Spatial association of SEMA3C with nerve endings/terminal Schwann cells in hair follicle isthmus region

Abstract Nerve endings and terminal Schwann cells (TSCs) specifically and densely surround hair follicle at isthmus area, forming a neuromuscular‐junction‐like structure called lanceolate complex. The interplay between neuronal components and epidermis in this specialized structure enables hair to properly sense complex stimuli from environments. However, how nerves precisely attach to and innervate this specific region during development remains to be elucidated. Here, we demonstrate that SEMA3C, a secreted protein member of semaphorin family responsible for axonal guidance, is localized right below sebaceous gland and in close approximation with nerve endings and TSCs processes all through the entire hair cycle. SEMA3C protein is deposited outside of epithelial cells and its expression is independent on the presence of nerve endings/TSCs. SEMA3C is also found in portions of dermal papilla at growth phase. The tight spatial association of SEMA3C with lanceolate complex suggests that it might play roles in establishment and/or maintenance of the lanceolate complex in hair follicle.