Graduate Theses, Dissertations, and Problem Reports 2013 Disulfide Bridging the Gap between Src and Cortactin: A New Paradigm in SH2 Domain-mediated Signaling Jason VanBuren Evans West Virginia University Follow this and additional works at: https://researchrepository.wvu.edu/etd Recommended Citation Evans, Jason VanBuren, "Disulfide Bridging the Gap between Src and Cortactin: A New Paradigm in SH2 Domain-mediated Signaling" (2013). Graduate Theses, Dissertations, and Problem Reports. 427. https://researchrepository.wvu.edu/etd/427 This Dissertation is protected by copyright and/or related rights. It has been brought to you by the The Research Repository @ WVU with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. 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Disulfide Bridging the Gap between Src and Cortactin: A New Paradigm in SH2 Domain-mediated Signaling Jason VanBuren Evans Dissertation Submitted to the School of Medicine at West Virginia University In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Cancer Cell Biology Laura Gibson, Ph.D., Chair Jun Liu, Ph.D. Karen Martin, Ph.D. Yong Qian, Ph.D. Robert Wysolmerski, Ph.D. Scott Weed, Ph.D., Mentor Cancer Cell Biology Program Morgantown, West Virginia 2013 Keywords: Src, SH2, Cortactin, Disulfide Abstract Disulfide Bridging the Gap between Src and Cortactin: A New Paradigm in SH2 Domain-mediated Signaling Jason V. Evans Src and cortactin are cytoplasmic proteins that are implicated in cancer progression and metastasis. Src is a non-receptor tyrosine kinase that also regulates normal cell homeostasis through phosphorylation of multiple downstream substrates. Cortactin is an actin binding protein and nucleation promoting factor that promotes the formation of stable branching networks within the actin cytoskeleton. Together, these proteins work in concert to promote the invasive and metastatic potential of tumor cells due to tyrosine phosphorylation of cortactin by Src. However, the mechanistic details of the interaction between Src and cortactin have never been elucidated. Collectively, this work aims to define how Src and cortactin interact to drive tumor cell invasion. The first study examines the mechanism of interaction between Src and cortactin, whereby the Src SH2 domain interacts with cortactin via a disulfide bond formation and that this binding event is necessary for the formation of pro-invasive invadopodia. The work here also defines a paradigm shift in how SH2 domain-containing proteins interact with reciprocal binding partners. The second study characterizes potential structural changes in cortactin resultant from phosphorylation by extracellular regulated protein kinases (ERKs) in order to gain structural insight into how cortactin conformation is regulated downstream of growth factor-mediated signaling events. The final study focuses on the creation of cortactin biosensor to directly monitor changes in cortactin conformation using FRET-based imaging. Taken together, these studies provide novel insights into the molecular events involved in regulating invasive tumor cell signal transduction and overall control of cortical actin dynamics during tumor metastasis. Dedication I would like to dedicate this to my wife, Tracie, and daughter, Roselyn. The two of you have been an infinite source of inspiration, courage, and strength. My accomplishments exist because of your love and support. iii Acknowledgements I would first like to acknowledge my wonderful wife, Tracie, for her continuous encouragement and support throughout this stage of my career. Beyond that, we have shared many memories with one another throughout our years together at WVU and in Morgantown. May this only be the beginning of our adventure in life! Together we have conquered many obstacles and have brought into this world a beautiful little girl, Roselyn Kate. This blessing to us has given me a new meaning and perspective on life. For this, I am grateful to you both for the person you have shown me I can be. I would also like to also thank my parents, Johnny and Linda Evans, for their 30+ years of love and support of myself and my dreams. Their teachings on hard work and being driven have structured the core of my personality that has allowed me to succeed in academic life as well as life in general. For that, you have my eternal thanks. Next I would like to thank my mentor, Scott Weed, Ph.D. Thank you ever so much for the opportunity to pursue my dreams in your lab. I have learned much from you in these past seven years, in both matters of science and research, as well as life. Thank you for your encouragement and confidence in my abilities. It will not go forgotten. To my committee, I would like to thank Dr. Laura Gibson, Dr. Jun Liu, Dr. Karen Martin, Dr. Yong Qian, and Dr. Robert Wysolmerski for sharing their experience and insight over the years. All of you have truly made committee meetings a source of knowledge and exciting ideas. Thank you. To past and present members of the Weed Lab, thank you for the shared laughter and pain the years have brought our way. It would have been a tough road to travel alone. Lastly, I would like to thank the Cancer Cell Biology program, West Virginia University, and the great state of West Virginia. To the CCB program, thank you for the opportunities over the years and providing the vessel to hone my scientific skills. In my experiences, our impact as a program and Cancer Center reaches well beyond our halls. To WVU, the experiences I’ve had since I started my undergraduate career in 2000 have been fantastic! The friends made and good times shared are memories that I will undoubtedly hold close to my heart for the rest of my life. Last, but most certainly not least, to the state of West Virginia. The state I was born and raised. The state I played in the mountains and streams as a child. The state that molded me into the person I am today. To you, I am forever grateful for your rugged beauty and I pray that your country roads always lead me home. iv Table of Contents Abstract……………………………………………………………………………...........ii Dedication………………………………………………………………………………….iii Acknowledgements……………………………………………………………………….iv Table of Contents…………………………………………………………………………v List of Figures……………………………………………………………………………..vi Glossary……………………………………………………………………………………vii Literature Review…………………………………………………………………………1 Src: Function and Domain-based Regulation Cortactin: Integrator of Actin Cytoskeletal Signaling Src and Cortactin: Phosphoregulation of the Actin Cytoskeleton SH2 Domains: Non-Conventional Interactions Study 1: Src Binds Cortactin Through a SH2 Domain............................................51 Cystine-mediated Linkage Study 2: Further Insights into Cortactin………………………………………………104 Conformational Regulation Study 3: Construction of a FRET-based Cortactin Biosensor……………………..115 Discussion………………………………………………………………………………..127 Appendix Curriculum Vitae…………………………………………………………………136 v List of Figures Literature Review 1. Src kinase structure and role in tumor invasion. 2. Cortactin structure and role in tumor invasion. 3. Src and cortatin work in concert to regulate cell motility and invasion. Study 1 1. Src SH2 Binding to Cortactin Does not Involve Tyrosine Phosphorylation and Binds Cortactin Repeats 1 and 5 2. Cortactin Cysteines 112 and 246 are Required for Src SH2 Domain Binding 3. Cysteine-containing Cortactin Peptides Dock Within the Src SH2 Phosphotyrosine Binding Region 4. Binding and Phosphorylation of Cortactin by Src is Redox Dependent and Requires Src C185 5. Src C-185 Forms a Cystine Bond with Cortactin C112 and C246 6. Cortactin C112/246 is Essential for Phosphotyrosine-based Cortactin Function 7. Model of cysteine-mediated interactions in cortactin regulation Table 1. Observed and predicted ion masses of GST-Src-SH2, GST-Src-SH2 + cortactin C112 and GST-Src-SH2 + cortactin C246 tryptic peptides Supplemental Figures: 1. Src Binding to Cortactin Requires the SH2 Domain and is Phosphotyrosine Independent 2. Phosphorylation of Recombinant Cortactin by Src and Mapping of Src SH2 Binding to the Cortactin Amino Terminal Domain 3. Schematic Diagram of Cortactin Constructs Used in this Study 4. Src SH2 Domain Does not Bind to the 5th Cortactin Repeat vi 5. Src SH2 R175A Retains Binding to Cortactin 6. Y-ion Analysis of Cystine bonding between Src C185 and cortactin C112 and C246 7. Expression of Cortactin Mutants in Cortactin Knockdown Cells and F-actin Co-sedimentation of Cortactin Mutants Study 2 1. Analysis of cortactin secondary structure following ERK1 phosphorylation Study 3 1. Design and testing of a FRET-based cortactin Biosensor 2. Creation and schematic of function of cortactin biosensor and controls vii Glossary 3D Three Dimensional Å Angstrom A Alanine ADF Actin Depolymerizing Factor AFAP Actin Filament Associated Protein Arp Actin related protein ATP Adenosine Triphosphate BCR Breakpoint Cluster Region C Celsius/Cysteine c- Cellular CAS Crk-associated substrate CBL Casitas B-lineage CD Circular Dichroism