Prion Like Proteins in Vesicle Trafficking

McKeith Pearson, Purdue University

Abstract

Vesicle trafficking is an important process critical for secretory and endocytic purposes, but it is also crucial for cell homeostasis, e.g., for maintenance of organelle identity and recycling of membrane components.The endomembrane-located adaptor protein Epsin R (Epsin-Related protein) is believed to be important for recycling of SNARES like Vti1b from endosomes to the trans Golgi network (TGN), although its involvement in TGN to endosome transport has been also proposed. Further highlighting its impact in cellular and organismal physiology, certain EPSIN R SNPshave been linked to schizophrenia and Epsin R deficiencies correlate with other pathological conditions related to epidermis homeostasis such as psoriasis and eczema.Epsin R belongs to the conserved Epsin family of adaptors and as such it presents a characteristic Epsin N-Terminal Homology (ENTH) domain and a largely unstructured Cterminus. The latter contains binding motifs for important elements of the vesicle trafficking machinery.Here we identified a C-terminal region of Epsin R with prion-like characteristics (Prion Forming Region or PFR). We found that GFP-Epsin R is localized in intracellular punctate structures colocalizing with different intracellular markers; however, in contrast to other epsin family members, Epsin R displayed puncta of different size and with different protein content with a substantial contribution of large/bright particles. Importantly, the C-terminal Epsin R’s PFR was required for Epsin R localization and for the formation of large and bright puncta. Further, these structures displayed characteristics shared with other prion-like proteins. Our results therefore suggest that Epsin R possesses PFR-dependent prion properties that play an important role in this adaptor’s localization and function.We propose a model in which prion-like proteins like Epsin R can rapidly and stably selfassemble at vesicle budding sites. These proteins would accelerate the formation of vesicle trafficking machinery and the recruitment of cargo. We also speculate that oligomerizing, selftemplating reactions would occur under strict control of several cellular factors such as chaperones and post-translational modifications (e.g., phosphorylation, ubiquitination, etc.) to assure quick and reversibleassociation of prion-like proteins.

Degree

Ph.D.

Advisors

Stauffacher, Purdue University.

Subject Area

Molecular biology|Physiology|Biology|Neurosciences|Sustainability

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