, and suggest a novel role for Rho GTPases in endothelial cell apoptosis.
Petrache
Irina
I
Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, 1830 Building, Room 527, Baltimore, MD 21224, USA.
Crow
Michael T
MT
Neuss
Michael
M
Garcia
Joe G N
JG
D000199:Actins / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D009218:Myosins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011651:Pulmonary Artery / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D054460:rho-Associated Kinases
D000199:Actins; D015703:Antigens, CD; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020169:Caspases; D009218:Myosins; D020741:rho GTP-Binding Proteins