Crescerin: Growing the Understanding of Microtubule Dynamics in Neural Primary Cilia

Eukaryotic primary cilia are microtubule (MT)-based organelles that project from the cell-surface of most mammalian cell types, including neural cells. Primary cilia are known to modulate key signaling pathways including Hedgehog signaling, involved in central nervous system development and homeostasis. Additionally, defects in primary cilia structure and function are known to cause genetic disorders commonly known as ciliopathies, which share abnormal central nervous system architecture and intellectual deficits as common clinical features. The ubiquity of primary cilia across mammalian cell types and the role of primary cilia in proper neurodevelopment and homeostasis underscores the importance of investigating the organelle and its molecular components. Crescerin is a cilia-specific microtubule associated protein family that regulates ciliary microtubules using arrayed tubulin-binding TOG domains. Prior research has discovered that, Crescerin1, through use of its arrayed tubulin-binding TOG domains, is essential for proper primary cilia structure and function as well as for promoting C. elegans ability to sense and respond to its environment. Since C. elegans serve as prime model organisms for better understanding the nervous system in higher organisms, these results imply that Crescerin1 and its TOG domains’ roles in the formation and function of primary cilia and in neurophysiological and behavioral responses are as essential in humans as they are in C. elegans. Thus, to better understand neural primary cilia, microtubule dynamics, and TOG domain-containing protein families in brain development and for diverse aspects of brain function, we employ a structure-function molecular-based approach. In the current study, we consider that solving and analyzing the structure-function of Crescerin1’s TOG 4 domain will advance knowledge of the role of TOG domains across TOG domain-containing protein families in regulating microtubule dynamics. It will advance understanding of the role of Crescerin1 in establishing proper neural primary cilia structure and function. We postulate that a functional understanding of Crescerin’s TOG domains at the atomic level will provide a framework to further investigate the structural microtubule dynamics mechanisms employed by neural primary cilia to promote proper central nervous system development and prevent central nervous system-related disorders. Therefore, using X-ray crystallography, we have purified multiple constructs of the predicted TOG domain and have used these purified proteins to obtain crystal structures. Through our work, we have begun to characterize Crescerin1 TOG 4 domain and its interactions with microtubules in the primary cilium.Bachelor of Scienc