Skin regeneration - Signal transduction in hair follicles

1.Lrig1是ErbB受体家族的负反馈调节因子，在毛囊和肠道干细胞中高度表达，并通过调节生长因子信号的振幅来控制其生态位的大小。MED1由人表皮角质形成细胞表达，并作为几种转录因子的协同激活因子发挥作用。Med1敲除小鼠提供了强有力的证据，证明Med1在维持角化细胞的静止和防止滤泡干细胞的耗尽中起重要作用。在缺氧条件下，真皮乳头细胞产生的瘦素（一种众所周知的脂肪因子）增加，这表明在退行期/休止期的缺氧促进了真皮乳头产生瘦素，为进入下一个生长期做准备。

1.Lrig1, a negative feedback regulator of the ErbB receptor family, was highly expressed by hair follicle and intestinal stem cells and controls the size of their niche by regulating the amplitude of growth factor signalling. MED1 is expressed by human epidermal keratinocytes and functions as a coactivator of several transcription factors. Med1 knockout mice provided an strong evidece that MED1 plays an important role in maintaining quiescence of keratinocytes and preventing depletion of the follicular stem cells.2.Production of leptin, a well-known adipokine, by dermal papilla cells increased under hypoxic condition, suggesting that hypoxia in catagen/telogen phase promotes leptin production by dermal papilla, preparing for entry into the next anagen.