After biosynthesis within the fibroblast, a procollagen molecule is secreted into the extracellular space where it must undergo a series of very ordered, time sensitive, and location sensitive sequential post-synthetic processing steps in order to become a mature cross-linked insoluble structural collagen fibril. We hypothesized that one fundamental independent mechanism by which chronic pressure overload (PO) increases myocardial fibrillar collagen content, causes the development of abnormal diastolic function and chronic heart failure is an alteration in post-synthetic procollagen processing. This overall hypothesis will be tested using 2 specific aims.
Specific Aim 1 : determine whether PO changes the balance between procollagen processing into mature cross-linked collagen fibrils vs. procollagen degradation.
Specific Aim 2 : determine in vitro, using murine primary cardiac fibroblast culture studies, whether a change in SPARC (Secreted Protein Acidic and Rich in Cysteine) expression or procollagen binding results in an isolated change in procollagen processing and fibrillar collagen deposition. PO will be produced by transverse aortic constriction (TAC) in mice. We will examine LV structure &function with echocardiography & catheterization, myocardial function with isolated papillary muscles studies, collagen content, composition and morphometric structure with histology &biochemistry, and procollagen synthesis, procollagen processing, and fibrillar collagen degradation rates with metabolic 14C and 3H proline labeling techniques. The mechanism by which TAC and SPARC alter post-synthetic procollagen processing will be examined using in vitro primary cardiac fibroblast culture studies. Thus, this project will examine whether alteration in SPARC-dependent procollagen processing is a fundamental mechanism by which PO increases myocardial fibrillar collagen content and causes diastolic dysfunction.

Public Health Relevance

Chronic heart failure (CHF) is a frequent cause of cardiovascular death and hospitalization;it is the only cardiovascular diagnosis that is increasing in incidence and prevalence. Defining the basic fundamental underlying mechanisms which cause CHF will lead to the development of new and more effective management strategies for patients with CHF. In this NIH R01 proposal we will examine the role played by changes in one such mechanism - the process by which newly synthesized and secreted procollagen is processed into mature collagen fibrils - during the development of chronic heart failure.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Cardiac Contractility, Hypertrophy, and Failure Study Section (CCHF)
Program Officer
Adhikari, Bishow B
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Medical University of South Carolina
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
Goldsmith, Edie C; Bradshaw, Amy D; Spinale, Francis G (2013) Cellular mechanisms of tissue fibrosis. 2. Contributory pathways leading to myocardial fibrosis: moving beyond collagen expression. Am J Physiol Cell Physiol 304:C393-402
Baicu, Catalin F; Zhang, Yuhua; Van Laer, An O et al. (2012) Effects of the absence of procollagen C-endopeptidase enhancer-2 on myocardial collagen accumulation in chronic pressure overload. Am J Physiol Heart Circ Physiol 303:H234-40
Baicu, Catalin F; Li, Jiayu; Zhang, Yuhua et al. (2012) Time course of right ventricular pressure-overload induced myocardial fibrosis: relationship to changes in fibroblast postsynthetic procollagen processing. Am J Physiol Heart Circ Physiol 303:H1128-34
Bradshaw, Amy D (2012) Diverse biological functions of the SPARC family of proteins. Int J Biochem Cell Biol 44:480-8
Trombetta-Esilva, Jessica; Bradshaw, Amy D (2012) The Function of SPARC as a Mediator of Fibrosis. Open Rheumatol J 6:146-55
Trombetta-Esilva, J; Yu, H; Arias, D N et al. (2011) LPS induces greater bone and PDL loss in SPARC-null mice. J Dent Res 90:477-82
Harris, Brett S; Zhang, Yuhua; Card, Lauren et al. (2011) SPARC regulates collagen interaction with cardiac fibroblast cell surfaces. Am J Physiol Heart Circ Physiol 301:H841-7
McCurdy, Sarah M; Dai, Qiuxia; Zhang, Jianhua et al. (2011) SPARC mediates early extracellular matrix remodeling following myocardial infarction. Am J Physiol Heart Circ Physiol 301:H497-505
Trombetta, Jessica M; Bradshaw, Amy D (2010) SPARC/osteonectin functions to maintain homeostasis of the collagenous extracellular matrix in the periodontal ligament. J Histochem Cytochem 58:871-9
Card, Lauren; Henderson, Nikki; Zhang, Yuhua et al. (2010) Expression in SPARC-null mice of collagen type I lacking the globular domain of the ?1(I) N-propeptide results in abdominal hernias and loss of dermal collagen. Matrix Biol 29:559-64