title: Role of hypoxia-induced transglutaminase 2 in pulmonary artery smooth muscle cell proliferation.
abstract: We previously reported that transglutaminase 2 (TG2) activity is markedly elevated in lungs of hypoxia-exposed rodent models of pulmonary hypertension (PH). Since vascular remodeling of pulmonary artery smooth muscle cells (PASMCs) is important in PH, we undertook the present study to determine whether TG2 activity is altered in PASMCs with exposure to hypoxia and whether that alteration participates in their proliferative response to hypoxia. Cultured distal bovine (b) and proximal human (h) PASMCs were exposed to hypoxia (3% O2) or normoxia (21% O2). mRNA and protein expression were determined by PCR and Western blot analyses. TG2 activity and function were visualized and determined by fluorescent labeled 5-pentylamine biotin incorporation and immunoblotting of serotonylated fibronectin. Cell proliferation was assessed by [(3)H]thymidine incorporation assay. At 24 h, both TG2 expression and activity were stimulated by hypoxia in bPASMCs. Activation of TG2 by hypoxia was blocked by inhibition of the extracellular calcium-sensing receptor or the transient receptor potential channel V4. In contrast, TG2 expression was blocked by inhibition of the transcription factor hypoxia-inducible factor-1α, supporting the presence of separate mechanisms for stimulation of activity and expression of TG2. Pulmonary arterial hypertension patient-derived hPASMCs were found to proliferate significantly more rapidly and respond to hypoxia more strongly than control-derived hPASMCs. Similar to bovine cells, hypoxia-induced proliferation of patient-derived cells was blocked by inhibition of TG2 activity. Our results suggest an important role for TG2, mediated by intracellular calcium fluxes and HIF-1α, in hypoxia-induced PASMC proliferation and possibly in vascular remodeling in PH.
authors.affiliation: Pulmonary, Critical Care and Sleep Division, Tufts Medical Center, Tupper Research Institute, Boston, Massachusetts;
authors.forename: Krishna C
authors.initials: KC
authors.lastname: Penumatsa
authors.affiliation: Pulmonary, Critical Care and Sleep Division, Tufts Medical Center, Tupper Research Institute, Boston, Massachusetts;
authors.forename: Deniz
authors.initials: D
authors.lastname: Toksoz
authors.affiliation: Pulmonary, Critical Care and Sleep Division, Tufts Medical Center, Tupper Research Institute, Boston, Massachusetts;
authors.forename: Rod R
authors.initials: RR
authors.lastname: Warburton
authors.affiliation: Departments of Chemistry and Chemical Engineering, Stanford University, Stanford, California; and.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hilmer
authors.affiliation: Pulmonary, Critical Care and Sleep Division, Tufts Medical Center, Tupper Research Institute, Boston, Massachusetts;
authors.forename: Tiegang
authors.initials: T
authors.lastname: Liu
authors.affiliation: Departments of Chemistry and Chemical Engineering, Stanford University, Stanford, California; and.
authors.forename: Chaitan
authors.initials: C
authors.lastname: Khosla
authors.affiliation: Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Suzy A A
authors.initials: SA
authors.lastname: Comhair
authors.affiliation: Pulmonary, Critical Care and Sleep Division, Tufts Medical Center, Tupper Research Institute, Boston, Massachusetts; bfanburg@tuftsmedicalcenter.org.
authors.forename: Barry L
authors.initials: BL
authors.lastname: Fanburg
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D002417:Cattle; D015687:Cell Hypoxia; D049109:Cell Proliferation; D002478:Cells, Cultured; D004789:Enzyme Activation; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000201:enzymology* / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000473:pathology / Q000503:physiopathology; D032389:Myocytes, Smooth Muscle / Q000201:enzymology* / Q000502:physiology; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011651:Pulmonary Artery / Q000473:pathology* / Q000503:physiopathology; D044169:Receptors, Calcium-Sensing / Q000037:antagonists & inhibitors / Q000378:metabolism; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism; D011503:Transglutaminases / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D004791:Enzyme Inhibitors; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D044169:Receptors, Calcium-Sensing; D050916:TRPV Cation Channels; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins
keywords: CaSR; HIF-1α; TG2; TRPV4; pulmonary artery smooth muscle cells