The winged-helix transcription factor Trident is expressed in cycling cells

Abstract

We describe the cloning and characterization of Trident , a novel member of the fork head/winged-helix family, from murine thymus. In the mouse embryo, the gene was expressed in all tissues, whereas in adult mice expression was only detected in the thymus. Further analysis revealed that Trident expression strictly correlated with cell cycling, independent of cell type. Timing of [3H]thymidine incorporation showed that mRNA and protein expression were strongly upregulated upon entry into the S phase of the cell cycle. Moreover, the protein was phosphorylated in M phase. PCR-mediated selection of optimal binding sites yielded a consensus motif resembling that of other family members. These results identify Trident as a transcription factor, which is likely involved in cell cycle-specific gene regulation.

Interaction of the fork head domain transcription factor MPP2 with the human papilloma virus 16 E7 protein: enhancement of transformation and transactivation

“…A third splice variant (hHFH-11A) contains an additional 38 aa in the region between the fkh domain and the E7 interaction domain (as indicated). While no splice variants were found for either mMPP2 (our unpublished data) or mTrident (Korver et al, 1997a), rWIN represents most likely a forth splice variant of the same gene with an insertion coding for 12 aa in the fkh domain. The human, rat, and murine MPP2 sequences are highly homologous and the identities of any two of the three sequences are in the range of 80% if the di erentially spliced exons are not taken into account.…”

“…The identi®cation of MPP2 sequences in various di erent cell types implies that it is expressed nearly ubiquitously. Nevertheless in adult humans and mice the expression of MPP2 seems to be con®ned to a restricted number of tissues, including thymus and testis and to lower levels in small intestine and colon (Ye et al, 1997;Korver et al, 1997a;S Andrecht and JM LuÈ scherFirzla , unpublished). A more detailed analysis of MPP2 expression revealed that it is associated with proliferating cells such as actively dividing T cells or tissues such as embryonic pancreas, lung, liver, and intestine that contains cycling cells (Yao et al, 1997;Ye et al, 1997;Korver et al, 1997c).…”

“…In all three cases degenerate PCR approaches were used to identify novel members of the fkh domain family. HFH-11 was identi®ed in a colon carcinoma cell line (Ye et al, 1997), WIN in an insulinoma cell line (Yao et al, 1997), and Trident in thymus tissue (Korver et al, 1997a). The respective protein sequences are summarized and compared to MPP2 in Figure 2.…”

“…Sequence identity between various isolates of MPP2 is very high (see below), suggesting that MPP2, Trident, HFH-11 and WIN are all encoded by the same gene. Human MPP2 (762 aa) is identical to hTrident and hWIN with the exception of 4 and 3 aa, respectively (Korver et al, 1997a;Yao et al, 1997). In addition a splice variant of hWIN encoding a protein with a 15 aa deletion spanning the C-terminal end of the fkh domain was identi®ed.…”

“…One of these partners was represented by four overlapping clones whose sequences were homologous to a previously identi®ed partial cDNA encoding M phase phosphoprotein 2 (MPP2) (Westendorf et al, 1994;Matsumoto-Taniura et al, 1996). We have cloned cDNAs encoding fulllength MPP2, which has recently been identi®ed as a transcription factor of the fork head (fkh)/winged-helix family of proteins [HFH-11 (Ye et al, 1997), WIN (Yao et al, 1997), Trident (Korver et al, 1997a)]. We demonstrate that MPP2 binds to E7 and a ects E7-induced transformation, and that E7 of HPV16, but not of HPV6, can stimulate transcription of MPP2.…”