Intercellular Communication

Progress made in the last 20 years clearly indicates that the cell surface is an extremely dynamic structure involved in fundamental processes such as cell motility, innervation, and cell adhesion. Of particular interest is the finding that, in several tissues, the cell surface is differen­ tiated at the intercellular region, thereby providing communicating chan­ nels between apposing cells. Although our actual knowledge of the precise structures and mecha­ in the complex process of intercellular communication is still nisms involved scanty, evidence has been presented that ions and molecules diffuse from cell to cell, establishing a physiological continuum. Embryonic differentia­ tion, cell growth, neoplasia, electrical synchronization in nerve and mus­ cles, as well as immune response seem to be related to ceIl communication. In organizing this volume, it has been our intention to provide the reader with an actual review of the processes involved in intercellular communication in normal tissues as well as in neoplasia. We sincerely believe that the opinions and experiences described herein will be of help in establishing new perspectives for the future of this exciting new field of cell biology. We wish to thank all the colleagues who joined us in the organization of this volume, as well as Plenum Publishing Corporation for making its appearance possible.

1 Gap Junctions in Development.- 1. Introduction.- 2. Gap Junctions as Mediators of Cell Coupling.- 2.1. Morphological Correlates of Coupling.- 2.2. Structure of Gap Junctions.- 2.2.1. Fine Structural Appearance.- 2.2.2. Variations in the Appearance of Gap Junctions.- 2.2.3. Models of Gap Junction Structure.- 2.3. Chemical Organization of Gap Junctions.- 2.3.1. Lipid Component.- 2.3.2. Protein Component.- 2.3.3. Carbohydrate Component.- 3. Formation of Gap Junctions.- 3.1. Formation of Gap Junctions in Vitro.- 3.2. Junctional Assembly in Situ.- 3.3. Fate of Gap Junctions.- 4. Gap Junctions in Development.- 4.1. Gap Junctions in Early Development.- 4.2. Gap Junctions in the Formation of the Nervous System.- 4.3. Gap Junctions and Growth Control.- 5. Possible Roles of Gap Junctions.- 5.1. Nature of the Message.- 5.2. Modulation of the Permeability of Gap Junctions.- 6. Conclusion.- References.- 2 Cell Contact Phenomena and Their Implication in Cell Communication.- 1. Introduction.- 2. A Theoretical Physical Approach to Cell Contact.- 3. Experimental Observations.- 4. Cell Surface Heterogeneity and Contact.- 5. Mechanisms of Cell Interactions over Long Distances.- 6. Contact and Junctions.- 7. Junctions and Cancer.- References.- 3 Junctional Permeability and Its Consequences.- 1. Introduction.- 2. Methods for Studying Junctional Permeability.- 2.1. Electrophysiological Techniques.- 2.2. Biochemical Techniques.- 2.2.1. Metabolic Cooperation.- 2.2.2. Prelabeling of Metabolite Pools.- 2.2.3. Cofactor Starvation.- 2.2.4. Feeder Effects.- 3. Junctions Are Permeable to Small Molecules.- 3.1. Nucleotides.- 3.2. Sugar Phosphates.- 3.3. Choline Phosphate.- 3.4. Amino Acids.- 3.5. Vitamin-Derived Cofactor.- 3.6. Inorganic Ions.- 3.7. Tracer Dyes.- 4. Junctions Are Not Permeable to Macromolecules.- 5. The Extent and Rate of Junctional Transfer Is Quantitatively Important.- 6. Junctions in Vivo Are the Same as Junctions in Culture.- 7. Lack of Specificity of Junction Formation and Junctional Permeability.- 8. Consequences of Junctional Permeability.- 8.1. The Cell and the Tissue.- 8.2. Intercellular Coordination and Control of Activity.- 8.3. Intercellular Coordination and Control of Growth.- 8.4. Intercellular Coordination and Control by Cyclic Nucleotides and Calcium.- 8.5. Control of the Cell Cycle.- 8.6. Feeder Layers in Tissue Culture.- 8.7. Embryonic Development and Induction.- References.- 4 Intercellular Communication in Heart Muscle.- 1. Morphological Considerations.- 1.1. The Development of Intercellular Junctions in Heart Muscles: Interaction of Embryonic Heart Cells.- 1.2. Synchronization of Cardiac Myocytes and Synchronization of Pulsation.- 2. Spread of Excitation in Heart Muscle.- 3. Intercellular Structures Involved in the Coupling Process in Adult Cardiac Muscle.- 4. The Permeability of the Intercellular Junctions.- 4.1. The Influence of Calcium on Junctional Permeability.- 4.2. Influence of Sr2+ on Junctional Conductance.- 4.3. The Effect of Intracellular Sodium Concentration on Intercellular Communication.- 5. Sodium Pump as a Regulatory Mechanism of Intercellular Communication.- 6. The Importance of Intercellular Junctions in the Healing-Over Process.- 7. Intercellular Junctions and the Synchronization of Pacemaker Cells.- 8. Uncoupling of Pacemaker Cells during Synaptic Inhibition.- 9. Conclusion.- References.- 5 Protein Semiconduction: An Alternative Explanation of Electrical Coupling.- 1. Introduction.- 2. The Channel Hypothesis.- 2.1. The Electron Microscopic Observations.- 2.2. The Permeability of the Channels.- 2.3. Junctional Rectification.- 2.4. The Permeability of the Junctions.- 3. The Passage of Substances across the Septum of the Lateral.- Giant Axon of the Crayfish.- 4. Summary.- References.- 6 Intercellular Communication and Cancer.- 1. Introduction.- 2. Coupling in Normal Cells.- 3. Metabolic Cooperation.- 4. Formation of Coupling Junctions.- 5. Coupling in Cancer Cells.- 6. The Structural Correlate of the “Permeable Cell Junction”.- 7. The Function of Gap Junctions in Normal Inexcitable Cells.- 8. Gap Junctions and Cancer.- References.- 7 Cell Interactions in Neuroblastoma.- 1. Cell Interactions in Neuroblastoma.- 1.1. Introduction.- 1.2. C1300 Neuroblastoma.- 1.3. Other Neuroblastomas.- 1.4. Cell Hybrids.- 2. Neuroblastoma Interactions in Vitro.- 2.1. Neuroblastoma-Muscle.- 2.2. Neuroblastoma-Nerve Interactions.- 2.3. Other Interactions.- 3. Neuroblastoma Interactions in Vivo.- 3.1. Differentiation in Tumors.- 4. Conclusion.- References.- 8 Cell Communication in the Immune Response.- 1. Introduction.- 2. Cellular Elements of the Immune Response.- 3. Aspects of the Biology of the Macrophage.- 4. T- and B-Cell Collaboration in Immune Responses.- 5. Lymphocyte-Macrophage Interactions.- 6. Cell Communication in Lymphocytes.- 6.1. Methods.- 6.2. Formation of the Junctions.- 6.3. Structure of the Junctions.- 6.4. Current Flow through the Junctions.- 6.5. Junctional Uncoupling.- References.- 9 Intercellular Communication in the Early Embryo.- 1. Introduction.- 2. Physiological Analysis of Junctional Communication.- 3. Junctional Communication in Embryos.- 4. Functional Aspects of Junctional Communication in the Amphibian Embryo.- 5. Conclusion.- References.