The recombinant proregion of transforming growth factor beta1 (latency-associated peptide) inhibits active transforming growth factor beta1 in transgenic mice.
All three isoforms of transforming growth factors beta (TGF-betal, TGF-beta2, and TGF-beta3) are secreted as latent complexes and activated extracellularly, leading to the release of the mature cytokines from their noncovalently associated proregions, also known as latency-associated peptides (LAPs). The LAP region of TGF-beta1 was expressed in a baculovirus expression system and purified to homogeneity. In vitro assays of growth inhibition and gene induction mediated by TGF-beta3 demonstrate that recombinant TGF-beta1 LAP is a potent inhibitor of the activities of TGF-betal, -beta2, and -beta3. Effective dosages of LAP for 50% neutralization of TGF-beta activities range from 4.7- to 80-fold molar excess depending on the TGF-beta isoform and activity examined. Using 125I-labeled LAP, we show that the intraperitoneal application route is effective for systemic administration of LAP. Comparison of concentrations of LAP in tissues shows a homogenous pattern in most organs with the exception of heart and muscle, in which levels of LAP are 4- to 8-fold lower. In transgenic mice with elevated hepatic levels of bioactive TGF-betal, treatment with recombinant LAP completely reverses suppression of the early proliferative response induced by TGF-beta1 in remnant livers after partial hepatectomy. The results suggest that recombinant LAP is a potent inhibitor of bioactive TGF-beta both in vitro and in vivo, after intraperitoneal administration. Recombinant LAP should be a useful tool for novel approaches to study and therapeutically modulate pathophysiological processes mediated by TGF-beta3.
Böttinger
E P
EP
Laboratory of Chemoprevention, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-5055, USA.
Factor
V M
VM
Tsang
M L
ML
Weatherbee
J A
JA
Kopp
J B
JB
Qian
S W
SW
Wakefield
L M
LM
Roberts
A B
AB
Thorgeirsson
S S
SS
Sporn
M B
MB
D000818:Animals; D002460:Cell Line; D006498:Hepatectomy; D007457:Iodine Radioisotopes; D008115:Liver Regeneration / Q000187:drug effects; D051379:Mice; D008822:Mice, Transgenic; D010446:Peptide Fragments; D011498:Protein Precursors; D011506:Proteins / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000097:blood / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053773:Transforming Growth Factor beta1
D007457:Iodine Radioisotopes; D010446:Peptide Fragments; D011498:Protein Precursors; D011506:Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1