Publications by authors named "Colin A B Jahoda"

48 Publications

Dominant effect of gap junction communication in wound-induced calcium-wave, NFAT activation and wound closure in keratinocytes.

J Cell Physiol 2021 Jun 27. Epub 2021 Jun 27.

Institute of Translational and Clinical Medicine, Medical School, Newcastle University, Newcastle upon Tyne, UK.

Wounding induces a calcium wave and disrupts the calcium gradient across the epidermis but mechanisms mediating calcium and downstream signalling, and longer-term wound healing responses are incompletely understood. As expected, live-cell confocal imaging of Fluo-4-loaded normal human keratinocytes showed an immediate increase in [Ca ] at the wound edge that spread as a calcium wave (8.3 µm/s) away from the wound edge with gradually diminishing rate of rise and amplitude. The amplitude and area under the curve of [Ca ] flux was increased in high (1.2 mM) [Ca ] media. 18α-glycyrrhetinic acid (18αGA), a gap-junction inhibitor or hexokinase, an ATP scavenger, blocked the wound-induced calcium wave, dependent in part on [Ca ] . Wounding in a high [Ca ] increased nuclear factor of activated T-cells (NFAT) but not NFkB activation, assessed by dual-luciferase receptor assays compared to unwounded cells. Treatment with 18αGA or the store-operated channel blocker GSK-7975A inhibited wound-induced NFAT activation, whereas treatment with hexokinase did not. Real-time cell migration analysis, measuring wound closure rates over 24 h, revealed that 18αGA essentially blocked wound closure whereas hexokinase and GSK-7975A showed relatively minimal effects. Together these data indicate that while both gap-junction communication and ATP release from damaged cells are important in regulating the wound-induced calcium wave, long-term transcriptional and functional responses are dominantly regulated by gap-junction communication.
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http://dx.doi.org/10.1002/jcp.30488DOI Listing
June 2021

Hair Follicle Dermal Cells Support Expansion of Murine and Human Embryonic and Induced Pluripotent Stem Cells and Promote Haematopoiesis in Mouse Cultures.

Stem Cells Int 2018 2;2018:8631432. Epub 2018 Aug 2.

Department of Biosciences, Durham University, Durham DH1 3LE, UK.

In the hair follicle, the dermal papilla (DP) and dermal sheath (DS) support and maintain proliferation and differentiation of the epithelial stem cells that produce the hair fibre. In view of their regulatory properties, in this study, we investigated the interaction between hair follicle dermal cells (DP and DS) and embryonic stem cells (ESCs); induced pluripotent stem cells (iPSCs); and haematopoietic stem cells. We found that coculture of follicular dermal cells with ESCs or iPSCs supported their prolonged maintenance in an apparently undifferentiated state as established by differentiation assays, immunocytochemistry, and RT-PCR for markers of undifferentiated ESCs. We further showed that cytokines that are involved in ESC support are also expressed by cultured follicle dermal cells, providing a possible explanation for maintenance of ES cell stemness in cocultures. The same cytokines were expressed within follicles in a pattern more consistent with a role in follicle growth activities than stem cell maintenance. Finally, we show that cultured mouse follicle dermal cells provide good stromal support for haematopoiesis in an established coculture model. Human follicular dermal cells represent an accessible and readily propagated source of feeder cells for pluripotent and haematopoietic cells and have potential for use in clinical applications.
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http://dx.doi.org/10.1155/2018/8631432DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6098861PMC
August 2018

Hierarchical patterning modes orchestrate hair follicle morphogenesis.

PLoS Biol 2017 Jul 11;15(7):e2002117. Epub 2017 Jul 11.

The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom.

Two theories address the origin of repeating patterns, such as hair follicles, limb digits, and intestinal villi, during development. The Turing reaction-diffusion system posits that interacting diffusible signals produced by static cells first define a prepattern that then induces cell rearrangements to produce an anatomical structure. The second theory, that of mesenchymal self-organisation, proposes that mobile cells can form periodic patterns of cell aggregates directly, without reference to any prepattern. Early hair follicle development is characterised by the rapid appearance of periodic arrangements of altered gene expression in the epidermis and prominent clustering of the adjacent dermal mesenchymal cells. We assess the contributions and interplay between reaction-diffusion and mesenchymal self-organisation processes in hair follicle patterning, identifying a network of fibroblast growth factor (FGF), wingless-related integration site (WNT), and bone morphogenetic protein (BMP) signalling interactions capable of spontaneously producing a periodic pattern. Using time-lapse imaging, we find that mesenchymal cell condensation at hair follicles is locally directed by an epidermal prepattern. However, imposing this prepattern's condition of high FGF and low BMP activity across the entire skin reveals a latent dermal capacity to undergo spatially patterned self-organisation in the absence of epithelial direction. This mesenchymal self-organisation relies on restricted transforming growth factor (TGF) β signalling, which serves to drive chemotactic mesenchymal patterning when reaction-diffusion patterning is suppressed, but, in normal conditions, facilitates cell movement to locally prepatterned sources of FGF. This work illustrates a hierarchy of periodic patterning modes operating in organogenesis.
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http://dx.doi.org/10.1371/journal.pbio.2002117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5507405PMC
July 2017

What Lies Beneath: Wnt/β-Catenin Signaling and Cell Fate in the Lower Dermis.

J Invest Dermatol 2016 06;136(6):1084-1087

School of Biological and Biomedical Sciences, Durham University, Durham, UK.

Dermal cell populations are markedly heterogeneous, and they have the capacity to differentiate into dynamic and complex dermal cell compartments. However, the regulatory processes that govern the establishment of each dermal subset remain unknown. Mastrogiannaki et al. provide evidence of Wnt/β-catenin signaling controlling adipogenic differentiation in the developing reticular dermis. They also show that overexpression of localized Wnt converts dermal adipose cells into a distinct fibroblast subtype, which leads to fibrosis and disrupted hair follicle cycling. These findings highlight the multifaceted roles of Wnt signaling in the normal development and pathology of skin, including the establishment of dermal identity. Further understanding of Wnt involvement and uncovering the roles of specific Wnt ligands could be useful for discovering new therapeutic targets in treating fibrosis-related disorders.
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http://dx.doi.org/10.1016/j.jid.2016.03.029DOI Listing
June 2016

Dermal white adipose tissue: a new component of the thermogenic response.

J Lipid Res 2015 Nov 24;56(11):2061-9. Epub 2015 Sep 24.

Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI.

Recent literature suggests that the layer of adipocytes embedded in the skin below the dermis is far from being an inert spacer material. Instead, this layer of dermal white adipose tissue (dWAT) is a regulated lipid layer that comprises a crucial environmental defense. Among all the classes of biological molecules, lipids have the lowest thermal conductance and highest insulation potential. This property can be exploited by mammals to reduce heat loss, suppress brown adipose tissue activation, reduce the activation of thermogenic programs, and increase metabolic efficiency. Furthermore, this layer responds to bacterial challenge to provide a physical barrier and antimicrobial disinfection, and its expansion supports the growth of hair follicles and regenerating skin. In sum, this dWAT layer is a key defensive player with remarkable potential for modifying systemic metabolism, immune function, and physiology. In this review, we discuss the key literature illustrating the properties of this recently recognized adipose depot.
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http://dx.doi.org/10.1194/jlr.R062893DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4617393PMC
November 2015

Giant Panda (Ailuropoda melanoleuca) Buccal Mucosa Tissue as a Source of Multipotent Progenitor Cells.

PLoS One 2015 23;10(9):e0138840. Epub 2015 Sep 23.

Durham University, School of Biological and Biomedical Sciences, Durham, DH1 3LE, United Kingdom.

Since the first mammal was cloned, the idea of using this technique to help endangered species has aroused considerable interest. However, several issues limit this possibility, including the relatively low success rate at every stage of the cloning process, and the dearth of usable tissues from these rare animals. iPS cells have been produced from cells from a number of rare mammalian species and this is the method of choice for strategies to improve cloning efficiency and create new gametes by directed differentiation. Nevertheless information about other stem cell/progenitor capabilities of cells from endangered species could prove important for future conservation approaches and adds to the knowledge base about cellular material that can be extremely limited. Multipotent progenitor cells, termed skin-derived precursor (SKP) cells, can be isolated directly from mammalian skin dermis, and human cheek tissue has also been shown to be a good source of SKP-like cells. Recently we showed that structures identical to SKPs termed m-SKPs could be obtained from monolayer/ two dimensional (2D) skin fibroblast cultures. Here we aimed to isolate m-SKPs from cultured cells of three endangered species; giant panda (Ailuropoda melanoleuca); red panda (Ailurus fulgens); and Asiatic lion (Panthera leo persica). m-SKP-like spheres were formed from the giant panda buccal mucosa fibroblasts; whereas dermal fibroblast (DF) cells cultured from abdominal skin of the other two species were unable to generate spheres. Under specific differentiation culture conditions giant panda spheres expressed neural, Schwann, adipogenic and osteogenic cell markers. Furthermore, these buccal mucosa derived spheres were shown to maintain expression of SKP markers: nestin, versican, fibronectin, and P75 and switch on expression of the stem cell marker ABCG2. These results demonstrate that giant panda cheek skin can be a useful source of m-SKP multipotent progenitors. At present lack of sample numbers means that we can only postulate why we were unable to obtain m-SKPs from the lion and red panda cultures. However the giant panda observations point to the value of archiving cells from rare species, and the possibilities for later progenitor cell derivation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0138840PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4580591PMC
May 2016

Defining dermal adipose tissue.

Exp Dermatol 2014 Sep;23(9):629-31

Centre for Stem Cells and Regenerative Medicine, King's College London, Great Maze Pond, London, UK.

Here, we explore the evolution and development of skin-associated adipose tissue with the goal of establishing nomenclature for this tissue. Underlying the reticular dermis, a thick layer of adipocytes exists that encases mature hair follicles in rodents and humans. The association of lipid-filled cells with the skin is found in many invertebrate and vertebrate species. Historically, this layer of adipocytes has been termed subcutaneous adipose, hypodermis and subcutis. Recent data have revealed a common precursor for dermal fibroblasts and intradermal adipocytes during development. Furthermore, the development of adipocytes in the skin is independent from that of subcutaneous adipose tissue development. Finally, the role of adipocytes has been shown to be relevant for epidermal homoeostasis during hair follicle regeneration and wound healing. Thus, we propose a refined nomenclature for the cells and adipose tissue underlying the reticular dermis as intradermal adipocytes and dermal white adipose tissue, respectively.
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http://dx.doi.org/10.1111/exd.12450DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4282701PMC
September 2014

Microenvironmental reprogramming by three-dimensional culture enables dermal papilla cells to induce de novo human hair-follicle growth.

Proc Natl Acad Sci U S A 2013 Dec 21;110(49):19679-88. Epub 2013 Oct 21.

Departments of Dermatology, Genetics and Development, and Systems Biology, Columbia University, New York, NY 10032.

De novo organ regeneration has been observed in several lower organisms, as well as rodents; however, demonstrating these regenerative properties in human cells and tissues has been challenging. In the hair follicle, rodent hair follicle-derived dermal cells can interact with local epithelia and induce de novo hair follicles in a variety of hairless recipient skin sites. However, multiple attempts to recapitulate this process in humans using human dermal papilla cells in human skin have failed, suggesting that human dermal papilla cells lose key inductive properties upon culture. Here, we performed global gene expression analysis of human dermal papilla cells in culture and discovered very rapid and profound molecular signature changes linking their transition from a 3D to a 2D environment with early loss of their hair-inducing capacity. We demonstrate that the intact dermal papilla transcriptional signature can be partially restored by growth of papilla cells in 3D spheroid cultures. This signature change translates to a partial restoration of inductive capability, and we show that human dermal papilla cells, when grown as spheroids, are capable of inducing de novo hair follicles in human skin.
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http://dx.doi.org/10.1073/pnas.1309970110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856847PMC
December 2013

Development of the mouse dermal adipose layer occurs independently of subcutaneous adipose tissue and is marked by restricted early expression of FABP4.

PLoS One 2013 26;8(3):e59811. Epub 2013 Mar 26.

School of Biological and Biomedical Sciences, Durham University, Durham, County Durham, United Kingdom.

The laboratory mouse is a key animal model for studies of adipose biology, metabolism and disease, yet the developmental changes that occur in tissues and cells that become the adipose layer in mouse skin have received little attention. Moreover, the terminology around this adipose body is often confusing, as frequently no distinction is made between adipose tissue within the skin, and so called subcutaneous fat. Here adipocyte development in mouse dorsal skin was investigated from before birth to the end of the first hair follicle growth cycle. Using Oil Red O staining, immunohistochemistry, quantitative RT-PCR and TUNEL staining we confirmed previous observations of a close spatio-temporal link between hair follicle development and the process of adipogenesis. However, unlike previous studies, we observed that the skin adipose layer was created from cells within the lower dermis. By day 16 of embryonic development (e16) the lower dermis was demarcated from the upper dermal layer, and commitment to adipogenesis in the lower dermis was signalled by expression of FABP4, a marker of adipocyte differentiation. In mature mice the skin adipose layer is separated from underlying subcutaneous adipose tissue by the panniculus carnosus. We observed that the skin adipose tissue did not combine or intermix with subcutaneous adipose tissue at any developmental time point. By transplanting skin isolated from e14.5 mice (prior to the start of adipogenesis), under the kidney capsule of adult mice, we showed that skin adipose tissue develops independently and without influence from subcutaneous depots. This study has reinforced the developmental link between hair follicles and skin adipocyte biology. We argue that because skin adipocytes develop from cells within the dermis and independently from subcutaneous adipose tissue, that it is accurately termed dermal adipose tissue and that, in laboratory mice at least, it represents a separate adipose depot.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0059811PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3608551PMC
January 2014

Isolation and establishment of hair follicle dermal papilla cell cultures.

Methods Mol Biol 2013 ;989:285-92

School of Biological and Biomedical Sciences, Durham University, Durham, UK.

The isolation of hair follicle dermal papilla cells has become an important technique in the field of cutaneous stem cell biology. These cells can be used for a number of biological and translational purposes. They are studied to identify the cellular characteristics and molecular factors that underpin the initiation, maintenance, and modulation of hair growth; to develop new human hair replacement techniques; and as a source of cells capable of being directed down a variety of different lineages. Here, we describe the isolation of hair follicle dermal papilla cells from both human and murine sources via the microdissection techniques used in our lab.
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http://dx.doi.org/10.1007/978-1-62703-330-5_22DOI Listing
September 2013

Generation and characterization of multipotent stem cells from established dermal cultures.

PLoS One 2012 30;7(11):e50742. Epub 2012 Nov 30.

School of Biological and Biomedical Sciences, Durham University, Durham, County Durham, United Kingdom.

Human multipotent skin derived precursor cells (SKPs) are traditionally sourced from dissociated dermal tissues; therefore, donor availability may become limiting. Here we demonstrate that both normal and diseased adult human dermal fibroblasts (DF) pre-cultured in conventional monolayers are capable of forming SKPs (termed m-SKPs). Moreover, we show that these m-SKPs can be passaged and that cryopreservation of original fibroblast monolayer cultures does not reduce m-SKP yield; however, extensive monolayer passaging does. Like SKPs generated from dissociated dermis, these m-SKPs expressed nestin, fibronectin and versican at the protein level. At the transcriptional level, m-SKPs derived from normal adult human DF, expressed neural crest stem cell markers such as p75NTR, embryonic stem cell markers such as Nanog and the mesenchymal stem cell marker Dermo-1. Furthermore, appropriate stimuli induced m-SKPs to differentiate down either mesenchymal or neural lineages resulting in lipid accumulation, calcification and S100β or β-III tubulin expression (with multiple processes). m-SKP yield was greater from neonatal foreskin cultures compared to those from adult DF cultures; however, the former showed a greater decrease in m-SKP forming capacity after extensive monolayer passaging. m-SKP yield was greater from adult DF cultures expressing more alpha-smooth muscle actin (αSMA). In turn, elevated αSMA expression correlated with cells originating from specimens isolated from biopsies containing more terminal hair follicles; however, αSMA expression was lost upon m-SKP formation. Others have shown that dissociated human hair follicle dermal papilla (DP) are a highly enriched source of SKPs. However, conversely and unexpectedly, monolayer cultured human hair follicle DP cells failed to form m-SKPs whereas those from the murine vibrissae follicles did. Collectively, these findings reveal the potential for using expanded DF cultures to produce SKPs, the heterogeneity of SKP forming potential of skin from distinct anatomical locations and ages, and question the progenitor status of human hair follicle DP cells.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0050742PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3511366PMC
May 2013

Human hair follicle dermal cells and skin fibroblasts show differential activation of NF-κB in response to pro-inflammatory challenge.

Exp Dermatol 2012 Feb 6;21(2):158-60. Epub 2011 Dec 6.

The underlying mechanism of immune privilege in hair follicle cell dermal papilla (DP) and sheath (DS) populations is not well understood, and the responsiveness of hair follicle dermal cells to pro-inflammatory challenge presently remains unknown. In this work, we describe acute NF-κB activation in human DS, DP and dermal fibroblast (DF) cells challenged with TNF-alpha and IL1-beta. In contrast, the DS and DP cells revealed an unexpected tolerance to bacterial LPS challenge relative to DF cells. Understanding follicle cell responses to typical pro-inflammatory stimuli is critical for diseases where collapse of hair follicle immune privilege is observed, and to further applications in autologous stem cell/wound healing therapeutics.
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http://dx.doi.org/10.1111/j.1600-0625.2011.01401.xDOI Listing
February 2012

Niche crosstalk: intercellular signals at the hair follicle.

Cell 2011 Sep;146(5):678-81

School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK.

A recent series of papers, including Festa et al. (2011) in this issue, has revealed unexpected interdependent relationships among cell populations residing in and around the hair follicle. These interactions between different lineages of stem cells are crucial for hair follicle growth and cycling and point to a complex crosstalk in stem cell niches.
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http://dx.doi.org/10.1016/j.cell.2011.08.020DOI Listing
September 2011

Modulation in proteolytic activity is identified as a hallmark of exogen by transcriptional profiling of hair follicles.

J Invest Dermatol 2011 Dec 11;131(12):2349-57. Epub 2011 Aug 11.

School of Biological and Biomedical Sciences, Durham University, Durham, UK.

Exogen is the process by which the hair follicle actively sheds its club fiber from the follicle. However, little is known about signals that govern the cellular mechanisms of shedding. Here, we have identified factors that are important in regulating either the retention or release of the hair club fiber from its epithelial silo within the follicle. Using the vibrissa follicle as our model, we isolated follicle segments containing club fibers and surrounding follicle tissue at different time points before their natural release from the hair follicle. We then performed microarray analysis to identify key molecular changes as the club fiber approached final release. Among the different classes of genes that were identified, we found changes in the expression pattern of protease inhibitors and proteases, suggesting that proteolysis may mediate fiber release, either through terminal differentiation or proteolytic cleavage. We validated transcriptional changes using reverse transcription-PCR, and further immunofluorescence analysis indicated that protease inhibitors surrounding the club fiber may have an important role in regulating the process of club fiber shedding. Our findings also highlighted that molecular differentiation of the innermost layer of cells immediately surrounding the club fiber, the companion(CL), is likely to be important in hair shedding.
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http://dx.doi.org/10.1038/jid.2011.227DOI Listing
December 2011

Genome-wide association study in alopecia areata implicates both innate and adaptive immunity.

Nature 2010 Jul;466(7302):113-7

Department of Dermatology, Columbia University, New York, New York 10032, USA.

Alopecia areata (AA) is among the most highly prevalent human autoimmune diseases, leading to disfiguring hair loss due to the collapse of immune privilege of the hair follicle and subsequent autoimmune attack. The genetic basis of AA is largely unknown. We undertook a genome-wide association study (GWAS) in a sample of 1,054 cases and 3,278 controls and identified 139 single nucleotide polymorphisms that are significantly associated with AA (P
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http://dx.doi.org/10.1038/nature09114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2921172PMC
July 2010

Modelling the hair follicle dermal papilla using spheroid cell cultures.

Exp Dermatol 2010 Jun 20;19(6):546-8. Epub 2010 Apr 20.

Human dermal papilla (DP) cells grown in two-dimensional (2D) culture have been studied extensively. However, key differences exist between DP cell activities in vivo and in vitro. Using a suspension method of cell culture to maintain DP cells, we created three-dimensional (3D) dermal spheres morphologically akin to intact (anagen) DPs. Analysis of these spheres using immunocytochemistry demonstrates that they have expression profiles different from papilla cells cultured in 2D but with many similarities to intact DPs. This method of DP cell culture may provide us with a tool to elucidate our understanding of signalling within the DP as it relates to induction, maintenance or even inhibition of hair growth.
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http://dx.doi.org/10.1111/j.1600-0625.2009.01007.xDOI Listing
June 2010

Effects of physiological electric fields on migration of human dermal fibroblasts.

J Invest Dermatol 2010 Sep 22;130(9):2320-7. Epub 2010 Apr 22.

School of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, UK.

Endogenous electric currents generated instantly at skin wounds direct migration of epithelial cells and are likely to be important in wound healing. Migration of fibroblasts is critical in wound healing. It remains unclear how wound electric fields guide migration of dermal fibroblasts. We report here that mouse skin wounds generated endogenous electric currents for many hours. Human dermal fibroblasts of both primary and cell-line cultures migrated directionally but slowly toward the anode in an electric field of 50-100 mV mm(-1). This is different from keratinocytes, which migrate quickly to the cathode. It took more than 1 hour for dermal fibroblasts to manifest detectable directional migration. Larger field strength (400 mV mm(-1)) was required to induce directional migration within 1 hour after onset of the field. Phosphatidylinositol-3-OH kinase (PI3 kinase) mediates cathode-directed migration of keratinocytes. We tested the role of PI3 kinase in anode-directed migration of fibroblasts. An applied electric field activated PI3 kinase/Akt in dermal fibroblasts. Dermal fibroblasts from p110gamma (a PI3 kinase catalytic subunit) null mice showed significantly decreased directional migration. These results suggest that physiological electric fields may regulate motility of dermal fibroblasts and keratinocytes differently, albeit using similar PI3 kinase-dependent mechanisms.
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http://dx.doi.org/10.1038/jid.2010.96DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2952177PMC
September 2010

Exogen involves gradual release of the hair club fibre in the vibrissa follicle model.

Exp Dermatol 2009 Sep;18(9):793-5

Exogen is a distinct phase of the hair cycle describing the process by which the hair club fibre is shed from the follicle. This process is difficult to study in human skin and little is known about the mechanisms involved in the release of club fibres. We sought an alternative model system to study exogen in more detail, and therefore utilised the vibrissa system on the rodent mystacial pad. The time at which a vibrissa club hair will be lost can be predicted, based on the relative lengths of the new growing fibre and old club fibre. This timing phenomenon was exploited to investigate the club fibre within the follicle as it approaches final release, revealing key changes in the adhesive state of the club fibre within the epithelial sac as it approached release. We propose that exogen should be subdivided to represent variations in the club fibre status.
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http://dx.doi.org/10.1111/j.1600-0625.2008.00833.xDOI Listing
September 2009

An improved method of human keratinocyte culture from skin explants: cell expansion is linked to markers of activated progenitor cells.

Exp Dermatol 2009 Aug 23;18(8):720-6. Epub 2009 Jun 23.

Department of Biological Sciences, University of Durham, Durham, DH1 3LE, UK.

Human keratinocyte primary cultures are commonly established by tissue dissociation and often rely on feeder cell supports and culture medium that is not defined. Further, contamination by unwanted fibroblasts can be problematic. Here, we developed a skin explant method for growing primary keratinocytes that was rapid, simple, and reliably generated keratinocyte cultures free of fibroblast contamination. The process capitalized on the observation that fibroblasts migrate out of adult skin explants later than epidermal cells, allowing the early harvesting of keratinocytes by trypsinization. When grown subsequently in defined medium in the absence of feeder cells, the explant-derived cells grew rapidly and could be cultured for multiple passages. Immunofluorescence microscopy revealed that a high percentage of cells harvested from the explant outgrowths expressed K15, while very few expressed the differentiation marker K10. Cells that were stained while migrating out from explants strongly expressed markers associated with progenitor cells, including p63, K15 and CD133, and displayed intense K6 expression, indicative of activated keratinocytes in wound-healing epidermis. By replenishing the explants with fresh medium after harvesting, further epidermal outgrowths could be obtained, offering the possibility of greatly increased keratinocyte yields for clinical applications.
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http://dx.doi.org/10.1111/j.1600-0625.2009.00900.xDOI Listing
August 2009

KGF and EGF signalling block hair follicle induction and promote interfollicular epidermal fate in developing mouse skin.

Development 2009 Jul 27;136(13):2153-64. Epub 2009 May 27.

School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, UK.

A key initial event in hair follicle morphogenesis is the localised thickening of the skin epithelium to form a placode, partitioning future hair follicle epithelium from interfollicular epidermis. Although many developmental signalling pathways are implicated in follicle morphogenesis, the role of epidermal growth factor (EGF) and keratinocyte growth factor (KGF, also known as FGF7) receptors are not defined. EGF receptor (EGFR) ligands have previously been shown to inhibit developing hair follicles; however, the underlying mechanisms have not been characterised. Here we show that receptors for EGF and KGF undergo marked downregulation in hair follicle placodes from multiple body sites, whereas the expression of endogenous ligands persist throughout hair follicle initiation. Using embryonic skin organ culture, we show that when skin from the sites of primary pelage and whisker follicle development is exposed to increased levels of two ectopic EGFR ligands (HBEGF and amphiregulin) and the FGFR2(IIIb) receptor ligand KGF, follicle formation is inhibited in a time- and dose-dependent manner. We then used downstream molecular markers and microarray profiling to provide evidence that, in response to KGF and EGF signalling, epidermal differentiation is promoted at the expense of hair follicle fate. We propose that hair follicle initiation in placodes requires downregulation of the two pathways in question, both of which are crucial for the ongoing development of the interfollicular epidermis. We have also uncovered a previously unrecognised role for KGF signalling in the formation of hair follicles in the mouse.
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http://dx.doi.org/10.1242/dev.031427DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2729337PMC
July 2009

Dynamic expression of Syndecan-1 during hair follicle morphogenesis.

Gene Expr Patterns 2009 Sep 7;9(6):454-60. Epub 2009 May 7.

School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK.

Syndecan-1 is a cell-surface heparan-sulphate proteoglycan that is involved in growth factor regulation, cell adhesion, proliferation, differentiation, blood coagulation, lipid metabolism, as well as tumour formation. In this study, investigation of discrete LCM captured dermal cells by semi-quantitative RT-PCR revealed Syndecan-1 mRNA transcripts were expressed only in the dermal condensation (DC) within this skin compartment during murine pelage hair follicle (HF) morphogenesis. Further immunofluorescence studies showed that, during early skin development, Syndecan-1 was expressed in the epidermis while being absent from the mesenchyme. As HF morphogenesis began ( approximately E14.5) Syndecan-1 expression was lost from the epithelial compartment of the HF and activated in HF mesenchymal cells. This Syndecan-1 expression profile was consistent between different hair follicle types including primary and secondary pelage, vibrissa, and tail hair follicles. Furthermore we show by using gene targeted mice lacking Syndecan-1 expression that Syndecan-1 is not required for follicle initiation and development.
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http://dx.doi.org/10.1016/j.gep.2009.04.004DOI Listing
September 2009

Keratin 10 (K10) is expressed suprabasally throughout the limbus of embryonic and neonatal rat corneas, with interrupted expression in the adult limbus.

Exp Eye Res 2009 Sep 1;89(3):435-8. Epub 2009 Apr 1.

The corneal epithelium is continuously replaced by epithelial stem cells located in the basal layer of the limbus, located at the margin of the cornea. Studying how the stem cell niche is established at the limbus during development of the eye may lead to better understanding and treatments for diseases associated with limbal deficiencies. Using two highly specific commercially available antibodies, K10 was consistently detected suprabasally throughout the developing limbal epithelium of late gestation (20.5 dpc) and neonatal rat corneas, with interrupted expression in adult rat limbal epithelium. RT-PCR confirmed K10 expression at the transcript level in embryonic, neonatal and adult rat eyes. We have identified a time point where early stages of limbal development may be facilitated by the suprabasal expression of K10.
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http://dx.doi.org/10.1016/j.exer.2009.03.018DOI Listing
September 2009

From telogen to exogen: mechanisms underlying formation and subsequent loss of the hair club fiber.

J Invest Dermatol 2009 Sep 2;129(9):2100-8. Epub 2009 Apr 2.

School of Biological and Biomedical Sciences, Durham University, Durham, UK.

The hair follicle has the unique capacity to undergo periods of growth, regression, and rest before regenerating itself to restart the cycle. This dynamic cycling capacity enables mammals to change their coats, and for hair length to be controlled on different body sites. More recently, the process of club fiber shedding has been described as a distinct cycle phase known as exogen, and proposed to be an active phase of the hair cycle. This review focuses on the importance of the shedding phase of the hair cycle and, in the context of current literature, analyzes the processes of club fiber formation, retention, and release, which may influence progression through exogen, particularly in relation to human hair.
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http://dx.doi.org/10.1038/jid.2009.66DOI Listing
September 2009

Id2, Id3, and Id4 proteins show dynamic changes in expression during vibrissae follicle development.

Dev Dyn 2008 Jun;237(6):1653-61

School of Biological and Biomedical Sciences, University of Durham, South Road, Durham, United Kingdom.

Id proteins are involved in the transcriptional control of many fundamental biological processes, including differentiation and lineage commitment. We studied Id2, Id3, and Id4 protein expression during different stages of rat vibrissa follicle development using immunohistochemistry. Id2 was highly expressed in the cytoplasm of specialized cells in the basal epidermis and outer root sheath during early stages of follicle development. These cells were identified as Merkel cells (MCs) by means of double-immunolabeling with synaptophysin and cytokeratin-20, and persisted in neonatal follicles. Id3 immunofluorescence was characterized by membrane-associated expression in basal epithelial cells of follicles early in development. Subsequently follicle epithelial cells switched to have strong nuclear labeling, also a feature of newly forming dermal papilla cells. Id4 expression was primarily associated with innervation of the developing follicle musculature. These observations illustrate dynamic expression patterns of Id2 and Id3 proteins in developing follicles and specifically link Id2 expression to Merkel cell specification.
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http://dx.doi.org/10.1002/dvdy.21574DOI Listing
June 2008

C/EBPalpha identifies differentiating preadipocytes around hair follicles in foetal and neonatal rat and mouse skin.

Exp Dermatol 2008 Aug 4;17(8):675-80. Epub 2008 Mar 4.

School of Biological and Biomedical Sciences, University of Durham, Durham, UK.

Previous studies have described a close anatomical association between hair follicles and subcutaneous adipocytes, yet little is known about the developmental origin of this preadipocyte population. Many transcription factors controlling adipogenesis in cell culture have been described; however, the molecular events governing the process of adipogenesis in rodent skin in vivo are largely unknown. In this study, we investigated the onset and progression of adipocyte differentiation in the skin of foetal and newborn rats and mice. We first analysed the temporo-spatial expression pattern of the transcription factor C/EBPalpha, a key player in adipocyte differentiation. Oil red O staining was then used to identify the presence of lipid within mature adipocytes in the same skin samples. In both species, nuclear staining of C/EBPalpha was first seen in cells around and below the bases of fully formed hair follicles in foetal dermis between 2 and 3 days before birth. Over time, increasing numbers of cells became labelled with C/EBPalpha, predominantly located between, rather than below, the hair follicles. Oil red O staining followed exactly the same pattern seen with the C/EBPalpha antibody, but with a delay of 12-24 h, and histomorphometry showed that the C/EBPalpha labelled cells matured into lipid filled adipocytes. These data show that C/EBPalpha is a useful developmental marker of preadipocytes in vivo. The close developmental association and physical proximity between the lower follicle and surrounding preadipocytes leads us to postulate that follicles control local adipogenic events, via signalling or by contributing to the preadipocyte pool.
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http://dx.doi.org/10.1111/j.1600-0625.2007.00689.xDOI Listing
August 2008

Dynamic expression of the zinc-finger transcription factor Trps1 during hair follicle morphogenesis and cycling.

Gene Expr Patterns 2008 Jan 25;8(2):51-7. Epub 2007 Oct 25.

Department of Genetics and Development, Columbia University, New York, NY, USA.

Mutations in the gene encoding the zinc finger transcription factor TRPS1 result in tricho-rhino-phalangeal syndrome, characterized by craniofacial and skeletal abnormalities, and sparse scalp hair. In this study, Trps1 was identified by microarray hybridization analysis as having a complex pattern of spatiotemporal regulation in murine skin during morphogenesis. During early skin development, Trps1 expression decreased in the epidermis while simultaneously increasing in the dermis. Trps1 was specifically expressed in the nuclei of mesenchymal cells during hair follicle morphogenesis. An analysis of Trps1 expression during postnatal murine hair follicle cycling revealed that the protein localized to the nuclei of dermal papillae cells during telogen and anagen. Additionally, we found that Trps1 consistently localized to the nuclei of dermal papillae cells and the highly proliferative epithelial cells of mouse, rat and human hair follicles.
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http://dx.doi.org/10.1016/j.modgep.2007.10.006DOI Listing
January 2008

Hair follicle stem cells.

Semin Cell Dev Biol 2007 Apr 13;18(2):245-54. Epub 2007 Feb 13.

Department of Biological Sciences, University of Durham, Durham, UK.

The increasing use of the hair follicle as a stem cell paradigm is due in part to the complex interplay between epithelial, dermal and other cell types, each with interesting differentiation potential and prospective therapeutic applications. This review focuses on research into the environmental niche, gene expression profiles and plasticity of hair follicle stem cell populations, where many recent advances have come about through novel technological and experimental approaches. We discuss major developmental pathways involved in the establishment and control of the epithelial stem cell niche, and evidence of plasticity between stem and transit amplifying cell populations.
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http://dx.doi.org/10.1016/j.semcdb.2007.02.003DOI Listing
April 2007

The Wnt inhibitor, Dickkopf 4, is induced by canonical Wnt signaling during ectodermal appendage morphogenesis.

Dev Biol 2007 May 2;305(2):498-507. Epub 2007 Mar 2.

Department of Genetics and Development, Columbia University, New York, NY, USA.

Ectodermal appendage morphogenesis requires continuous epithelial-mesenchymal cross-talk during development. Canonical Wnt signaling has been shown to be pivotal during this process and its inhibition leads to the absence of any morphological or molecular signs of appendage formation, including hair follicles (HFs). In the mouse, primary HFs arise in utero starting just before E14.5, when the first morphological signs of a placode are discernible. In this study, our goal was to identify novel factors expressed during primary HF morphogenesis. We performed transcriptional profiling of the developing epidermis at 12 h intervals between E12.5 and E15.5. One of the significantly differentially expressed genes was the Wnt inhibitor Dickkopf 4, Dkk4. We show that Dkk4 mRNA increases sharply in the dorso-lateral epidermis around E14 and then decreases until E15.5. Using whole mount in situ hybridization, we show that Dkk4 mRNA is localized to the pre-placodes at sites of presumptive epithelial-mesenchymal interactions during appendage morphogenesis, including the dental lamina, mammary gland, eccrine gland, and primary and secondary HFs. In silico analysis, reporter gene assays as well as in vitro transfections of LEF1 and beta-catenin show that Dkk4 is a potential downstream target of canonical Wnt signaling. In addition, we demonstrate a direct physical interaction between LEF1/beta-catenin complex and the Dkk4 promoter using ChIP. We propose that Dkk4 acts in a negative feedback loop to attenuate canonical Wnt signaling, and may facilitate a switch to the non-canonical Wnt planar cell polarity (PCP) pathway that is involved in cell movements during morphogenesis.
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http://dx.doi.org/10.1016/j.ydbio.2007.02.035DOI Listing
May 2007
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