The 2.3 kb smooth muscle myosin heavy chain promoter directs gene expression into the vascular system of transgenic mice and rabbits.
BACKGROUND
Smooth muscle cells (SMC) are a preferential target for gene therapeutic approaches in atherosclerosis and restenosis. However, the undesirable expression of putative therapeutic genes in tissues other than the vascular wall is a considerable safety limitation for clinical trials, thus requiring the identification of a smooth-muscle-specific promoter sequence. Since the 2.3 kb rabbit Smooth Muscle Myosin Heavy Chain (SMHC) promoter was shown to be transcriptionally active in primary vascular but not visceral or other non-SMC in vitro, this fragment was chosen for in vivo analysis.


RESULTS
Transgenic mice and rabbits were established expressing a luciferase reporter gene under control of the 2.3 kb rabbit SMHC promoter. In contrast to the endogenous expression pattern of the SMHC gene both species revealed light emission predominantly in the arterial system including coronary arteries. Low activities were measured in large veins and the gastrointestinal system. In situ hybridization of murine embryos using a luciferase riboprobe confirmed reporter gene expression in large arteries with no detectable mRNA in the viscera. Unlike adult animals, ectopic luciferase activities were found in ventricular myocardium during murine development ceasing 1 week post partum.


CONCLUSIONS
In two animal species, the 2.3 kb SMHC promoter appeared to be effective in discriminating between the pathways regulating vascular and visceral smooth muscle gene expression. The vascular-specific expression profile of the 2.3 kb SMHC promoter suggests that the 2.3 kb SMHC promoter contains the regulatory elements necessary for selective gene targeting into vascular SMC of large arteries including coronary arteries in vivo.
Franz
W M
WM
Medizinische Klinik II, University of Lübeck, Germany. franz@medinf.mu-luebeck.de
Mueller
O J
OJ
Fleischmann
M
M
Babij
P
P
Frey
N
N
Mueller
M
M
Besenfelder
U
U
Moorman
A F
AF
Brem
G
G
Katus
H A
HA
D000818:Animals; D030801:Animals, Genetically Modified; D003331:Coronary Vessels / Q000378:metabolism*; D015870:Gene Expression; D005786:Gene Expression Regulation; D018390:Gene Targeting; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D017403:In Situ Hybridization; D008156:Luciferases / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D012045:Regulatory Sequences, Nucleic Acid; D014781:Viscera / Q000196:embryology / Q000378:metabolism
D012333:RNA, Messenger; D008156:Luciferases; D018995:Myosin Heavy Chains