TitleMembrane remodeling by novel regulators of the recycling endosome
NamePant, Saumya (author), Rongo, Christopher (chair), Grant, Barth (internal member), Driscoll, Monica (internal member), Matsumura, Fumio (internal member), Carr, Chavela (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectCell and Developmental Biology,
DescriptionEndocytic recycling is the process where by molecules traffic from endosomes back to the plasma membrane. This process is crucial for the maintenance of cellular homeostasis and cell polarity. C. elegans RME-1 and its mammalian homolog mRme-1/EHD1 are required for exit of cargo from the recycling endosome. The mechanism by which they control cargo exit has led to a proposal that they may function in formation of carrier tubules that break off from the recycling endosome. Recent studies suggested parallels of EHD family to the Dynamin GTPase superfamily of mechanoenzymes which function in membrane fission at the clathrin coated pit. Through a bioinformatics based screen we identified an interaction between RME-1 and AMPH-1, the only C. elegans member of Amphiphysin/BIN1 family of BAR-domain proteins. In mammalian neuronal synapses, Amphiphysin family proteins regulate the recruitment and activity of Dynamin for formation of vesicles. We established that AMPH-1 co localizes with RME-1 on recycling endosomes in vivo, amph-1 deletion mutants are defective in recycling endosome morphology and function and that AMPH-1 and RME-1 cooperatively promote the recycling of transmembrane cargo. in vitro we found that purified recombinant AMPH-1/RME-1 co-assemble on membranes to produce short, coated tubules which are qualitatively distinct from those produced by either protein alone. We have established that AMPH-1 and RME-1 serve as a novel membrane tubulation and possibly fission machinery at the recycling endosome, an interaction that is conserved in mammals.
We also investigated the function of a serine/threonine kinase of the germinal center kinase family (GCK-2) which is known to bind two Rabs, RAB-10 and RAB-8, which function in endocytic recycling. We established that GCK-2 is a novel effector of RAB-8 in regulating RME-1 labeled recycling endosomes. In select functions, it may serve as a RAB-10 effector. This may be an example of RABs being sequentially activated by binding the same effector. This study identifies a novel function for a germinal center kinase proteins whose only known function relates to the MAPK signaling cascade.
We recently established an interaction between GCK-2 and AMPH-1. We hypothesize that this interaction could serve as a hub which ties together the major recycling endosome interactions mapped for RME-1/AMPH-1 as well as with RAB-8/RAB-10.
NoteIncludes bibliographical references (p. 292-304)
Noteby Saumya Pant
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.