Establishment of an in vitro organoid model of dermal papilla of human hair follicle.

Human hair dermal papilla (DP) cells are specialized mesenchymal cells that play a pivotal role in hair regeneration and hair cycle activation. The current study aimed to first develop three-dimensional (3D) DP spheroids (DPS) with or without a silk-gelatin (SG) microenvironment, which showed enhanced DP-specific gene expression, resulting in enhanced extracellular matrix (ECM) production compared with a monolayer culture. We tested the feasibility of using this DPS model for drug screening by using minoxidil, which is a standard drug for androgenic alopecia. Minoxidil-treated DPS showed enhanced expression of growth factors and ECM proteins. Further, an attempt has been made to establish an in vitro 3D organoid model consisting of DPS encapsulated by SG hydrogel and hair follicle (HF) keratinocytes and stem cells. This HF organoid model showed the importance of structural features, cell-cell interaction, and hypoxia akin to in vivo HF. The study helped to elucidate the molecular mechanisms to stimulate cell proliferation, cell viability, and elevated expression of HF markers as well as epithelial-mesenchymal crosstalks, demonstrating high relevance to human HF biology. This simple in vitro DP organoid model system has the potential to provide significant insights into the underlying mechanisms of HF morphogenesis, distinct molecular signals relevant to different stages of the hair cycle, and hence can be used for controlled evaluation of the efficacy of new drug molecules.

Rhizobial and mycorrhizal symbioses in Lotus japonicus require lectin nucleotide phosphohydrolase, which acts upstream of calcium signaling.

Nodulation in legumes requires the recognition of rhizobially made Nod factors. Genetic studies have revealed that the perception of Nod factors involves LysM domain receptor-like kinases, while biochemical approaches have identified LECTIN NUCLEOTIDE PHOSPHOHYDROLASE (LNP) as a Nod factor-binding protein. Here, we show that antisense inhibition of LNP blocks nodulation in Lotus japonicus. This absence of nodulation was due to a defect in Nod factor signaling based on the observations that the early nodulation gene NODULE INCEPTION was not induced and that both Nod factor-induced perinuclear calcium spiking and calcium influx at the root hair tip were blocked. However, Nod factor did induce root hair deformation in the LNP antisense lines. LNP is also required for infection by the mycorrhizal fungus Glomus intraradices, suggesting that LNP plays a role in the common signaling pathway shared by the rhizobial and mycorrhizal symbioses. Taken together, these observations indicate that LNP acts at a novel position in the early stages of symbiosis signaling. We propose that LNP functions at the earliest stage of the common nodulation and mycorrhization symbiosis signaling pathway downstream of the Nod factor receptors; it may act either by influencing signaling via changes in external nucleotides or in conjunction with the LysM receptor-like kinases for recognition of Nod factor.