Validation Of Temperature-Sensitive And Ca²⁺-Permeable TRPV3 Channel Activation For Inhibition Of Hair Growth

Hair growth starts from hair follicles that reside in dermis.Abnormal hair growth is an early sign of hair follicle disease or systemic illness such as alopecia or hair loss.Therefore,understanding the dysfunctional hair follicle is fundamental to alleviating dermatologic or systemic diseases with hair abnormalities.The warm temperature-activated Ca²⁺-permeable TRPV3 channel protein is abundantly expressed in the skin keratinocytes and hair apparatus.In human,dysfunctional TRPV3（W692G、G573C and G573S）causes congenital Olmsted syndrome characterized by skin diseases and alopecia,in rodents,the spontaneous gain-of-function mutation of TRPV3 gene causes hair loss and AD-like dermatitis in DS-Nh mice and WBN/Kob-Ht rats.Conversely,TRPV3-deficient mice exhibit phenotypes of curly whiskers,a thin cuticle,wavy hair and misaligned hair follicles,indicating a critical role of TRPV3 in normal morphogenesis of hair and hair follicle development,but the relationship between TRPV3and hair growth remains largely unknown.In our study,we use TRPV3 agonist natural carvacrol and TRPV3 inhibition natural forsythoside B as pharmacological tools,using a combination of animal and cell experiments to explore the mechanism of pharmacological regulation of TRPV3 channel on hair growth.Objective:To validate TRPV3 as a therapeutic target,we investigated the effect of pharmacological modulation of TRPV3 on hair growth using a combination of biochemical and cell biology,immunohistochemical and pharmacological approaches.Methods:Western blot and immunohistochemical experiments were used to verify the expression of TRPV3 channel in skin and hair follicles;Whole-cell patch clamp recordings was used to explore functional expression of TRPV3 in ORS cells;In vivo,we investigate the effect of TRPV3 on hair growth in C57BL/6 mice by using pharmacological tools of TRPV3（agonist:carvacrol,inhibitor:forsythiaside B）;In cellular level,we investigate the effect of TRPV3 on the viability of human follicle ORS cells with high expression of TRPV3.Results:The high expression of TRPV3 channel in mouse skin keratinocytes and ORS cells was confirmed by Western blot and immunohistochemical experiments.Forsythiaside B inhibits TRPV3-like current induced by carvacrol in hair follicle outer root sheath cells.In animal experiments,the activation of TRPV3 by natural carvacrol inhibit hair growth by delaying hair growth cycle,inhibiting hair elongation and decreasing the number of hair follicles.The inhibition of TRPV3 by forsythiaside B alleviate hair growth inhibition induced by carvacrol.In cell experiment,the activation of TRPV3 by natural carvacrol induces cell death of ORS cells in a dose-dependent manner,forsythiaside B reverses cell death induced by carvacrol.Conclusions:1.The warm-temperature activated Ca²⁺-permeable TRPV3 channel is critical for regulation of hair growth.2.Pharmacological activation of TRPV3 by agonist natural carvacrol inhibited hair growth by inducing the hair ORS cells death.3.Specific inhibition of TRPV3 by natural forsythoside B（FB）resulted in a significant reversal of hair growth inhibition induced by carvacrol.4.Topical inhibition of TRPV3 may represent a promising therapy for hair loss or hair follicle-related skin diseases.