A Modified L. Monocytogenes Internalin B Peptide Is a Hepatocyte Growth Factor Mimetic.

Abstract

Hepatocyte growth factor (HGF) plays a key role in tissue homeostasis and repair in many organs including lung, heart, kidney, liver, and skin. HGF is a heterodimer comprised of an N−terminal hairpin, four kringle domains, and a serine protease−like domain with a total of 20 intramolecular disulfide bonds. Due to its complex structure, large scale synthesis of full length HGF has not been possible in quantities sufficient for clinical use, despite its potential therapeutic uses. Listeria monocytogenes, an facultative intracellular pathogen, binds to the HGF receptor c−Met via its surface protein internalin B (InlB) as a part of its cellular invasion mechanism. The InlB protein N−terminal domain is comprised of a cap structure, a leucine rich repeat domain (LRR), and an interrepeat region (IR) (total, aa 36−321) that together bind to and partially activate the HGF receptor c−Met. The LRR domain has a stable β−sheet structure, and is easily produced in large quantities using standard E. coli protein synthesis systems. We demonstrate that the extended LRR domain has motogenic and anti−apoptotic activity in primary pulmonary artery endothelial cells (PAEC). This peptide also activates p42/p44 MAPK but not Akt. We have produced a modified extended LRR dimer (2XLRR), that activates both p42/p44 MAPK as well as Akt in PAEC. This added pathway of signal transduction is associated with a gain of cell proliferation in biological function. The modified InlB LRR dimer may be a useful reagent to induce tissue repair. This abstract is funded by: NIH R01 HL073929. Am J Respir Crit Care Med 179;2009:A5365 Internet address: www.atsjournals.org Online Abstracts Issue