DrosophilaPipe protein activity in the ovary and the embryonic salivary gland does not require heparan sulfate glycosaminoglycans

Abstract

The Drosophila pipe gene encodes ten related proteins that exhibit amino acid sequence similarity to vertebrate heparan sulfate 2-O-sulfotransferase. One of the Pipe isoforms, which is expressed in the ventral follicular epithelium, is a key determinant of embryonic dorsoventral polarity, suggesting that Pipe-mediated sulfation of a heparan sulfate proteoglycan provides a spatial cue for dorsoventral axis formation. We used several approaches to investigate this possibility in the work described here. We determined the nucleotide alterations in 11 different pipealleles. Ten of the mutations specifically affect the pipe isoform that is expressed in the ovary. Among these ten mutations, two alter an amino acid in the putative binding site for 3′-phosphoadenosine 5′-phosphosulfate, the universal sulfate donor. Using Alcian Blue, a histochemical stain that detects sulfated glycans, we observed a novel, pipe-dependent macromolecule in the embryonic salivary glands. Genes known to participate in the formation of heparan sulfate in Drosophila are not required for the production of this material. To investigate whether a heparan sulfate proteoglycan is involved in pipe function in dorsoventral patterning, we generated females carrying follicle cell clones mutant for heparan sulfate synthesis-related genes. Embryos from follicles with mutant clones did not exhibit a dorsalized phenotype. Taken together, our data provide evidence that Pipe acts as a sulfotransferase, but argue against the hypothesis that the target of Pipe is a heparan sulfate glycosaminoglycan.

Graded Dorsal and Differential Gene Regulation in the Drosophila Embryo

“…1998). pipe encodes a protein sharing homology with vertebrate heparan sulfate 2-O-sulfotransferases, but likely functions independent of heparan (Zhu et al 2005).…”

Identification and Characterization of a Novel Drosophila 3′-Phosphoadenosine 5′-Phosphosulfate Transporter

“…The lethality of the fly lines Act5C-GAL4/ϩ;UAS-dPAPST2-IR [1]/ϩ and Act5C-GAL4/UAS-dPAPST2-IR [2] also suggests the presence of dPAPST2-predominant tissue(s) or the distinct role of dPAPST2 from that of sll, although they exhibit similar ubiquitous distribution in the adult fly. The SLL, PAPSS, and PIPE proteins are involved in the production of an Alcian blue-positive sulfated macromolecule, which is not HS, in the embryonic salivary glands (12). The expression of dPAPST2 in the central nervous system may suggest the involvement of this gene in the synthesis of sulfated glycolipids or the HNK-1 epitope.…”

“…A mutation in the sll gene resulted in defects in multiple signaling pathways, including those of Wingless and Hedgehog signaling (7). The sll gene is also required for the determination of the embryonic dorsal/ventral axis, possibly for the activation of the signaling cascade that is initiated by the product of the putative sulfotransferase gene pipe (7,10).In the Drosophila embryonic salivary glands, both sll and the PAPS synthase gene (papss) are required for the production of sulfated macromolecules (7,11,12). The Drosophila genome contains a single PAPS synthase gene, whereas two isoforms of this gene have been identified in mammals (13,14).…”

“…In the Drosophila embryonic salivary glands, both sll and the PAPS synthase gene (papss) are required for the production of sulfated macromolecules (7,11,12). The Drosophila genome contains a single PAPS synthase gene, whereas two isoforms of this gene have been identified in mammals (13,14).…”

Combinatorial expression patterns of heparan sulfate sulfotransferases in zebrafish: III. 2‐O‐sulfotransferase and C5‐epimerases

“…Drosophila contains two genes, which show high homology to other 2-OSTs, HS2ST, and pipe (Sergeev et al, 2001). Although pipe resembles an HS 2-OST, recent evidence suggests Pipe functions as a sulfotransferase for a substrate other than HS (Zhu et al, 2005).…”