Claudin-19 Expression at the Neuromuscular Junction.
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Date
2009-02-23
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Abstract
Terminal Schwann cells (TSCs) sit close together to form a cap over each neuromuscular junction. It is not known how TSCs interact with each other, but their close physical relationship suggests that they might form cell-cell adhesions. Adherens junctions and tight junctions are well-studied formations of cell-cell adhesions and are typically expressed near each other in the same cells. Previous research has shown that M-cadherin, one of the adherens junction proteins, colocalizes with a TSC marker, suggesting the presence of adherens junctions and tight junctions in TSCs. Additionally, claudin-19, one of the tight junction proteins, is known to be expressed by myelinating Schwann cells, but it is unknown whether claudin-19 is also expressed by TSCs. I therefore hypothesize that claudin-19 is expressed by TSCs and is involved in TSC-TSC interactions. To begin to address this hypothesis, immunolabeling against claudin-19, Schwann cells, and acetylcholine receptors was performed on both cryostat sections and whole-mount of mouse muscles. Claudin-19 expression was found at neuromuscular junctions and was localized to the axon-terminal transition, where myelin ends and TSCs begin. After denervation of the muscle and degeneration of all axons, claudin-19 expression was still present at some neuromuscular junctions. These results show for the first time the expression of claudin-19 in Schwann cells at the rodent neuromuscular junction.
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Keywords
axon, claudin-19, nerve terminal, tight junction, neuromuscular junction, Terminal Schwann cells
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Degree
MS
Discipline
Zoology
