Aurora-A, a centrosomal serine-threonine kinase, orchestrates several key aspects of cell division. However, the regulatory pathways for the protein stability and kinase activity of Aurora-A are ...still not completely understood. In this study, PUM2, an RNA-binding protein, is identified as a novel substrate and interacting protein of Aurora-A. Overexpression of the PUM2 mutant which fails to interact with Aurora-A, and depletion of PUM2 result in a decrease in the amount of Aurora-A. PUM2 physically binds to the D-box of Aurora-A, which is recognized by APC/C(Cdh1). Overexpression of PUM2 prevents ubiquitination and enhances the protein stability of Aurora-A, suggesting that PUM2 protects Aurora-A from APC/C(Cdh1)-mediated degradation. Moreover, association of PUM2 with Aurora-A not only makes Aurora-A more stable but also enhances the kinase activity of Aurora-A. Our study suggests that PUM2 plays two different but important roles during cell cycle progression. In interphase, PUM2 localizes in cytoplasm and plays as translational repressor through its RNA binding domain. However, in mitosis, PUM2 physically associates with Aurora-A to ensure enough active Aurora-A at centrosomes for mitotic entry. This is the first time to reveal the moonlight role of PUM2 in mitosis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The epidermal growth factor receptor (EGFR), which is up-regulated in lung cancer, involves the activation of mitogenic signals and triggers multiple signaling cascades. To dissect these EGFR ...cascades, we used 14 different phospho-EGFR antibodies to quantify protein phosphorylation using an in situ proximity ligation assay (in situ PLA). Phosphorylation at EGFR-Thr654 and -Ser1046 was EGF-dependent in the wild-type (WT) receptor but EGF-independent in a cell line carrying the EGFR-L858R mutation. Using a ProtoAarray™ containing ∼5000 recombinant proteins on the protein chip, we found that AURKA interacted with the EGFR-L861Q mutant. Moreover, overexpression of EGFR could form a complex with AURKA, and the inhibitors of AURKA and EGFR decreased EGFR-Thr654 and -Ser1046 phosphorylation. Immunohistochemical staining of stage I lung adenocarcinoma tissues demonstrated a positive correlation between AURKA expression and phosphorylation of EGFR at Thr654 and Ser1046 in EGFR-mutant specimens, but not in EGFR-WT specimens. The interplay between EGFR and AURKA provides an explanation for the difference in EGF dependency between EGFR-WT and EGFR-mutant cells and may provide a new therapeutic strategy for lung cancer patients carrying EGFR mutations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The mitotic spindle is an essential molecular machine for chromosome segregation during mitosis. Achieving a better understanding of its organization at the topological level remains a daunting task. ...To determine the functional connections among 137 mitotic spindle proteins, a protein-protein interaction network among queries was constructed. Many hub proteins, which connect more than one query and serve as highly plausible candidates for expanding the mitotic spindle proteome, are ranked by conventional degree centrality and a new subnetwork specificity score. Evaluation of the ranking results by literature reviews and empirical verification of SEPT6, a novel top-ranked hub, suggests that the subnetwork specificity score could enrich for putative spindle-related proteins. Topological analysis of this expanded network shows the presence of 30 3-cliques and six 4-cliques (fully connected subgraphs) that, respectively, reside in eight kinetochore-associated complexes, of which seven are evolution conserved. Notably, these complexes strikingly form dependence pathways for the assembly of the kinetochore complex. These analyses indicate the feasibility of using network topology, i.e. cliques, to uncover novel pathways to accelerate our understanding of potential biological processes.
碩士
國立陽明大學
生化暨分子生物研究所
95
Aurora-A is a centrosomal serine-threonine kinase that orchestrates key aspects of cell division. Over-expression of Aurora-A has been found in a wide range of tumors and has ...been implicated in oncogenic transformation. Aurora-A is also known to be involved in the polyadenylation of cyclin B1 mRNA and the control of translational initiation in Xenopus oocytes and human somatic cultured cells. Pumilio homology protein 2 (PUM2) is considered as RNA-binding protein for translational repression and also involved in regulating the length of poly(A) tails in cyclin B1 mRNA. Three components, CPEB (CPE-binding protein), Maskin and PUM2, play a crucial role in repression of polyadenylatoin. These components form complex with cap-binding protein eIF4E and lead to cyclin B1 mRNA translationally dormant. Aurora-A then stimulates polyadenylation by phosphorylating CPEB causing dissociation of PUM2-CPEB-Maskin-eIF4E complex followed by poly(A) elongation and translational initiation. Surprisingly, Maskin is identified as the homologue of a well characterized Aurora-A substrate, TACC3. In addition, Maskin and CPEB are also present on the mitotic apparatus and involved in microtubule assembly in mitotic cells, raising the possibility that PUM2 might have dual roles in controlling cell cycle progression like Maskin and CPEB. In this study, we demonstrate that human PUM2 is a novel substrate and interacting protein of Aurora-A. PUM2 and Aurora-A affects cell cycle progression and arrests cells at G2/ M phase synergistically. Moreover, PUM2 physically interacting with Aurora-A is required for maintaining Aurora-A protein stability and enhancing its kinase activity. Aurora-A is less susceptible to ubiquitination in cells overexpressed with PUM2. The data suggest that binding of PUM2 might protect Aurora-A from being attack by APC/C-mediated degradation. We further speculate that the proper phosphorylation and accumulation of PUM2 at the centrosome might provide a scaffold for the recruitment of other Aurora-A activator, which might trigger the increase of Aurora-A activity dramatically and cause mitotic commitment. Together, these results suggest a novel mechanism of PUM2 in regulation of Aurora-A by physical interaction, instead of using well-characterized mechanism of translational repression.
Successful integration of advanced semiconductor devices with biological systems will accelerate basic scientific discoveries and their translation into clinical technologies. In neuroscience ...generally, and in optogenetics in particular, the ability to insert light sources, detectors, sensors, and other components into precise locations of the deep brain yields versatile and important capabilities. Here, we introduce an injectable class of cellular-scale optoelectronics that offers such features, with examples of unmatched operational modes in optogenetics, including completely wireless and programmed complex behavioral control over freely moving animals. The ability of these ultrathin, mechanically compliant, biocompatible devices to afford minimally invasive operation in the soft tissues of the mammalian brain foreshadow applications in other organ systems, with potential for broad utility in biomédical science and engineering.
A method for forming efficient, ultrathin GaN light‐emitting diodes (LEDs) and for their assembly onto foreign substances is reported. The LEDs have lateral dimensions ranging from ∼1 mm × 1 mm to ...∼25 μm × 25 μm. Quantitative experimental and theoretical studies show the benefits of small device geometry on thermal management, for both continuous and pulsed‐mode operation, the latter of which suggests the potential use of these technologies in bio‐integrated contexts.
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