The Role Of Keratin 24 In Hair Loss

BackgroundAs the main component of epithelial cell skeleton,keratins are the primary structural component of epithelium,hair and nail.Keratins were initially considered to be only involved in maintaining cell structure.Later and further studies revealed its multiple functions.Keratins are not only used as molecular markers of epithelial proliferation and differentiation in the diagnosis and differential diagnosis of epithelial derived tumors,but also involved in a variety of biological reactions,such as cell proliferation,migration,apoptosis and so on.In the past 10 years,a large number of hair follicle specific epithelial keratins have been found,and keratin 75 is the first epithelial keratin to be found specifically expressed in hair follicles.Type II keratins including k6irs1,k6irs2,k6irs3 and k6irs4(now keratin 71-keratin 74)and type I keratins including k25irs1,k25irs2,k25irs3 and k25irs4(now keratin 25-keratin 28)are specifically expressed in the inner root sheath of the hair follicle.It had beed found that some of those keratins had relationship with hair disorders.But for keratin 24(K24),there is no research about its association with hair loss.ObjectiveTo study the hair loss phenomenon of K24 transgenic mice and observe the law of hair loss.To explore the relationship between K24 and hair loss as well as the role of K24 in the hair follicle.MethodsThe K24 transgenic mouse model was constructed.Identification was carried out by extracting the toe DNA and skin tissues of the mice respectively to do the PCR amplification ?western blot and q RT-PCR test.K24 transgenic mice with hair loss were observed and photographed to record the hair loss process.The expression and localization of K24 in the mouse skin were studied by immunofluorescence.The expression of K24 in the hair loss region of K24 transgenic mice was detected by western blot,which was compared with the none hair loss region? recovered hair loss region of K24 transgenic mice and the normal skin of WT mice.Scanning electron microscopy and transmission electron microscopy were used to observe hairs and skin tissues in hair loss region and to explore the ultrastructural changes.The autophagy mechanism of hair loss mice was studied by immunohistochemistry and western blot.Western blot was used to detect the relationship between K24 and Wnt / ?-catenin signaling pathway and IL-1A,as well as the change of K24 in the hair follicle cycle.To test the differentially expressed proteins(DEPs)in K24 transgenic mice by Tandem Mass Tag(TMT)proteomic analysis.Results1.K24 transgenic mice showed hair loss phenomenon.The process was as follows: the initiation of hair loss was about 2-3 weeks of age,and the sign continued after that.At about postnatal day of 3-4 weeks,the scope of hair loss area reached to the peak.Some of the hair loss mice were prone to be bald all over the back as well as the abdomen and the legs.But The rage of hair loss in some of these mice just restricted to the posterior part of back.According to this different extent of hair loss,the time of new hair regrowth varied.Hair loss lasted for about 2-3 weeks,and the hair coat developed normally until the end of their lives.2.K24 was mainly expressed in the outer layer of the epidermis,it expressed highly in the outer root sheath and hair shaft of the hair follicle in mice.3.K24 was highly expressed in hair loss region.The expression of K24 in hair loss region of K24 transgenic mice was higher than none hair loss region and recovered hair loss region of K24 transgenic mice,as well as the normal skin of WT mice.4.There might be no association between hair loss in K24 transgenic mice and autophagy.5.The expression of K24 was contrary to the trend of ?-catenin which was related to hair follicle growth and hair regeneration,while consistent with the hair follicle inhibitor,il-1a.6.The expression of K24 was high in the anagen,declining in the catagen,and at the lowest level in the telogen.7 Hair follicle-related keratins were down-regulated in K24 transgenic mice.Conclusion1.K24 transgenic mice showed hair loss phenotype,and there was a law in the process of hair loss.2.K24 was expressed in the outer root sheath and hair shaft of the hair follicle.3.K24 influenced the hair follicle and hair growth through several ways.4.K24 changed periodically in the hair follicle cycle.