Oligodendrocyte cytoskeletal dynamics and transport

National Institute Of Neurological Disorders And Stroke

Investigators

Linked publications, trials & patents

Abstract

The laboratory closed at NINDS in July of 2023, with the PI transferring to a new position at the University of California, Berkeley. This summary represents a partial year summary. We have pursued the following goals: 1. Understanding the contribution of TPPP in neurological diseases. 2. Characterizing a mouse model in which mRNA transport in oligodendrocytes is defective. 3. Extending our research to astrocytes and microglia. 4. Pursuing collaborations. 5. Helping trainees transition to new positions. On the TPPP project, we have made significant progress and a manuscript was uploaded as a preprint in June. In human brains, we found that TPPP aggregates in MSA (multiple systems atrophy). In recombinant protein biophysical assays, we performed experiments to understand how TPPP performs its normal function to make new microtubules. Together, this project firmly establishes that TPPP is important in MSA. On the mRNA transport project, we have a working manuscript. We are specifically looking at Mbp (myelin basic protein) as the mRNA cargo. Mbp is the most abundant mRNA in oligodendrocytes and encodes a locally translated protein that is found inside the myelin sheath. Our mouse model lacks the 3 UTR region of Mbp mRNA (but contains the coding region) and was rederived by the NIMH transgenic core this spring. These animals display tremors 3 months of age and have profound motor deficits. We have now finished additional extensive behavioral analysis showing that they also have gait defects. We have finished electron microscopy analysis of both their central nervous system and peripheral nervous system myelin. We characterized Mbp mRNA transport using primary rodent oligodendrocyte cultures. Together, these data show that mRNA transport is crucial for myelination in vivo. In addition, we investigated how astrocyte make their extensive processes and branches. This project looked at 3 classes of cytoskeleton in primary ramified astrocytes: microtubules, actin, and intermediate filaments. We are putting together a short manuscript on our results. We have completed the following collaborations: 1. John Hammer (NIH, NHLBI). Dr. Hammer and I jointly recruited a research fellow, Srinivasarao Repudi, who will work on the role of different myosins in oligodendrocyte development and myelination. He discovered that myosin V actually does not affect oligodendrocyte maturation, which is different from one published observation. 2. Jeff Huang (Georgetown). We added different metabolites to primary oligodendrocyte cultures to determine whether in vivo effects observed in the Huang Lab in an in vivo remyelination model act directly on oligodendrocyte or indirectly via microglia and macrophages. We expect that a manuscript will be submitted in Winter 2023. 3. Jeff Huang (Georgetown). We added conditioned microglial media to primary cultured oligodendrocytes to determine whether senescent microglia secrete factors that prevent oligodendrocytes from differentiating and expressing key myelin proteins. A manuscript is currently in revision. We continued our collaboration with Dr. Susanne Bechstedt (McGill). Dr. Bechstedt is a long-term collaborator and we continue to work on TPPPs molecular function. Finally, several trainees pursued career transitions: 1. Hunter Richardson (postbac) started MD/PhD program at U. Chicago 2. Joseph Nowacki (postbac) started MD program at Rowan / Cooper Union. 3. William Barclay (postdoc) started detail/internship at NIH OITE (Office of Intramural Training and Education)