Reference Report

Reference
Citation	Martinek, N., Shahab, J., Saathoff, M., Ringuette, M. (2008). Haemocyte-derived SPARC is required for collagen-IV-dependent stability of basal laminae in Drosophila embryos. J. Cell Sci. 121(10): 1671--1680. (Export to RIS)
FlyBase ID	FBrf0205193
Publication Type	Research paper
PubMed ID	18445681
PubMed Abstract	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.
DOI	10.1242/jcs.021931
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Language of Publication	English
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Publication Type	Journal
Abbreviation	J. Cell Sci.
Title	Journal of Cell Science
Publication Year	1966-
ISBN/ISSN	0021-9533
Data from Reference
Aberrations (3)
	Df(2L)sc19-8 Df(3R)nm136 Df(3R)Tl-P
Alleles (17)
	BM-40-SPARC^KK108185 BM-40-SPARC^nm136 BM-40-SPARC^Scer\UAS.cMa Cg25C²³⁴ Cg25C⁴¹² His2Av^72b His2Av⁸¹⁰ His2Av^+t4.0 His2Av^L1602 His2Av^nm136 His2Av^{T:Avic\GFP-S65T} Rcom\RA^Scer\UAS.cSa Scer\GAL4^Cg.PA Scer\GAL4^da.G32 Scer\GAL4^gcm-rA87.P Scer\GAL4^sca-109-68 Scer\GAL4^srp.Hemo
Constructs (8)
	P{Cg-GAL4.A} P{GAL4-da.G32} P{His2Av^{T:Avic\GFP-S65T}} P{His2AvD^+t4.0} P{KK108185} P{srp.Hemo-GAL4} P{UAS-RA} P{UAS-SPARC.M}
Genes (16)
	BM-40-SPARC CadN Cg25C crb futsch hb His2Av LanA LanB1 LanB2 Nrt Rcom\RA repo Scer\GAL4 trol vkg
Insertions (3)
	P{GawB}gcm^rA87.P P{GawB}sca^109-68 P{lacW}His2Av^L1602
Natural transposons (1)
	P-element