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Drosophila myoblast city encodes a conserved protein that is essential for myoblast fusion, dorsal closure, and cytoskeletal organization.

Erickson MR, Galletta BJ, Abmayr SM - J. Cell Biol. (1997)

Bottom Line: It is also expressed in the pole cells and in ectodermally derived tissues, including the epidermis.Consistent with this latter expression, mbc mutant embryos exhibit defects in dorsal closure and cytoskeletal organization in the migrating epidermis.Both the mesodermal and ectodermal defects are reminiscent of those induced by altered forms of Drac1 and suggest that mbc may function in the same pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology and Center for Gene Regulation, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.

ABSTRACT
The Drosophila myoblast city (mbc) locus was previously identified on the basis of a defect in myoblast fusion (Rushton et al., 1995. Development [Camb.]. 121:1979-1988). We describe herein the isolation and characterization of the mbc gene. The mbc transcript and its encoded protein are expressed in a broad range of tissues, including somatic myoblasts, cardial cells, and visceral mesoderm. It is also expressed in the pole cells and in ectodermally derived tissues, including the epidermis. Consistent with this latter expression, mbc mutant embryos exhibit defects in dorsal closure and cytoskeletal organization in the migrating epidermis. Both the mesodermal and ectodermal defects are reminiscent of those induced by altered forms of Drac1 and suggest that mbc may function in the same pathway. MBC bears striking homology to human DOCK180, which interacts with the SH2-SH3 adapter protein Crk and may play a role in signal transduction from focal adhesions. Taken together, these results suggest the possibility that MBC is an intermediate in a signal transduction pathway from the rho/rac family of GTPases to events in the cytoskeleton and that this pathway may be used during myoblast fusion and dorsal closure.

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MBC sequence and alignment with human DOCK180 as well as related open reading frames. The alignment was done using  Clustal W and presented using Boxshade. Black boxes indicate amino acid identity, while gray boxes indicate amino acid similarity to  MBC. Arrowheads highlight mutations found in mbc alleles. The consensus Crk-binding sites (PPxLPxK) of DOCK180 are underlined.  A potential Crk-binding site in MBC is noted with dots. Stars mark essential SH3 consensus residues (Musacchio et al., 1994). The GenBank/EMBL/DDBJ accession numbers are D86964 for the myeloblast-specific cDNA KIAA0209, Z81032 and Z81054 for the C. elegans ORFs, and AA110899 for the mouse expressed sequence tag. mbc sequence data are available from GenBank/EMBL/DDBJ under  accession number AF007805.
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Figure 2: MBC sequence and alignment with human DOCK180 as well as related open reading frames. The alignment was done using Clustal W and presented using Boxshade. Black boxes indicate amino acid identity, while gray boxes indicate amino acid similarity to MBC. Arrowheads highlight mutations found in mbc alleles. The consensus Crk-binding sites (PPxLPxK) of DOCK180 are underlined. A potential Crk-binding site in MBC is noted with dots. Stars mark essential SH3 consensus residues (Musacchio et al., 1994). The GenBank/EMBL/DDBJ accession numbers are D86964 for the myeloblast-specific cDNA KIAA0209, Z81032 and Z81054 for the C. elegans ORFs, and AA110899 for the mouse expressed sequence tag. mbc sequence data are available from GenBank/EMBL/DDBJ under accession number AF007805.

Mentions: A single full-length transcript of ∼7.5 kb was detected by Northern analysis throughout development using cloned DNA fragments within the 34-kb region described above. Although full-length clones were not obtained, several small overlapping cDNA clones provided most of the coding sequence of this transcript. The sequence of a small region not covered in the cDNA clones was obtained from embryonic mRNA by reverse transcriptase PCR amplification and sequencing. The embryonic transcript is ∼7.4 kb, with a coding sequence of 5,910 nts. Untranslated regions at the 5′ and 3′ ends of the isolated cDNAs are 560 and 906 bp, respectively. While the genomic organization of mbc has not been analyzed completely, a minimum of eight introns have been identified in a genomic region that spans at least 16 kb. The cDNA sequence has been submitted to GenBank and is not reproduced herein. The deduced amino acid sequence is shown in Fig. 2.


Drosophila myoblast city encodes a conserved protein that is essential for myoblast fusion, dorsal closure, and cytoskeletal organization.

Erickson MR, Galletta BJ, Abmayr SM - J. Cell Biol. (1997)

MBC sequence and alignment with human DOCK180 as well as related open reading frames. The alignment was done using  Clustal W and presented using Boxshade. Black boxes indicate amino acid identity, while gray boxes indicate amino acid similarity to  MBC. Arrowheads highlight mutations found in mbc alleles. The consensus Crk-binding sites (PPxLPxK) of DOCK180 are underlined.  A potential Crk-binding site in MBC is noted with dots. Stars mark essential SH3 consensus residues (Musacchio et al., 1994). The GenBank/EMBL/DDBJ accession numbers are D86964 for the myeloblast-specific cDNA KIAA0209, Z81032 and Z81054 for the C. elegans ORFs, and AA110899 for the mouse expressed sequence tag. mbc sequence data are available from GenBank/EMBL/DDBJ under  accession number AF007805.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2141626&req=5

Figure 2: MBC sequence and alignment with human DOCK180 as well as related open reading frames. The alignment was done using Clustal W and presented using Boxshade. Black boxes indicate amino acid identity, while gray boxes indicate amino acid similarity to MBC. Arrowheads highlight mutations found in mbc alleles. The consensus Crk-binding sites (PPxLPxK) of DOCK180 are underlined. A potential Crk-binding site in MBC is noted with dots. Stars mark essential SH3 consensus residues (Musacchio et al., 1994). The GenBank/EMBL/DDBJ accession numbers are D86964 for the myeloblast-specific cDNA KIAA0209, Z81032 and Z81054 for the C. elegans ORFs, and AA110899 for the mouse expressed sequence tag. mbc sequence data are available from GenBank/EMBL/DDBJ under accession number AF007805.
Mentions: A single full-length transcript of ∼7.5 kb was detected by Northern analysis throughout development using cloned DNA fragments within the 34-kb region described above. Although full-length clones were not obtained, several small overlapping cDNA clones provided most of the coding sequence of this transcript. The sequence of a small region not covered in the cDNA clones was obtained from embryonic mRNA by reverse transcriptase PCR amplification and sequencing. The embryonic transcript is ∼7.4 kb, with a coding sequence of 5,910 nts. Untranslated regions at the 5′ and 3′ ends of the isolated cDNAs are 560 and 906 bp, respectively. While the genomic organization of mbc has not been analyzed completely, a minimum of eight introns have been identified in a genomic region that spans at least 16 kb. The cDNA sequence has been submitted to GenBank and is not reproduced herein. The deduced amino acid sequence is shown in Fig. 2.

Bottom Line: It is also expressed in the pole cells and in ectodermally derived tissues, including the epidermis.Consistent with this latter expression, mbc mutant embryos exhibit defects in dorsal closure and cytoskeletal organization in the migrating epidermis.Both the mesodermal and ectodermal defects are reminiscent of those induced by altered forms of Drac1 and suggest that mbc may function in the same pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology and Center for Gene Regulation, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.

ABSTRACT
The Drosophila myoblast city (mbc) locus was previously identified on the basis of a defect in myoblast fusion (Rushton et al., 1995. Development [Camb.]. 121:1979-1988). We describe herein the isolation and characterization of the mbc gene. The mbc transcript and its encoded protein are expressed in a broad range of tissues, including somatic myoblasts, cardial cells, and visceral mesoderm. It is also expressed in the pole cells and in ectodermally derived tissues, including the epidermis. Consistent with this latter expression, mbc mutant embryos exhibit defects in dorsal closure and cytoskeletal organization in the migrating epidermis. Both the mesodermal and ectodermal defects are reminiscent of those induced by altered forms of Drac1 and suggest that mbc may function in the same pathway. MBC bears striking homology to human DOCK180, which interacts with the SH2-SH3 adapter protein Crk and may play a role in signal transduction from focal adhesions. Taken together, these results suggest the possibility that MBC is an intermediate in a signal transduction pathway from the rho/rac family of GTPases to events in the cytoskeleton and that this pathway may be used during myoblast fusion and dorsal closure.

Show MeSH
Related in: MedlinePlus