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Cold Spring Harbor Perspectives in... Apr 2018Cell-cell junctions link cells to each other in tissues, and regulate tissue homeostasis in critical cell processes that include tissue barrier function, cell... (Review)
Review
Cell-cell junctions link cells to each other in tissues, and regulate tissue homeostasis in critical cell processes that include tissue barrier function, cell proliferation, and migration. Defects in cell-cell junctions give rise to a wide range of tissue abnormalities that disrupt homeostasis and are common in genetic abnormalities and cancers. Here, we discuss the organization and function of cell-cell junctions primarily involved in adhesion (tight junction, adherens junction, and desmosomes) in two different epithelial tissues: a simple epithelium (intestine) and a stratified epithelium (epidermis). Studies in these tissues reveal similarities and differences in the organization and functions of different cell-cell junctions that meet the requirements for the specialized functions of each tissue. We discuss cell-cell junction responses to genetic and environmental perturbations that provide further insights into their roles in maintaining tissue homeostasis.
Topics: Adherens Junctions; Animals; Cell Movement; Cell Proliferation; Desmosomes; Epithelial Cells; Epithelium; Homeostasis; Humans; Intercellular Junctions; Intestinal Mucosa; Signal Transduction; Tight Junctions; Wound Healing
PubMed: 28600395
DOI: 10.1101/cshperspect.a029181 -
Journal of Musculoskeletal & Neuronal... Jun 2004Ligaments are specialized connective tissues with very interesting biomechanical properties. They have the ability to adapt to the complex functions that each are... (Review)
Review
Ligaments are specialized connective tissues with very interesting biomechanical properties. They have the ability to adapt to the complex functions that each are required to perform. While ligaments were once thought to be inert, they are in fact responsive to many local and systemic factors that influence their function within the organism. Injury to a ligament results in a drastic change in its structure and physiology and creates a situation where ligament function is restored by the formation of scar tissue that is biologically and biomechanically inferior to the tissue it replaces. This article will briefly review the basic structure, physiology and function of normal versus healing knee ligaments, referring specifically to what is known about two of the most extensively studied and clinically relevant knee ligaments, the anterior cruciate (ACL) and medial collateral (MCL) ligaments of the knee. Those readers wishing for more comprehensive sources of information on ligament biology and biomechanics are referred to many excellent reviews on these topics.
Topics: Biomechanical Phenomena; Humans; Ligaments; Wound Healing
PubMed: 15615126
DOI: No ID Found -
International Journal of Molecular... Apr 2020Thermogenesis is the production of heat that occurs in all warm-blooded animals. During cold exposure, there is obligatory thermogenesis derived from body metabolism as... (Review)
Review
Thermogenesis is the production of heat that occurs in all warm-blooded animals. During cold exposure, there is obligatory thermogenesis derived from body metabolism as well as adaptive thermogenesis through shivering and non-shivering mechanisms. The latter mainly occurs in brown adipose tissue (BAT) and muscle; however, white adipose tissue (WAT) also can undergo browning via adrenergic stimulation to acquire thermogenic potential. Thyroid hormone (TH) also exerts profound effects on thermoregulation, as decreased body temperature and increased body temperature occur during hypothyroidism and hyperthyroidism, respectively. We have termed the TH-mediated thermogenesis under thermoneutral conditions "activated" thermogenesis. TH acts on the brown and/or white adipose tissues to induce uncoupled respiration through the induction of the uncoupling protein (Ucp1) to generate heat. TH acts centrally to activate the BAT and browning through the sympathetic nervous system. However, recent studies also show that TH acts peripherally on the BAT to directly stimulate Ucp1 expression and thermogenesis through an autophagy-dependent mechanism. Additionally, THs can exert Ucp1-independent effects on thermogenesis, most likely through activation of exothermic metabolic pathways. This review summarizes thermogenic effects of THs on adipose tissues.
Topics: Adipose Tissue; Adipose Tissue, Beige; Adipose Tissue, Brown; Adipose Tissue, White; Animals; Energy Metabolism; Glucose; Humans; Mitochondria; Oxidation-Reduction; Thermogenesis; Thyroid Hormones
PubMed: 32344721
DOI: 10.3390/ijms21083020 -
Cell and Tissue Research Oct 2017The degradation of cartilage in the human body is impacted by aging, disease, genetic predisposition and continued insults resulting from daily activity. The burden of... (Review)
Review
The degradation of cartilage in the human body is impacted by aging, disease, genetic predisposition and continued insults resulting from daily activity. The burden of cartilage defects (osteoarthritis, rheumatoid arthritis, intervertebral disc damage, knee replacement surgeries, etc.) is daunting in light of substantial economic and social stresses. This review strives to broaden the scope of regenerative medicine and tissue engineering approaches used for cartilage repair by comparing and contrasting the anatomical and functional nature of the meniscus, articular cartilage (AC) and nucleus pulposus (NP). Many review papers have provided detailed evaluations of these cartilages and cartilage-like tissues individually but none have comprehensively examined the parallels and inconsistencies in signaling, genetic expression and extracellular matrix composition between tissues. For the first time, this review outlines the importance of understanding these three tissues as unique entities, providing a comparative analysis of anatomy, ultrastructure, biochemistry and function for each tissue. This novel approach highlights the similarities and differences between tissues, progressing research toward an understanding of what defines each tissue as distinctive. The goal of this paper is to provide researchers with the fundamental knowledge to correctly engineer the meniscus, AC and NP without inadvertently developing the wrong tissue function or biochemistry.
Topics: Animals; Biomechanical Phenomena; Cartilage, Articular; Collagen; Humans; Meniscus; Nucleus Pulposus; Regeneration; Tissue Engineering
PubMed: 28413859
DOI: 10.1007/s00441-017-2613-0 -
Nature Sep 2022Adipose tissues communicate with the central nervous system to maintain whole-body energy homeostasis. The mainstream view is that circulating hormones secreted by the...
Adipose tissues communicate with the central nervous system to maintain whole-body energy homeostasis. The mainstream view is that circulating hormones secreted by the fat convey the metabolic state to the brain, which integrates peripheral information and regulates adipocyte function through noradrenergic sympathetic output. Moreover, somatosensory neurons of the dorsal root ganglia innervate adipose tissue. However, the lack of genetic tools to selectively target these neurons has limited understanding of their physiological importance. Here we developed viral, genetic and imaging strategies to manipulate sensory nerves in an organ-specific manner in mice. This enabled us to visualize the entire axonal projection of dorsal root ganglia from the soma to subcutaneous adipocytes, establishing the anatomical underpinnings of adipose sensory innervation. Functionally, selective sensory ablation in adipose tissue enhanced the lipogenic and thermogenetic transcriptional programs, resulting in an enlarged fat pad, enrichment of beige adipocytes and elevated body temperature under thermoneutral conditions. The sensory-ablation-induced phenotypes required intact sympathetic function. We postulate that beige-fat-innervating sensory neurons modulate adipocyte function by acting as a brake on the sympathetic system. These results reveal an important role of the innervation by dorsal root ganglia of adipose tissues, and could enable future studies to examine the role of sensory innervation of disparate interoceptive systems.
Topics: Adipose Tissue; Adipose Tissue, Beige; Animals; Axons; Energy Metabolism; Ganglia, Spinal; Homeostasis; Hormones; Mice; Organ Specificity; Sensory Receptor Cells; Subcutaneous Fat; Sympathetic Nervous System; Thermogenesis
PubMed: 36045288
DOI: 10.1038/s41586-022-05137-7 -
Cell Stem Cell Dec 2021During embryogenesis, paracrine signaling between tissues in close proximity contributes to the determination of their respective cell fate(s) and development into...
During embryogenesis, paracrine signaling between tissues in close proximity contributes to the determination of their respective cell fate(s) and development into functional organs. Organoids are in vitro models that mimic organ formation and cellular heterogeneity, but lack the paracrine input of surrounding tissues. Here, we describe a human multilineage iPSC-derived organoid that recapitulates cooperative cardiac and gut development and maturation, with extensive cellular and structural complexity in both tissues. We demonstrate that the presence of endoderm tissue (gut/intestine) in the organoids contributed to the development of cardiac tissue features characteristic of stages after heart tube formation, including cardiomyocyte expansion, compartmentalization, enrichment of atrial/nodal cells, myocardial compaction, and fetal-like functional maturation. Overall, this study demonstrates the ability to generate and mature cooperative tissues originating from different germ lineages within a single organoid model, an advance that will further the examination of multi-tissue interactions during development, physiological maturation, and disease.
Topics: Cell Differentiation; Endoderm; Humans; Induced Pluripotent Stem Cells; Myocytes, Cardiac; Organoids; Pluripotent Stem Cells
PubMed: 34861147
DOI: 10.1016/j.stem.2021.11.007 -
Redox Biology Jul 2021Loss of perivascular adipose tissue (PVAT) impairs endothelial function and enhances atherosclerosis. However, the roles of PVAT thermoregulation in vascular...
Loss of perivascular adipose tissue (PVAT) impairs endothelial function and enhances atherosclerosis. However, the roles of PVAT thermoregulation in vascular inflammation and the development of atherosclerosis remains unclear. Bone morphogenetic protein 4 (BMP4) transforms white adipocyte to beige adipocyte, while promotes a brown-to-white shift in inter-scapular brown adipose tissue (BAT). Here, we found that knockdown of BMP4 in PVAT reduced expression of brown adipocyte-characteristic genes and increased endothelial inflammation in vitro co-culture system. Ablating BMP4 expression either in adipose tissues or specifically in BAT in ApoE mice demonstrated a marked exacerbation of atherosclerotic plaque formation in vivo. We further demonstrated that proinflammatory factors (especially IL-1β) increased in the supernatant of BMP4 knockdown adipocytes. Overexpression of BMP4 in adipose tissues promotes browning of PVAT and protects against atherosclerosis in ApoE mice. These findings uncover an organ crosstalk between PVAT and blood endothelial cells that is engaged in atherosclerosis.
Topics: Adipose Tissue; Adipose Tissue, Brown; Adipose Tissue, White; Animals; Anti-Inflammatory Agents; Atherosclerosis; Bone Morphogenetic Protein 4; Endothelial Cells; Mice
PubMed: 33895484
DOI: 10.1016/j.redox.2021.101979 -
Cells Jun 2022In the process of mechanotransduction, the cells in the body perceive and interpret mechanical stimuli to maintain tissue homeostasis and respond to the environmental... (Review)
Review
In the process of mechanotransduction, the cells in the body perceive and interpret mechanical stimuli to maintain tissue homeostasis and respond to the environmental changes. Increasing evidence points towards dysregulated mechanotransduction as a pathologically relevant factor in human diseases, including inflammatory conditions. Skin is the organ that constantly undergoes considerable mechanical stresses, and the ability of mechanical factors to provoke inflammatory processes in the skin has long been known, with the Koebner phenomenon being an example. However, the molecular mechanisms and key factors linking mechanotransduction and cutaneous inflammation remain understudied. In this review, we outline the key players in the tissue's mechanical homeostasis, the available data, and the gaps in our current understanding of their aberrant regulation in chronic cutaneous inflammation. We mainly focus on psoriasis as one of the most studied skin inflammatory diseases; we also discuss mechanotransduction in the context of skin fibrosis as a result of chronic inflammation. Even though the role of mechanotransduction in inflammation of the simple epithelia of internal organs is being actively studied, we conclude that the mechanoregulation in the stratified epidermis of the skin requires more attention in future translational research.
Topics: Dermatitis; Epidermis; Humans; Inflammation; Mechanotransduction, Cellular; Psoriasis; Skin Diseases
PubMed: 35805110
DOI: 10.3390/cells11132026 -
Cell Stem Cell Apr 2023Tissues with a high turnover rate produce millions of cells daily and have abundant regenerative capacity. At the core of their maintenance are populations of stem cells... (Review)
Review
Tissues with a high turnover rate produce millions of cells daily and have abundant regenerative capacity. At the core of their maintenance are populations of stem cells that balance self-renewal and differentiation to produce the adequate numbers of specialized cells required for carrying out essential tissue functions. Here, we compare and contrast the intricate mechanisms and elements of homeostasis and injury-driven regeneration in the epidermis, hematopoietic system, and intestinal epithelium-the fastest renewing tissues in mammals. We highlight the functional relevance of the main mechanisms and identify open questions in the field of tissue maintenance.
Topics: Animals; Intestinal Mucosa; Stem Cells; Epidermis; Cell Differentiation; Homeostasis; Mammals
PubMed: 37028402
DOI: 10.1016/j.stem.2023.03.008 -
Current Opinion in Genetics &... Jun 2023The white adipose tissue's primary roles are to store and mobilise energy, which is very different from the brown adipose tissue's function of using fuel to generate... (Review)
Review
The white adipose tissue's primary roles are to store and mobilise energy, which is very different from the brown adipose tissue's function of using fuel to generate heat and maintain the body temperature. The adipose tissues (ATs), co-ordinately with the other organs, sense energetic demands and inform of their reserves before embarking on energetically demanding physiological functions. It is not surprising that ATs exhibit highly integrated regulatory mechanisms mediated by a diversified secretome, including adipokines, lipokines, metabolites and a repertoire of extracellular miRNAs that contribute to integrating the function of the AT niche and connect the AT through paracrine and endocrine effects with the whole organism. Characterising the adipose secretome, its changes in health and disease, regulation by ageing and gender and their contribution to energy homoeostasis is necessary to optimise its use for personalised strategies to prevent or reverse metabolic diseases.
Topics: Humans; Adipose Tissue; Adipokines; Obesity; Metabolic Diseases; Adiposity
PubMed: 37099831
DOI: 10.1016/j.gde.2023.102046