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Download study guide: information flow V
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study guide: information flow V! You should be able to: ! provide specific examples of receptor-signal interactions & predict how disruptions (caused by mutations or treatment with a chemical) would impact molecular and cellular phenotypes! describe how the chemical properties of signals affect receptor localization! predict how mutations in signals and receptors involved in fertilization in plants or animals would impact molecular and cellular phenotypes! describe the molecular events of that make it possible for a white blood cell (neutrophil) to pursue a bacterial cell & predict how disruptions at different stages in the signaling pathway (caused by mutations or treatment with a chemical) would alter molecular & cellular phenotypes! explain how a genetic screen could be used to identify signal molecules, signal transduction proteins & second messengers! explain how Cyclins/CDKs regulate the cell cycle & explain how cell cycle checkpoints are an example of signal integration! describe the role of protein degradation in the cell cycle! study guides for each week:! information flow V! You should be able to use these words/phrases appropriately while completing the tasks described in the previous slide! ! signal! Cyclin-dependent kinases (Cdk)! receptor! M-phase promoting factor (MPF)! signal transduction! Cell-cycle checkpoints! second messenger! G0, G1, S, G2, M phases! kinases! negative feedback! phosphatases! ubiquitin! biofilm! proteasome! Cyclin! ! Info Flow V Signal recognition, Fertilization! SIGNAL PRODUCTION! SIGNAL PERCEPTION (INPUT)! SIGNAL RELAY (TRANSDUCTION)! RESPONSE (OUTPUT)! Compare and contrast these two signaling pathways! What does it mean to say that a signal is “transduced?”! ! ! ! ! ! Why would a signal need to be transduced? ! ! ! Where do second messengers fit in these pathways?! Consider all the ways that gene expression can be controlled in eukaryotes. How many of these could respond to cell-cell signaling? ! Fertilization in animals and plants: how do gametes find each other? Answer: Chemotaxis!! Jeff Rifell! Yasmeen ! Hussain! Chemotaxis: LUREs are small proteins (~65 amino acids) that guide pollen tubes! ! ! ! ! ! ! Alvarez et al., 2014 ! Sperm swim towards chemoattractant ! ! ! ! ! ! Ward 1985 (a) pre-injection (f) 90 s post-injection! Sea Urchin Sperm Chemotaxis! Speract! ! What role does cGMP play?! Ca+2?! Ca+2! twitch of the flagella! Alvarez 2014! What do you conclude from these results?! sperm from L. pictus! sperm from S. purpuratus! Guerrero 2010! speract purified from L. pictus add at time 0! A second receptor binding event occurs at the egg surface! egg receptor for sperm! Outside of cell Oligosaccharide Plasma membrane Protein Inside of cell Glycoprotein Info Flow V Signal processing, Innate Immunity! SIGNAL PRODUCTION! SIGNAL PERCEPTION (INPUT)! SIGNAL RELAY (TRANSDUCTION)! RESPONSE (OUTPUT)! What do you observe? ! Are there signals being sent & received? ! 18 19 What did you observe? ! Are there signals being sent & received? ! 20 The Bacteria Scanning Electron Micrograph From D. Kunkel Staphlococcus aureus = 1 µm can cause serious infec4ons Streptococcus pyogenes; Transmission Electron Micrograph by V. FischeB 21 THE NEUTROPHIL 22 Signal Transduction! ! How do neutrophils track bacteria?! 1. Cue 1. Creleased ue released ! CUE 2. Membrane receptor! binds the cue and is activated! 3. Activated receptor, activates LOCALIZED signaling molecules! 4. Activated signals stimulate changes in actin dyanamics! 24 How do neutrophils track bacteria?! Pseudomonas aeruginosa! Planktonic or biofilm lifestyle! Model for biofilm studies ! Opportunistic human pathogen! Causes chronic biofilm infections in lungs of cystic fibrosis patients! Microbiol. Immunol. 26(2):113-117! Why canʼt P. aeruginosa infections be eradicated? ! Planktonic bacteria! (free-living)! Mature bacterial biofilm! Biofilms are more resistant to antibiotics than planktonic cells.! Fuqua, C. and E.P. Greenberg. 2002. Nat. Rev. Mol. Cell. Biol. Sep;3(9):685-95! Bacterial cells that from wrinkly colonies are in the lungs of some cystic fibrosis patients and are resistant to antibiotics! Hypothesis: There is a signal that changes gene expression and leads to a change of phenotype (from planktonic/smooth to biofilm/wrinkly)! ! How would you test this hypothesis?! PAO1(lab strain) YW1 (from CF lung) % cells stuck together more very wrinkly smooth less What type of proteins might be involved in a phenotype switch like this?! P. aeruginosa rugose small colony variants have adaptations likely to promote persistence in the CF lung. J Bacteriol. 2009! 29 Environmental Microbiology 31 MAR 2014! Second messengers are small molecules that elicit an intracellular response after a receptor binds a signal! cyclic-di-GMP! genes involved in biofilm formation! (cell surface proteins, motility & others) ! Environmental Microbiology MAR 2014! Nature Reviews Microbiology APR 2009! High intracellular c-di-GMP is correlated with increased biofilm formation by P. aeruginosa.! High c-di-GMP (ΔwspF)! Low c-di-GMP (WT)! 24 h biofilms! Hickman et al., PNAS 2005! Info Flow V Signal integration, Cell cycle! SIGNAL PRODUCTION! SIGNAL PERCEPTION (INPUT)! SIGNAL RELAY (TRANSDUCTION)! RESPONSE (OUTPUT)! Cellular signaling pathways are connected in networks! signal perception! secondary signal transduction! response! What do the arrows imply?! tertiary B C Interactions can take many forms! positive C A secondary B tertiary What information might a cell require before proceeding through the cell cycle?! INTERPHASE G1 S (DNA synthesis) G2 What information might a cell require during the cell cycle?! INTERPHASE G1 S (DNA synthesis) G2 Checkpoints are sites of signal integration! G1 checkpoint! Control! system! G1! M! M checkpoint! G2 checkpoint! G2! S! What is being illustrated here?! G0! G1 checkpoint! G1! G1! What conclusions can you draw from these experiments?! extract A = no treatment! extract B = extract + enzymes that destroy all mRNAs! CDK binds to cyclin (=MPF) and becomes an active kinase! Activated protein can perform! a cell cycle function! MPF promotes entry into mitosis & then the cyclin disappears ! extract C = extract B + mRNA encoding cyclin! extract D = extract B + cyclin mRNA with a mutation that makes the protein very stable (unable to be degraded)! Both production and degradation of Cyclin are critical for cell cycle progression! Degraded cyclin Cyclin is degraded G2 Cdk checkpoint MPF Cyclin in accumulaJon Cycl Cdk A sequence known as a destruction box! Mutations in the box = no degradation = cyclins always there = cell cycle cannot be completed! Add ubiquitin => Go to the proteasome! Where might different signaling pathways act to affect the cell cycle?!
