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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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Genetic and molecular map of cytological region 95BC.  (A) Deficiencies are represented by horizontal bars and lethal  complementation groups by vertical lines. Groups l(3)95BCa-d  have not been oriented with respect to each other. (B) Molecular  map of the region between the distal breakpoints of Df(3R)CA15  and Df(3R)mbc-15A, indicating P1, cosmid, and bacteriophage  lambda clones (gray lines). EcoRI sites are indicated. The location of the mbc gene is indicated by a hatched bar, and the direction of transcription is marked by the arrow. (C) A Southern blot  of EcoRI/BamHI-digested DNA that was enriched for various  deficiency chromosomes, including isogenic ru st e and mbcF6.4 as  controls. The test probe is a 2.8-kb EcoRI fragment from P1  clone DS07442 (upper band) while the control probe is a fragment from MHC (lower band).
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Figure 1: Genetic and molecular map of cytological region 95BC. (A) Deficiencies are represented by horizontal bars and lethal complementation groups by vertical lines. Groups l(3)95BCa-d have not been oriented with respect to each other. (B) Molecular map of the region between the distal breakpoints of Df(3R)CA15 and Df(3R)mbc-15A, indicating P1, cosmid, and bacteriophage lambda clones (gray lines). EcoRI sites are indicated. The location of the mbc gene is indicated by a hatched bar, and the direction of transcription is marked by the arrow. (C) A Southern blot of EcoRI/BamHI-digested DNA that was enriched for various deficiency chromosomes, including isogenic ru st e and mbcF6.4 as controls. The test probe is a 2.8-kb EcoRI fragment from P1 clone DS07442 (upper band) while the control probe is a fragment from MHC (lower band).

Mentions: Df(3R)CA15 and Df(3R)CA2 were obtained by imprecise excision of the homozygous lethal P-element insertion l(3)04684 (Bloomington Stock Center, Bloomington, IN). Mobilization occurred in flies carrying l(3)04684 over Sb, Delta2-3 ry, and excision events were recovered over MKRS or TM2. 677 excision events were analyzed. 330 imprecise excision events were identified by lack of complementation of Df(3R)mbc-F5.3/ TM3 (see Fig. 1). These were subsequently reevaluated for lack of complementation of l(3)95BCd and l(3)01152 and complementation of mbcS4. Four deficiencies were obtained, two of which are shown in Fig. 1.


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)

Genetic and molecular map of cytological region 95BC.  (A) Deficiencies are represented by horizontal bars and lethal  complementation groups by vertical lines. Groups l(3)95BCa-d  have not been oriented with respect to each other. (B) Molecular  map of the region between the distal breakpoints of Df(3R)CA15  and Df(3R)mbc-15A, indicating P1, cosmid, and bacteriophage  lambda clones (gray lines). EcoRI sites are indicated. The location of the mbc gene is indicated by a hatched bar, and the direction of transcription is marked by the arrow. (C) A Southern blot  of EcoRI/BamHI-digested DNA that was enriched for various  deficiency chromosomes, including isogenic ru st e and mbcF6.4 as  controls. The test probe is a 2.8-kb EcoRI fragment from P1  clone DS07442 (upper band) while the control probe is a fragment from MHC (lower band).
© Copyright Policy
Related In: Results  -  Collection

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Figure 1: Genetic and molecular map of cytological region 95BC. (A) Deficiencies are represented by horizontal bars and lethal complementation groups by vertical lines. Groups l(3)95BCa-d have not been oriented with respect to each other. (B) Molecular map of the region between the distal breakpoints of Df(3R)CA15 and Df(3R)mbc-15A, indicating P1, cosmid, and bacteriophage lambda clones (gray lines). EcoRI sites are indicated. The location of the mbc gene is indicated by a hatched bar, and the direction of transcription is marked by the arrow. (C) A Southern blot of EcoRI/BamHI-digested DNA that was enriched for various deficiency chromosomes, including isogenic ru st e and mbcF6.4 as controls. The test probe is a 2.8-kb EcoRI fragment from P1 clone DS07442 (upper band) while the control probe is a fragment from MHC (lower band).
Mentions: Df(3R)CA15 and Df(3R)CA2 were obtained by imprecise excision of the homozygous lethal P-element insertion l(3)04684 (Bloomington Stock Center, Bloomington, IN). Mobilization occurred in flies carrying l(3)04684 over Sb, Delta2-3 ry, and excision events were recovered over MKRS or TM2. 677 excision events were analyzed. 330 imprecise excision events were identified by lack of complementation of Df(3R)mbc-F5.3/ TM3 (see Fig. 1). These were subsequently reevaluated for lack of complementation of l(3)95BCd and l(3)01152 and complementation of mbcS4. Four deficiencies were obtained, two of which are shown in Fig. 1.

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