Jayanti Tokas1, Rubina Begum1, Shalini Jain2 and Hariom Yadav2 Protein kinases : Role in cell signaling & implication in human pathologies Jayanti Tokas1, Rubina Begum1, Shalini Jain2 and Hariom Yadav2 1Department of Biotechnology, JMIT, Radaur 2 NIDDK, National Institute of Health, Bethesda,MD20892, USA Email: yadavhariom@gmail.com

Protein Kinase

30% of all proteins may be modified 518 protein kinase genes=human kinome space 20% of all eukaryotic genes(human genome project) Approx 30=tumor suppressor 218 genes=human diseases Approx 100 dominant oncogenes

Kinases Protein phosphorylation cell signaling Reversible protein phosphorylation as a biological regulatory mechanism Edmond H. Fischer and Edwin G. Krebs (1992 Nobel Prize for Physiology and Medicine). Post-translational modification in the cell • Cell growth/proliferation • Differentiation • Viability/survival • Homeostasis • Effector function (e.g. cytotoxicity, cytokine production) • Cell death ‘signal’

Signal Transduction and Kinase Pathways Adaptor proteins Nucleus MAP kinase, • Transcription factors – Bind consensus sequence on promoter – May form complexes – May itself be transcribed following cellular activation Effector enzymes

Classification On the basis of amino acid : Tyrosine kinases, Serine threonine (PKC, Plk,Rho Kinases) Receptor (EGFR,FGFR,PDGFR) non receptor (JAK,src,Abl,MAPK)

antikinase inhibitors Tyrosine kinase structure function: Related pathologies Check points Serine threonine kinases Related pathology Check points antikinase inhibitors

Structure Bioblar structure N and c N-beta sheets C-alpha helix ATP bind-cleft at intetrsection

Mechanisms of Activation of Normal TKs. How they function: Mechanisms of Activation of Normal TKs. May oligomerise ligand survival Differentiation Motility Proliferation

Control Autoinhihibitory transmembrane interactions cytoplasmic juxtamembrane region further inhibits the enzyme by interacting with the kinase domain Autophosphorylation---. reorient critical amino acid residues increasing catalytic activity inhibitor proteins and lipids IF CONTROL LOST Loss of function Gain of function

Mechanisms of TK Dysregulation PDGF EGF VEGF FGF KL PDGFR EGFR HER2 c-KIT FGFR3 Overexpression of receptor or ligand

EGFR Superfamily with 4 receptors C-ERBB C-ERBB2 C-ERBB3 C-ERBB4 Cell proliferation Inhibition of apoptosis Angiogenesis Cell motility metastasis

carcinogenesis Carcinogenesis: Dysregulation colorectal cancer, lung cancer(enhanced responsiveness),glioblastoma multiforme(constitutive active) Dysregulation Cell proliferation inh of apoptosis angiogenesis metastasis carcinogenesis Over expressed & mutated Deletions(exon 2-7:alternative splicing) or point mutations(Ile654Val)

Check points

FLT3 C-KIT PDGFR EGFR HER2 Mutation in receptor tyrosine kinase causing constitutive expression

PDGFR Tyrosine kinase fibroblasts,smooth muscles of lung and airways Mesenchymal cell migration and proliferation Angiogenesis and blood vessel maintainance Dysfunction: Abnormal vasulature irregular diameter leakiness

Glioblastoma Atherosclerosis Pathological conditions:del(4q12) ; t(4;22) Adenocarcinoma Breast Colon Prostate Stomach

FGFR(1-4) Cell growth Differentiation Chemotaxis Angiogenesis Cell survival SKELETAL SYSTEM Dysfunction 60 mutations FGFR2 craniosynostosis syndrom(premature ossification of skull) Pfeiffer syndrome(additional fingers FGFR3 achondroplasia(dwarfism) Gly380Arg Gly375Cys Carcinogenesis:prostate, cervical ,bladder, colorectal cancer

Check points

Fusion of TK to partner protein ABL PDGFR FGFR1 FGFR3 JAK2

Bcr-Abl C-Abl Non receptor tyrosine kinase Role: Regulation of cell cycle,cellular response to genotoxic stress Apoptosis neuronal development Regulation :actin binding PI3 binding C-Bcr localised in cytoplasm during mitosis(role in cell cycle regulation)

Related to CML(chronic myeloid leukemia) Bcr-Abl t(9:22) Related to CML(chronic myeloid leukemia) prevent apoptosis even in the absence of growth factors Mitogenic signaling Altered adhesion to matrix TARGET-imatinim mesylate mechanism

Check points

A serine threonine kinase:PKC Response to Growth factors Hormones Drugs 11 related kinases Unregulated in GIST Diagnostic marker therapeutic target ATP binding domain inhibitors Erbstatin Therapeutic targets

Targeting Receptor Monoclonal antibodies Herceptin, licensed for Her 2 receptor-positive Breast cancer

Small molecular inhibitors Various protein tyrosine kinase inhibitors TYRosine PHOSphorylation INhibitors tyrophosphins Competitive with substrate(eg.Itaconic acid) Competitive with ATP(Quinolines)(main thrust) ATP binding fold more specific

1. How many other kinase targets opened for exploration? A LOOK AHEAD 1. How many other kinase targets opened for exploration? 2. Majority of kinases remain largely uncharacterized.

Current challenges and future directions

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