ABSTRACT
The circadian rhythm regulates the physiology and behavior of living organisms in a time-dependent manner. Clock genes have distinct roles including the control over gene expression mediated by the transcriptional activators CLOCK and BMAL1, and the suppression of gene expression mediated by the transcriptional repressors PER1/2 and CRY1/2. The balance between gene expression and repression is key to the maintenance of tissue homeostasis that is disrupted in the event of an injury. In the skin, a compromised epithelial barrier triggers a cascade of events that culminate in the mobilization of epithelial cells and stem cells. Recruited epithelial cells migrate towards the wound and reestablish the protective epithelial layer of the skin. Although we have recently demonstrated the involvement of BMAL and the PI3K signaling in wound healing, the role of the circadian clock genes in tissue repair remains poorly understood. Here, we sought to understand the role of BMAL1 on skin healing in response to injury. We found that genetic depletion of BMAL1 resulted in delayed healing of the skin as compared to wild-type control mice. Furthermore, we found that loss of Bmal1 was associated with the accumulation of Reactive Oxygen Species Modulator 1 (ROMO1), a protein responsible for inducing the production of intracellular reactive oxygen species (ROS). The slow healing was associated with ROS and superoxide dismutase (SOD) production, and pharmacological inhibition of the oxidative stress signaling (ROS/SOD) led to cellular proliferation, upregulation of Sirtuin 1 (SIRT1), and rescued the skin healing phenotype of Bmal1-/- mice. Overall, our study points to BMAL1 as a key player in tissue regeneration and as a critical regulator of ROMO1 and oxidative stress in the skin.
Subject(s)
ARNTL Transcription Factors/physiology , Antioxidants/pharmacology , Epidermis/physiology , Gene Expression Regulation , Oxidative Stress/drug effects , Reactive Oxygen Species/metabolism , Wound Healing/drug effects , Animals , Circadian Rhythm , Epidermis/drug effects , Male , Membrane Proteins/metabolism , Mice , Mice, Knockout , Mitochondrial Proteins/metabolism , Phosphatidylinositol 3-Kinases/metabolismABSTRACT
Head and neck cancer (HNSCC) are one of the most common solid malignancies of the world, being responsible for over 350,000 deaths every year. Much of the complications in managing and treating HNSCC advent from the complex genetic and epigenetic landscape of the disease. Emerging information has shown promising results in targeting BRD4, an epigenetic regulator bromodomain that functions as a scaffold for transcription factors at promoters and super-enhancers. Here we show that by disrupting the interaction between BRD4 and histones using the bromodomain inhibitor JQ1, HNSCC cells undergo cell growth arrest followed by cellular senescence. Mechanistically, JQ1 negatively impacted the phosphorylation levels of SIRT1 along with the acetylation levels of mutant p53 (active). In vivo administration of JQ1 resulted in disruption of HNSCC growth along with the activation of cellular senescence, observed by the accumulation of DNA double-strand breaks, p16ink4, accumulation of senescence-associated beta-galactosidase, and loss of phosphorylated Sirt1ser47. Furthermore, we also demonstrate that JQ1 was efficient in reducing the population of cancer stem cells from HNSCC xenografts.
Subject(s)
Azepines/pharmacology , Cell Cycle Proteins/antagonists & inhibitors , Cellular Senescence , Cyclin-Dependent Kinase Inhibitor p21/metabolism , Epigenome , Head and Neck Neoplasms/pathology , Neoplastic Stem Cells/pathology , Transcription Factors/antagonists & inhibitors , Triazoles/pharmacology , Animals , Apoptosis , Biomarkers, Tumor , Cell Cycle , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cell Proliferation , Cyclin-Dependent Kinase Inhibitor p21/genetics , Female , Gene Expression Regulation, Neoplastic , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/genetics , Head and Neck Neoplasms/metabolism , Histones/genetics , Histones/metabolism , Humans , Mice , Mice, Nude , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/metabolism , Prognosis , Squamous Cell Carcinoma of Head and Neck/drug therapy , Squamous Cell Carcinoma of Head and Neck/genetics , Squamous Cell Carcinoma of Head and Neck/metabolism , Squamous Cell Carcinoma of Head and Neck/secondary , Survival Rate , Transcription Factors/genetics , Transcription Factors/metabolism , Tumor Cells, Cultured , Xenograft Model Antitumor AssaysABSTRACT
The aim of this study was to evaluate the Toll like signaling pathway and atrophy after sleep deprivation (SD) in rat masticatory muscles: masseter and temporal. A total of 24 animals was distributed into three groups: Control group (CTL, n = 8), subjected to SD for 96 h (SD96, n = 8) and subjected to SD for 96 h more 96 h of sleep recovery (SD96 + R, n = 8). Histopathological analysis revealed the presence of acute inflammatory cells, congested vessels, fibrosis, and high cellularity in the skeletal muscle fibers from masseter and temporal submitted to SD. These morphological alterations were not observed in the control group since neither inflammatory cells nor congested vessels were observed to this group. In the group SD96 + R, the absence of inflammation was noticed to the masseter only. In this group, COX-2 and TNF-alpha downregulation were detected when comparing to control group. MyD88 and pIKK decreased in SD96 and SD96 + R groups being pNFKBp50 downregulatated in SD96 + R. MyD88 expression increased in rats submitted to SD96 and SD96 + R in temporal when compared to control group. On the other hand, pIKK decreased the protein expression in groups SD96 and SD96 + R while pNFKBp50 showed a decreased protein expression in group SD96 only. The activation of atrophy by means of MAFbx upregulation was detected in temporal muscle in SD96 and SD96 + R when compared to control. In summary, our results show that SD is able to induce morphological alterations in rat masticatory muscles. Toll like signaling pathway and atrophy play important roles in ethiopathogenesis induced by SD, being dependent of skeletal muscle type.
