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thr + kinase)

Distribution by Scientific Domains

Chemistry	66%

Selected Abstracts

AATYK1A phosphorylation by Cdk5 regulates the recycling endosome pathway

GENES TO CELLS, Issue 7 2010
Tetsuya Takano
Trafficking of recycling endosomes (REs) is regulated by the small GTPase, Rab11A; however, the regulatory mechanism remains elusive. Apoptosis-associated tyrosine kinase 1A (AATYK1A) is a Ser/Thr kinase expressed highly in brain. We have recently shown that AATYK1A localizes to Rab11A-positive RE and is phosphorylated at Ser34 by cyclin-dependent kinase 5 (Cdk5). Here, we have investigated a role of AATYK1A and its phosphorylation in recycling endosomal trafficking using Chinese hamster ovary-K1 (CHO-K1) cells. AATYK1A localizes predominantly to Rab11A-positive pericentrosomal endocytic recycling compartment (ERC). Phosphorylation at Ser34 of AATYK1A disrupts its accumulation in the pericentrosomal ERC. Consistently, phosphorylation-mimic mutant (AATYK1A-S34D) did not accumulate in the ERC and additionally attenuated ERC formation. ERC formation suppression can be reversed by constitutively active Rab11A-Q70L, suggesting a functional link between AATYK1A phosphorylation and Rab11A activity. Although no direct interaction between AATYK1A and Rab11A could be detected, the exchange of guanine nucleotides bound to Rab11A was significantly reduced in the presence of the phosphorylation-mimic AATYK1A-S34D. Together, our results reveal a regulatory role for AATYK1A in the formation of pericentrosomal ERC. They furthermore indicate that Cdk5 can disrupt ERC formation via Ser34 phosphorylation of AATYK1A. Finally, our data suggest a mechanism by which AATYK1A signaling couples Cdk5 to Rab11A activity. [source]

Methylation-Associated Silencing of Death-Associated Protein Kinase Gene in Laryngeal Squamous Cell Cancer,

THE LARYNGOSCOPE, Issue 8 2005
Wei-Jia Kong MD
Abstract Objectives/Hypothesis: Death-associated protein kinase (DAPK) is a Ca2+/calmodulin-regulated Ser/Thr kinase that functions as a positive mediator of programmed cell death. It has been found that DAPK gene is frequently inactivated by its promoter hypermethylation in some cancers and tumor cell lines. However, it is not clear whether promoter hypermethylation of DAPK gene exists in laryngeal squamous cell cancer (LSCC). The aim of this study was to investigate the promoter methylation status of the DAPK gene in LSCC and the effect of 5-Aza-2'-deoxycytidine (5-Aza-CdR), a demethylating agent, on Hep-2 cells, a human laryngeal cancer cell line, and on xenografts of Hep-2. Methods: Methylation-specific polymerase chain reaction (PCR) and reverse-transcription PCR techniques were used to determine the promoter methylation status and mRNA expression of DAPK gene in LSCC. Furthermore, Hep-2 cells in vitro and in vivo were treated by 5-Aza-CdR to explore the effect of demethylating agents on DAPK mRNA expression and tumor growth. Results: Hypermethylation of DAPK gene promoter was found in 39 (67.2%) of 58 LSCC samples. There was no significant difference in the promoter hypermethylation rate among the samples of different histologic grades or samples from patients with different T stages. However, there was significant difference in methylation status of DAPK gene between the samples from patients in N0 stages and those from patients in N1 stages. No promoter hypermethylation of DAPK gene was found in any of the five normal laryngeal tissue samples. DAPK mRNA expression was not detected in tumor specimens with promoter hypermethylation. On the contrary, DAPK mRNA expression was observed in the unmethylated tumor specimens, specimens from tissues adjacent to the tumor, and normal laryngeal tissues samples. Promoter hypermethylation of DAPK gene was found, and no DAPK mRNA expression was detected in Hep-2 cells. DAPK mRNA expression in Hep-2 cells and xenografts could be restored by treating cells and xenografts with 5-Aza-CdR. The tumors' xenografts, induced by way of Hep-2 cell injection in nude mice treated with 5-Aza-CdR, were obviously smaller than those in nude mice treated with phosphate-buffered saline. Conclusions: Abnormal loss of DAPK expression could be associated with aberrant promoter region methylation in the LSCC. 5-Aza-CdR may slow the growth of Hep-2 cells in vitro and in vivo by reactivating tumor suppressor gene DAPK silenced by de novo methylation. [source]

Structural analysis of an MK2,inhibitor complex: insight into the regulation of the secondary structure of the Gly-rich loop by TEI-I01800

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2010
Aiko Fujino
Mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2 or MK2) is a Ser/Thr kinase from the p38 mitogen-activated protein kinase signalling pathway and plays an important role in inflammatory diseases. The crystal structure of the complex of human MK2 (residues 41,364) with the potent MK2 inhibitor TEI-I01800 (pKi = 6.9) was determined at 2.9,Å resolution. The MK2 structure in the MK2,TEI-I01800 complex is composed of two domains, as observed for other Ser/Thr kinases; however, the Gly-rich loop in the N-terminal domain forms an ,-helix structure and not a ,-sheet. TEI-I01800 binds to the ATP-binding site as well as near the substrate-binding site of MK2. Both TEI-I01800 molecules have a nonplanar conformation that differs from those of other MK2 inhibitors deposited in the Protein Data Bank. The MK2,TEI-I01800 complex structure is the first active MK2 with an ,-helical Gly-rich loop and TEI-I01800 regulates the secondary structure of the Gly-rich loop. [source]

Purification, crystallization and preliminary X-ray diffraction of a proteolytic fragment of PDK1 containing the pleckstrin homology domain

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2004
David Komander
3-Phosphoinositide-dependent protein kinase-1 (PDK1) is a Ser/Thr kinase with an essential role in insulin and growth-factor signalling. PDK1 activity towards protein kinase B (PKB) is partially regulated by its pleckstrin homology (PH) domain, which preferentially binds to 3-phosphoinositides. However, the precise molecular mechanism of this regulation is not well understood. Here, the cloning, purification and crystallization of a 150-amino-acid C-terminal region of PDK1 containing the PH domain is reported. A crystal of the PDK1 PH domain grown in the presence of inositol 1,3,4,5-tetrakisphosphate and derivatized with AuCN diffracted to 1.5,Å at a synchrotron source. Diffraction data collected near the Au edge resulted in an anomalous Patterson map with a 30, peak. [source]

High-resolution crystal structure of human Mapkap kinase 3 in complex with a high affinity ligand

PROTEIN SCIENCE, Issue 1 2010
Robert Cheng
Abstract The Mapkap kinases 2 and 3 (MK2 and MK3) have been implicated in intracellular signaling pathways leading to the production of the pro-inflammatory cytokine tumor necrosis factor alpha. MK2 has been pursued by the biopharmaceutical industry for many years for the development of a small molecule anti-inflammatory treatment and drug-like inhibitors have been described. The development of some of these compounds, however, has been slowed by the absence of a high-resolution crystal structure of MK2. Herein we present a high-resolution (1.9 Å) crystal structure of the highly homologous MK3 in complex with a pharmaceutical lead compound. While all of the canonical features of Ser/Thr kinases in general and MK2 in particular are recapitulated in MK3, the detailed analysis of the binding interaction of the drug-like ligand within the adenine binding pocket allows relevant conclusions to be drawn for the further design of potent and selective drug candidates. [source]