The aim of this proposal is to identify the endogenous factors responsible for growth and differentiation of circular and longitudinal gastric and intestinal smooth muscle in the guinea pig and human, and characterize their cell surface receptors and the signal transduction pathways to which the receptors are coupled. The focus is on growth factors shown in preliminary studies to be effective in stimulating growth in cultures of intestinal circular and longitudinal muscle. Three classes of growth factors will be examined: (i) GRP/bombesin and its homologue, neuromedin B, which are released from enteric neurons; (ii) 5-HT which is released from mast cells in response to inflammation and which interacts with distinct 5-HT and S-HT4 receptors on smooth muscle; and (iii) peptide growth factors (TGF alpha, TGF beta, IGF-I and II) that are either normally expressed or induced in smooth muscle. In various cells, these factors interact with receptors coupled to signaling pathways via GTP-binding regulatory proteins or more directly via receptor/tyrosine kinases. In preliminary studies, we have shown that cultured intestinal muscle retains its characteristic phenotype and maintains its ability to express beta-tropomyosin and enteric smooth muscle-specific gamma-actin, possesses a complement of G protein-coupled and tyrosine kinase-coupled receptors capable of stimulating muscle growth, Ca2+ mobilization and contraction. The first specific aim is to identify the presence and secretion of growth factors (TGF alpha, IGF-I and IGF-II, TGF beta) in gastric and intestinal smooth muscle cultures by radioimmunoassay and immunocytochemistry, and determine their effects, and those of 5-HT, GRP and NMB on cell growth (thymidine uptake and protein synthesis), differentiation (expression of beta-tropomyosin and enteric smooth muscle-specific gamma-actin), and muscle function (Ca2+ mobilization, contraction and relaxation). The second specific aim is to characterize the expression and properties of cell surface receptors for growth factors in cultured gastric and intestinal smooth muscle cells by radioligand binding in conjunction with selective receptor protection. The third specific aim is to characterize the signal transduction pathways coupled to receptors mediating growth and differentiation by measuring the activity of effector enzymes (phosphoinositide-specific PLC beta-l and PLC~-l, and phosphatidylcholinespecific PLC, PLD and PLA2), and second messengers (IP3, diacylglycerol, arachidonic acid, and Ca2+, and the activities of protein kinase C, tyrosine kinase and MAP kinases- 2). The studies will provide a framework for understanding the intracellular mechanisms regulating growth and differentiation in enteric smooth muscle.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
1R29DK049691-01
Application #
2150563
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1995-09-25
Project End
2000-06-30
Budget Start
1995-09-25
Budget End
1996-06-30
Support Year
1
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Virginia Commonwealth University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
City
Richmond
State
VA
Country
United States
Zip Code
23298
Li, Chao; Iness, Audra; Yoon, Jennifer et al. (2015) Noncanonical STAT3 activation regulates excess TGF-?1 and collagen I expression in muscle of stricturing Crohn's disease. J Immunol 194:3422-31
Li, Chao; Vu, Kent; Hazelgrove, Krystina et al. (2015) Increased IGF-IEc expression and mechano-growth factor production in intestinal muscle of fibrostenotic Crohn's disease and smooth muscle hypertrophy. Am J Physiol Gastrointest Liver Physiol 309:G888-99
Li, Chao; Kuemmerle, John F (2014) Mechanisms that mediate the development of fibrosis in patients with Crohn's disease. Inflamm Bowel Dis 20:1250-8
Li, Chao; Flynn, Robert S; Grider, John R et al. (2013) Increased activation of latent TGF-?1 by ?V?3 in human Crohn's disease and fibrosis in TNBS colitis can be prevented by cilengitide. Inflamm Bowel Dis 19:2829-39
Kuemmerle, John F (2012) Insulin-like growth factors in the gastrointestinal tract and liver. Endocrinol Metab Clin North Am 41:409-23, vii
Flynn, Robert S; Mahavadi, Sunila; Murthy, Karnam S et al. (2011) Endogenous IGFBP-3 regulates excess collagen expression in intestinal smooth muscle cells of Crohn's disease strictures. Inflamm Bowel Dis 17:193-201
Mahavadi, Sunila; Flynn, Robert S; Grider, John R et al. (2011) Amelioration of excess collagen I?I, fibrosis, and smooth muscle growth in TNBS-induced colitis in IGF-I(+/-) mice. Inflamm Bowel Dis 17:711-9
Grider, J R; Heuckeroth, R O; Kuemmerle, J F et al. (2010) Augmentation of the ascending component of the peristaltic reflex and substance P release by glial cell line-derived neurotrophic factor. Neurogastroenterol Motil 22:779-86
Flynn, Robert S; Murthy, Karnam S; Grider, John R et al. (2010) Endogenous IGF-I and alphaVbeta3 integrin ligands regulate increased smooth muscle hyperplasia in stricturing Crohn's disease. Gastroenterology 138:285-93
Hazelgrove, Krystina B; Flynn, Robert S; Qiao, Li-Ya et al. (2009) Endogenous IGF-I and alpha v beta3 integrin ligands regulate increased smooth muscle growth in TNBS-induced colitis. Am J Physiol Gastrointest Liver Physiol 296:G1230-7

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