Signal Transduction and the Related Disorders

1. Signal Transduction and the Related Disorders

2. Basic Concept of Cell Signaling (trans-membranous signaling) The process in which cells sensethe extracellular stimuli through membranous or intracellular receptors, transducethe signals via intracellular molecules, and thus regulatethe biological function of the cells

3. Major pathways for cell signaling G-protein-mediated pathway Adenylate cyclase mediated pathway Phospholipase mediated pathway Small G-protein-mediated pathway Non-G-protein-mediated pathway Receptor tyrosine kinase mediated pathway Receptor serine/threonine kinase mediated pathway Receptor guanilate cyclase mediated pathway Intracellular (unclear) receptor mediated pathway

4. Aberrant Cell Signaling and the Related Disorders

5. General process for transmembrane signal transduction

6. 1. Aberrant Signal

7. Types of cellular signals • Physical signals • Light, electronic, mechanic, UV, heat, volume or osmotic, etc • Chemical signals • Hormones, neurotransmitters, GFs, cytokines; odor molecules; ATP, active oxygen; drugs, toxins, etc

8. Modes for the function of endogenous signals Endocrine Act on a far away organ via blood circulation, seen in most hormones Paracrine Act on a nearby target, seen in GFs, PG, NO Autocrine Act on itself after secreted, seen in GFs, especially in tumor tissues Intricrine Act on itself before secreted, seen in nuclear receptors Synaptic:Presynaptic to postsynaptic, seen in neurotransmitters

9. Aberrant Signal (Signal Excess) ischemia, epilepsy, neurodegenerative diseases extracellular glutamate/aspartic acid NMDAR activation Ca2+ influx [Ca2+]i , activation of enzymes excitatory intoxication

10. Aberrant Signal (Signal Insufficiency) Lesions in pancreatic -cell Decreased insulin production hyperglycemia Diabetes (Type I)

11. Aberrant Signal(autoimmune-thyropathy) Stimulatory Ab TSH-R 30~35aa residues Gs Gq AC PLC cAMP DG IP3 PKC Ca2+ Thyroid proliferation & secretion hyperthyroidism Blocking Ab TSH-R 295~302 385~395 AA residues Binding of TSH to R↓ hypothyroidism

12. 2. Aberrant Receptor in Cell Signaling • Receptor gene mutation • Receptor down regulation or • desensitization

13. Receptor Gene Mutation — Genetic insulin-resistant diabetes Insulin+R Activate RPTK IRS PI3K Ras/Raf/ MEK/ERK Glycogen Synthesis, Cell Transport proliferation & Utilization IR gene mutations Disturbances in synthesis in transfer to the membrane in affinity to insulin in RPTK activation in proteolysis Type II Diabetes

14. Response of the insulin receptor kinase (IRK) to ligand binding • Heterotetramer (2, 2) • Insulin binding leads to change in structure • Conformation change activates -subunit TK activity • -subunit phosphorylates Tyr residues on cytoplasmic domains as well as downstream substrates (IRS)

15. Three-dimensional structures of the insulin receptor tyrosine kinase (IRK) IRK conformational change upon activation loop phosphorylation. The N-terminal lobe of IRK is colored white and the C-terminal lobe is colored dark grey. The activation loop (green) contains autophosphorylation sites Y1158, Y1162 and Y1163, and the catalytic loop (orange) contains the putative catalytic base, D1132. Also shown are the unbound/bound ATP analog and tyrosine-containing substrate peptide (pink). [Hubbard, EMBO J. 16, 5572 (1997)]

16. Once Tyr-Phosphorylated, the IRK activity trigerrs a number of signaling pathways • Phosphatidylinositol 3-hydroxy kinase, makes PIP2,PIP3 • Grb2, Sos, activates Ras • Activation of PLC

17. Receptor Tyrosine Kinases

18. Receptor Gene Mutation (NDI) ADH + ADHV2-R Gene mutation Gs V2R synthase↓ or affinity↓ cAMP ADH reaction in collecting tubules↓ AQP2 moves to lumen side in collecting tubules Diuresis Permeability↑ Nephrogenic Ddiabetes Insipidus H2O absorption 

19. Secondary Abnormality in Receptors (Heart failure) • Myocardial hypertrophy • -R1 down regulated or desensitized Reaction to catecholamine Myocardial contraction Alleviate Accelerate myocardial lesion heart failure

20. 3. Aberrant G-protein in Cell Signaling

21. G-protein-Mediated Pathway

22. Activation of Adenylate Cyclase by Gs

23. GTPase Regulation of G-Protein Activity

24. G-protein gene mutation—pituitarytumor Gs gene mutation GHRH Pituitary Gs GH GTPase activity Persistent activation of Gs Persistent activation of AC cAMP Pituitary proliferation and secretion Acromegaly or Gigantism

25. G-protein gene mutation—type 1A-PHP Type 1A PHP is a genetic disease caused by Gsgene mutation type 1A Gs gene mutation expression of Gs disconnection between PTH receptor and AC hyperphosphatemia type 1B the target organ resists to PTH， the Gs is normal

26. G-protein modification——cholera Cholera toxin Gsribosylation at Arg201 Inactivation of GTPase Persistent activation of Gsand cAMP Conformational alteration of intestinal epithelia Cl- and H2O to lumen of intestine Diarrhea and dehydration Circulation failure

27. 4. Aberrant Intracellular Signaling

28. Aberrant intracellular Signaling Pro-carcinogen of phorbolester PKC persistent activation Growth factors Cancer gene expression Na+/H+ exchange  Intracellular pH↑/ K+↑ Cell proliferation (Cancer)

29. Aberrant intracellular Signaling The intracellular signaling involves various messengers, transducers and transcription factors. Disorders can occur in any of these settings. 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

30. 5.Multiple Abnormalities in Signaling Pathway

31. The sympathetic regulation in heart failure Normal Hypertrophy, heart failure CA Density of SN↓；tyrosine hydroxylase↓ β-R down regulated； pH↓→ reaction of R to CA↓ 1R Gs Gs↓，function↓；Gi， function  cAMP

32. cAMP Ca2+channel SR phospholamban Ca2+ influx Ca2+ pump SR pump↓ SR Ca2+channel [Ca2+] i ↓ Myocardial dilation [Ca2+] i Myocardial contraction H+ inhibits binding of Ca2+ to troponin

33. Multifactor Aberrancies and Cancer (Enhancement of proliferating signals) • Ligands (GFs) • Receptors (overexpression, activation of TPK) • Intracellular transducers： Ras mutation Ras-GTPase Ras activation Raf MEK ERK Proliferation TUMOR

34. Multifactor Aberrancies and Cancer (Deficits in proliferation-inhibiting signal) 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

35. 6. Same Stimulant Induces Different Responses (the same stimuli can act on different receptors)

36. Infectious Shock -R β-R KCa2+ Excitatory sympathetic nerve stimuli IP3/DG pathway Gs Gq AC pathway PLC AC cAMP IP3 DG PKA PKC Ca2+ Ca2+pump MLCK CaMK Myosin [Ca2+]i Artery Contraction A-V shunt

37. 7. Different Signals Induces the Same Pathologic Response (different receptors use the same pathway or by cross-talk)

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

39. Cross talk—how 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 Myocardial Hypertrophy

40. 9. Principles for Treatment of Aberrant Signaling-related Diseases

41. Principles for Treatment • To regulate the level of extracellular molecules • To regulate the structure and the function of receptors • To regulate the level and modifications of intracellular messenger molecules and transducers • To regulate the level of nuclear transcription factors

42. LPS TNF IL-1

43. Regulating of signal transduction in treatment of diseases

44. 10. Application of Signal Transduction in Scientific Research

45. Regulating Signal Transduction in Research P P P P P P Normal tau Normal tau P P P P P P P P P P P P P P P P P P P AD p- tau S9/21 S9/21 S9/21 S473 T308 Active GSK-3/ Inactive GSK-3/ Active GSK-3/ Inactive PKB PDK1/PDK2 PI3-K GF-109203X PKC AD p- tau Caspase-3 P P P WT

46. Mutation TSH + R Gs Gq Ras AC PLC Raf cAMP DAG ERK PKA PKC Thyroxine Secretion Thyroid Gland Growth Loss of function Hypothyroidism Gain of function Hyperthyroidism Gain or loss of function mutations?

47. Dominant negative effect? Mutation causes not only self-dysfunction but also inactivates or inhibits wild type counterparts The mutation is called dominant negative mutant For example, mutated nuclear receptor competes with wild type receptors to bind to the target gene and thus inhibits the transcription activity of wild type genes