C-Jun N-Terminal Kinase Signaling Guides the Migration of Interneurons During Cortical Development
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Graduate Theses, Dissertations, and Problem Reports 2017 C-Jun N-Terminal Kinase Signaling Guides the Migration of Interneurons During Cortical Development Abigail K. Myers Follow this and additional works at: https://researchrepository.wvu.edu/etd Recommended Citation Myers, Abigail K., "C-Jun N-Terminal Kinase Signaling Guides the Migration of Interneurons During Cortical Development" (2017). Graduate Theses, Dissertations, and Problem Reports. 6285. https://researchrepository.wvu.edu/etd/6285 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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For more information, please contact [email protected]. c-Jun N-terminal kinase signaling guides the migration of interneurons during cortical development Abigail K Myers 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 Neuroscience Eric S Tucker, Ph.D., Chair Peter Mathers, Ph.D. Ariel Agmon, Ph.D. Scott Weed, Ph.D. Shuo Wei, Ph.D. Neuroscience Graduate Program Morgantown, WV 2017 Keywords: c-Jun N-Terminal Kinase (JNK), cortical interneurons, developmental cortical disorders, migration Copyright 2017 Abigail K Myers Abstract c-Jun N-terminal kinase signaling guides the migration of interneurons during cortical development Abigail K Myers The cerebral cortex, responsible for higher order functions, is a layered structure that relies on the precise wiring of two main types of neurons, excitatory neurons and inhibitory interneurons. In order to maintain a critical balance of excitation and inhibition in the cortex, a smaller, yet very diverse, population of cortical interneurons provides inhibition to a much larger cohort of excitatory neurons. This makes interneurons a vulnerable population where the slightest perturbations to their location and wiring with excitatory neurons can contribute to the acquisition of neurological disorders like autism, schizophrenia and epilepsy. During development, cortical interneurons migrate tangentially from the medial and caudal ganglionic eminences in the ventral forebrain to the cortex. Unlike cortical excitatory neurons that are born in the ventricular zone of the dorsal forebrain and migrate radially on radial glial scaffolding, cortical interneurons are born in the ventral forebrain and migrate tangentially, primarily using molecular guidance cues in the extracellular environment to enter, navigate, and form streams in the nascent cerebral cortex. As development proceeds, interneurons depart from migratory streams on diagonal or radial trajectories in order to populate the cortical plate, where they eventually segregate into layers and make synaptic connections with other cortical neurons. Signaling pathways allow interneurons to express the correct complement of cell surface guidance receptors, transduce signals associated with the activation of those receptors, and facilitate the rearrangement of their cytoskeleton in order to aid in their travel. These processes are essential for the proper entrance of cortical interneurons into the cerebral cortex, their exit from migratory streams, and ultimately their layering in the cortical plate. Yet, how intracellular signaling pathways govern these processes remains largely unknown. The c-Jun N-terminal kinase (JNK) signaling pathway, primarily known for its role in cell death, plays a large role in cell migration by activating downstream targets that modify the cytoskeleton and cell architecture. However, its importance in cortical interneuron migration has not been established. This work, organized into four main chapters including two main data chapters and an appendix, provides the first evidence that cortical interneurons use JNK signaling to enter and navigate in the developing cerebral cortex. In the first data chapter, we establish that Jnk is present within cortical interneurons and Jnk1 is required for their entry into the cerebral cortex between embryonic day (E) E12.5 and E13.5 of mouse development. The second data chapter provides evidence that JNK signaling is important for maintaining migratory streams and that pharmacological inhibition or genetic ablation of Jnk from interneurons incites their exit from migratory streams and subsequent entry into the cortical plate between E14.5 and E15.5. Further, the work provided in the Appendix indicates disruption to the localization of Jnk- phosphorylated doublecortin, a microtubule associating protein important for branching of the leading processes of the migrating interneurons. Together, this work suggests that JNK signaling plays a critical role during cortical interneuron migration and may provide insight into how neurodevelopmental disorders like epilepsy, autism and schizophrenia could arise. ii Dedication To my family, friends, and mentors, thank you for all your love and support throughout all of my education iii Acknowledgements I would like to take a few moments to thank the many people that have helped me throughout my career as a PhD graduate student. To my advisor, Dr. Eric Tucker, thank you for teaching me everything you know about lab techniques, experiments, and publishing papers, as well as giving me the opportunity to attend conferences and introducing me to colleagues to help me network with others. Thank you for working with me as a team to train other students that have come into and through the lab and for teaching me how to manage and run a lab. Last, but not least thank you for taking me on as your first graduate student. I know this experience hasn’t been without its ups and downs, but thank you for sticking with me and working through all the challenging points. You have taught me so much about the field, and I have grown so much from this experience. To my committee members, Dr. Pete Mathers, Dr. Scott Weed, Dr. Aric Agmon, and Dr. Shuo Wei, thank you for all your guidance, support, and feedback on projects and papers. To Dr. Dey, thank you for all your support and for providing a listening ear, direction, and feedback when I had a problem or needed advice. I genuinely appreciated our meetings and talks and everything that came out of them. To Dr. Randy Kulesza and my teaching professors, thank you for giving me the opportunity to teach, for being patient with me while I learned the best strategies to teach, and for teaching me the most up-to-date ways of keeping students engaged. To my past and current labmates (John, Danielle, Neha, Bree, Emily, Kathryn, Katie, Emily, John, Kelly, Michael, Steven, Jessica, Skye, Catherine), thank you for all your help with the mouse colony and experiments. I am so glad every one of you decided to join the lab. Each one of you has taught me something new, and I am grateful that I have had the opportunity to work with all of you. Thank you for being patient with me during hectic experiment times and defense times, and most of all thank you for your support and friendship. I wish you all the best of luck with your projects and future endeavors. To Dr. Amanda Ammer and Dr. Karen Martin, thank you for your help with everything confocal. Thank you for including me in training sessions, being my never-ending source of answers when things went wrong with the confocal imaging, and for making my work environment flexible with Imaris. I loved working with you both. Thank you to my graduate student colleagues and friends (both inside and outside the neuroscience program). I would not have made it this far without the many lunches, dinners, drinks, walks, talks, and hugs. I never thought that I would have grown so much while I was here at WVU, but I had the best friends to help me through everything I faced. I am so grateful for every single one of our friendships. Thank you to my family and family friends for your guidance, support, and love throughout all of my schooling. Specifically, I would like to thank my parents, Sue and Tom, my brother, Aaron, my sister-in-law, Natalie, my Aunt Donna, Grammie, my best friend, Liz, and my love, Russ, for always being there to celebrate my successes and to encourage me through my struggles. Words cannot describe how much your unwavering love and kindness means to me. iv Table of Contents Abstract .................................................................................................................................... ii Dedication ................................................................................................................................iii Acknowledgements .................................................................................................................iv Table of Contents ..................................................................................................................... v List of Figures .........................................................................................................................vii List of Abbreviations ...............................................................................................................ix