Aberrant Cell Signaling and Related Disorders

1. Aberrant Cell Signaling and Related Disorders Jimin Shao (邵吉民) Tel: 88208209 E-mail: shaojimin@zju.edu.cn

2. Cell signaling and signal transduction Disorders of signal transduction systems and mechanisms of diseases Research in signal transduction

3. Cell signaling and Signal transduction--- Concept, Pathways, Function, and Regulation (1) Direct Intercellular Communication Gap Junction Intercellular Communication (2) Signaling by plasma-membrane bound molecules (3) Receptor-Mediated Intercellular communication Gap Junction

4. Receptor-Mediated Signal Transduction Systems Receptors: • Cell Surface Receptors: • - Ion Channel Linked Receptors • - G-protein Coupled Receptors (GPCR) • - Enzyme Linked Receptors • Receptor tyrosine kinases • Tyrosine-kinase-associated receptors • Receptor serine/threonine kinases • Receptor guanylyl cyclases • others • - Others • Nuclear Receptors: • - Steroid Receptors • - Retinoid Receptors • - Orphan Receptors

6. General process for transmembrane signal transduction • Synthesis and secretion of signaling molecules • Receptor binding and initiation of intracellular signaling pathway • Regulation of cellular metabolism, function, gene expression, etc • Down-regulation or termination of cellular responses

8. Cell Signal Transduction Pathways--Physiological functions--Metabolism--Cell cycle, growth, differentiation, and apoptosis--Responses to stress--etc. LPS TNF IL-1

9. Disorders of signal transduction systems and Mechanisms of Diseases • Causes: • Gene mutation-- Function loss or gain • Change of quantity of signal proteins • Change of activity of signal proteins • Epigenetic changes • Autoimmune diseases • Secondary changes

10. Pathogenesis: • Abnormality: • Ligands, Receptors, Post-receptor pathways, Effectors Down-regulation / interruption of signaling • Signal Insufficiency • Receptors down-regulation / desensitization: decreased quantity, binding affinity, inhibitory Ab, cofactor disorders, function loss, etc. • Defects in Adaptors, Signal transducers, Effectors (Enzymes, Transcription factors, etc) Up-regulation / over-activation of signaling • Signal Excess • Receptor up-regulation, hypersensitivity, stimulatory Ab, etc • Signal transducers, TFs: over-expression, persistent activation • Others

11. 1. Aberrant Signal

12. (1) Aberrant Signal (Signal Insufficiency) • Insulin receptor (IR): heterotetramer (2, 2) • Insulin binding leads to change in conformation • Activates IR -subunit PTK activity • -subunit phosphorylates Tyr residues on cytoplasmic domains as well as downstream substrates (IRS) Viral infections or other damages to pancreatic -cell insulin production hyperglycemia Diabetes (Type I)

13. (2) Aberrant Signal (Signal Excess) ischemia, epilepsy, neurodegenerative diseases extracellular glutamate/aspartic acid NMDAR activation (N-methyl-D-aspartate receptor, Ion Channel Linked Receptor) Ca2+ influx [Ca2+]i , activation of enzymes excitatory intoxication

14. 2. Aberrant Receptor in Cell Signaling

15. Disturbance of receptors can occur in: • gene level, • processes of protein synthesis, post-translational modification, conformation, oligomerization, translocation, endocytosis, degradaion, etc. Receptor alterations in number, structure, function, and regulation can result in: • down-regulation: decrease in number of receptors • desensitization: decreased response to ligand stimulation • up regulation: increase in number of receptors • hypersensitivity: increased response to ligand stimulation, or self-activation without ligands Receptor diseases: receptor alterations --- changes of ligand-receptor signaling --- abnormal cellular effects --- diseases

16. （1）Receptor Gene Mutation Insulin + IR Activate RPTK IRS PI3K Ras/Raf/ MEK/ERK Glycogen Synthesis, Cell Transport proliferation & Utilization Genetic insulin-resistant diabetes: IR gene mutations Disturbances in synthesis transfer to the membrane affinity to insulin PTK activity proteolysis Type II Diabetes

17. Stimulatory Ab TSH-R（GPCR) 30~35 residues Gs Gq AC PLC cAMP DAG IP3 PKC Ca2+ Thyroid proliferation & secretion of thyroxine  hyperthyroidism (2) Autoimmune diseases-thyropathy Blocking Ab TSH-R 295~302 385~395 residues Binding of TSH to R↓ hypothyroidism

18. Graves病（弥漫性毒性甲状腺肿） • 刺激性抗体模拟TSH 的作用 • 促进甲状腺素分泌和甲状腺腺体生长 • 女性>男性 • 甲亢、甲状腺弥漫性肿大、突眼 • 桥本病 (Hashimoto’s thyroditis,慢性淋巴细胞性甲状腺炎) • 阻断性抗体与TSH受体结合 • 减弱或消除了TSH的作用 • 抑制甲状腺素分泌 • 甲状腺功能减退、黏液性水肿

19. Heart failure, Myocardial hypertrophy • -adrenergic receptors (GPCR) down regulated or desensitized Reaction to catecholamines Myocardial contraction Alleviate Accelerate myocardial lesion heart failure (3)Secondary Abnormality in Receptors

20. 受体异常疾病

22. 3. Aberrant G-protein in Cell Signaling

23. Pituitarytumor:Gs gene mutation At Arg201 or Gln227 Hypothalamus GHRH Pituitary gland GHRH-R Gs Ac cAMP GH GTPase activity Persistent activation of Gs Persistent activation of AC cAMP Pituitary proliferation and secretion Acromegaly in adults Gigantism in children (1) G-protein gene mutation

25. (2) G-protein modification Cholera toxin intestinal epithelia Gsribosylation at Arg201 Inactivation of GTPase Persistent activation of Gs and Ac, cAMP secretion of chloride into the lumen, inhibition of sodium uptake from the lumen, Large volums of fluid into the lumen of the gut Diarrhea and dehydration Circulation failure

26. 4. Aberrant intracellular Signaling • The intracellular signaling involves various messengers, transducers, and transcription factors. • Disorders can occur in any of these settings, e.g.: -- Calcium overload is a general pathological process in various diseases; -- The level of NO is positively correlated with ischemic injury; -- Stimulation of NF-B is seen in various inflammatory responses

27. Pro-carcinogen of phorbol ester （diglyceride (DG) analogy） PKC persistent activation Growth factors Cancer gene expression Na+/H+ exchange  Intracellular pH↑/ K+↑ Cell proliferation (Cancer) --Aberrant intracellular Signaling in carcinogenesis

28. 5.Multiple Abnormalities in Signaling Pathway

29. Major signaling pathways relevant to cancer

30. Multifactor Aberrancies in Cancer ---Enhancement of proliferating signals Ligands (GFs): e.g. EGF Receptors (overexpression, activation of TPK): e.g. EGFR Intracellular signal transducers： Ras gene mutation Ras-GTPase Ras activation Raf MEK ERK Proliferation TUMOR

31. TGF- + TGF-R PSTK activation Smad-phosphorylation P21/P27/P15 expression Cdk4 inhibition Cell cycle arrests at G1 phase Inhibits cell proliferation (pro-apoptosis) Gene mutation Negative regulation Lymphoma, liver cancer, Stomach cancer ---Deficits in proliferation-inhibiting signals

33. Jason I. Herschkowitz and Xiaoyong Fu. MicroRNAs Add an Additional Layer to the Complexity of Cell Signaling. Sci. Signal.4 (184), jc5. [DOI: 10.1126/scisignal.2002182]

34. 6. Relationship between • Stimulants and Pathological Effects • --Same Stimulant Induces Different Responses • (the same stimuli can act on different receptors) • --Different Signals Induces the Same Pathologic Response • (different receptors use the same pathway or by cross-talk)

35. --Different receptors use same pathways GPCR, RTK, Cytokines Rs PLC Ras PI-3K PKC Raf PKB MEK ERK

36. --Cross talk: hypertension leads to myocardial hypertrophy Mechanic stimuli GF TGF- NE, AT-II Na+, Ca2+ influx Na+-H+ exchange PLC TPK PSTK Ca2+/PKC Ras Smad-P Alkalization Raf MAPK Transcription factors, target genes Target proteins Myocardial Hypertrophy

38. Stratagy: • To regulate the level of extracellular molecules • To regulate the structure and the function of receptors • To regulate the level and modifications of modification enzymes, messengers, signal transducers, transcription factors, effectors, etc • Target therapy: • Breast cancer: EGFR overexpression –Herceptin (mAB) • Chronic myeloid leukemia (CML): Bcr-Abl (abnormal tyrosine kinase) — Gleevec (small compound inhibitor) 7. Principles for Treatment of Aberrant Signaling-related Diseases

39. Research in Signal Transduction Progress and Strategy