Transgenic overexpression of a stable Plasminogen Activator Inhibitor-1 variant.
BACKGROUND
Plasminogen Activator Inhibitor-1 (PAI-1) is a member of the Serine Protease Inhibitor (SERPIN) gene family and a key regulator of fibrinolysis. PAI-1 is unique among SERPINs in its spontaneous transition to a latent, inactive state, with a half-life of approximately 2 hours under physiologic conditions. The biologic importance of the PAI-1 transition to latency is unknown. This study aimed to engineer transgenic overexpression of a stable murine PAI-1 variant to examine the physiologic effects in vivo from delayed transition of PAI-1 to latency.


METHODS
Ten independent transgenic lines were generated with expression of a stable PAI-1 variant driven by the hybrid CMV/chicken beta-actin promoter.


RESULTS
Plasma PAI-1 levels in the transgenic founders ranged from 3.1+/-0.1 ng/mL to 1268.8+/-717.0 ng/mL. Quantitative PCR analysis in 3 transgenic lines demonstrated elevated PAI-1 mRNA in multiple tissues, with the highest increases observed in liver, brain, heart, and kidney. The fold-increase in PAI-1 mRNA over wild-type ranged from 2-fold to >2000-fold. Immunohistochemistry showed increased PAI-1 in liver, kidney, heart, spleen, and lung. Histologic examination of transgenic mice showed no evidence of thrombosis. The two founders with the highest plasma PAI-1 levels failed to produce any transgenic offspring that survived to weaning, although genotyping of expired pups revealed successful transmission of the transgene.


CONCLUSIONS
These results suggest that high expression of a stable variant of PAI-1 may be lethal in mice, while more moderate expression is generally well tolerated and produces no apparent thrombosis.
Fahim
Abigail T
AT
Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States.
Wang
He
H
Feng
Jining
J
Ginsburg
David
D
D000818:Animals; D008168:Lung / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D017395:Plasminogen Activator Inhibitor 1 / Q000097:blood / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D019076:Transgenes
D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger
Blood. 1996 Jun 1;87(11):4718-22
8639841
J Thromb Haemost. 2005 Jan;3(1):35-45
15634264
Dev Biol. 1986 Nov;118(1):9-18
3770310
Nature. 1992 Jan 16;355(6357):270-3
1731226
J Biol Chem. 1994 Jun 10;269(23):15957-60
8206889
N Engl J Med. 1992 Dec 10;327(24):1729-33
1435917
Curr Opin Pharmacol. 2005 Apr;5(2):149-54
15780823
Blood. 2000 Jan 15;95(2):577-80
10627465
Nature. 1991 Oct 10;353(6344):576-8
1922367
J Biol Chem. 1992 Apr 15;267(11):7588-95
1559996
Transgenic Res. 1993 Jan;2(1):29-32
8513336
J Clin Invest. 1996 Jan 1;97(1):232-7
8550840
J Biol Chem. 1994 Nov 4;269(44):27657-62
7961684
Mol Reprod Dev. 1999 Sep;54(1):43-8
10423296
Thromb Haemost. 1995 Nov;74(5):1305-9
8607114
Gene. 1991 Dec 15;108(2):193-9
1660837
Nature. 1994 Mar 31;368(6470):419-24
8133887
Bone. 2007 Dec;41(6):995-1004
17888748
Nature. 1990 Jul 5;346(6279):74-6
2366866
Blood. 1997 Jul 1;90(1):204-8
9207454
Exp Cell Res. 1998 Oct 10;244(1):367-9
9770380
Circulation. 2002 Jul 23;106(4):491-6
12135951
Diabet Med. 1993 Aug-Sep;10(7):638-42
8403825
Eur J Biochem. 1989 Dec 22;186(3):523-33
2514093
Blood. 1991 Feb 1;77(3):528-32
1899347
Biochem Biophys Res Commun. 2004 Mar 5;315(2):363-8
14766216
J Biol Chem. 1988 Oct 25;263(30):15454-61
2459123
J Clin Invest. 1993 Dec;92(6):2756-60
8254029
FEBS Lett. 1997 May 5;407(3):313-9
9175875
J Mol Biol. 2001 Jan 26;305(4):773-83
11162091
Arterioscler Thromb Vasc Biol. 2003 Jan 1;23(1):78-84
12524228
Genesis. 2000 Nov-Dec;28(3-4):167-74
11105060
J Mol Endocrinol. 2007 Jul;39(1):9-16
17601881
Nucleic Acids Res. 1997 Jul 15;25(14):2745-51
9207020
Lancet. 1987 Jul 4;2(8549):3-9
2885513
N Engl J Med. 1985 Dec 19;313(25):1557-63
3934538
EMBO J. 1995 Jul 3;14(13):2969-77
7621813