Chapter 6- Cell-cell communication _________-interaction between two or more distinct cells or tissues _________- the cell of tissue producing the signal __________- the cell or tissue being induced _________ the ability to respond to a given inducer More definitions Pax6 null Wild-type Example- Pax6 is required for optic vesicle to respond to an inducer, but Pax6 is not the inducer Hence, Pax6 makes cells _____________ Fig. 6.2 Lacking nose and eyes

1.Instructive vs permissive interactions _____________ interaction-Tissue A requires tissue B to respond in a certain way (analogy to a book _______________) ____________ interaction-Tissue A does not require tissue B to respond in a certain way, but only needs to be in a certain environment (analogy to a book ______________)

__________- sheets of cells from any germ layer ____________- unconnected cells (from mesoderm or neural crest) All organs have both of these cell types Epithelial-mesenchymal interactions _______ specificity ________ specificity Wing Foot Thigh Mesen- chyme Wing epithelium Thus, mesenchyme __________ epithelium Fig. 6.7

Epithelial-mesenchymal interactions Regional specificity _______ specificity Frog gastrula Newt gastrula Frog gastrula Thus, mesenchyme dictates _______ type, but epithelium dictates ____ of the organ Newt with tadpole suckers Frog with newt “balancers”

Paracrine factors __________factors- diffusible molecules that can travel small distances to signal a neighboring cell __________signaling- cell-cell interactions by direct contact Fibroblast growth factor (FGF) – binds FGF receptors (FGFRs) These are receptor tyrosine kinases Example of _________ signaling FGF (________) FGFR (______) __________________ yields activation and subsequent phosphorylation of a second protein

Other well-known paracrine factors _________ family- (3 in vertebrates)-create boundaries, induce development _____ family- (15 in vertebrates)- limb polarity, muscle development _________ superfamily (>30 members)- bone, kidney, neuronal, etc. differentiation

Ion channel-linked No details shown G-protein-linked Enzyme-linked Gq Go G proteins PKC Gs Golf PKA CREB Gene P Adenylyl cyclase cAMPAMP PIP DAG IP3 Ca++ from ER MAP-kinase (ERK) Ras Raf (a MAPKKK) MAPKK (e.g.MEK) NFkB Gene IkB/NFkB Elk-1 Gene P Grb2 GNRPs (e.g. Sos) Jak Gene TGF-  PDGF, EGF, IF ,and  IL-2,IL-3, IL-4, IL-6 Gene Nucleus Cytoplasm Elk-1jun JNK Fos jun AP1 Fos jun AP1 Cell surface receptor pathways BLA512 1/5/98 update JNK MEKK (a MAPKKK) JNKK TNF  TRADD FADD TRAF Cell death IkB/NFkB PLC  STAT NIK IKK Smad STAT Smad PLC  Caspases

Signal transduction pathways Phosphorylation is key A. Receptor tyrosine kinase (RTK) 1.________ binds receptor 2.Receptor undergoes _______ 3.Receptor ____________ occurs 4.Receptor __________________ 5.Receptor binds _____________ 6.Adaptor protein binds ________ 7.G-protein recruits ____ 8.Raf phophorylates ____ 9.____ phosphorylates ERK 10.ERK phosphoryates a ____________________ 11.Transcription is ____________ Fig General pathway

B. TGF-  signalling- a simpler pathway Fig Ligand binds _______ 2.Two _______ receptors dimerize 3._____________________ occurs 4.Receptor phosphorylates ________ 5.SMADs ___________ 6.SMADs enter _________and bind ____ 7.Transcription is _____________

C. JAK-STAT pathway- also a simpler pathway Fig. 6.21

D. Wnt signaling If mutate B-catenin, constitutive activation of myc gene– Tumor formation

Apoptosis Jacobson et al., Cell 88:347 (1997)

Too much and too little Too little- ___________ Splenomegaly Lymphadenopathy Cholangiocarcinoma Hepatocellular Carcinoma Too much- ________________ disease Alcohol-induced liver disease Autoimmune disease Primary biliarry cirrhosis Wilson’s disease Ischemia reperfusion injury Virus hepatitis Fas-null mice Spleen Lymph nodes

Fig Apaf-1 knock-out Wild-type ElegansMammals Apoptosis is required for normal development Fig. 6.27

Receptor-mediated Apoptosis Caspases-3, -6 and -7 Protective Cleavage of Death substrates structural proteins (e.g. actin) kinases (e.g. MEKK, PKC) cell cycle proteins (pRb, PARP) DNA repair enzymes DNA nucleases Anti-apoptotic proteins (Bcl-2)

Hoechst Monitoring Apoptosis by ______________

100 bp ladder 1000 bp ladder 0h3h7h0h3h7h Fg-14 M38 1 kb 0.5kb 2 kb Monitoring Apoptosis by _______________ 5 kb

Hoechst TUNEL 1000X 400X 1000X M38 Fg14 Monitoring Apoptosis by _________

An example of __________ signaling _________ signaling Cell 1 Cell 2 Delta (Ligand) Notch (receptor)

Another example of ____________ signaling The ___________________ The stuff between cells Affects cell adhesion, _______________, epithelial sheet formation Includes collagen, proteoglycans, fibronectin and laminin _______ are the _______________ for extracellular matrix molecules

Integrin Fibronectin Actin Integrins interact with both extracellular and intracellular scaffolds

Another form of communication- _______transmission of signals through __________________ Does not requires a __________, only regulation of small molecules through a port Ports are composed of _______________ Fig. 6.38

Signaling pathways exhibit ____________- A major challenge in biology- How to get specificity from _______________pathways Example: Two pathways direct lymphocyte development Point of _________ Fig. 6.40

CD14 LPS LPB TLR-4 LPS-mediated apoptosis: Which pathway is defective? NF-  B NF-kB-responsive genes NIK IKK PDTC IkB Proteasome SN50 A1, A20,,Fas, FasL,TNF, Bcl2, TRAF1,2, c-IAP1,2 IL1R1 MyD88 IRAK TAK1 TRAF6 MEKK1, 2, 3 PKC p105 p65 TPL-2 ROS FADD Caspase 8 ALLN, HMA Apoptosis P38 MAPK Calyculin A, Okadaic Acid Sorb. P38 MAPK JNKK JNK c-jun P105 phos, degraded FasR FasL FADD Caspase 8 TNF TNFR TRADD RIP TRAF2 TGFBR TNF EGFR MEK ERK1,2 PD098059