Bronchial myogenesis involves the differentiation of local embryonic mesenchymal cells into smooth muscle (SM) cells. The mechanisms that determine this process are largely unknown. Our recent studies suggested that laminin-2 induces SM differentiation by promoting mesenchymal cell spreading/elongation ( 1-3). In unrelated studies we found that heterogeneous ribonucleoprotein-H (hnRNP-H), an RNA-binding protein involved in alternative splicing, inhibits SM differentiation and bronchial myogenesis. Based on our preliminary data, we hypothesize that bronchial myogenesis involves activation of a laminin-integrin mediated pathway that results in downregulation of hnRNP-H. This in turn causes a switch in serum response factor (SRF) pre-mRNA alternative splicing that favors SM gene expression. We also hypothesize that altered hnRNP-H levels contribute to the myofibroblast phenotype seen in lung disease. The studies proposed in this application will address these hypotheses.
Aim #1 will elucidate whether stimulation of SM differentiation by laminin-2 involves regulation of hnRNP-H and what is the signaling pathway connecting them. Based on preliminary studies we will focus on integrins alpha1beta1 and alpha2beta1, RhoA and MAPK 38.
Aim #2 will establish the role of hnRNP-H in SRF pre-mRNA alternative splicing and how each SRF isoform impacts on hnRNP-H-mediated SM differentiation. It has been recently shown that SRF pre-mRNA splices into dominant positive and negative isoforms and our preliminary data suggest that these are involved in bronchial myogenesis.
Aim #3 will determine whether modulation of hnRNP-H levels/activity affects the phenotype of mature SM cells, fibroblasts and lung myofibroblasts. The myofibroblasts will be studied using a bleomycin model of lung fibrosis. Our pilot data showed a decrease in hnRNP-H levels in this model. In summary, this project will define a novel molecular pathway controlling bronchial myogenesis. This pathway may be shared by many different myogenic stimuli. We anticipate that these studies will provide novel knowledge that will advance considerably our understanding of lung development and diseases caused by, or resulting from abnormal SM quantity, distribution and function.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL067100-02
Application #
6530760
Study Section
Special Emphasis Panel (ZRG1-REB (01))
Program Officer
Berberich, Mary Anne
Project Start
2001-04-01
Project End
2006-02-28
Budget Start
2002-03-01
Budget End
2003-02-28
Support Year
2
Fiscal Year
2002
Total Cost
$271,996
Indirect Cost
Name
Wayne State University
Department
Pathology
Type
Schools of Medicine
DUNS #
City
Detroit
State
MI
Country
United States
Zip Code
48202
Shi, Jinghua; Badri, Kameswara Rao; Choudhury, Ranginee et al. (2006) P311-induced myofibroblasts exhibit ameboid-like migration through RalA activation. Exp Cell Res 312:3432-42
Jakkaraju, Sandhya; Zhe, Xiaoning; Pan, Desi et al. (2005) TIPs are tension-responsive proteins involved in myogenic versus adipogenic differentiation. Dev Cell 9:39-49
Zhe, Xiaoning; Yang, Yan; Schuger, Lucia (2005) Imbalanced plasminogen system in lymphangioleiomyomatosis: potential role of serum response factor. Am J Respir Cell Mol Biol 32:28-34
Paliwal, Seema; Shi, Jinghua; Dhru, Urmil et al. (2004) P311 binds to the latency associated protein and downregulates the expression of TGF-beta1 and TGF-beta2. Biochem Biophys Res Commun 315:1104-9
Zhe, Xiaoning; Schuger, Lucia (2004) Combined smooth muscle and melanocytic differentiation in lymphangioleiomyomatosis. J Histochem Cytochem 52:1537-42
Zhe, Xiaoning; Yang, Yan; Jakkaraju, Sandhya et al. (2003) Tissue inhibitor of metalloproteinase-3 downregulation in lymphangioleiomyomatosis: potential consequence of abnormal serum response factor expression. Am J Respir Cell Mol Biol 28:504-11
Yang, Yan; Zhe, Xiaoning; Phan, Sem H et al. (2003) Involvement of serum response factor isoforms in myofibroblast differentiation during bleomycin-induced lung injury. Am J Respir Cell Mol Biol 29:583-90
Jakkaraju, Sandhya; Zhe, Xiaoning; Schuger, Lucia (2003) Role of stretch in activation of smooth muscle cell lineage. Trends Cardiovasc Med 13:330-5
Pan, Desi; Zhe, Xiaoning; Jakkaraju, Sandhya et al. (2002) P311 induces a TGF-beta1-independent, nonfibrogenic myofibroblast phenotype. J Clin Invest 110:1349-58
Beqaj, Safedin; Jakkaraju, Sandhya; Mattingly, Raymond R et al. (2002) High RhoA activity maintains the undifferentiated mesenchymal cell phenotype, whereas RhoA down-regulation by laminin-2 induces smooth muscle myogenesis. J Cell Biol 156:893-903