The Texas Medical Center Library DigitalCommons@TMC The University of Texas MD Anderson Cancer Center UTHealth Graduate School of The University of Texas MD Anderson Cancer Biomedical Sciences Dissertations and Theses Center UTHealth Graduate School of (Open Access) Biomedical Sciences 8-2012 CHARACTERIZATION AND TREATMENT OF A NOVEL MOUSE MODEL OF TSC-ASSOCIATED AUTISM Rachel Michelle Reith Follow this and additional works at: https://digitalcommons.library.tmc.edu/utgsbs_dissertations Part of the Medicine and Health Sciences Commons Recommended Citation Reith, Rachel Michelle, "CHARACTERIZATION AND TREATMENT OF A NOVEL MOUSE MODEL OF TSC- ASSOCIATED AUTISM" (2012). The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences Dissertations and Theses (Open Access). 266. https://digitalcommons.library.tmc.edu/utgsbs_dissertations/266 This Dissertation (PhD) is brought to you for free and open access by the The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences at DigitalCommons@TMC. It has been accepted for inclusion in The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences Dissertations and Theses (Open Access) by an authorized administrator of DigitalCommons@TMC. For more information, please contact [email protected]. CHARACTERIZATION AND TREATMENT OF A NOVEL MOUSE MODEL OF TSC-ASSOCIATED AUTISM by Rachel Michelle Reith, B.S. APPROVED: ______________________________ Michael J. Gambello, M.D., Ph.D., Supervisory Professor ______________________________ Pramod Dash, Ph.D. ______________________________ Raymond J. Grill, Ph.D. ______________________________ Gilbert J. Cote, Ph.D. ______________________________ Cheryl L. Walker, Ph.D. ______________________________ Dos D. Sarbassov, Ph.D. APPROVED: ____________________________ Dean, The University of Texas Graduate School of Biomedical Sciences at Houston i CHARACTERIZATION AND TREATMENT OF A NOVEL MOUSE MODEL OF TSC-ASSOCIATED AUTISM A DISSERTATION Presented to the Faculty of The University of Texas Health Science Center at Houston and The University of Texas M. D. Anderson Cancer Center Graduate School of Biomedical Sciences in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY by Rachel Michelle Reith, B.S. Houston, Texas August 2012 ii “You will be enriched in every way so that you can be generous on every occasion, and though us your generosity will result in thanksgiving to God.” 2 Corinthians 9:11 iii Acknowledgements Isaac Newton once said “if I have seen further than others, it is by standing upon the shoulders of giants.” My success would not have been possible without these giants in my own life. First, I have to thank my Lord and Savior, Jesus Christ. This is more for me, because you already know my thoughts. Psalm 139:2 says “You know when I sit and when I rise; you perceive my thoughts from afar.” Philippians 4:13 says: “I can do all this through him who gives me strength.” Thank you for your strength, for without it I am nothing. I give you the glory. Thank you also for your love. Romans 8:38-39 says “For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord.” Next, I want to thank Dr. Gambello. I can’t even fully express what you mean to me. You have challenged me in so many ways. I know that I exasperate you at times, but I hope that you have seen me bear fruit. I have grown as a scientist and a person under your leadership. Thank you also for the balance of independence and guidance. You were there to guide me when I needed, but you also allowed me to develop as an independent scientist. I will carry on your legacy. Thank you to my lab mates: Sharon Way, Jim McKenna, and Henry Wu. Your work formed the foundation of my studies. You have also helped me in this project in many ways. You covered my injections so I could take a much needed break or go on interviews. But you also gave me so much advice, guidance, and definitely some laughs. Thank you to my committee members (Pramod Dash, Ray Grill, Gil Cote, Cheryl Walker, and Dos Sarbassov). You have given me a lot of helpful advice over the years. However, your vote of confidence means the most to me. Thank you for even trying to make me graduate earlier! Thank you Dr. Dash for taking over as my “chair” after Dr. Gambello departed. Thank you both to Dr. Cote and Dr. Grill for your personal and scientific advice. I have always felt that your doors were open for me to come with questions. iv Thank you Dr. Northrup and Dr. Filipek for allowing me to shadow in clinic. Seeing patients with both TSC and autism have really helped me in my heart for researching these disorders. It is great to put a human perspective on my mouse model. Thank you also to Dr. Northrup for speaking opportunities to share my work with families and patients with TSC. Thank you to both the Center for Clinical and Translational Science program and the Schissler family for your generous support. Truly, this research would not have been possible without you. Thank you Meagan Walker and Jennifer Dulin for your helpful suggestions on my dissertation. Thank you to those who got me interested in science and helped me to develop as a scientist. Particularly to my undergraduate research advisor, Dr. Beckingham, who allowed me to explore my own hypothesis. Making that project “my own” was my first step in developing as a true scientist. Thank you Dr. Carolyn Smith. The promise of a great post doc position in your lab has kept me going in these final months of stress. I look forward to our research together. To the mice. Oh, the hours I tortured you. Thank you for not biting me…much. Thank you for giving your life to the pursuit of science. Thank you to the pediatrics IT department. How many hours of your time were consumed with my endless computer problems? Thank you for your patience and help dealing with them. Now, we will have to go and find a roof to throw that computer off one of these days. Thank you to my dad. You have taught me what it is to work hard in life. I do not believe that I would be where I am today without your influence and certainly not without your support. Thank you to my mom. You are more my friend than anything. Thank you for dealing with me while I have been stressed out and taking care of what was necessary. Thank you for offering to help me watch mouse videos. Thank you for arranging everything for our celebration. Thank you for so much more. v Thank you to Cameron Jeter for being a voice of encouragement as someone who has done this before. I am so happy for our friendship. To all of my family and friends. Many of you have taken time out of your days to be at my defense. But more than that, you have taken time out of your lives to invest in mine. I cannot measure the effect you have had on me. Nor can I conceive of how much I will miss you when I move. Thank you to Teahouse. You knew my order and had my drink made before I even checked out. Without you, I would have been much less caffeinated. I also need to thank my cat. Not only did you help me watch hours of mouse videos, but you even wanted more! vi CHARACTERIZATION AND TREATMENT OF A NOVEL MOUSE MODEL OF TSC- ASSOCIATED AUTISM Publication No.________* Rachel Michelle Reith, B.S. Supervisory Professor: Michael J. Gambello, M.D., Ph.D. Tuberous sclerosis complex (TSC) is a dominant tumor suppressor disorder caused by mutations in either TSC1 or TSC2. The proteins of these genes form a complex to inhibit the mammalian target of rapamycin complex 1 (mTORC1), which controls protein translation and cell growth. TSC causes substantial neuropathology, often leading to autism spectrum disorders (ASDs) in up to 60% of patients. The anatomic and neurophysiologic links between these two disorders are not well understood. However, both disorders share cerebellar abnormalities. Therefore, we have characterized a novel mouse model in which the Tsc2 gene was selectively deleted from cerebellar Purkinje cells (Tsc2f/-;Cre). These mice exhibit progressive Purkinje cell degeneration. Since loss of Purkinje cells is a well-reported postmortem finding in patients with ASD, we conducted a series of behavior tests to assess if Tsc2f/-;Cre mice displayed autistic-like deficits. Using the three chambered social choice assay, we found that Tsc2f/-;Cre mice showed behavioral deficits, exhibiting no preference between a stranger mouse and an inanimate object, or between a novel and a familiar mouse. Tsc2f/-;Cre mice also demonstrated increased repetitive behavior as assessed with marble burying activity. Altogether, these results demonstrate that loss of Tsc2 in Purkinje cells in a haploinsufficient background lead to behavioral deficits that are characteristic of human autism. Therefore, Purkinje cells loss and/or dysfunction may be an important link between TSC and ASD. Additionally, we have examined some of the cellular mechanisms resulting from mutations in Tsc2 leading to Purkinje cell death. Loss of Tsc2 led to upregulation of vii mTORC1 and increased cell size. As a consequence of increased protein synthesis, several cellular stress pathways were upregulated. Principally, these included altered calcium signaling, oxidative stress, and ER stress. Likely as a consequence of ER stress, there was also upregulation of ubiquitin and autophagy.