Periodic Reporting for period 2 - MyeRIBO (Deconstructing the Translational Control of Myelination by Specialized Ribosomes)
Berichtszeitraum: 2021-01-01 bis 2022-06-30
The myelin sheath is essential for neuronal function and health: myelinating glial cells speedup propagation of axonal potentials, fuel the energetic demands and regulate the ionic environment of neurons. Lesions to the myelin sheath thus result in devastating neurological disorders that include multiple sclerosis, diabetic neuropathy and Charcot-Marie-Tooth disease. Myelination involves a striking expansion of the glial cell membrane that relies on an exceptional increase in protein and lipid synthesis rates. Decades of dedicated research has uncovered a complex transcriptional program that drives this process, whereas translational control mechanisms, on the other hand, have received little attention. There is emerging evidence, enabled by modern techniques, that ribosomes, typically viewed as invariant, passive molecular machines, may instead be heterogeneous in composition, with particular ribosomal components having a ‘specialized’ regulatory capacity for preferential translation of specific mRNAs. In MyeRIBO, I propose that translation control by specialized ribosomes is a novel layer of regulation that shapes the proteome of the myelinating glial cell. I will exploit advances in cryo-EM and quantitative proteomics analyses to discover the nature and diversity of ribosomes in myelinating cells, employ genome-wide ribosome profiling to obtain mechanistic insights into selective mRNA translation by heterogeneous ribosomes, and generate genetic mouse models to determine the functional consequences of this specialization for myelination in vivo. Notably, I will study the implication of this mechanism in pathogenesis of injury-induced demyelination and diabetic neuropathy, and evaluate the targeting of specialized ribosomal components as a preclinical strategy. MyeRIBO will push further the boundaries of our current understanding of the molecular control of myelination, which could have a profound impact for understanding neural development and myelin disorders.
The project started officially on October 1st 2020. Along this 1.5-month period, we have been optimizing the culture conditions for our in vitro model of myelination that will be the basis for all our discovery (Aim 1), mechanistic (Aim 2), and functional assays (Aim 3 and 4) of ribosome specialization. We have also been optimizing some of the analytical techniques (e.g. polysome profiling and Ribo-Seq). Finally, we have purchased the different mice models (e.g. RiboTaq) that we need for this project and started the breeding for our in vivo characterization of ribosome specialization.
The proposed methods entail studying the implication of this mechanism in pathogenesis of injury-induced demyelination and diabetic neuropathy, and evaluating the targeting of specialized ribosomal components as a preclinical strategy. In vitro and in vivo analyses are to be performed on mice for the biological impact of ribosomal heterogeneity on Schwann cell myelination. Findings will then be translated to models of myelin disorders to evaluate the impact of this regulatory mechanism on disease pathogenesis and development of potential preclinical therapeutic strategies.