Abstract
Rab27a/b are known to play an important role in the transport of melanosomes, with their knockout causing silvery gray hair. However, the relationship between Rab27a/b and hair growth is not well known. To evaluate the role of Rab27a/b in hair cycle, we investigated the expression of Rab27a/b during hair cycling and human outer root sheath (hORS) cells. The expression of Rab27a in ORS cells was mainly detected at the anagen, whereas expression of Rab27b in ORS, and epidermal cells was strongly expressed at the telogen. Additionally, Rab27a/b were expressed in the Golgi of hORS cells. To evaluate the role of Rab27a/b in hair growth, telogen-to-anagen transition animal and vibrissae hair follicles (HFs) organ culture models were assayed using Rab27a/b siRNAs. The knockdown of Rab27a or Rab27b suppressed or promoted hair growth, respectively. These results were also confirmed in human dermal papilla cells (hDPCs) and hORS cells, showing the opposite mitogenic effects. Moreover, Rab27b knockdown increased the expression levels of various growth factors in the hDPCs and hORS cells. Overall, the opposite temporal expression patterns during hair cycling and roles for hair growth of Rab27a/b suggested that Rab27a/b might regulate the hair cycle. Therefore, our study may provide a novel solution for the development of hair loss treatment by regulating Rab27a/b levels.
Highlights
Alopecia is a hair loss disease that occurs for a variety of reasons, including stress, aging, and hormonal abnormalities [1]
In human hair follicles (HFs) at the anagen phase, Rab27a is mainly distributed in human outer root sheath (hORS) cells and matrix cells and was slightly distributed in human dermal papilla cells (hDPCs) in the bulb region
When the subcellular localization of Rab27a and Rab27b was examined in hORS cells, both Rab27a and Rab27b were strongly expressed in hORS cells and especially colocalized with the Golgi marker (Figure 1D), suggesting that both Rab27a and Rab27b were expressed in the Golgi of hORS cells
Summary
Alopecia is a hair loss disease that occurs for a variety of reasons, including stress, aging, and hormonal abnormalities [1]. In the case of alopecia areata, steroids have often been used to treat hair loss [2]. Trends in today’s hair loss treatments and clinical studies appear to be more focused on biological approaches [4]. These trends show approaches that promote hair growth by promoting the proliferation of hair follicles (HFs) constituent cells or by extending or promoting the anagen phase of the hair cycle [5,6,7]
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