Document Type


Date of Degree

Spring 2017

Access Restrictions


Degree Name

MS (Master of Science)

Degree In

Molecular Physiology and Biophysics

First Advisor

Pieper, Andrew

First Committee Member

Stamnes, Mark

Second Committee Member

Weiner, Joshua


Autism Spectrum Disorders (ASDs) are a diverse group of diseases that share the common features of deficits in social communication and rigid, repetitive behavior patterns. Most genetic alterations related to ASD can be broadly split into two categories – those pertaining to mTOR/PI3K signaling, and those pertaining to synaptic connections and structure. While a number of synaptic scaffolding proteins have been linked to ASD via human genetic studies and mouse models, SAP90/PSD95 associated protein 3 (SAPAP3) has not. Loss of SAPAP3 in mice, however, results in compulsive grooming behavior, which parallels one of the core features of ASD. On a molecular level, loss of SAPAP3 results in increased signaling via the group I metabotropic glutamate receptor mGluR5. As mGluR5 is known to regulate protein transcription and translation, we conducted a proteomic comparison of sapap3-/- mice relative to sapap3+/+ mice. We identified a number of differentially regulated proteins, the majority of which were upregulated in sapap3-/- mice. Of those, we chose to further investigate collapsin response mediator protein 2 (CRMP2), due to its role in regulating dendritic branching and neurogenesis. We found abnormalities in both dendritic branching and postnatal neurogenesis in sapap3-/- mice, changes which may contribute to some of their behavioral phenotypes. We also found that ultrasonic vocalization, a form of communication for mice, is altered in neonatal sapap3-/- mice. Taken together, these findings provide new direction that could lead to future therapeutics for patients with ASD, as well as an early read-out of the effectiveness of any potential treatment.

Public Abstract

Autism Spectrum Disorders (ASDs) comprise a diverse group of diseases that share the core features of social communication deficits and rigid, repetitive behavior patterns. Recent advances in understanding the genetics behind ASD have prompted the creation of mouse models to better understand how this disease arises, with the hope of paving the way for development of new treatments for patients suffering from ASD. A common theme to emerge from the recent surge in ASD genetic studies has been a role for proteins of the neuronal synapse, the point where two neurons meet and communicate. Here, we explore whether removal of the gene for synapse scaffolding protein synapse associated protein 90/postsynaptic density protein 95 associated protein 3 (SAPAP3) from the mouse genome is sufficient to cause ASD- like behavior. We found that the molecular changes caused by loss of SAPAP3 have far-reaching consequences, including affecting how neurons extend their processes to communicate with their neighbors, and also the survival rate of newborn adult neurons. We also found that without SAPAP3, newborn mice communicate with their mother differently than with their normal non-genetically altered littermates. We believe this information helps clarify some of the molecular mechanisms that may lead to ASD, and that this mouse model provides an opportunity to help develop new treatments for ASD.


v, 50 pages


Includes bibliographical references (pages 40-50).


Copyright © 2017 Natalya S. Tesdahl

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Biophysics Commons