Alternative splicing of papilin and the diversity of Drosophila extracellular matrix during embryonic morphogenesis

Abstract

Papilins are extracellular matrix proteins that share a particular, common order of types of protein domains. They occur widely, from nematodes to man, and can differ in the number of repeats of a given type of domain. Protein variety is increased by differential splicing of pre-mRNA. We report that Drosophila, which has a compact genome, expresses three splice variants of papilin during embryogenesis in developmentally defined patterns. These isoforms have different numbers of Kunitz and IgC2 domains. The papilin isoforms are expressed in specific cell types and contribute to different extracellular matrices in gastrulation folds, early mesoderm, heart formation, basement membranes, and elaboration of the excorporeal peritrophic membrane that lines the gut. This finding indicates an unexpectedly broad spectrum of different pericellular matrices in Drosophila embryos. Such papilin-containing matrices have developmental as well as functional significance, as we previously showed that both suppression of papilin synthesis and ectopic overexpression lethally disrupt organogenesis. Developmental Dynamics 226:634 -642, 2003.

Haemocyte-derived SPARC is required for collagen-IV-dependent stability of basal laminae inDrosophilaembryos

“…The pattern of SPARC mRNA expression prior to ES11 has not been previously shown possibly due to the absorption of SPARC probe by the haemocytes and fat body, which express SPARC at high levels during late embryogenesis. The expression pattern of SPARC in haemocytes is consistent with other studies demonstrating that haemocytes secrete ECM components, such as collagen IV, laminin, tiggrin, glutactin, peroxidasin, and papilin (Fessler and Fessler, 1989;Fogerty et al, 1994;Mirre et al, 1988;Kramerova et al, 2003;Yasothornsrikul et al, 1997).…”

The kunitz domain protein BLI-5 plays a functionally conserved role in cuticle formation in a diverse range of nematodes

“…This protein has likewise recently been shown not to possess serine, trypsin nor chymotrypsin protease inhibiting activity [39,40]. This finding was consistent with the absence of key residues from the bovine pancreatic trypsin inhibitor motif (Fx (3) GCx (6) FYx (5) C); [32,40].…”

Genetics of Extracellular Matrix Remodeling During Organ Growth Using the Caenorhabditis elegans Pharynx Model

“…In Drosophila, Papilin is abundantly present in most ECM and is essential for development (Campbell et al 1987;Kramerova et al 2000Kramerova et al , 2003Fessler et al 2004). In C. elegans, MIG-6S and MIG-6L are secreted proteins that contribute to the ECM and genetically interact with the ADAMTS protease MIG-17 and with collagen IV (Kawano et al 2009).…”