PubMed · 12575930
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
Philipp Selenko, Michael Sattler. 2003. Switching off the switch.. https://doi.org/10.1016/s0969-2126(03)00012-1
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Nijmegen breakage syndrome (NBS) is a rare genetic instability syndrome associated with a high incidence of lymphoid malignancies. The NBS1 protein has been implicated in telomere biology suggesting that cells from NBS patients might have deficient telomere maintenance capacity. In this study we characterized spontaneously immortalized T-cell lines derived from three NBS patients regarding growth characteristics, telomere biology, expression of cell-cycle regulators, and response to DNA damage to understand the role of NBS1 in the immortalization process. In all the NBS T-cell lines the acquisition of an immortal phenotype was associated with telomere length stabilization, high telomerase activity, and increased mRNA expression of the catalytic subunit of telomerase (hTERT), together with c-myc up-regulation. Our findings provide evidence that telomere length maintenance was intact in the T lymphocytes in the absence of a full-length NBS protein, presumably due to the presence of an alternatively transcribed NBS protein of 70 kDa. Normal protein expression patterns for pRb and p53 in all the immortal lines coincided with altered expression of some cell-cycle proteins as well as with an impaired G1/S arrest after gamma irradiation, despite a seemingly normal p53/p21 pathway. The here described, spontaneously immortalized NBS derived T-cell lines can be useful in future analysis of the biologic effects in the NBS.
Explore the source record for details and available documents.
MKK5 expressed as a glutathione S-transferase fusion protein in human embryonic kidney 293 cells activated full-length extracellular-signal-regulated protein kinase (ERK)5 (ERK5wt) as well as the isolated catalytic domain (ERK5cat) in vitro. Activation was accompanied by the phosphorylation of Thr(219) and Tyr(221), the former residue being phosphorylated preferentially. ERK5cat phosphorylated at Thr(219), but not Tyr(221), possessed 10% of the activity of the doubly phosphorylated protein towards myelin basic protein, whereas ERK5cat phosphorylated at Tyr(221) alone was much less active. Activated ERK5 phosphorylated itself at a number of residues, including Thr(28), Ser(421), Ser(433), Ser(496), Ser(731) and Thr(733). ERK5 phosphorylated at Thr(219), but not Tyr(221), phosphorylated itself at a similar rate to ERK5 phosphorylated at both Thr(219) and Tyr(221). Activated ERK5 also phosphorylated mitogen-activated protein kinase kinase 5 (MKK5) extensively at Ser(129), Ser(137), Ser(142) and Ser(149), which are located within the region in MKK5 that is thought to interact with ERK5.