Developmental Biology

Weighing Down CTBF in the Cytoplasm

Science's STKE  25 Jul 2000:
Vol. 2000, Issue 42, pp. tw2
DOI: 10.1126/stke.2000.42.tw2

Tight regulation of gene expression is essential for early development. Brzostowski et al. describe a mechanism by which the activity of the maternally derived CCAAT box transcription factor (CBTF) can be controlled. CBTF activity is controlled in part by its subcellular localization: the protein is cytoplasmic before fertilization and translocates to the nucleus at the gastrula stage. Two isoforms of CBTF subunits, each of which has two consensus double-stranded RNA binding domains (dsRBD), were found in a complex with nontranslating messenger ribonucleoproteins in pre-gastrula stage Xenopus embryos. Mutation of the dsRBDs inhibited dsRNA binding in vitro, and when the mutated proteins were expressed in embryos, they exhibited premature nuclear accumulation. Injection of the oocytes with RNase led to nuclear accumulation of CBTF, confirming that RNA acts as a cytoplasmic anchor for CBTF before degradation of the maternal mRNA.

Brzostowski, J., Robinson, C., Orford, R., Elgar, S., Scarlett, G., Peterkin, T., Malartre, M., Kneale, G., Wormington, M., and Guille, M. (2000) RNA-dependent cytoplasmic anchoring of a transcription factor subunit during Xenopus development. EMBO J. 19: 3683-3693. [Full Text] [Abstract]