Genetic regulation of engrailed and wingless in Tribolium segmentation and the evolution of pair-rule segmentation.
In Drosophila, primary pair-rule genes establish the parasegmental boundaries and indirectly control the periodic expression of the segment polarity genes engrailed (en) and wingless (wg) via regulation of secondary pair-rule genes. Although orthologs of some Drosophila pair-rule genes are not required for proper segmentation in Tribolium, segmental expression of Tc-en and Tc-wg is conserved. To understand how these segment polarity genes are regulated, we examined the results of expressing one or two pair-rule genes in the absence of the other known pair-rule genes. Expression of one or both of the secondary pair-rule genes, Tc-sloppy-paired (Tc-slp) and Tc-paired (Tc-prd), activated Tc-wg in the absence of the primary pair-rule genes, Tc-even-skipped (Tc-eve), Tc-runt (Tc-run) and Tc-odd-skipped (Tc-odd). Tc-eve alone failed to activate Tc-wg or Tc-en, but in combination with Tc-run or Tc-prd activated Tc-en. These results, interpreted within the pair-rule gene expression patterns, suggest separate models for the genetic regulation of the juxtaposed expression of Tc-wg and Tc-en at odd- and even-numbered parasegmental boundaries, respectively. Conserved interactions between eve and prd at the anterior boundary of odd-numbered parasegments may reflect an ancestral segmentation mechanism that functioned in every segment prior to the evolution of pair-rule segmentation.
Choe
Chong Pyo
CP
Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
Brown
Susan J
SJ
D000818:Animals; D005075:Biological Evolution; D019521:Body Patterning; D004330:Drosophila / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D017344:Genes, Insect; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014231:Tribolium / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D051155:Wnt1 Protein / Q000235:genetics* / Q000378:metabolism
D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D014157:Transcription Factors; D051155:Wnt1 Protein; C087327:engrailed protein, Tribolium; C074622:wg protein, Drosophila