SIGNALING FROM THE CELL SURFACE TO THE NUCLEUS

1. SIGNALING FROM THE CELL SURFACE TO THE NUCLEUS • PROTEIN KINASE A • PHOSPHORYLATION AND ACTIVATION OF CREB TRANSCRIPTION FACTOR • RECEPTOR SERINE KINASES - RECEPTORS FOR THE TGF-ß SUPERFAMILY • PHOSPHORYLATION AND ACTIVATION OF SMAD TRANSCRIPTION FACTORS • PARTNERING WITH OTHER TRANSCRIPTION FACTORS TO ACTIVATE TRANSCRIPTION OF SPECIFIC GENES • PROTEIN- TYROSINE KINASE RECEPTORS • RECEPTORS LINKED TO PROTEIN- TYROSINE KINASES - THE CYTOKINE RECEPTOR SUPERFAMILY • RECEPTORS LINKED TO PROTEOSOME- MEDIATED DEGRADATION OF INHIBITORS OF SPECIFIC TRANSCRIPTION FACTORS

2. SIGNALING PATHWAYS LEADING TO ACTIVATION OF TRANSCRIPTION FACTORS AND MODULATION OF GENE EXPRESSION FOLLOWING LIGAND BINDING TO CERTAIN GS PROTEIN–LINKED RECEPTORS

3. TGF-b: Key Roles in Controlling Cell Proliferation and Synthesis of the Extracellular Matrix TGF-b1 Hinck et al., (1996) Biochemistry THE TGF- ß SUPERFAMILY INCLUDES TGF- ß1, TGF- ß2, TGF- ß3, ACTIVIN, INHIBIN, MULLERIAN INHIBITING SUBSTANCE, AND AT LEAST 16 BONE MORPHOGENETIC PROTEINS

4. TGF-b: Key Roles in Controlling Cell Proliferation and Synthesis of the Extracellular Matrix BIOLOGICAL FUNCTIONS OF TGF-ß INCLUDE: • INHIBITION OF CELL PROLIFERATION • INDUCES INHIBITORS OF CYCLIN - DEPENDENT KINASES • TYPE II RECEPTOR FREQUENTLY LOST OR MUTATED IN CANCERS • INDUCTION OF SYNTHESIS OF EXTRACELLULAR MATRIX PROTEINS: FIBRONECTIN, COLLAGENS, PROTEOGLYCANS • INHIBITION OF SYNTHESIS OF EXTRACELLULAR PROTEASES: COLLAGENASE, PLASMINOGEN ACTIVATOR • INDUCTION OF SYNTHESIS OF INHIBITORS OF EXTRACELLULAR PROTEASES • PROMOTION OF CELL MATRIX AND CELL- CELL ATTACHMENT

5. Schematic diagram of formation of mature dimeric TGFb proteins from secreted monomeric TGFb precursors.

6. THE TGFb SIGNALING PATHWAY TGFb SIGNALS THROUGH HETEROMERIC COMPLEXES OF TYPES I AND II SERINE/THREONINE KINASE RECEPTORS, LEADING TO PHOSPHORYLATION OF EITHER SMAD2 OR SMAD3. A COMPLEX OF ONE OF THESE PHOSPHORYLATED SMAD PROTEINS AND SMAD4 THEN TRANSLOCATES TO THE NUCLEUS, WHERE IT BINDS TO OTHER TRANSCRIPTION FACTORS TO ACTIVATE TRANSCRIPTION OF A VARIETY OF GENES

7. THE TGFbSIGNALING PATHWAY

8. COMBINATORIAL ACTIVATION OF TRANSCRIPTION BY SMAD PROTEINS SMAD3 PROTEINS BIND ONLY TO 4 BASE PAIRS OF DNA: 5’ AGAC 3’ EACH TFE3 TRANSCRIPTION FACTOR BINDS TO A 3 BASE PAIR SEQUENCE 5’ CAC 3’ A DIMER OF TWO TFE3s BINDS TO A 6 BASE PAIR SEQUENCE 5’ CACGTG 3’ (GTG IS THE COMPLEMENT OF CAC) THUS A SEQUENCE 5’ AGACxxxCACGTG 3’ BINDS ONE SMAD3 PROTEIN AND ONE TFE3 DIMER IN A PRECISE ARRANGEMENT, ALLOWING FOR TRANSCRIPTION ACTIVATION, IN THIS CASE OF THE PAI-1 GENE.

10. Role of TGF-b in Human Cancer

11. Human Diseases with Alterations in the TGF-b Signaling Pathway

12. SIGNALING FROM THE CELL SURFACE TO THE NUCLEUS • RECEPTORS LINKED TO PROTEIN- TYROSINE KINASES - THE CYTOKINE RECEPTOR SUPERFAMILY • PHOSPHOTYROSINE RESIDUES BINDING TO SPECIFIC SH2 DOMAINS • ACTIVATION OF STAT TRANSCRIPTION FACTORS • PARTNERING OF STATs WITH OTHER TRANSCRIPTION FACTORS • TERMINATION OF SIGNALING BY ACTIVATION OF PROTEIN TYROSINE PHOSPHATASES • INHIBTION OF SIGNALING BY PROTEINS CONTAINING ONLY SH2 DOMAINS • RECEPTORS LINKED TO PROTEOSOME- MEDIATED DEGRADATION OF INHIBITORS OF CERTAIN TRANSCRIPTION FACTORS

13. EPO ACTS TO STIMULATE THE PROLIFERATION AND DIFFERENTIATION OF ERYTHROID PROGENITOR CELLS TO MATURE RED CELLS HEMATOPOIESIS

16. EPO “GENE KNOCK- OUT” MICE ARE NORMAL EXCEPT THEY HAVE NO ADULT- TYPE RED BLOOD CELLS AND DIE AT EMBRYONIC DAY 14

19. STRUCTURE OF HUMAN GROWTH HORMONE LIKE EPO AND OTHER CYTIOKINES, GROWTH HORMONE FORMS A 4- ALPHA HELIX BUNDLE. AMINO ACIDS THAT BIND TO THE FIRST GROWTH HORMONE RECEPTOR ARE IN GREEN; THOSE THAT BIND TO THE SECOND GROWTH HORMONE RECEPTOR ARE IN BLUE

20. STRUCTURE OF THE EXTERNAL SEGMENT OF THE HUMAN GROWTH HORMONE RECEPTOR THE PLASMA MEMBRANE IS AT THE BOTTOM OF THE FIGURE AMINO ACIDS THAT BIND GROWTH HORMONE ARE IN BLUE AMINO ACIDS THAT BIND THE SECOND MOLECULE OF GROWTH HORMONE RECEPTOR ARE IN GREEN

21. THREE- DIMENSIONAL STRUCTURE OF THE COMPLEX OF ONE MOLECULE OF HUMAN GROWTH HORMONE AND TWO GROWTH HORMONE RECEPTORS PLASMA MEMBRANE IS AT THE BOTTOM OF THE FIGURE

22. SIGNAL TRANSDUCTION PROTEINS THAT BIND TO THE CYTOSOLIC DOMAIN OF THE ERYTHROPOIETIN RECEPTOR

23. TWO POSSIBLE MECHANISMSBY WHICH EPO ACTIVATESTHE EPO RECEPTOR

24. SIGNAL TRANSDUCTION BY THE EPO RECEPTOR ACTIVATED JAK2 PHOSPHORYLATES UP TO 8 TYROSINE RESIDUES ON THE CYTOSOLOC DOMAIN OF THE EPO RECEPTOR. EACH PHOSPHOTYROSINE CAN FORM THE “DOCKING SITE” FOR THE SH2 DOMAIN OF A SIGNAL TRANSDUCTION PROTEIN

25. MODEL OF AN SH2 DOMAIN BOUND TO A SHORT TARGET PEPTIDE. IN THIS TARGET PEPTIDE, THE PHOSPHOTYROSINE (P-TYR) AND ISOLEUCINE (+3ILE) FIT INTO A TWO- PRONGED SOCKET ON THE SURFACE OF THE SH2 DOMAIN. THE PHOSPHATE GROUP COVALENTLY ATTACHED TO THE TYROSINE RESIDUE IS LIGHT BLUE.

26. DIMERIZATION OF STAT PROTEINS LEADS TO FORMATION OF A FUNCTIONALLY ACTIVE TRANSCRIPTION FACTOR

27. TERMINATION OF SIGNAL TRANSDUCTION BY THE EPO RECEPTOR

28. TERMINATION OF SIGNAL TRANSDUCTION BY THE EPO RECEPTOR #2

29. GENERAL STRUCTURE AND ACTIVATION OF RECEPTOR TYROSINE KINASES (RTKS) AS WITH THE EPO RECEPTOR, LIGAND BINDING INDUCES A CONFORMATIONAL CHANGE THAT PROMOTES OR STABILIZES RECEPTOR DIMERS. THE KINASE ACTIVITY OF EACH SUBUNIT OF THE DIMERIC RECEPTOR INITIALLY PHOSPHORYLATES TYROSINE RESIDUES NEAR THE CATALYTIC SITE IN THE OTHER SUBUNIT, CAUSING ITS ACTIVATION. SUBSEQUENTLY, TYROSINE RESIDUES IN OTHER PARTS OF THE CYTOSOLIC DOMAIN BECOME PHOSPHORYLATED AND SERVE AS DOCKING SITES FOR SH2 DOMAINS OF SIGNALING PROTEINS

30. Structure of the FGF - FGR Receptor Complex

34. Structures of MAP kinase in its inactive, unphosphorylated form and active, phosphorylated formPhosphorylation of MAP kinase by MEK at tyrosine 185 (pY185) and threonine 183 (pT183) leads to a marked conformational change in the phosphorylation lip (red).

35. Cycling of the Ras protein between the inactive form with bound GDP and the active form with bound GTP

36. Activation of Ras following binding of a ligand to a RTK

37. Model of SH3 domain bound to a short target peptide

38. Kinase cascade that transmits signals downstream from activated Ras protein

39. Signaling pathways leading to activation of transcription factors and modulation of gene expression following ligand binding to RTKs

40. Activation of protein kinase B by the PI- 3’ kinase signaling pathway (part 1). 

41. Activation of protein kinase B by the PI- 3’ kinase signaling pathway (part 2). 

42. Cleavage of PIP2 by phospholipase C (PLC) yields DAG and IP3.

43. Elevation of cytosolic Ca2+ via the inositol-lipid signaling pathway

44. UBIQUITIN-MEDIATED PATHWAY FOR DEGRADATION OF CELLULAR PROTEINS A CONJUGATING ENZYME CATALYZES FORMATION OF A PEPTIDE BOND BETWEEN THE SMALL PROTEIN UBIQUITIN (UB) AND THE SIDE-CHAIN –NH2 OF A LYSINE RESIDUE IN A TARGET PROTEIN. ADDITIONAL UB MOLECULES ARE ADDED, FORMING A MULTIUBIQUITIN CHAIN. THIS CHAIN DIRECTS THE TAGGED PROTEIN TO A PROTEASOME, WHICH CLEAVES THE PROTEIN INTO NUMEROUS SMALL PEPTIDE FRAGMENTS. PROTEOLYSIS OF UBIQUITIN- TAGGED PROTEINS OCCURS ALONG THE INNER WALL OF THE CORE.

45. ACTIVATION OF THE TRANSCRIPTION FACTOR NF-kB MANY DIFFERENT EXTRACELLULAR SIGNALS CAN INDUCE ACTIVATION OF NF-kB; THESE SIGNALS ACTIVATE AN I-kB KINASE COMPLEX. THIS COMPLEX PHOSPHORYLATES TWO N-TERMINAL SERINE RESIDUES IN I-kB. PHOSPHORYLATED I-kB IS UBIQUITINATED AND SUBSEQUENTLY DEGRADED BY THE PROTEOSOME. REMOVAL OF I-kB UNMASKS THE NUCLEAR LOCALIZATION SITES IN BOTH THE P50 AND P65 SUBUNITS OF NF-kB. NF-kB ENTERS THE NUCLEUS, BINDS TO SPECIFIC SEQUENCES IN DNA AND REGULATES TRANSCRIPTION.