High copy arrays containing a sequence upstream of mec-3 alter cell migration and axonal morphology in C. elegans.
BACKGROUND
The Caenorhabditis elegans gene mec-3 encodes a LIM-homeodomain protein that is a master regulator of touch receptor neuron genes. Two of the touch neurons, the ALM neurons, are generated in the anterior of the animal and then migrate to near the middle of the animal. In animals transformed with a sequence upstream of mec-3, the ALM touch receptor neurons failed to migrate to their normal positions and sometimes migrated in the wrong direction, and the PLM touch receptor neurons showed axonal defects. Here we characterize this effect and identify the sequence causing the cell migration and axonal defects.


RESULTS
The ALM migration defect did not result from RNA interference (RNAi), nonspecific effects of carrying a transgenic array, expression of GFP, or the marker gene used to make the transformants. Instead, the ALM migration defect resulted from transgenic arrays containing many copies of a specific 104 bp DNA sequence. Transgenic arrays containing this sequence did not affect all cell migrations.


CONCLUSIONS
The mec-3 upstream sequence appeared to be sequestering (titrating out) a specific DNA-binding factor that is required for the ALMs to migrate correctly. Because titration of this factor could reverse the direction of ALM migrations, it may be part of a program that specifies both the direction and extent of ALM migrations. mec-3 is a master regulator of touch receptor neuron genes, so the factor or factors that bind this sequence may also be involved in specifying the fate of touch receptor neurons.
Toms
N
N
Louisiana State University Health Sciences Center-Shreveport, Department of Biochemistry and Molecular Biology, Shreveport, USA. eaamod@lsuhsc.edu
Cooper
J
J
Patchen
B
B
Aamodt
E
E
D024506:5' Flanking Region / Q000235:genetics*; D000818:Animals; D030801:Animals, Genetically Modified; D001369:Axons / Q000737:chemistry / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D002465:Cell Movement / Q000235:genetics*; D003080:Cold Temperature / Q000009:adverse effects; D015342:DNA Probes / Q000235:genetics; D018628:Gene Dosage; D005819:Genetic Markers / Q000235:genetics; D049452:Green Fluorescent Proteins; D018398:Homeodomain Proteins / Q000235:genetics; D060850:LIM-Homeodomain Proteins; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D014110:Touch / Q000235:genetics; D014157:Transcription Factors
D029742:Caenorhabditis elegans Proteins; D015816:Cell Adhesion Molecules, Neuronal; D015342:DNA Probes; D005819:Genetic Markers; D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C072005:mec-3 protein, C elegans; D049452:Green Fluorescent Proteins