In C. elegans, the Q cells are bilaterally symmetric neuroblasts present in the posterior body region of the worm at hatching. During the first larval stage, the Q cells divide and migrate. QR and its descendents migrate anteriorly whereas QL and its descendents migrate posteriorly. Several genes that regulate the anterior migrations of QR and its descendents have been identified. These include: 1)
lin-39, a homeobox gene required in QR and its descendents for migration (Wang B. et al, 1993; Clark S. et al, 1993); 2)
mig-13, a novel transmembrane protein required outside of QR and its descendents for migration (Sym M et al, 1999); and 3)
egl-20, a Wnt homolog expressed in cells in the tail region (Whangbo J.. and Kenyon C, 1999). Two mutant screens (Mary Sym and Queelim Ch'ng) were conducted to identify additional genes that regulate the migration of QR and its descendents. From these screens, mutations in two new genes were identified that cause certain cells in the QR lineage to stop migrating prematurely. These two genes seem likely to be involved in guidance rather than in providing cells with the ability to migrate because, in these mutants, other cells sometimes migrate in the wrong direction. Current efforts are directed toward cloning these two genes and determining how these genes regulate the migration of QR and its descendents together with genes previously known to regulate these migrations. References: Clark SG, Chisholm AD, and Horvitz HR. 1993. Control of Cell Fates in the Central Body Region of C. elegans by the Homeobox Gene
lin-39. Cell 74: 43-55. Sym M, Robinson N, Kenyon C. 1999.
mig-13 Positions Migrating Cells Along Anteroposterior Body Axis of C. elegans. Cell 98: 26-36. Wang BB, Muller-Immergluck MM, Austin, J, Robinson, NT, Chisholm, A, Kenyon, C. A Homeotic Gene Cluster Patterns the Anteroposterior Body Axis of C.. elegans. Cell 74: 29-42. Whangbo J, Kenyon, C. A Wnt Signaling System that Specifies Two Patterns of Cell Migration in C. elegans. Molecular Cell 4: 851-858.