TBP is not universally required for zygotic RNA polymerase II transcription in zebrafish

General transcription factors TFIIA, B, D, E, F, H, and RNA polymerase II ( Pol II) are required for accurate initiation of Pol II transcription. The T ATA binding protein (TBP), a subunit of TFIID, is responsible for recogniti on of the TATA box, a core element shared by a category of class II promote rs [1]. Recently, novel TBP-like factors (TLFs) have been described in meta zoan organisms [2]. In spite of the numerous in vitro studies describing th e general role of TBP in RNA polymerase II (Pol II) transcription initiatio n, the precise function of TBP and the newly described TLF is poorly unders tood in vivo. We inhibited TBP and TLF function in zebrafish embryos to stu dy the role of these factors during zygotic transcription. A dominant-negat ive variant of TLF mRNA and a TBP morpholino antisense oligo was used to bl ock either TLF or TBP function, Both TBP-or TLF-blocked embryos developed n ormally until the midblastula stage; however, they then failed to gastrulat e. Several zygotic regulatory genes were downregulated by a block in either TBP or TLF function, while others were differentially affected. These resu lts suggest that TBP is not universally required for Pol II transcription i n vertebrates and that there is a differential requirement for TBP and TLF during early embryogenesis.