Zic Genes Involved in Convergent Extension

Jocelyn Waggoner, Christa Merzdorf and Jennifer Forecki, Montana State University, Culbertson Hall, 100, Bozeman, MT 59717

Convergent extension is a cellular movement during embryonic development, in which cells intercalate along an axis to allow changes in tissue shape. This lateral-to-medial movement of cells in a plane is required for gastrulation and neural tube closure. During gastrulation, cells migrate into the interior of the embryo at the dorsal lip of the blastopore. Knockout of zic transcription factors in mice results in defects in gastrulation, however, it is not understood by which mechanism mutations in zic genes cause these defects. The aquaporin 3b gene acts directly downstream of Zic transcription factors and is required for convergent extension. Based on published data in mice, I hypothesized that zic2 and zic3 regulate convergent extension via aqp3b. In Xenopus laevis, all five zic genes are expressed in dorsal blastopore tissue while it undergoes convergent extension. Dorsal mesoderm (‘Keller’) explants from gastrula embryos allow analysis of convergent extension in an isolated tissue. A knockdown method (using morpholino oligonucleotides) for each of the 5 zic genes was combined with the Keller explant method to study which of the very similar zic genes is required for convergent extension. Explants in which any one of the five zic genes was inhibited showed normal elongation/extension. Inhibition of zic1 or zic4 resulted in constriction defects in less than 35% of explants, and zic5 showed no constriction defects. However, inhibition of zic3 or zic2 resulted in 78.3% and 75.7% constriction defects respectively. This indicated that zic3 and zic2 expression is required for convergence cell movements, which has not been previously shown for zic genes. Furthermore, convergence defects caused by zic3 MOs and zic2 MOs were rescued with aquaporin 3b mRNA (reducing constriction defects to 29% and 19% respectively), suggesting that both zic2 and zic3 act through aqp3b to affect convergence. Future experiments will further explore this relationship.

Additional Abstract Information

Presenter: Jocelyn Waggoner

Institution: Montana State University Bozeman

Type: Poster

Subject: Biology

Status: Approved

Time and Location

Session: Poster 2
Date/Time: Mon 3:00pm-4:00pm
Session Number: 2626