Molecular Cloning and Characterization of the Murine Staf cDNA Encoding a Transcription Activating Factor for the Selenocysteine tRNA Gene in Mouse Mammary Gland

Abstract

We have isolated and characterized a cDNA encoding a transcription activating factor for the mouse selenocysteine tRNA (

Transcriptional Regulation of the Mouse Cytosolic Chaperonin Subunit Gene Ccta/t-Complex Polypeptide 1 by Selenocysteine tRNA Gene Transcription Activating Factor Family Zinc Finger Proteins

“…This is consistent with the fact that Ccta mRNA is detectable in all types of cells and tissues (33,14,15), although expression levels differ considerably. In mouse tissues, ZNF143 mRNA is more abundant in thymus than in brain or lung (23), which is similar to the expression pattern of mouse Ccta/Tcp-1 mRNA (33). On the other hand, the mouse ZNF76 mRNA is detectable in 20-day-old and adult testis but not in liver, brain, kidney, or spleen (21), suggesting that ZNF76 is especially abundant in testis germ cells compared with other types of cells.…”

“…Thus, our results are consistent with the previous findings that Staf can stimulate not only the transcription by RNA polymerase III but also the transcription by RNA polymerase II (19,20). These characteristics appear to be conserved between Xenopus Staf and mammalian homologues (23)(24)(25).…”

“…7), ZNF76 may contribute to the very strong expression of Ccta gene in testis, whereas ZNF143 is likely to contribute to general expression of the Ccta gene. It is also known that DNA binding activity of mouse ZNF143 is stimulated in mammary gland at pregnant and lactating stages (23), when mammary cells proliferate very rapidly. In agreement with this observation, the expression of CCT subunit genes, including Ccta, are up-regulated during cell growth (15), and the expression level of CCT is particularly high in FM3A mammary tumor cells (15).…”

“…The DNA binding zinc-finger domains of these proteins show 84% amino acid sequence identity (24). C, comparison of the CAE1 and CAE2 sequences, ZNF76/ZNF143 (mammalian homologues of Staf) binding sequences of the mouse tRNA sec gene (m-tRNA sec -SBS) (23), and human U6 RNA gene (h-U6-SBS) (24), and Xenopus Staf binding consensus sequences determined by PCR-mediated affinity selection of binding DNAs (Staf cons. 1) (19) or footprint assay of native gene promoters (Staf cons.…”

“…There are seven zinc-finger repeats for DNA binding in the middle of the Staf molecule and the amino-terminal portion contains a transcription activation domain. Two mammalian homologues of Staf, ZNF76 and ZNF143, have been isolated (21,22) and shown to recognize very similar sequences (23)(24)(25). ZNF76 and ZNF143 are considered to play basically the same role as Staf, whereas the expression levels in various tissues are different between the two homologues.…”