CAT-2 amplifies the agonist-evoked force of airway smooth muscle by enhancing spermine-mediated phosphatidylinositol-(4)-phosphate-5-kinase-gamma activity.
We investigated the effect the loss of the CAT-2 gene (CAT-2-/-) has on lung resistance (R(L)) and tracheal isometric tension. The R(L) of CAT-2-/- mice at a maximal dose of acetylcholine (ACh) was decreased by 33.66% (P = 0.05, n = 8) compared with that of C57BL/6 (B6) mice. The isometric tension of tracheal rings from CAT-2-/- mice showed a significant decrease in carbachol (CCh)-induced force generation (33.01%, P < 0.05, n = 8) compared with controls. The isoproterenol- or the sodium nitroprusside-induced relaxation was not affected in tracheal rings from CAT-2-/- mice. The activity of iNOS and arginase in lung tissue lysates of CAT-2-/- mice was indistinguishable from that of B6 mice. Furthermore, the expression of phospholipase-Cbeta (PLC-beta) and phosphatidylinositol-(4)-phosphate-5-kinase-gamma (PIP-5K-gamma) was examined in the lung tissue of CAT-2-/- and B6 mice. The expression of PIP-5K-gamma but not PLC-beta was significantly reduced in CAT-2-/- compared with B6 mice. The reduced airway smooth muscle (ASM) contractility to CCh seen in the CAT-2-/- tracheal rings was completely reversed by pretreating the rings with 100 muM spermine. This increase in the CAT-2-/- tracheal ring contraction upon spermine pretreatment correlated with a recovery of the expression of PIP-5K-gamma. Our data indicates that CAT-2 exerts control over ASM force development through a spermine-dependent pathway that directly correlates with the expression level of PIP-5K-gamma in the lung.
Chen
Hang
H
Inflammation Department, Wyeth Research, 200 Cambridge Park Drive, Cambridge MA 02140, USA.
Macleod
Carol
C
Deng
Bijia
B
Mason
Lawrence
L
Kasaian
Marion
M
Goldman
Samuel
S
Wolf
Stan
S
Williams
Cara
C
Bowman
Michael R
MR
D000109:Acetylcholine / Q000494:pharmacology; D000403:Airway Resistance / Q000502:physiology*; D000818:Animals; D001119:Arginase / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D027202:Cationic Amino Acid Transporter 2 / Q000172:deficiency / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000502:physiology*; D007545:Isoproterenol / Q000494:pharmacology; D008168:Lung / Q000201:enzymology / Q000502:physiology*; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009130:Muscle, Smooth / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D013096:Spermine / Q000494:pharmacology*; D014132:Trachea / Q000502:physiology*
D027202:Cationic Amino Acid Transporter 2; D004791:Enzyme Inhibitors; D009599:Nitroprusside; D013096:Spermine; D009569:Nitric Oxide; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D002217:Carbachol; D019001:Nitric Oxide Synthase; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase; D001119:Arginase; D007545:Isoproterenol; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester