Kinesin-2 Motors Regulate GLI Protein Function.

Kinesin-2 motors;Hedgehog Signaling;GLI proteins;Molecular;Cellular and Developmental Biology;Science;Cell and Developmental Biology

Carpenter, Brandon S.Wong, Sunny ;

University of Michigan

关键词: Kinesin-2 motors;    Hedgehog Signaling;    GLI proteins;    Molecular;    Cellular and Developmental Biology;    Science;    Cell and Developmental Biology;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/116727/bscarp_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Hedgehog (HH) signaling is an evolutionary conserved pathway that is indispensable for embryonic development and adult tissue homeostasis. GLI proteins are the transcriptional effector molecules of the HH signaling pathway that act in the nucleus to both activate and repress HH target gene expression. GLI proteins traffic between multiple subcellular compartments including the nucleus, cytoplasm, and primary cilium. Disruption in GLI trafficking results in defects in GLI protein activity, yet the mechanisms regulating these trafficking events are unclear. Kinesin-2 motor complexes, namely the heterotrimeric KIF3A/KIF3B/KAP3 complex and the homodimeric KIF17 complex, regulate both ciliary and non-ciliary transport of protein cargo, but whether these motor complexes regulate GLI proteins directly has not been tested. To examine a role for the heterotrimeric KIF3A/KIF3B/KAP3 kinesin-2 motor complex in regulating GLI activity, I performed a series of structure-function analyses using biochemical, cell signaling and in vivo approaches that define novel, specific interactions between GLI proteins and two components of this complex, KAP3 and KIF3A. I find that all three mammalian GLI proteins interact with KAP3 and map specific interaction sites in both proteins. Further, I find that GLI proteins interact selectively with KIF3A, but not KIF3B and that GLI interacts synergistically with KAP3 and KIF3A. Using a combination of cell signaling assays and chicken in ovo electroporations, I demonstrate that KAP3 interactions restrict GLI activator, but not GLI repressor function. These data suggest that GLI interactions with KIF3A/KIF3B/KAP3 complexes are essential for proper GLI transcriptional activity.Further, I provide evidence that homodimeric KIF17 interacts with all mammalian GLI proteins and that GLI1 protein expression is decreased in cells stably expressing a dominant-negative version of KIF17. Finally, I show that KIF17 and GLI proteins are expressed in overlapping cell layers in the developing cerebellum, and that Kif17-/- mice display smaller cerebella. These data suggest a model in which KIF17 is playing a tissue-specific role in regulating HH signaling through interactions with GLI proteins.Together, my findings define novel interactions between GLI proteins and two distinct kinesin-2 motor complexes and further demonstrate that these interactions are required for proper GLI transcriptional activity.