Expression of SPARC during development of the chicken chorioallantoic membrane: evidence for regulated proteolysis in vivo

ML Iruela-Arispe, TF Lane, D Redmond, M Reilly, RP Bolender, TJ Kavanagh and EH Sage

Department of Biological Structure, University of Washington School of Medicine, Seattle 98195, USA.

SPARC is a secreted glycoprotein that has been shown to disrupt focal adhesions and to regulate the proliferation of endothelial cells in vitro. Moreover, peptides resulting from the proteolysis of SPARC exhibit angiogenic activity. Here we describe the temporal synthesis, turnover, and angiogenic potential of SPARC in the chicken chorioallantoic membrane. Confocal immunofluorescence microscopy revealed specific expression of SPARC protein in endothelial cells, and significantly higher levels of SPARC were observed in smaller newly formed blood vessels in comparison to larger, developmentally older vessels. SPARC mRNA was detected at the earliest stages of chorioallantoic membrane morphogenesis and reached maximal levels at day 13 of embryonic development. Interestingly, steady-state levels of SPARC mRNA did not correlate directly with protein accumulation; moreover, the protein appeared to undergo limited degradation during days 10-15. Incubation of [125I]-SPARC with chorioallantoic membranes of different developmental ages confirmed that extracellular proteolysis occurred during days 9-15, but not at later stages (e.g., days 17-21). Comparison of peptides produced by incubation with chorioallantoic membranes with those generated by plasmin showed an identical pattern of proteolysis. Plasmin activity was present throughout development, and in situ zymography identified sites of plasminogen activator activity that corresponded to areas exhibiting high levels of SPARC expression. Synthetic peptides from a plasmin- sensitive region of SPARC, between amino acids 113-130, stimulated angiogenesis in the chorioallantoic membrane in a dose-dependent manner; in contrast, intact SPARC was inactive in similar assays. We have shown that SPARC is expressed in endothelial cells of newly formed blood vessels in a manner that is both temporally and spatially restricted. Between days 9 and 15 of chorioallantoic membrane development, the protein undergoes proteolytic cleavage that is mediated, in part, by plasmin. SPARC peptides released specifically by plasmin induce angiogenesis in vivo. We therefore propose that SPARC acts as an intrinsic regulator of angiogenesis in vivo.

Volume 6, Issue 3, pp. 327-343, 03/01/1995
Copyright © 1995 by The American Society for Cell Biology

This article has been cited by other articles:

				A Charest, A Pepin, R Shetty, C Cote, P Voisine, F Dagenais, P Pibarot, and P Mathieu Distribution of SPARC during neovascularisation of degenerative aortic stenosis Heart, December 1, 2006; 92(12): 1844 - 1849. [Abstract] [Full Text] [PDF]

				J. Kzhyshkowska, G. Workman, M. Cardo-Vila, W. Arap, R. Pasqualini, A. Gratchev, L. Krusell, S. Goerdt, and E. H. Sage Novel Function of Alternatively Activated Macrophages: Stabilin-1-Mediated Clearance of SPARC J. Immunol., May 15, 2006; 176(10): 5825 - 5832. [Abstract] [Full Text] [PDF]

				M. T. Sweetwyne, R. A. Brekken, G. Workman, A. D. Bradshaw, J. Carbon, A. W. Siadak, C. Murri, and E. H. Sage Functional Analysis of the Matricellular Protein SPARC with Novel Monoclonal Antibodies J. Histochem. Cytochem., June 1, 2004; 52(6): 723 - 733. [Abstract] [Full Text] [PDF]

				E. H. Sage, M. Reed, S. E. Funk, T. Truong, M. Steadele, P. Puolakkainen, D. H. Maurice, and J. A. Bassuk Cleavage of the Matricellular Protein SPARC by Matrix Metalloproteinase 3 Produces Polypeptides That Influence Angiogenesis J. Biol. Chem., September 26, 2003; 278(39): 37849 - 37857. [Abstract] [Full Text] [PDF]

				A. D. Bradshaw, M. J. Reed, and E. H. Sage SPARC-null Mice Exhibit Accelerated Cutaneous Wound Closure J. Histochem. Cytochem., January 1, 2002; 50(1): 1 - 10. [Abstract] [Full Text] [PDF]

				G. Davis, K. Pintar Allen, R Salazar, and S. Maxwell Matrix metalloproteinase-1 and -9 activation by plasmin regulates a novel endothelial cell-mediated mechanism of collagen gel contraction and capillary tube regression in three-dimensional collagen matrices J. Cell Sci., January 3, 2001; 114(5): 917 - 930. [Abstract] [PDF]

				R. Thomas, L. D. True, J. A. Bassuk, P. H. Lange, and R. L. Vessella Differential Expression of Osteonectin/SPARC during Human Prostate Cancer Progression Clin. Cancer Res., March 1, 2000; 6(3): 1140 - 1149. [Abstract] [Full Text]

				Q. Yan and E. H. Sage SPARC, a Matricellular Glycoprotein with Important Biological Functions J. Histochem. Cytochem., December 1, 1999; 47(12): 1495 - 1506. [Full Text]

				D Ribatti, D Leali, A Vacca, R Giuliani, A Gualandris, L Roncali, M. Nolli, and M Presta In vivo angiogenic activity of urokinase: role of endogenous fibroblast growth factor-2 J. Cell Sci., January 12, 1999; 112(23): 4213 - 4221. [Abstract] [PDF]

				C. Kupprion, K. Motamed, and E. H. Sage SPARC (BM-40, Osteonectin) Inhibits the Mitogenic Effect of Vascular Endothelial Growth Factor on Microvascular Endothelial Cells J. Biol. Chem., November 6, 1998; 273(45): 29635 - 29640. [Abstract] [Full Text] [PDF]

				E. I. Wallner, Q. Yang, D. R. Peterson, J. Wada, and Y. S. Kanwar Relevance of extracellular matrix, its receptors, and cell adhesion molecules in mammalian nephrogenesis Am J Physiol Renal Physiol, October 1, 1998; 275(4): F467 - F477. [Abstract] [Full Text] [PDF]

				P. Bagavandoss, E. H. Sage, and R. B. Vernon Secreted Protein, Acidic and Rich in Cysteine (SPARC) and Thrombospondin in the Developing Follicle and Corpus Luteum of the Rat J. Histochem. Cytochem., September 1, 1998; 46(9): 1043 - 1050. [Abstract] [Full Text]

				A. M. Delany and E. Canalis Basic fibroblast growth factor destabilizes osteonectin mRNA in osteoblasts Am J Physiol Cell Physiol, March 1, 1998; 274(3): C734 - C740. [Abstract] [Full Text] [PDF]