Oligodendrocyte cytoskeletal dynamics and transport

National Institute Of Neurological Disorders And Stroke

Investigators

Linked publications & trials

Abstract

This is the second year of our lab/unit and we have pursued the following goals: 1. Lab set up and lab member recruitment. 2. Understanding the contribution of TPPP in neurological diseases. 3. Characterizing a mouse model in which mRNA transport in oligodendrocytes is defective. 4. Extending our research to astrocytes and microglia. 5. Pursuing collaborations. 6. Writing reviews. Our lab set up and member recruitment is complete with 7 members. In terms of lab composition, we currently have 1 research fellow (who has finished 1 postdoc already), 2 postdoctoral fellows (1 IRTA and 1 visiting), 1 graduate student (via independent GPP program through Georgetown), and 3 postbac IRTA fellows. One postdoctoral IRTA fellow has successfully transitioned to a position in industry. We have continued to purchase and receive additional pieces of equipment, including an incubating shaker, sonicator, small benchtop shaker, and additional freezers. We anticipate the arrival in the next fiscal year of specialized equipment, including stereotaxic injection device, complex wheel behavioral assay, vibratome, and homogenizer for recombinant protein purification from bacteria. On the TPPP project, we have made significant progress and plan to submit a manuscript on these results in Fall 2022. 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 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 are also continuing to characterize Mbp mRNA transport using primary rodent oligodendrocyte cultures. Together, these data will show that mRNA transport is crucial for myelination in vivo. We plan to submit a manuscript on this set of experiments in Winter 2022. Additionally, a new project in the lab will look at adapter proteins and motor proteins involved in mRNA transport from the perspective of minimal biophysical motility assays. In addition, we recently began culturing primary rodent astrocytes and microglia. A new project in the lab will investigate how astrocyte make their extensive processes and branches. We have completed the following collaborations: 1. Damaris Lorenzo Lab (Univ. of North Carolina, now Univ. of Pennsylvania). We performed cellular experiments to understand whether the giant ANK2 isoform (440kDa) is expressed in oligodendrocytes. We also worked with the NINDS electron microscopy core to determine whether the giant-ANK2 knockout mouse has any myelin defects. This was published in eLife in Fall 2021. 2. Yannick Poitelon and Sophie Belin (Albany Medical College). We performed electron microscope experiments to determine whether assess peripheral nerve healing after injury. We expect that a manuscript will be submitted in Winter 2022. We are currently pursuing the following collaborations: 1. Susanne Bechstedt (McGill). Dr. Bechstedt is a long-term collaborator and we continue to work on TPPPs molecular function. We will pursue experiments in 3D oligodendrocyte cultures. We anticipate that Dr. Lena Koslover (UCSD) will perform computational modeling of microtubule dynamics. 2. 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. 3. 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 2022. 4. 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. We expect that a manuscript will be submitted in Winter 2022. Finally, we published two invited literature reviews: 1. Frontiers Cell and Dev. Bio. This review was on childhood leukodystrophies with genetic etiologies and their underlying molecular and cellular causes. We profiled 35 different leukodystrophies and this is perhaps the most comprehensive and up-to-date review of leukodystrophies. 2. Curr. Opin. Cell Bio. This review focused on trafficking of vesicular cargos through satellite ER and Golgi in axons and dendrites. It also included information on satellite ER and Golgi in glial processes.