4i41
Crystal Structure of human Ser/Thr kinase Pim1 in complex with mitoxantrone
Structural highlights
FunctionPIM1_HUMAN Proto-oncogene with serine/threonine kinase activity involved in cell survival and cell proliferation and thus providing a selective advantage in tumorigenesis. Exerts its oncogenic activity through: the regulation of MYC transcriptional activity, the regulation of cell cycle progression and by phosphorylation and inhibition of proapoptotic proteins (BAD, MAP3K5, FOXO3). Phosphorylation of MYC leads to an increase of MYC protein stability and thereby an increase of transcriptional activity. The stabilization of MYC exerted by PIM1 might explain partly the strong synergism between these two oncogenes in tumorigenesis. Mediates survival signaling through phosphorylation of BAD, which induces release of the anti-apoptotic protein Bcl-X(L)/BCL2L1. Phosphorylation of MAP3K5, an other proapoptotic protein, by PIM1, significantly decreases MAP3K5 kinase activity and inhibits MAP3K5-mediated phosphorylation of JNK and JNK/p38MAPK subsequently reducing caspase-3 activation and cell apoptosis. Stimulates cell cycle progression at the G1-S and G2-M transitions by phosphorylation of CDC25A and CDC25C. Phosphorylation of CDKN1A, a regulator of cell cycle progression at G1, results in the relocation of CDKN1A to the cytoplasm and enhanced CDKN1A protein stability. Promote cell cycle progression and tumorigenesis by down-regulating expression of a regulator of cell cycle progression, CDKN1B, at both transcriptional and post-translational levels. Phosphorylation of CDKN1B,induces 14-3-3-proteins binding, nuclear export and proteasome-dependent degradation. May affect the structure or silencing of chromatin by phosphorylating HP1 gamma/CBX3. Acts also as a regulator of homing and migration of bone marrow cells involving functional interaction with the CXCL12-CXCR4 signaling axis.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedThe rational design of selective kinase inhibitors remains a great challenge. Here we describe a physics-based approach to computationally modeling the kinase inhibitor selectivity profile. We retrospectively assessed this protocol by computing the binding profiles of 17 well-known kinase inhibitors against 143 kinases. Next, we predicted the binding profile of the chemotherapy drug mitoxantrone, and chose the predicted top five kinase targets for in vitro kinase assays. Remarkably, mitoxantrone was shown to possess low nanomolar inhibitory activity against PIM1 kinase and to inhibit the PIM1-mediated phosphorylation in cancer cells. We further determined the crystal complex structure of PIM1 bound with mitoxantrone, which reveals the structural and mechanistic basis for a novel mode of PIM1 inhibition. Although mitoxantrone's mechanism of action had been originally thought to act through DNA intercalation and type II topoisomerase inhibition, we hypothesize that PIM1 kinase inhibition might also contribute to mitoxantrone's therapeutic efficacy and specificity. A new target for an old drug: identifying mitoxantrone as a nanomolar inhibitor of PIM1 kinase via kinome-wide selectivity modeling.,Wan X, Zhang W, Li L, Xie Y, Li W, Huang N J Med Chem. 2013 Mar 28;56(6):2619-29. doi: 10.1021/jm400045y. Epub 2013 Mar 15. PMID:23442188[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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