Sec61α is required for dorsal closure during Drosophila embryogenesis through its regulation of Dpp signaling

Abstract

During dorsal closure in Drosophila, signaling events in the dorsalmost row of epidermal cells (DME cells) direct the migration of lateral epidermal sheets towards the dorsal midline where they fuse to enclose the embryo. A Jun amino-terminal kinase (JNK) cascade in the DME cells induces the expression of Decapentaplegic (Dpp). Dpp signaling then regulates the cytoskeleton in the DME cells and amnioserosa to affect the cell shape changes necessary to complete dorsal closure. We identified a mutation in Sec61a that specifically perturbs dorsal closure. Sec61a encodes the main subunit of the translocon complex for co-translational import of proteins into the ER. JNK signaling is normal in Sec61a mutant embryos, but Dpp signaling is attenuated and the DME cells fail to maintain an actinomyosin cable as epithelial migration fails. Consistent with this model, dorsal closure is rescued in Sec61a mutant embryos by an activated form of the Dpp receptor Thick veins. Developmental Dynamics 239:784-797,

Distinct tissue distributions and subcellular localizations of differently phosphorylated forms of the myosin regulatory light chain in Drosophila

“…5B and C). Similar patterns of expression have been described for both Sqh and Zip (Franke et al, 2005; Wang and Ward, 2010; Young et al, 1993). In contrast to the specific localization of Sqh1P along the actin cable, Sqh2P is strongly upregulated throughout the DME cells during the initiation phase of dorsal closure (stage 13; Fig.…”

“…We also generated an antibody against full-length Sqh protein to use as a control (initially described in Wang and Ward, 2010). To test the specificity of these antibodies, we conducted western blotting of lysates from wild type imaginal discs.…”

“…The animals were boosted according to standard protocols until strong immunoreactivity was observed on immunoblots and on tissue stains. The guinea pig anti-Sqh1P serum was subsequently affinity purified at PRF&L. Antibodies specific for full-length Sqh are described in Wang and Ward (2010). It should be noted that a commercially available antibody to the monophosphorylated version of vertebrate MRLC differs slightly from the peptide we used for Sqh1P (vertebrate sequence: R-P-Q-R-A-T-S*-N-V-F-A-C) (Matsumura et al, 1998).…”

Genome-wide RNAi Screen Identifies SEC61A and VCP as Conserved Regulators of Sindbis Virus Entry

“…dVCP, dUFD1L, dNPLOC4, and dSEC61A are essential genes (Leon and McKearin, 1999; Wang and Ward, 2010). Therefore, we used heat shock-inducible in vivo RNAi to deplete these proteins in adult flies and found that depletion of each component of the VCP-UFD1L-NPLOC4 complex as well as SEC61A significantly attenuated SINV infection (Fig.…”

Macroglobulin complement-relatedencodes a protein required for septate junction organization and paracellular barrier function inDrosophila

“…Nrg 17 was identified by absence of immunostaining by Nrg-specific antibodies. Lethal phase and phenotypic analysis of the resulting dead Mcr mutant embryos was performed as described (Wang and Ward, 2010). …”