QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 29 April 2008
doi: 10.1242/jcs.021931

This Article Figures Only Full Text Full Text (PDF) Supplementary Material All Versions of this Article: jcs.021931v1 121/10/1671    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Martinek, N. Articles by Ringuette, M. Search for Related Content PubMed PubMed Citation Articles by Martinek, N. Articles by Ringuette, M. Social Bookmarking                         What's this?

Haemocyte-derived SPARC is required for collagen-IV-dependent stability of basal laminae in Drosophila embryos

Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, M5S 3G5, Canada

^* Author for correspondence (e-mail: ringuet{at}csb.utoronto.ca)

Accepted 24 February 2008

SPARC is an evolutionarily conserved collagen-binding extracellular matrix (ECM) glycoprotein whose morphogenetic contribution(s) to embryonic development remain elusive despite decades of research. We have therefore used Drosophila genetics to gain insight into the role of SPARC during embryogenesis. In Drosophila embryos, high levels of SPARC and other basal lamina components (such as network-forming collagen IV, laminin and perlecan) are synthesized and secreted by haemocytes, and assembled into basal laminae. A SPARC mutant was generated by P-element mutagenesis that is embryonic lethal because of multiple developmental defects. Whereas no differences in collagen IV immunostaining were observed in haemocytes between wild-type and SPARC-mutant embryos, collagen IV was not visible in basal laminae of SPARC-mutant embryos. In addition, the laminin network of SPARC-mutant embryos appeared fragmented and discontinuous by late embryogenesis. Transgenic expression of SPARC protein by haemocytes in SPARC-mutant embryos restored collagen IV and laminin continuity in basal laminae. However, transgenic expression of SPARC by neural cells failed to rescue collagen IV in basal laminae, indicating that the presence of collagen IV deposition requires SPARC expression by haemocytes. Our previous finding that haemocyte-derived SPARC protein levels are reduced in collagen-IV-mutant embryos and the observation that collagen-IV-mutant embryos showed a striking phenotypic similarity to SPARC-mutant embryos suggests a mutual dependence between these major basal laminae components during embryogenesis. Patterning defects and impaired condensation of the ventral nerve cord also resulted from the loss SPARC expression prior to haemocyte migration. Hence, SPARC is required for basal lamina maturation and condensation of the ventral nerve cord during Drosophila embryogenesis.

Key words: SPARC, Collagen IV, Basal lamina, Ventral nerve cord, Haemocyte

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				J. M. Urbano, C. N. Torgler, C. Molnar, U. Tepass, A. Lopez-Varea, N. H. Brown, J. F. de Celis, and M. D. Martin-Bermudo Drosophila laminins act as key regulators of basement membrane assembly and morphogenesis Development, December 15, 2009; 136(24): 4165 - 4176. [Abstract] [Full Text] [PDF]

				S. Sangaletti and M. P. Colombo Macrophages Orchestrate the Tumor Microenvironment Am. Assoc. Cancer Res. Educ. Book, April 18, 2009; 2009(1): 209 - 214. [Full Text] [PDF]

				E. Hohenester, T. Sasaki, C. Giudici, R. W. Farndale, and H. P. Bachinger Structural basis of sequence-specific collagen recognition by SPARC PNAS, November 25, 2008; 105(47): 18273 - 18277. [Abstract] [Full Text] [PDF]