Molecular Biology of RGS Proteins (eBook)

Front Cover 
1 
Progress in 
4 
Copyright Page 
5 
Contents 
6 
Contributors 
12 
Preface 
14 
Chapter 1: RGS Proteins: The Early Days 16
I. Reflection 16
II. Identification 18
III. Function 20
IV. Family 21
V. Mechanism 23
VI. Structure 25
VII. Perspective 25
References 26
Chapter 2: Insights into RGS Protein Function from Studies in Caenorhabditis elegans 
30 
I. Introduction 31
A. C. elegans as a Model Organism for the Analysis of Molecular Mechanisms 31
B. G Protein Signaling and RGS Proteins in C. elegans 31
II. Experimental Approaches for Identifying the Functions of C. elegans RGS Proteins 38
III. The Physiological Roles of Specific RGS Proteins in C. elegans 41
A. RGS Proteins That Function in C. elegans Development 41
B. RGS Proteins That Function in the Adult C. elegans Nervous System 43
IV. Principles of RGS Function That Emerge from Studies in C. elegans 46
A. The In Vivo Specificity of RGS Proteins to Galpha-Subunits 
47 
B. Multiple RGS Proteins Can Regulate One Galpha-Subunit 
48 
C. Determining the Requirement for Multiple Domains in One RGS Protein 51
D. The Unconventional Heterotrimer Model for R7 RGS Protein Function 53
V. Remaining Questions Regarding the In Vivo Functions of RGS Proteins 56
A. What is the In Vivo Function of the Remaining C. elegans RGS Proteins? 56
B. Why Do RGS Proteins Exist? 57
References 58
Chapter 3: Regulators of G Protein Signaling Proteins as Central Components of G Protein-Coupled Receptor Signaling Complexes 64
I. Introduction 65
II. Overview of RGS Proteins 65
A. RGS Protein Structure Determines Function 66
III. RGS Protein Interactions with GPCRs 67
A. GPCRs Interact Directly with RGS Proteins 69
B. Indirect GPCR/RGS Protein Interactions 72
C. Implied RGS Protein and GPCR Interactions 74
D. RGS Proteins also Interact with Non-GPCR Receptors and Ion Channels 76
E. Factors that Dictate RGS Protein Localization at the Plasma Membrane 77
IV. GPCRs Serve as Platforms for Molecular Signaling 78
V. Summary and Perspectives 81
References 82
Chapter 4: Structure and Function of Regulator of G Protein Signaling Homology Domains 90
I. Introduction 91
II. The Canonical RH Domain 92
III. The RGS Protein RH Domain 98
A. Signaling Context 98
B. Galpha Binding, GAP Activity, and Selectivity 
98 
C. Ternary Complexes of RGS Proteins, Galpha Subunits, and Effectors 
102 
D. Interface of RGS9 with Gbeta5: An RH Domain in a Modular Setting 
103 
E. Other Interaction Sites 104
IV. The Axin RH Domain 105
A. Signaling Context 105
B. Structural Adaptations of the Axin RH Domain 105
C. Interaction with APC 105
V. The RhoGEF RH Domain 106
A. Signaling Context 106
B. Structural Adaptations of the RhoGEF RH Domain 107
C. Interaction with the Effector Site of Galpha13 
108 
VI. The GRK RH Domain 109
A. Signaling Context 109
B. Structural Adaptations of the GRK RH Domain 110
C. Interaction with the Kinase Domain 112
D. Interaction with the PH Domain 113
E. Interaction with Galphaq 
114 
VII. Structurally Uncharacterized RH Domains 115
A. Two Tandem RH Domains in D-AKAP2 116
B. The Sorting Nexins 116
C. RGSL ``Family´´ RH Domains 117
VIII. Perspectives 117
References 120
Chapter 5: Nuclear Trafficking of Regulator of G Protein Signaling Proteins and Their Roles in the Nucleus 
130 
I. Introduction 131
II. Subcellular Localization of RGS Proteins 132
III. Nuclear Trafficking of RGS Proteins 136
A. Mechanisms Controlling Protein Nucleocytoplasmic Transport 136
B. NLSs and NESs in RGS Proteins 137
C. Posttranslational Modifications of RGS Proteins that Affect Their Nuclear Trafficking 145
D. Binding Partners Affecting Nuclear Trafficking of RGS Proteins 148
IV. Potential Roles of RGS Proteins in the Nucleus 153
A. RGS Proteins in Cell Death 154
B. RGS Proteins in Cell Cycle Regulation and Cell Division 154
C. RGS Proteins in Transcription Regulation 156
D. RGS Protein in Stress Response 160
E. RGS Proteins in Nuclear G Protein Signaling 162
V. Conclusions 162
References 163
Chapter 6: Structure, Function, and Localization of Gbeta5-RGS Complexes 
172 
I. Introduction 173
A. G Proteins, RGS Proteins, and R7 Family 173
B. Gbeta5 is a Unique G Protein beta Subunit That Interacts with RGS Proteins of the R7 Family 174
II. Structure of Gbeta5-R7 Complexes. The Role of RGS, GGL, and DEP Domains 176
A. Multidomain Organization of Gbeta5-R7 Complexes 176
B. RGS Domain and GAP Activity 179
C. The Role of Gbeta5 within the Complex 180
D. Function of the DEP Domain 183
E. Other Binding Partners of the DEP Domain 185
III. Expression and Subcellular Localization of Gbeta5-R7 Proteins 188
A. Regional Expression of R7 Family in the CNS 188
B. Expression of R7 Family RGS Proteins in the Retina 190
C. Do Peripheral Tissues Express R7 Family RGS Proteins? 191
D. Regulation of R7 Family Expression 193
E. Subcellular Localization of Gbeta5-R7 Proteins 195
F. Molecular Mechanisms of Gbeta5-R7 Membrane Association 196
G. Nuclear Localization of Gbeta5-R7 Complexes 197
H. R7 Family Membrane Anchoring Proteins, R7BP, and R9AP 200
IV. Other Protein-Protein Interactions and Phosphorylation of R7 Family Proteins 205
V. Physiological Role of Gbeta5-R7 Complexes: A Brief Summary of In Vivo Studies 207
VI. Conclusions 208
References 209
Chapter 7: Biology and Functions of the RGS9 Isoforms 220
I. Introductory Remarks 221
II. RGS9 Exists as Two Splice Isoforms with Distinct Nonoverlapping Expression Patterns 221
III. RGS9 Isoforms are Modular Multidomain Proteins 222
IV. Gbeta5 is an Obligatory Subunit of RGS9 223
V. The DEP Domain Mediates RGS9 Association with a Novel Class of Membrane Anchors 224
VI. The PGL Domain is the Unique Structural Feature of the RGS9-2 Isoform 224
VII. Spatial Organization of the RGS9Gbeta5 Complex 225
VIII. RGS9-2Gbeta5SR7BP Regulates G Protein Signaling in the Striatum 226
IX. RGS9-1Gbeta5LR9AP Regulates Visual Signal Transduction in Vertebrate Photoreceptors 228
X. The Role of the Effector Enzyme in Regulating Transducin GTPase and the Concept of Affinity Adapters 231
XI. Comparing the Functional Properties of RGS9 Isoforms Expressed in the Same Cell Type Suggests a Hypothesis on the Evolutionary Origin of Phototransduction 
233 
XII. Mechanisms Regulating the Galpha Recognition Selectivity and Catalytic Activity of RGS9 
234 
Acknowledgments 
236 
References 236
Chapter 8: The Role of Gbeta5 in Vision 244
I. Introduction 244
II. The Biochemistry of Gbeta5 245
III. An Overview of the Visual System 250
IV. RGS9-1 Expression Level Determines the Duration of Rod Phototransduction 252
V. The Involvement of Gbeta5S/R7RGS in the mGluR6 Pathway in ON-Bipolar Cells 254
VI. Spontaneous Retinal Activity and Retinogeniculate Projections 256
VII. Future Directions 258
References 259
Chapter 9: Regulation of Immune Function by G Protein-Coupled Receptors, Trimeric G Proteins, and RGS Proteins 
264 
I. Introduction 265
II. G Protein-Coupled Receptors 267
A. Gi- and Gq-Coupled Receptors 267
B. Gs-Coupled Receptors 272
C. G12/13-Coupled Receptors 273
III. Heterotrimeric G Proteins 275
A. Gi Subfamily 275
B. Gq Subfamily 277
C. Gs Subfamily 278
D. G12/13 Subfamily 278
E. Gbetagamma 280
IV. RGS Proteins 280
A. Modulation of RGS Protein Expression 281
B. Analysis of Genetically Modified Mice 281
V. Heterotrimeric G Protein- and RGS Protein-Mediated Modulation of Lymphocyte Migration and Trafficking 284
A. Gi-Mediated Control of Lymphocyte Trafficking 284
B. RGS Protein-Mediated Regulation of Lymphocyte Trafficking 286
VI. Downstream Signaling Events and Regulatory Proteins in Heterotrimeric G Protein-Mediated Cell Migration 287
A. Signaling Network in Dictyostelium, Neutrophils, and Other Cell Types 287
B. Downstream Signaling Events in Lymphocyte Migration 292
VII. Spatiotemporal Dynamics of Heterotrimeric G Protein Signaling Components in Migrating Cells 296
VIII. Conclusions 298
Acknowledgments 298
References 298
Chapter 10: Regulators of G Protein Signaling in Neuropsychiatri 
314 
I. G Protein-Coupled Receptors (GPCRs) and CNS Disorders 315
II. The Diverse Family of RGS Proteins 315
III. RGS Protein Expression in the Brain 316
IV. RGS9-2 and Drug Addiction 317
V. RGS9-2 and Parkinson's Disease 320
VI. RGS7 in Addiction and Anxiety Disorders 322
VII. The RZ Family Members Modulate Opioidergic and Dopaminergic Responses 325
VIII. RGS2 in Anxiety Disorders 327
IX. RGS2 in Schizophrenia 328
X. RGS4 and Scizophrenia 330
XI. RGS4 in Nociception, Analgesia, and Addiction 337
XII. Regulators of G Protein Signaling and Neuronal Survival 340
XIII. RGS Proteins as Drug Targets 341
XIV. Summary 341
References 341
Chapter 11: Identification of Ligands Targeting RGS Proteins: High-Throughput Screening and Therapeutic Potential 350
I. Introduction 351
A. Genetic Mouse Models 351
B. RGS Proteins as Drug Targets 353
II. Targeting RGS Proteins 354
A. The RH Domain 354
III. Rationally Designed RGS Inhibitors 355
IV. HTS for RGS Ligands 356
A. Flow Cytometry Protein Interaction Assay (FCPIA) and CCG-4986 356
B. Multiplex FCPIA 357
C. High-Throughput Flow Cytometry 358
D. Differential Scanning Fluorimetry 359
E. Yeast-Based Screening Methods 359
F. Peptide Library Screening Methods 360
G. RGS Modulator Peptides 361
H. Capillary Electrophoresis Methods 362
V. Unique Compounds 363
VI. Targeting Accessory Domains 364
VII. Conclusions 365
References 366
Index 
372 
Color Plate 
382