The TAF10-containing TFIID and SAGA transcriptional complexes are dispensable for early somitogenesis in the mouse embryo

Cell fate and patterning during development are controlled by gene expression. Pre-initiation complex (PIC) formation at promoters is crucial to recruit the transcriptional machinery. The PIC has mainly been studied in vitro, and little is known about its composition and function during development. TAF10 is a subunit of TFIID and of the transcriptional co-activator SAGA. Here we characterized TFIID and SAGA's composition during mouse development. Our data indicate that TAF10 is required for TFIID and SAGA assembly. To analyse TAF10-dependent gene regulation during development, we conditionally deleted Taf10 in the mesoderm. Our results provide evidence for a time window during which Taf10 loss in the presomitic mesoderm (PSM) does not prevent cyclic gene transcription or PSM patterning while lateral plate differentiation is profoundly altered. During this period, global steady state mRNA levels are not significantly affected in the PSM although the expression of a subset of specific genes is dysregulated. Together, our data demonstrate a differential sensibility of mesodermal tissues to the lack of TAF10. This supports a differential requirement for TAF10 by the general transcriptional machinery during different developmental processes.