Long-term funding of our research by GM allowed us to uncover mechanisms by which the conserved Ypt/Rab GTPases regulate all membrane-associated trafficking pathways, including autophagy, in yeast and human cells. At the same time, two R21 grants from NINDS have enabled us to develop our work with human cells on mutations associated with neurodevelopmental disorders relevant to our interests in Rab1-regulated autophagy. One focus of our recent work funded by the R35 has been on Rab1 GTPase, which like its yeast homolog Ypt1, is required for and coordinates early steps of the secretory and autophagy pathways. We showed that depletion of Rab1 causes Golgi fragmentation and autophagy defects in human tissue culture cells. Importantly, both Golgi fragmentation and autophagy defects are associated with AD and ADRD. Moreover, Rab1 was also implicated in ADRD. I am very interested in applying our knowledge and expertise to AD/ADRD research. A supplement for my R35 would allow us to study the effect of Ypt1/Rab1 depletion, inhibition or activation on the AD/ADRD-associated Golgi fragmentation, autophagy defects, protein aggregation and toxicity. We have experience in working with yeast and human cell lines using all the techniques we need for accomplishing the proposed experiments for this supplement. In addition, I have a collaborator, Sue Liebman (LOS), an expert in using AD/ADRD yeast models, who will assist us with advice and reagents for establishing yeast AD/ADRD yeast models in my lab. Findings from this research will provide mechanistic insights on how Ypt1 and Rab1A/B regulate Golgi morphology and autophagy in normal yeast and human cells and in AD/ADRD cellular model systems. In addition, these findings will be used for applying for an RO1, or multi-PI grant with my collaborators, about the role of Rab1 in AD and/or ADRD. For that future application, I have two additional collaborators in my institute who will help us with establishing and using human cellular models for AD and PD (Swetha Gowrishankar), and for studying neuronal-specific processes (Simon Alford). If successful, our research could lead to defining Rab1 as a therapeutic target for ADRD.

Current research in my lab derives from my pioneering work about the conserved family of small GTPases termed Rabs in humans and Ypts in yeast, which regulates intracellular trafficking (Cell 1988, and Science 1991). As a postdoctoral fellow, I established the role of the first Ypt/Rab GTPase, Ypt1, in secretion and autophagy and showed that its function is conserved from yeast to mammalian cells. As a PI, I continued to delineate the mechanisms of Ypt/Rab GTPases action, including their upstream regulation and downstream function. My work has challenged concepts held by others in this dynamic field and uncovered fascinating new details. Relevant to this proposal is my work on the regulation of Golgi morphology and autophagy, a cellular recycling pathway, by Ypt1/Rab1 GTPases and their TRAPP complexes activators. Yeast has provided us with a simple model system for understanding the basic principles of Ypt/Rab function (NIH funded for 26 years), which turned out to be relevant to multiple human diseases, including cancer and neurodegeneration disorders. We used the first R21 to launch studies on Rab1 and TRAPP in human cell lines based on our ideas for Ypt1 and TRAPP in yeast. By modeling a neurodevelopmental disorder caused by a recessive mutation in a TRAPP subunit in yeast, we showed that the analogous mutation results in an autophagy block in yeast and in patients’ primary fibroblasts (collaboration with Christodoulou, Brain, 2020). This work points to the importance of autophagy in neuronal cells and to the value of modeling in yeast human mutations in conserved genes and processes.