Primary cilia-mediated intercellular signaling in hair follicles

Abstract

Dermal papilla cells (DPCs) play a major role in the physiology of hair follicles. The dynamic hair growth is achieved through the sound intercellular communication. It has been demonstrated that the interactive characteristics of DPCs become more remarkable upon the spheroid formation. However, the molecular basis of the activation has remained unclear. Here we show that the novel function of sensory organelle, i.e., primary cilia, of DPCs in the intercellular interaction with other cells. When the formation of primary cilia was inhibited, the DPC-conditioned media became less effective in the augmenting activity of the cellular proliferation of other mesenchymal stromal cells. In the same condition, it was revealed that the gene expression of FGF10 was down-regulated in DPCs. These results indicate that the primary cilia is involved in the production of the growth factor, which could in turn augment the cell growth. Compared to monolayered cells, spheroidal DPCs showed considerably longer primary cilia. The microsphere accordingly supported the growth of the acceptor cells more efficiently than the 2D cultured cells. However, the proliferation efficiency became lower as the spheroidal size became larger. Interestingly, the appearance frequency of primary cilia was reduced in the larger spheroids while the length of the residual organelle kept unchanged. Collectively, our current findings suggest that DPCs tune both the length and the appearance frequency of primary cilia, through which the cells regulate the production of signaling molecules and thereby communicate with other cells.