The morphogenetic contributions of SPARC and collagen IV during drosophila embryogenesis

受精后不久，多细胞生物合成并分泌结构和功能多样化的细胞外基质（ECM）分子的复杂混合物。除了作为组织组织和稳定性的支架外，ECM分子还调节细胞的存活和行为。我实验室的研究重点是利用果蝇的遗传可追溯性来研究SPARC （Secreted Protein, acid， Rich in半胱氨酸）在胚胎发育中的作用。SPARC是一种具有多种生物活性的胶原结合ECM蛋白。我们对果蝇的研究表明，SPARC在胚胎基底层与IV型胶原共定位。基底膜是一层特殊的ECM，将上皮细胞与下层结缔组织分开。上皮细胞与基底层的相互作用对上皮细胞的功能和结缔组织的稳定性至关重要。SPARC表达的缺失导致胚胎发育过程中基底膜稳定性下降和神经系统形成失败导致死亡。我们利用基因组工程的最新进展培育了一系列表达突变的SPARC的果蝇，目的是确定SPARC的哪个结构域/部分负责胚胎缺陷。由于SPARC和IV型胶原之间的直接相互作用已经在体外被证实，我们正在进行研究以确定SPARC和IV型胶原是否在体内相互作用。我们的数据表明，在缺乏SPARC的情况下，神经缺陷是由于Notch-Delta信号受损，强调了发育过程中的信号转导是如何由ECM分子调节的。

Shortly after fertilization, multicellular organisms synthesize and secrete a complex mixture of structurally and functionally diverse extracellular matrix (ECM) molecules. In addition to acting as scaffolding for the organization and stability of tissues, ECM molecules regulate cell survival and behavior. Research in my laboratory is focused on using the genetic tractability of the fruit fly Drosophila melanogaster to investigate the contribution of SPARC (Secreted Protein, Acidic, Rich in Cysteine) during embryo development. SPARC is a collagen-binding ECM protein with diverse biological activities. Our studies with Drosophila indicate that SPARC co-localizes with collagen IV in embryonic basal laminae. A basal lamina is a thin sheet of specialized ECM that separates epithelial cells from underlying connective tissue. The interaction of epithelial cells with basal laminae is critical for epithelial cell functions and connective tissue stability. The loss of SPARC expression leads to death during embryonic development due to decreased basal laminae stability and failure of the nervous system to form. We have generated a series of flies that express mutant SPARC using recent advances in genome engineering for the purpose of determining which domain/portion of SPARC is responsible for the embryonic defects. Since a direct interaction between SPARC and collagen IV in basal laminae has been demonstrated in vitro, we are carrying out studies to determine if SPARC and collagen IV interact in vivo. Our data indicate that the neural defects are due to compromised Notch-Delta signaling in the absence of SPARC, underscoring how signal transduction during development is regulated by ECM molecules.