Offprints of the author's articles inserted / Bibliography: leaves [122]-145 / vii, 147 leaves, [22] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1985

No / Chemotherapy has severe side effects in normal rapidly proliferating organs, such as hair follicles, and causes massive apoptosis in hair matrix keratinocytes followed by hair loss. To define the molecular signature of hair follicle response to chemotherapy, human scalp hair follicles cultured ex vivo were treated with doxorubicin (DXR), and global microarray analysis was performed 3 hours after treatment. Microarray data revealed changes in expression of 504 genes in DXR-treated hair follicles versus controls. Among these genes, upregulations of several tumor necrosis factor family of apoptotic receptors (FAS, TRAIL (tumor necrosis factor–related apoptosisinducing ligand) receptors 1/2), as well as of a large number of keratin-associated protein genes, were seen after DXR treatment. Hair follicle apoptosis induced by DXR was significantly inhibited by either TRAIL-neutralizing antibody or caspase-8 inhibitor, thus suggesting a previously unreported role for TRAIL receptor signaling in mediating DXR-induced hair loss. These data demonstrate that the early phase of the hair follicle response to DXR includes upregulation of apoptosis-associated markers, as well as substantial reorganization of the terminal differentiation programs in hair follicle keratinocytes. These data provide an important platform for further studies toward the design of effective approaches for the management of chemotherapy-induced hair loss.

No / Hair follicle development and its postnatal regeneration are characterized by dramatic changes in its microanatomy and cellular activity, which are controlled by multiple signalling pathways, transcription factors and epigenetic regulators, including microRNAs (miRNAs). miRNAs and their targets form remarkably diverse regulatory networks, playing a key role in the execution of gene expression programmes in the different cell lineages of the hair follicle. This review summarizes the roles of miRNAs in the control of hair follicle development, cycling and hair pigmentation, emphasizes the remaining problems/unanswered questions, and provides future directions in this rapidly growing and exciting area of research / MRC

Bibliography: leaves 87-113. / xi, 113, [72] leaves, [42] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Presents results from an investigation into the regulation of hair-specific gene expression, including attempts to produce an immortalised hair follicle cortical cell line for this purpose and the use of mouse transgenesis and invitro gel mobility shift assays. / Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1995

Lack of hair due to alopecia or skin grafting procedures causes significant distress due to hair's role in social and sexual communication. Only limited pharmacological agents are currently available to stimulate hair growth; their development is hampered by inappropriate model systems. Most research involves large terminal scalp follicles rather than the clinical targets of tiny vellus or intermediate follicles. The overall aim of this thesis was to develop a novel model system based on intermediate hair follicles. Initially, intermediate follicles from female pre-auricular skin were characterised and compared to matched terminal follicles. Intermediate follicles were smaller, less pigmented, shorter and possessed a more 'tubular' bulb morphology than their more 'bulbous' terminal counterparts. Significant correlations were demonstrated between various hair follicle measurements and corresponding dermal papilla diameters. Isolated terminal follicles grew significantly more than intermediate hair follicles in organ culture for 9 days. Testosterone (10nM), the major regulator of human hair growth, increased only intermediate follicle growth; the anti-androgen, cyproterone acetate (1¿M), prevented this stimulation, unlike the 5¿-reductase type 2 inhibitor finasteride (40ng/ml). Immunohistochemistry demonstrated androgen receptor and 5¿-reductase type 2 proteins in both follicle types, while quantitative real-time PCR and gene microarray analysis detected their increased gene expression in intermediate follicles. Thus, smaller intermediate follicles showed major morphological and gene expression differences to terminal follicles in vivo and retained significant, biologically-relevant differences in vitro in organ culture including androgen-responsiveness. Therefore, intermediate hair follicles offer a novel, exciting, more clinically relevant, albeit technically difficult, model for future investigations into hair growth.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xv, 137 p.; also includes graphics. Includes bibliographical references (p. 122-137). Available online via OhioLINK's ETD Center

Over the past decade the concept that the hair follicle plays an important role in cutaneous wound repair has been established. Several elegant lineage tracing studies have demonstrated that hair follicle derived cells contribute to the long term maintenance of the epidermis following repair, while an absence of hair follicles is known to delay repair. The exact mechanisms surrounding hair follicle derived repair are unknown. Moreover, while multiple stem cell niches are present within the hair follicle, their relative importance during wound repair is still unclear. The hair follicle is also a regenerative mini-organ, undergoing regular cycles of growth and regression throughout life, yet surprisingly this has not been previously investigated with respect to wound repair. Data presented in this thesis reveals an unappreciated, yet fundamental link between the independent processes of hair cycle and wound repair, with a substantial acceleration in the rate of repair (~50%) observed in anagen phase. Importantly, the hair follicle appears to play a global role in repair, with differences in the contribution of multiple cell types to wound repair. In addition, this thesis addresses the early kinetics of hair follicle wound response for the first time. Anagen hair follicles are found predisposed to a more rapid and extensive response to injury, suggesting a higher overall percentage of repair derived from the hair follicle in anagen phase. Surprisingly, the bulge stem cell region, while critical for hair cycle appears to play little role in the events immediately following injury, and is not required for initiation of re-epithelialisation. Gene expression profiling reveals numerous genes associated with anagen accelerated repair, and identifies altered modulation of the immune system as a key mechanism. Further, anagen wounds are associated with an upregulation of developmental transcription factors, which may imply a more regenerative healing phenotype. These data reveal numerous targets with the potential to accelerate repair, which now require validation for their therapeutic potential. These targets could be of importance in promoting the repair of chronic wounds, an area of unmet clinical need. More generally, this thesis has established hair cycle as an important experimental variable, which must be controlled for in all future in vivo murine wounding studies.

Yes / Skin development is governed by complex programs of gene activation and silencing, including microRNA-dependent modulation of gene expression. Here, we show that miR-214 regulates skin morphogenesis and hair follicle (HF) cycling by targeting β-catenin, a key component of the Wnt signaling pathway. miR-214 exhibits differential expression patterns in the skin epithelium, and its inducible overexpression in keratinocytes inhibited proliferation, which resulted in formation of fewer HFs with decreased hair bulb size and thinner hair production. The inhibitory effects of miR-214 on HF development and cycling were associated with altered activities of multiple signaling pathways, including decreased expression of key Wnt signaling mediators β-catenin and Lef-1, and were rescued by treatment with pharmacological Wnt activators. Finally, we identify β-catenin as one of the conserved miR-214 targets in keratinocytes. These data provide an important foundation for further analyses of miR-214 as a key regulator of Wnt pathway activity and stem cell functions during normal tissue homeostasis, regeneration, and aging.

No / Bone morphogenetic protein (BMP) signaling is involved in the regulation of a large variety of developmental programs, including those controlling organ sizes. Here, we show that transgenic (TG) mice overexpressing the BMP antagonist noggin (promoter, K5) are characterized by a marked increase in size of anagen hair follicles (HFs) and by the replacement of zig-zag and auchen hairs by awl-like hairs, compared with the age-matched WT controls. Markedly enlarged anagen HFs of TG mice show increased proliferation in the matrix and an increased number of hair cortex and medulla cells compared with WT HFs. Microarray and real-time PCR analyses of the laser-captured hair matrix cells show a strong decrease in expression of Cdk inhibitor p27(Kip1) and increased expression of selected cyclins in TG vs. WT mice. Similar to TG mice, p27(Kip1) knockout mice also show an increased size of anagen HFs associated with increased cell proliferation in the hair bulb. Primary epidermal keratinocytes (KC) from TG mice exhibit significantly increased proliferation and decreased p27(Kip1) expression, compared with WT KC. Alternatively, activation of BMP signaling in HaCaT KC induces growth arrest, stimulates p27(Kip1) expression, and positively regulates p27(Kip1) promoter activity, thus further supporting a role of p27(Kip1) in mediating the effects of BMP signaling on HF size. These data suggest that BMP signaling plays an important role in regulating cell proliferation and controls the size of anagen HFs by modulating the expression of cell-cycle-associated genes in hair matrix KC.

No / Here, we studied how epithelial energy metabolism impacts overall skin development by selectively deleting intraepithelial mtDNA in mice by ablating a key maintenance factor (TfamEKO), which induces loss of function of the electron transport chain (ETC). Quantitative (immuno)histomorphometry demonstrated that TfamEKO mice showed significantly reduced hair follicle (HF) density and morphogenesis, fewer intrafollicular keratin15+ epithelial progenitor cells, increased apoptosis, and reduced proliferation. TfamEKO mice also displayed premature entry into (aborted) HF cycling by apoptosis-driven HF regression (catagen). Ultrastructurally, TfamEKO mice exhibited severe HF dystrophy, pigmentary abnormalities, and telogen-like condensed dermal papillae. Epithelial HF progenitor cell differentiation (Plet1, Lrig1 Lef1, and β-catenin), sebaceous gland development (adipophilin, Scd1, and oil red), and key mediators/markers of epithelial–mesenchymal interactions during skin morphogenesis (NCAM, versican, and alkaline phosphatase) were all severely altered in TfamEKO mice. Moreover, the number of mast cells, major histocompatibility complex class II+, or CD11b+ immunocytes in the skin mesenchyme was increased, and essentially no subcutis developed. Therefore, in contrast to their epidermal counterparts, pilosebaceous unit stem cells depend on a functional ETC. Most importantly, our findings point toward a frontier in skin biology: the coupling of HF keratinocyte mitochondrial function with the epithelial–mesenchymal interactions that drive overall development of the skin and its appendages.