http://www.math.pku.edu.cn/teachers/xirb/Courses/UndergraduateThesis2014/1-s2.0-S0092867412007787-main.pdf

A landscape of driver mutations in melanoma

Universal sample preparation method for proteome analysis

Radiotherapy is one of the most successful cancer therapies. Here the effect of irradiation on antigen presentation by MHC class I molecules was studied. Cell surface expression of MHC class I molecules was increased for many days in a radiation dose-dependent manner as a consequence of three responses. Initially, enhanced degradation of existing proteins occurred which resulted in an increased intracellular peptide pool. Subsequently, enhanced translation due to activation of the mammalian target of rapamycin pathway resulted in increased peptide production, antigen presentation, as well as cytotoxic T lymphocyte recognition of irradiated cells. In addition, novel proteins were made in response to γ-irradiation, resulting in new peptides presented by MHC class I molecules, which were recognized by cytotoxic T cells. We show that immunotherapy is successful in eradicating a murine colon adenocarcinoma only when preceded by radiotherapy of the tumor tissue. Our findings indicate that directed radiotherapy can improve the efficacy of tumor immunotherapy.

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Radiation modulates the peptide repertoire, enhances MHC class I expression, and induces successful antitumor immunotherapy

The family of interferon (IFN) proteins has now more than reached the potential envisioned by early discovering virologists: IFNs are not only antivirals with a spectrum of clinical effectiveness against both RNA and DNA viruses, but are also the prototypic biological response modifiers for oncology, and show effectiveness in suppressing manifestations of multiple sclerosis. Studies of IFNs have resulted in fundamental insights into cellular signalling mechanisms, gene transcription and innate and acquired immunity. Further elucidation of the multitude of IFN-induced genes, as well as drug development strategies targeting IFN production via the activation of the Toll-like receptors (TLRs), will almost certainly lead to newer and more efficacious therapeutics. Our goal is to offer a molecular and clinical perspective that will enable IFNs or their TLR agonist inducers to reach their full clinical potential.

Interferons at age 50: past, current and future impact on biomedicine.

Polo-like kinases (Plks) are increasingly recognized as key regulators of mitosis, meiosis and cytokinesis. In agreement with a broad range of proposed functions during cell division, Plks are subject to complex temporal and spatial control. Recent findings are uncovering the mechanisms of Plk regulation, notably their targeting to different cellular structures through interactions with phosphorylated docking proteins. Moreover, information is emerging on the substrate specificity of Plks and the role of individual substrates in M-phase progression.

Polo-like kinases and the orchestration of cell division.

https://www.cell.com/cell/pdf/S0092-8674(07)01463-8.pdf

Cytokinesis: placing and making the final cut.

Mitotic kinases of the Polo and Aurora families are key regulators of chromosome segregation and cytokinesis. Here, we have investigated the role of MKlp1 and MKlp2, two vertebrate mitotic kinesins essential for cytokinesis, in the spatial regulation of the Aurora B kinase. Previously, we have demonstrated that MKlp2 recruits Polo-like kinase 1 (Plk1) to the central spindle in anaphase. We now find that in MKlp2 but not MKlp1-depleted cells the Aurora B-INCENP complex remains at the centromeres and fails to relocate to the central spindle. MKlp2 exerts dual control over Aurora B localization, because it is a binding partner for Aurora B, and furthermore for the phosphatase Cdc14A. Cdc14A can dephosphorylate INCENP and may contribute to its relocation to the central spindle in anaphase. We propose that MKlp2 is involved in the localization of Plk1, Aurora B, and Cdc14A to the central spindle during anaphase, and that the integration of signaling by these proteins is necessary for proper cytokinesis.

/pdf/relocation-of-aurora-b-from-centromeres-to-the-central-4i2wqhp77z.pdf

Relocation of Aurora B from centromeres to the central spindle at the metaphase to anaphase transition requires MKlp2

Multiple mitotic kinesins and microtubule-associated proteins (MAPs) act in concert to direct cytokinesis (Glotzer, M. 2005. Science. 307:1735-1739). In anaphase cells, many of these proteins associate with an antiparallel array of microtubules termed the central spindle. The MAP and microtubule-bundling protein PRC1 (protein-regulating cytokinesis 1) is one of the key molecules required for the integrity of this structure (Jiang, W., G. Jimenez, N.J. Wells, T.J. Hope, G.M. Wahl, T. Hunter, and R. Fukunaga. 1998. Mol. Cell. 2:877-885; Mollinari, C., J.P. Kleman, W. Jiang, G. Schoehn, T. Hunter, and R.L. Margolis. 2002. J. Cell Biol. 157:1175-1186). In this study, we identify an interaction between endogenous PRC1 and the previously uncharacterized kinesin KIF14 as well as other mitotic kinesins (MKlp1/CHO1, MKlp2, and KIF4) with known functions in cytokinesis (Hill, E., M. Clarke, and F.A. Barr. 2000. EMBO J. 19:5711-5719; Matuliene, J., and R. Kuriyama. 2002. Mol. Biol. Cell. 13:1832-1845; Kurasawa, Y., W.C. Earnshaw, Y. Mochizuki, N. Dohmae, and K. Todokoro. 2004. EMBO J. 23:3237-3248). We find that KIF14 targets to the central spindle via its interaction with PRC1 and has an essential function in cytokinesis. In KIF14-depleted cells, citron kinase but not other components of the central spindle and cleavage furrow fail to localize. Furthermore, the localization of KIF14 and citron kinase to the central spindle and midbody is codependent, and they form a complex depending on the activation state of citron kinase. Contrary to a previous study (Di Cunto, F., S. Imarisio, E. Hirsch, V. Broccoli, A. Bulfone, A. Migheli, C. Atzori, E. Turco, R. Triolo, G.P. Dotto, et al. 2000. Neuron. 28:115-127), we find a general requirement for citron kinase in human cell division. Together, these findings identify a novel pathway required for efficient cytokinesis.

/pdf/kif14-and-citron-kinase-act-together-to-promote-efficient-2ixap9sz7n.pdf

KIF14 and citron kinase act together to promote efficient cytokinesis

The bipolar mitotic spindle is responsible for segregating sister chromatids at anaphase. Microtubule motor proteins generate spindle bipolarity and enable the spindle to perform mechanical work. A major change in spindle architecture occurs at anaphase onset when central spindle assembly begins. This structure regulates the initiation of cytokinesis and is essential for its completion. Central spindle assembly requires the centralspindlin complex composed of the Caenorhabditis elegans ZEN-4 (mammalian orthologue MKLP1) kinesin-like protein and the Rho family GAP CYK-4 (MgcRacGAP). Here we describe a regulatory mechanism that controls the timing of central spindle assembly. The mitotic kinase Cdk1/cyclin B phosphorylates the motor domain of ZEN-4 on a conserved site within a basic amino-terminal extension characteristic of the MKLP1 subfamily. Phosphorylation by Cdk1 diminishes the motor activity of ZEN-4 by reducing its affinity for microtubules. Preventing Cdk1 phosphorylation of ZEN-4/MKLP1 causes enhanced metaphase spindle localization and defects in chromosome segregation. Thus, phosphoregulation of the motor domain of MKLP1 kinesin ensures that central spindle assembly occurs at the appropriate time in the cell cycle and maintains genomic stability.

Cell cycle regulation of central spindle assembly

Spatial and temporal coordination of polo-like kinase 1 (Plk1) activity is necessary for mitosis and cytokinesis, and this is achieved through binding to phosphorylated docking proteins with distinct subcellular localizations. Although cyclin-dependent kinase 1 (Cdk1) creates these phosphorylated docking sites in metaphase, a general principle that explains how Plk1 activity is controlled in anaphase after Cdk1 inactivation is lacking. Here, we show that the microtubule-associated protein regulating cytokinesis (PRC1) is an anaphase-specific binding partner for Plk1, and that this interaction is required for cytokinesis. In anaphase, Plk1 creates its own docking site on PRC1, whereas in metaphase Cdk1 phosphorylates PRC1 adjacent to this docking site and thereby prevents binding of Plk1. Mutation of these Cdk1-sites results in a form of PRC1 that prematurely recruits Plk1 to the spindle during prometaphase and blocks mitotic progression. The activation state of Cdk1, therefore, controls the switch of Plk1 localization from centrosomes and kinetochores during metaphase, to the central spindle during anaphase.

Ulrike Gruneberg

Papers

Cytokinesis: placing and making the final cut.

Relocation of Aurora B from centromeres to the central spindle at the metaphase to anaphase transition requires MKlp2

KIF14 and citron kinase act together to promote efficient cytokinesis

Cell cycle regulation of central spindle assembly

Choice of Plk1 docking partners during mitosis and cytokinesis is controlled by the activation state of Cdk1