TY - JOUR
T1 - G-protein expression and intimal hyperplasia after arterial injury
T2 - A role for Gαi proteins
AU - Davies, Mark G.
AU - Mason, David P.
AU - Tran, P. Kiet
AU - Deou, Jesse
AU - Hawkins, Suzanne
AU - Clowes, Alexander W.
N1 - Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2001
Y1 - 2001
N2 - Purpose: Guanine nucleotide binding protein (G-protein) coupled receptors are involved in smooth muscle cell proliferation, but the role of G-proteins in arterial intimal hyperplasia has not been defined. This study examines the expression of G-proteins in the developing intimal hyperplasia after balloon injury of the rat carotid artery and specifically tests the hypothesis that the pertussis toxin sensitive G i G-protein subunit plays a role in the initiation of intimal hyperplasia. Methods: In vitro responses to serum stimulation (10% fetal bovine serum) were examined in the presence and absence of pertussis toxin (PTx). After a standard balloon injury in male Sprague-Dawley rats, the expression of G-protein subunits (α o, α i, α q, α s, and βγ) was determined by means of Western blotting in the first 28 days. Thereafter, a second set of animals was allocated to control and PTx-treated (a Gα i inhibitor; 500 ng/mL in an externally applied 30% pluronic gel) groups. Smooth muscle cell proliferation was estimated by means of thymidine analogue 5-bromo-2′ deoxyuridine incorporation 2 days after injury, and vessel dimensions were determined by means of videomorphometry 14 days after injury. Results: There was inhibition of DNA synthesis and smooth muscle cell proliferation in response to serum with an IC 50 of 100 ng/mL. Three days after balloon injury, there was an increase in Gα i3 expression, which decreased at days 7, 14, and 28, compared with the uninjured carotid. Gα q expression increased in a time-dependent manner. There was a marked time-dependent increase in Gβγ in the 28 days. Gα i2 and Gα s isoforms (45 and 52 kDa) did not change significantly with time. There was no major change in Gα i1 and Gα o in the study period. At 14 days, PTx treatment reduced intimal hyperplasia by 52% (63 ± 4 μm vs 30 ± 5 μm, control vs PTx; P < .001). Medial smooth muscle cell proliferation at day 2 was decreased in the PTx group, compared with that in the gel-coated group (15% ± 2% and 26% ± 3%; P = .02). Conclusion: After balloon injury, there is a time-dependent increase in G-protein expression, which is subunit specific. Activation of PTx sensitive G-proteins (Gα i) is involved during the initiation of intimal hyperplasia after arterial injury, and their inhibition results in a decrease in early medial cell proliferation. This acute interruption of G i signaling produces a long-term decrease in intimal hyperplasia.
AB - Purpose: Guanine nucleotide binding protein (G-protein) coupled receptors are involved in smooth muscle cell proliferation, but the role of G-proteins in arterial intimal hyperplasia has not been defined. This study examines the expression of G-proteins in the developing intimal hyperplasia after balloon injury of the rat carotid artery and specifically tests the hypothesis that the pertussis toxin sensitive G i G-protein subunit plays a role in the initiation of intimal hyperplasia. Methods: In vitro responses to serum stimulation (10% fetal bovine serum) were examined in the presence and absence of pertussis toxin (PTx). After a standard balloon injury in male Sprague-Dawley rats, the expression of G-protein subunits (α o, α i, α q, α s, and βγ) was determined by means of Western blotting in the first 28 days. Thereafter, a second set of animals was allocated to control and PTx-treated (a Gα i inhibitor; 500 ng/mL in an externally applied 30% pluronic gel) groups. Smooth muscle cell proliferation was estimated by means of thymidine analogue 5-bromo-2′ deoxyuridine incorporation 2 days after injury, and vessel dimensions were determined by means of videomorphometry 14 days after injury. Results: There was inhibition of DNA synthesis and smooth muscle cell proliferation in response to serum with an IC 50 of 100 ng/mL. Three days after balloon injury, there was an increase in Gα i3 expression, which decreased at days 7, 14, and 28, compared with the uninjured carotid. Gα q expression increased in a time-dependent manner. There was a marked time-dependent increase in Gβγ in the 28 days. Gα i2 and Gα s isoforms (45 and 52 kDa) did not change significantly with time. There was no major change in Gα i1 and Gα o in the study period. At 14 days, PTx treatment reduced intimal hyperplasia by 52% (63 ± 4 μm vs 30 ± 5 μm, control vs PTx; P < .001). Medial smooth muscle cell proliferation at day 2 was decreased in the PTx group, compared with that in the gel-coated group (15% ± 2% and 26% ± 3%; P = .02). Conclusion: After balloon injury, there is a time-dependent increase in G-protein expression, which is subunit specific. Activation of PTx sensitive G-proteins (Gα i) is involved during the initiation of intimal hyperplasia after arterial injury, and their inhibition results in a decrease in early medial cell proliferation. This acute interruption of G i signaling produces a long-term decrease in intimal hyperplasia.
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U2 - 10.1067/mva.2001.111748
DO - 10.1067/mva.2001.111748
M3 - Article
C2 - 11174797
AN - SCOPUS:0035106637
VL - 33
SP - 408
EP - 418
JO - Journal of Vascular Surgery
JF - Journal of Vascular Surgery
SN - 0741-5214
IS - 2
ER -