Acquired peripheral neuropathy commonly results from diabetes, chemotherapy and HIV/AIDS, and therefore imposes a considerable, and increasing, health care burden on society. Effective treatment of neuropathy requires an understanding of the interactions between glia and axons in the peripheral nerve. Myelinating Schwann cells have been studied extensively, but less is known about non-myelinating Schwann cells. Because they are associated with unmyelinated sensory fibers that transmit pain, they are likely to participate in the pathology associated with diabetic and other small-fibe neuropathies. Furthermore, Schwann cell-specific mutations in genes that are important for cellular metabolism strongly affect unmyelinated axon stability, revealing an important but little explored link between these cells and peripheral nerve disease. Therefore an understanding of the biology of non-myelinating Schwann cells is an important approach toward developing new treatments for peripheral nerve diseases. We have developed several independent approaches for obtaining gene expression profiles of non-myelinating Schwann cells in order to identify new markers for these cells, and to identify mechanisms whereby their functional impairment in disease, particularly metabolic disease, affects peripheral nerve function. In addition, we have generated transgenic mice that express two proteins, an eGFP-tagged ribosomal protein, and tamoxifen-inducible Cre recombinase, in non-myelinating Schwann cells. The tagged ribosomal protein will permit the isolation and profiling of polyribosome-associated mRNAs in non-myelinating Schwann cells by translating ribosome affinity purification, or TRAP, a powerful method for determining gene expression profiles of specific cell types. The Cre recombinase will permit us to specifically manipulate gene expression in non-myelinating Schwann cells, or ablate them entirely. Such experiments are necessary to dissect the complex interactions between non-myelinating Schwann cells and their associated axons. These new transgenic mouse lines will permit us to establish gene expression signatures of non-myelinating Schwann cells after genetic or environmental perturbation and in models of inherited or acquired PNS disease. In particular we will use these methods to investigate the molecular aspects of how metabolic deficits lead to unmyelinated axon loss and neuropathy. Through the identification and manipulation of genes altered in non-myelinating Schwann cells in health and disease, we hope to gain new insights into the underlying pathology and open up new avenues for treatment of peripheral neuropathies.

Public Health Relevance

Recent work has accentuated the crucial roles that non-myelinating cells play in the peripheral nervous system, but many aspects of their biology are poorly understood. This research will generate gene expression profiles of non-myelinating Schwann cells, and will characterize new transgenic mice that will enable inspection of healthy non-myelinating Schwann cells as well as those with mitochondrial dysfunctional. The identification and perturbation of genes associated with metabolic perturbation of these cells will advance our understanding of the interactions between these cells and the axons with which they associate, and may lead to new treatments for peripheral nerve diseases.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Exploratory/Developmental Grants (R21)
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Cellular and Molecular Biology of Glia Study Section (CMBG)
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Morris, Jill A
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Washington University
Schools of Medicine
Saint Louis
United States
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Kim, Sungsu; Maynard, Jason C; Strickland, Amy et al. (2018) Schwann cell O-GlcNAcylation promotes peripheral nerve remyelination via attenuation of the AP-1 transcription factor JUN. Proc Natl Acad Sci U S A 115:8019-8024
Beirowski, Bogdan; Wong, Keit Men; Babetto, Elisabetta et al. (2017) mTORC1 promotes proliferation of immature Schwann cells and myelin growth of differentiated Schwann cells. Proc Natl Acad Sci U S A 114:E4261-E4270
Kim, Sungsu; Maynard, Jason C; Sasaki, Yo et al. (2016) Schwann Cell O-GlcNAc Glycosylation Is Required for Myelin Maintenance and Axon Integrity. J Neurosci 36:9633-46
Beirowski, Bogdan; Babetto, Elisabetta; Golden, Judith P et al. (2014) Metabolic regulator LKB1 is crucial for Schwann cell-mediated axon maintenance. Nat Neurosci 17:1351-61