Dynamic and differential Oct-1 expression during early Xenopus embryogenesis: persistence of Oct-1 protein following down-regulation of the RNA.

As a first step towards the elucidation of the role of the transcription factor Oct-1 in development, we prepared a monoclonal antibody to study the spatio-temporal distribution of Oct-1 protein in vivo. Here we report differential expression of the Oct-1 gene in the Xenopus embryo both at the RNA and the protein level. Transcripts and protein are detected in ectodermal and mesodermal cell lineages, in which the expression exhibits a pattern of progressive spatial restriction in the course of development. The Oct-1 expression as reported here is not correlated with cell density or cell proliferation in the embryo. Our results suggest a role of Oct-1 in the specification and differentiation of neuronal and neural crest cells. In many other cells, the developmental decision to down regulate Oct-1 is delayed, probably due to a high stability of the protein.