miRNAs are important post-transcriptional regulators of gene expression which play vital roles in the arrays of physiological processes, including skin and hair follicle (HF) development. In this study, the role for miR-214 in the skin and HF development and their postnatal physiological regeneration was investigated. miR-214 exhibits discrete expression patterns in the epidermis and HF in developing and postnatal skin, and is highly expressed in the epithelial stem cells and their lineage-committed progenies. The effects of miR-214 on HF morphogenesis and cycle progression were evaluated by using doxycyclineinducible miR-214 transgenic mice (K14-rtTA/TRE-miR-214). Keratinocyte specific miR-214 overexpression during skin embryogenesis resulted in the partial inhibition of HF induction and formation of the HF reduced in size producing thinner hair. Overexpression of miR-214 in telogen skin caused retardation of the anagen progression and HF growth. Inhibitory effects of miR- 214 on HF development and cycling were associated with supressed activity of stem cells, reduced proliferation in the hair matrix, and altered differentiation. miR-214 induced complex changes in gene expression programs in keratinocytes, including inhibition of cyclins and cyclin-dependent kinases and several essential components of Wnt, Edar, Shh and Bmp signalling pathways, whereas β-catenin acts as a novel conserved miR-214 target. Indeed, the inhibitory effects of miR-214 on HF development were rescued by intracutaneous delivery of pharmacological Wnt activator. Thus, this study demonstrated that by targeting β-catenin and, therefore, interfering with Wnt signalling activity miR-214 may act as one of the upstream effectors of the signalling cascades which govern HF morphogenesis and cycling.

京都大学 / 0048 / 新制・課程博士 / 博士(医科学) / 甲第21695号 / 医科博第99号 / 新制||医科||7(附属図書館) / 京都大学大学院医学研究科医科学専攻 / (主査)教授 生田 宏一, 教授 Shohab YOUSSEFIAN, 教授 齊藤 博英 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

miRNAs are important post-transcriptional regulators of gene expression which play vital roles in the arrays of physiological processes, including skin and hair follicle (HF) development. In this study, the role for miR-214 in the skin and HF development and their postnatal physiological regeneration was investigated. miR-214 exhibits discrete expression patterns in the epidermis and HF in developing and postnatal skin, and is highly expressed in the epithelial stem cells and their lineage-committed progenies. The effects of miR-214 on HF morphogenesis and cycle progression were evaluated by using doxycyclineinducible miR-214 transgenic mice (K14-rtTA/TRE-miR-214). Keratinocyte specific miR-214 overexpression during skin embryogenesis resulted in the partial inhibition of HF induction and formation of the HF reduced in size producing thinner hair. Overexpression of miR-214 in telogen skin caused retardation of the anagen progression and HF growth. Inhibitory effects of miR- 214 on HF development and cycling were associated with supressed activity of stem cells, reduced proliferation in the hair matrix, and altered differentiation. miR-214 induced complex changes in gene expression programs in keratinocytes, including inhibition of cyclins and cyclin-dependent kinases and several essential components of Wnt, Edar, Shh and Bmp signalling pathways, whereas 􀁅-catenin acts as a novel conserved miR-214 target. Indeed, the inhibitory effects of miR-214 on HF development were rescued by intracutaneous delivery of pharmacological Wnt activator. Thus, this study demonstrated that by targeting 􀁅-catenin and, therefore, interfering with Wnt signalling activity miR-214 may act as one of the upstream effectors of the signalling cascades which govern HF morphogenesis and cycling.

In addition to the well-characterized Induced Pluripotent Stem cells (iPSCs) that closely resemble Embryonic Stem cells (ESCs), a recent study has proven the existence of a stable state, resembling partially reprogrammed cells, termed F-class iPSCs. To study these distinct iPSC states, a reprogramming dataset has been generated, featuring the parallel analysis of multiple molecular platforms. MicroRNAs (miRNAs) are small RNA regulators of gene expression whose critical role in reprogramming is now being realized. In the present study, small RNA deep sequencing data from this novel reprogramming dataset was used to identify miRNAs that are likely to enhance reprogramming by detecting significantly up-regulated miRNAs in ESC-like iPSCs versus F-class iPSCs. These candidate miRNAs were cloned and overexpressed in reprogramming mouse embryonic fibroblasts and their effect on reprogramming efficiency was measured. miR-214 was discovered to increase iPSC generation efficiency, marking the first reprogramming-related role for this microRNA.

In addition to the well-characterized Induced Pluripotent Stem cells (iPSCs) that closely resemble Embryonic Stem cells (ESCs), a recent study has proven the existence of a stable state, resembling partially reprogrammed cells, termed F-class iPSCs. To study these distinct iPSC states, a reprogramming dataset has been generated, featuring the parallel analysis of multiple molecular platforms. MicroRNAs (miRNAs) are small RNA regulators of gene expression whose critical role in reprogramming is now being realized. In the present study, small RNA deep sequencing data from this novel reprogramming dataset was used to identify miRNAs that are likely to enhance reprogramming by detecting significantly up-regulated miRNAs in ESC-like iPSCs versus F-class iPSCs. These candidate miRNAs were cloned and overexpressed in reprogramming mouse embryonic fibroblasts and their effect on reprogramming efficiency was measured. miR-214 was discovered to increase iPSC generation efficiency, marking the first reprogramming-related role for this microRNA.