1. General idea and concepts of cell-cell signaling Cell signaling: Mechanisms that one cell uses to communicate and influence the behavior of another cell. In a broader sense, the signaling could include environmental cues received by a cell such as smell, light, mechanic pressure, and heat etc. Three ways of cell signaling long-ranch signaling by secreted molecules contact signaling by plasma-membrane-bound molecules contact signaling via GAP junctions

2. Receptors: a. Enzymed-linked receptors -receptor protein kinases: tyrosine kinases, serine/thronine kinases - receptors coupled to protein kinases -protein tyrosine phosphatase receptors -ANF receptor, ligand binding leads to activation of intrinsic guanylyl cyclase catalytic domain b. G protein-linked seven transmembrane receptors c. Ion channel-linked receptors d. Intracellular Receptors--Steriod hormone receptors e. Receptors with death domain

3. Signal transduction pathways -Wnt signaling pathway -Map kinase pathway -Notch signaling pathway -cell death pathways - genetic pathway - biochemical pathway - death signaling pathway - engulfment signaling pathway

4. Embryo development Mosaic Development (autonomous specification: determined by local determinants and no cell-cell interaction) Experimental test: remove one blastomere, the blastomere still develop as it will be in the original embryo Regulative Development (conditional specificaiton: determined by cell-cell interaction and local determinants not important; e.g. mouse) Experimental test: if remove one blastomere, the other blastomere will take over and the embryo is fine. Intermediate (Xenopus, fly and C. elegans)

5. Experimental systems Yeast C. elegans Drosophila Mouse Human cultured cells

6. Approaches and techniques Genetic approaches Suppressor screen Enhancer screen Phenotypic screen Epistasis analyis Complementation tests Mosaic analysis Transformation rescue Sequencing of mutations

7. Biochemical approaches Co-IP hard-core purification mass spectrometer analysis Western blot analysis Enzymatic assays (kinases, proteases) Pulse chase experiments Molecular Biological approaches Over-expression dsRNA injection Cell Biological approaches Cell or tissue isolation, mixing, and transplantation Micro-manipulation Immunostaining GFP fusion labeling LacZ staining

8. Advantage or disadvantage of various approaches Genetics approach Help systematically identify the important components in a particular biological process Help determine the genetic relationships among different genes in the same pathway. But genetics can not reveal the mechanisms underlying the biological process. Biochemical approaches Very effective in elucidating the detailed mechanisms underlying a biological process. Can also help identify components of a biological process but usually can not reveal the whole picture and is restricted by the availability and relative quantity of materials, the experimental techniques or methods.

9. Good luck! Keep reading and thinking