Project description:Wound healing is essential to repair the skin after injury. In the epidermis, distinct stem cells (SCs) populations contribute to wound healing. However, how SCs balance proliferation, differentiation and migration to repair a wound remains poorly understood. Here we show the cellular and molecular mechanisms that regulate wound healing in mouse tail epidermis. Using a combination of proliferation kinetics experiments and molecular profiling, we identify the gene signatures associated with proliferation, differentiation and migration in different regions surrounding the wound. Functional experiments show that SC proliferation, migration and differentiation can be uncoupled during wound healing. Lineage tracing and quantitative clonal analysis reveal that, following wounding, progenitors divide more rapidly, but conserve their homeostatic mode of division, leading to their rapid depletion whereas SCs become active, giving rise to new progenitors that expand and repair the wound. These results have important implications for tissue regeneration, acute and chronic wound disorders.
Project description:Wound healing is essential to repair the skin after injury. In the epidermis, distinct stem cells (SCs) populations contribute to wound healing. However, how SCs balance proliferation, differentiation and migration to repair a wound remains poorly understood. Here we show the cellular and molecular mechanisms that regulate wound healing in mouse tail epidermis. Using a combination of proliferation kinetics experiments and molecular profiling, we identify the gene signatures associated with proliferation, differentiation and migration in different regions surrounding the wound. Functional experiments show that SC proliferation, migration and differentiation can be uncoupled during wound healing. Lineage tracing and quantitative clonal analysis reveal that, following wounding, progenitors divide more rapidly, but conserve their homeostatic mode of division, leading to their rapid depletion whereas SCs become active, giving rise to new progenitors that expand and repair the wound. These results have important implications for tissue regeneration, acute and chronic wound disorders.
Project description:Bone morphogenetic protein (BMP) signalling plays a key role in the control of skin development and postnatal remodelling by regulating keratinocyte proliferation, differentiation and apoptosis. To study the role of BMPs in wound-induced epidermal repair, we used transgenic mice overexpressing the BMP downstream component Smad1 under the control of a K14 promoter as an in vivo model, as well as ex vivo and in vitro assays. K14-caSmad1 mice exhibited retarded wound healing associated with significant inhibition of proliferation and increased apoptosis in healing wound epithelium. Furthermore, microarray and qRT-PCR analyses revealed decreased expression of a number of cytoskeletal/cell motility-associated genes including wound-associated keratins (Krt16, Krt17) and Myo5a, in the epidermis of K14- caSmad1 mice versus wild-type controls during wound healing. BMP treatment significantly inhibited keratinocyte migration ex vivo, and primary keratinocytes of K14-caSmad1 mice showed retarded migration compared to wild-type controls. Finally, siRNA-mediated silencing of Bmpr-1B in primary mouse keratinocytes accelerated cell migration and was associated with increased expression of Krt16, Krt17 and Myo5a compared to controls. Thus, this study demonstrates that BMPs inhibit keratinocyte proliferation, cytoskeletal organization and migration in regenerating skin epithelium during wound healing, and raises a possibility for using BMP antagonists for the management of chronic wounds. Two-condition experiment, Wild type vs. Smad1 overexpressing mice. Biological replicates: 2 replicates.
Project description:Skin wound healing is one of the major prevalent medical problems in the worldwide. Wound healing involves multi-process synergy and re-epithelialization is an essential part of wound healing. Histone H3K36 tri-methylase Setd2 has been extensively studied in different biological processes and diseases. However, the function of Setd2 in the wound healing remains unclear. To elucidate the biological role of Setd2 in the skin wound healing, conditional gene targeting was employed to establish epidermis-specific Setd2-deficient mice. We found that Setd2 deficiency resulted in accelerated re-epithelialization during cutaneous wound healing by promoting keratinocytes proliferation and migration. Furthermore, we demonstrated that loss of Setd2 activated the AKT/mTOR pathway, and pharmacological inhibitions of AKT and mTOR with MK2206 and rapamycin delayed wound closure, respectively. In conclusion, our results reveal the essential role of Setd2 in skin wound healing that is Setd2 loss promotes cutaneous wound healing via activation of AKT/mTOR signaling.
Project description:Skin wound healing is one of the major prevalent medical problems in the worldwide. Wound healing involves multi-process synergy and re-epithelialization is an essential part of wound healing. Histone H3K36 tri-methylase Setd2 has been extensively studied in different biological processes and diseases. However, the function of Setd2 in the wound healing remains unclear. To elucidate the biological role of Setd2 in the skin wound healing, conditional gene targeting was employed to establish epidermis-specific Setd2-deficient mice. We found that Setd2 deficiency resulted in accelerated re-epithelialization during cutaneous wound healing by promoting keratinocytes proliferation and migration. Furthermore, we demonstrated that loss of Setd2 activated the AKT/mTOR pathway, and pharmacological inhibitions of AKT and mTOR with MK2206 and rapamycin delayed wound closure, respectively. In conclusion, our results reveal the essential role of Setd2 in skin wound healing that is Setd2 loss promotes cutaneous wound healing via activation of AKT/mTOR signaling.
Project description:Bone morphogenetic protein (BMP) signalling plays a key role in the control of skin development and postnatal remodelling by regulating keratinocyte proliferation, differentiation and apoptosis. To study the role of BMPs in wound-induced epidermal repair, we used transgenic mice overexpressing the BMP downstream component Smad1 under the control of a K14 promoter as an in vivo model, as well as ex vivo and in vitro assays. K14-caSmad1 mice exhibited retarded wound healing associated with significant inhibition of proliferation and increased apoptosis in healing wound epithelium. Furthermore, microarray and qRT-PCR analyses revealed decreased expression of a number of cytoskeletal/cell motility-associated genes including wound-associated keratins (Krt16, Krt17) and Myo5a, in the epidermis of K14- caSmad1 mice versus wild-type controls during wound healing. BMP treatment significantly inhibited keratinocyte migration ex vivo, and primary keratinocytes of K14-caSmad1 mice showed retarded migration compared to wild-type controls. Finally, siRNA-mediated silencing of Bmpr-1B in primary mouse keratinocytes accelerated cell migration and was associated with increased expression of Krt16, Krt17 and Myo5a compared to controls. Thus, this study demonstrates that BMPs inhibit keratinocyte proliferation, cytoskeletal organization and migration in regenerating skin epithelium during wound healing, and raises a possibility for using BMP antagonists for the management of chronic wounds.
Project description:Injuries to the skin can result in non-healing wounds, characterized by prolonged inflammation, failure to close, and chronic pain. Basal keratinocytes in the epidermis respond to signals activated following injury by proliferating, migrating, and differentiating to restore the epidermal barrier. The skin is densely innervated by peripheral sensory nerves, which contribute to the wound repair response. Although it is known that nerves are important for successful wound healing, the underlying cellular mechanisms of this phenomenon, and particularly the role of nerves in directing keratinocyte re-epithelialization, are poorly understood. To explore the relationship between sensory nerves and keratinocyte function in vitro, we cultured keratinocytes with conditioned media collected from dorsal root ganglia (DRG) in both homeostatic and post-wounding conditions and found that keratinocyte migration and proliferation, functions essential for re-epithelialization, were modulated by DRG conditioned media. Using a proteomic approach, we characterized the secretome of cultured DRG and identified key factors essential for wound healing, including extracellular matrix proteins, growth factors, and metabolic factors involved with ATP production, which was correlated with an increase in ATP rates of keratinocytes cultured in DRG conditioned medium. Our results advance our understanding of the microenvironmental cues that direct keratinocyte function during key events of cutaneous wound healing in vitro to drive the development of therapeutics that target dysregulated re-epithelialization in non-healing wounds.
Project description:The mitogen-activated protein kinase kinase (MEK) kinase 1 (MEKK1), also known as MAP3K1, mediates activin B (ActB) signals required for eyelid epithelium morphogenesis during mouse fetal development. The present study investigates the role of MEKK1 in epithelial wound healing, another activin-regulated biological process. In a skin wound model, injury markedly stimulates MEKK1 expression and activity, which are in turn required for the expression of genes involved in extracellular matrix (ECM) homeostasis. MEKK1 ablation or down-regulation by interfering RNA significantly delays skin wound closure and impairs activation of Jun NH2-terminal kinases, induction of plasminogen activator inhibitor (PAI)-1, and restoration of cell-cell junctions of the wounded epidermis. Conversely, expression of wild-type MEKK1 accelerates reepithelialization of full-thickness skin and corneal debridement wounds by mechanisms involving epithelial cell migration, a cell function that is partially abolished by neutralizing antibodies for PAI-1 and metalloproteinase III. Our data suggest that MEKK1 transmits wound signals, leading to the transcriptional activation of genes involved in ECM homeostasis, epithelial cell migration, and wound reepithelialization.
Project description:While considerable progress has been made towards understanding the complex processes and pathways that regulate human wound healing, regenerative medicine has been unable to develop therapies that coax the natural wound environment to heal scar-free. The inability to induce perfect skin regeneration stems partly from our limited understanding of how scar-free healing occurs in a natural setting. Here we have investigated the wound repair process in adult axolotls and demonstrate that they are capable of perfectly repairing full thickness excisional wounds made on the flank. In the context of mammalian wound repair, our findings reveal a substantial reduction in hemostasis, reduced neutrophil infiltration and a relatively long delay in production of new extracellular matrix (ECM) during scar-free healing. Additionally, we test the hypothesis that metamorphosis leads to scarring and instead show that terrestrial axolotls also heal scar-free, albeit at a slower rate. Analysis of newly forming dermal ECM suggests that low levels of fibronectin and high levels of tenascin-C promote regeneration in lieu of scarring. Lastly, a genetic analysis during wound healing comparing epidermis between aquatic and terrestrial axolotls suggests that matrix metalloproteinases may regulate the fibrotic response. Our findings outline a blueprint to understand the cellular and molecular mechanisms coordinating scar-free healing that will be useful towards elucidating new regenerative therapies targeting fibrosis and wound repair. We used microarray analysis to determine the gene expression changes that take place during scar free wound healing in aquatic and terrestrial axolotl salamanders. Epidermal tissue was harvested using a 4mm biopsy punch. Two wounds were made along the flank and posterior to the forelimbs. Harvested epidermis was pooled for each animal. Four biological replicates were collected from uninjured epidermis (D0) and at 1, 3, and 7 days post injury.