Alternative titles; symbols
HGNC Approved Gene Symbol: DTL
Cytogenetic location: 1q32.3 Genomic coordinates (GRCh38): 1:212,035,748-212,105,013 (from NCBI)
Using RNA fingerprinting to identify genes differentially regulated during retinoic acid (RA)-induced neuronal differentiation of NT2 embryonic carcinoma cells, followed by screening an NT2 cell cDNA library, Cheung et al. (2001) cloned DTL, which they called RAMP. The deduced 730-amino acid protein has a calculated molecular mass of 79.4 kD. RAMP is rich in serines, threonines, and basic residues. It has 2 WD repeats, a putative leucine zipper, a nuclear localization signal, a putative SH3-binding motif, 5 potential glycosylation sites, and several potential phosphorylation sites. Northern blot analysis detected transcripts of 5 and 3 kb predominantly in placenta and testis, with much lower expression in skeletal muscle. Northern and RNA dot blot analyses revealed several RAMP transcripts in all fetal tissues examined. Dot blot analysis also showed RAMP expression in all adult hematopoietic tissues examined, with highest levels in thymus and bone marrow. Western blot analysis detected RAMP in the crude nuclear and nuclear matrix fractions of transfected Chinese hamster ovary (CHO) cells. Immunohistochemical analysis localized RAMP in the nuclear region of transfected CHO cells, although expression was also detected in the cytoplasm. In vitro translation resulted in an 85-kD RAMP protein.
Jin et al. (2006) reported that the human DTL protein, which they called CDT2, contains 7 WD repeats.
Cheung et al. (2001) found that RAMP mRNA and protein levels decreased in NT2 cells following RA treatment. RAMP translocated from the interphase nucleus to the metaphase cytoplasm during mitosis. During late-stage cytokinesis, RAMP concentrated at the midzone of dividing daughter cells. RAMP mRNA levels showed a positive correlation with the rate of cell proliferation, and overexpression of RAMP in NT2 cells induced a transient increase in proliferation.
Using coimmunoprecipitation and Western blot analysis, Jin et al. (2006) found that CDT2 interacted with DDB1 (600045) and CUL4A (603137) following their cotransfection in human embryonic kidney cells. Endogenous DDB1 also interacted with endogenous CDT2 and with DCAF1 (617259). A conserved WDXR motif in CDT2 was required for DDB1 binding. In Xenopus egg extracts and human cells, CDT2 functioned to destroy the replication licensing protein CDT1 (605525) in S phase and after DNA damage. Depletion of CDT2 caused rereplication and checkpoint activation. In Xenopus, Cdt1 and Pcna (176740) recruited Cdt2 to replication forks, where Cdt1 was ubiquitinated. Jin et al. (2006) concluded that CDT2 is a conserved component of the CUL4-DDB1 E3 ligase that is essential for CDT1 destruction and to ensure proper cell cycle regulation of DNA replication.
By mass spectrometric analysis, Higa et al. (2006) identified over 20 WD40 repeat-containing (WDR) proteins that interacted with the CUL4-DDB1-ROC1 (RBX1; 603814) complex, including L2DTL. Sequence alignment revealed that most of the interacting WDR proteins had a centrally positioned WDxR/K submotif. Knockdown studies suggested that the WDR proteins functioned as substrate-specific adaptors. For example, inactivation of L2DTL, but not other WDR proteins, prevented CUL4-DDB1-dependent proteolysis of CDT1 following gamma irradiation. Inactivation of WDR5 (609012) or EED (605984), but not other WDR proteins, altered the pattern of CUL4-DDB1-dependent histone H3 (see 602810) methylation.
Using FISH, Cheung et al. (2001) mapped the DTL gene to chromosome 1q32.1-q32.2.
Cheung, W. M. W., Chu, A. H., Chu, P. W. K., Ip, N. Y. Cloning and expression of a novel nuclear matrix-associated protein that is regulated during the retinoic acid-induced neuronal differentiation. J. Biol. Chem. 276: 17083-17091, 2001. [PubMed: 11278750] [Full Text: https://doi.org/10.1074/jbc.M010802200]
Higa, L. A., Wu, M., Ye, T., Kobayashi, R., Sun, H., Zhang, H. CUL4-DDB1 ubiquitin ligase interacts with multiple WD40-repeat proteins and regulates histone methylation. Nature Cell Biol. 8: 1277-1283, 2006. [PubMed: 17041588] [Full Text: https://doi.org/10.1038/ncb1490]
Jin, J., Arias, E. E., Chen, J., Harper, J. W., Walter, J. C. A family of diverse Cul4-Ddb1-interacting proteins includes Cdt2, which is required for S phase destruction of the replication factor Cdt1. Molec. Cell 23: 709-721, 2006. [PubMed: 16949367] [Full Text: https://doi.org/10.1016/j.molcel.2006.08.010]