Expression of the axolotl homologue of mouse chaperonin t-complex protein-1 during early development.

Molecular chaperones assist in the folding of proteins, but their role during development is not well understood. Here we report the temporal and spatial expression pattern of the axolotl homologue of mouse chaperonin TCP-1 during normal amphibian embryogenesis and in several models of abnormal embryogenesis. A partial axolotl TCP-1 cDNA (646 bp; 519 coding bp) isolated by 3' RACE PCR shows considerable homology to mouse TCP-1. Developmental Northerns and RT-PCR analyses of whole axolot1 embryos revealed a low level of maternal TCP-1 transcripts in fertilized eggs. The maternal transcripts were down-regulated to a non-detectable level in early gastrulae. Zygotic TCP-1 transcripts first appeared during gastrulation. They were mainly expressed in mid-neurula and later stage embryos. Whole-mount in situ hybridization studies showed abundant TCP-1 transcripts in the blastopore at the mid-gastrula stage and in the brain and spinal cord beginning at the neurula stage, and in the somites (myotomes) at the tailbud stage. RT-PCR analysis of TCP-1 expression in axolotl embryos treated with either high salt (causing exogastrulation) or ultraviolet (UV) irradiation (causing ventralization) substantiated the correlation between TCP-1 expression and neural and somitic development. In high salt-induced exogastrulated embryos TCP-1 mRNA was detectable in the ectoderm part (with neural tissues) but not in its exogastrulated endoderm part. Lower levels of TCP-1 expression were detected in UV-irradiated, ventralized embryos with smaller head and reduced neural and somitic tissues. Normal levels of TCP-1 expression were detected in embryos with double axes/heads. These studies provide strong evidence that at the transcript level axolotl chaperonin TCP-1 is regulated both temporally and spatially during embryogenesis, especially in neural and somitic development.