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The Journal of Biological Chemistry Apr 2003
Review
Topics: Animals; Basement Membrane; Cell Differentiation; Extracellular Matrix; Humans; Muscle Contraction; Muscle Fibers, Skeletal; Muscle, Skeletal
PubMed: 12556454
DOI: 10.1074/jbc.R200027200 -
American Journal of Respiratory and... Mar 2006In normal human lung, single alveolar fibroblasts link capillary endothelium to type 2 pneumocytes through apertures in the endothelial and epithelial basal laminae.... (Comparative Study)
Comparative Study
RATIONALE
In normal human lung, single alveolar fibroblasts link capillary endothelium to type 2 pneumocytes through apertures in the endothelial and epithelial basal laminae. These fibroblasts are hypothesized to play a role in cellular communication between the endothelium and epithelium and are positioned to provide leukocytes a surface on which they may migrate through the interstitium.
OBJECTIVES
To determine whether fibroblasts link the endothelium to the epithelium in emphysematous lung and to compare basal lamina aperture frequency with previously published results.
METHODS
We performed transmission electron microscopy serial section three-dimensional reconstructions of emphysematous regions of human alveolar wall and a quantitative analysis of basal lamina apertures beneath 403 type 2 pneumocytes.
MEASUREMENTS AND MAIN RESULTS
Our three-dimensional reconstruction demonstrated that the fibroblasts subtending type 2 pneumocytes in emphysematous lung no longer link these epithelial cells to the capillary endothelium through basal lamina apertures. Basal lamina apertures may be absent below some type 2 pneumocytes. Our morphometric analysis showed that their frequency and area beneath type 2 pneumocytes is significantly reduced in emphysematous regions when compared with nonemphysematous regions of matched control lung.
CONCLUSIONS
We conclude that the endothelial/fibroblast/epithelial linkage is disrupted in emphysematous human lungs and postulate this disruption may disturb leukocyte migration and account for their accumulation in the alveolar interstitium of emphysematous lung tissue.
Topics: Basement Membrane; Fibroblasts; Humans; Image Processing, Computer-Assisted; In Vitro Techniques; Microscopy, Electron, Transmission; Pulmonary Alveoli; Pulmonary Emphysema; Severity of Illness Index
PubMed: 16415275
DOI: 10.1164/rccm.200509-1434OC -
Biomedical Research (Tokyo, Japan) 2018The epithelial basal lamina of the small intestine forms a felt-like sheet at the base of the epithelium. Previous studies have shown that the basal lamina has numerous...
The epithelial basal lamina of the small intestine forms a felt-like sheet at the base of the epithelium. Previous studies have shown that the basal lamina has numerous fenestrations, which are produced by leukocytes penetrating through the basal lamina. In this study, we aimed to directly visualize fenestrations of the rat basal lamina in intestinal villi by scanning electron microscopy (SEM) after removal of the villous epithelium by osmium maceration and ultrasonic treatment. Structural changes in fenestrations were then investigated in relation to dietary conditions. SEM of these tissues revealed the presence of fenestrations in the villous epithelial basal lamina in all segments of the small intestine, although the number was the highest in the jejunum. The present study also showed that the number and size of fenestrations increased after feeding in the jejunum, whereas changes were unclear in the ileum. These findings suggested that the basal lamina fenestrations were changed through the dynamics of migrating leukocytes in dietary conditions and may also be related to the regulation of nutrient absorption, particularly as lipids are transported from the intercellular space of the epithelium to the lamina propria.
Topics: Animals; Basement Membrane; Cell Movement; Diet; Epithelial Cells; Intestinal Absorption; Intestinal Mucosa; Intestine, Small; Leukocytes; Rats
PubMed: 29669985
DOI: 10.2220/biomedres.39.65 -
Acta Ophthalmologica May 2016To study the structure of the anterior lens epithelial cells (aLECs) and the contacts of the aLECs with the basal lamina (BL) in order to understand their role in the...
PURPOSE
To study the structure of the anterior lens epithelial cells (aLECs) and the contacts of the aLECs with the basal lamina (BL) in order to understand their role in the lens epithelium's function.
METHODS
The aLCs (BL and associated aLECs) were obtained from routine uneventful cataract surgery, prepared for and studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal microscopy.
RESULTS
SEM shows that the basal surface of the aLECs (~10-15 μm) is with aLECs foldings (~1-3 μm) and extensions (~0.5-3 μm) attached to the BL. Confocal microscopy images of the basal sections of the aLECs after membrane staining also suggest that the basal part of aLECs has foldings (~1-3 μm). TEM shows in the aLECs basal parts, towards BL, the structures that look like entanglement (~1-4 μm). In cases where there is a swelling of the cytoplasm and offset of the aLECs from the BL, individual extensions (~0.5-2 μm) that extend to the BL are visible by TEM.
CONCLUSIONS
We provide detail evidence about the structural organization of the aLECs, in particular about their basal side which is in contact with the BL. This is supported by the complementary use of three techniques, SEM, TEM and confocal microscopy, each of them showing the same morphological features, the extensions and the entanglements of the aLECs cytoplasmic membrane at the border with the BL. The basal surface of the aLECs is increased. It suggests the functional importance of the contact between aLECs and BL.
Topics: Anterior Capsule of the Lens; Basement Membrane; Capsulorhexis; Cataract Extraction; Cell Adhesion; Epithelial Cells; Humans; Microscopy, Confocal; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission
PubMed: 26581784
DOI: 10.1111/aos.12902 -
Investigative Ophthalmology & Visual... Nov 2020Basal laminar deposit (BLamD) is a consistent finding in age-related macular degeneration (AMD). We quantified BLamD thickness, appearance, and topography in eyes of...
PURPOSE
Basal laminar deposit (BLamD) is a consistent finding in age-related macular degeneration (AMD). We quantified BLamD thickness, appearance, and topography in eyes of aged donors with and without AMD and evaluated its relationship to other components of the retinal pigment epithelium-basal lamina/Bruch's membrane (RPE-BL-BrM) complex.
METHODS
Donor eyes (n = 132) were classified as normal (n = 54), early to intermediate AMD (n = 24), geographic atrophy (GA; n = 13), and neovascular AMD (NV; n = 41). In high-resolution histology, we assessed RPE, BLamD, and BrM thicknesses and phenotypes at 3309 predefined locations in the central (foveal and perifovea) and superior (perifoveal) sections. Pre-mortem optical coherence tomography (OCT) imaging of a 90-year-old woman was compared to postmortem histopathology.
RESULTS
In non-atrophic areas of AMD eyes, the RPE-BLamD is thick (normal = 13.7 µm, early-intermediate = 16.8 µm, GA = 17.4 µm, NV = 18.7 µm), because the BLamD is thick (normal = 0.3 µm, early-intermediate = 5.5 µm, GA = 4.1 µm, NV = 5.3 µm). RPE layer thickness is similar across these stages. Disease-associated variants of BLamD (thick, late, basal mounds) cluster subfoveally. A thick BLamD is visible on OCT as a hyporeflective split in the RPE-BL-BrM complex. BrM is thin (3.5 µm) in NV (normal = 4.2 µm, early to intermediate = 4.4 µm, and GA = 4.2 µm).
CONCLUSIONS
The RPE-BL-BrM complex is thick in AMD, driven by the accumulation and expansion of BLamD rather than expansion of either three-layer BrM, RPE-BL, or RPE. BLamD is clinically appreciable by OCT in some patients as a non-neovascular "split RPE-BL-BrM complex" or "double-layer sign." BLamD may contribute toward the formation and progression of high-risk drusen yet also exhibit protective properties.
Topics: Aged; Aged, 80 and over; Basement Membrane; Bruch Membrane; Female; Humans; Macular Degeneration; Male; Phenotype; Retinal Pigment Epithelium; Tomography, Optical Coherence; Visual Acuity
PubMed: 33186466
DOI: 10.1167/iovs.61.13.19 -
Open Biology Feb 2021The basement membrane (BM) is a special type of extracellular matrix that lines the basal side of epithelial and endothelial tissues. Functionally, the BM is important... (Review)
Review
The basement membrane (BM) is a special type of extracellular matrix that lines the basal side of epithelial and endothelial tissues. Functionally, the BM is important for providing physical and biochemical cues to the overlying cells, sculpting the tissue into its correct size and shape. In this review, we focus on recent studies that have unveiled the complex mechanical properties of the BM. We discuss how these properties can change during development, homeostasis and disease via different molecular mechanisms, and the subsequent impact on tissue form and function in a variety of organisms. We also explore how better characterization of BM mechanics can contribute to disease diagnosis and treatment, as well as development of better and models that not only impact the fields of tissue engineering and regenerative medicine, but can also reduce the use of animals in research.
Topics: Animals; Basement Membrane; Homeostasis; Humans; Mechanical Phenomena
PubMed: 33593159
DOI: 10.1098/rsob.200360 -
Glycobiology Jul 2015Associations between cells and the basement membrane are critical for a variety of biological events including cell proliferation, cell migration, cell differentiation... (Review)
Review
Associations between cells and the basement membrane are critical for a variety of biological events including cell proliferation, cell migration, cell differentiation and the maintenance of tissue integrity. Dystroglycan is a highly glycosylated basement membrane receptor, and is involved in physiological processes that maintain integrity of the skeletal muscle, as well as development and function of the central nervous system. Aberrant O-glycosylation of the α subunit of this protein, and a concomitant loss of dystroglycan's ability to function as a receptor for extracellular matrix (ECM) ligands that bear laminin globular (LG) domains, occurs in several congenital/limb-girdle muscular dystrophies (also referred to as dystroglycanopathies). Recent genetic studies revealed that mutations in DAG1 (which encodes dystroglycan) and at least 17 other genes disrupt the ECM receptor function of dystroglycan and cause disease. Here, we summarize recent advances in our understanding of the enzymatic functions of two of these disease genes: the like-glycosyltransferase (LARGE) and protein O-mannose kinase (POMK, previously referred to as SGK196). In addition, we discuss the structure of the glycan that directly binds the ECM ligands and the mechanisms by which this functional motif is linked to dystroglycan. In light of the fact that dystroglycan functions as a matrix receptor and the polysaccharide synthesized by LARGE is the binding motif for matrix proteins, we propose to name this novel polysaccharide structure matriglycan.
Topics: Basement Membrane; Dystroglycans; Extracellular Matrix; Mutation; Polysaccharides
PubMed: 25882296
DOI: 10.1093/glycob/cwv021 -
American Journal of Physiology.... Jan 2002Patch clamp experiments were conducted to study the effects of basal lamina (basement membrane) of chicken ovarian follicle on membrane Ca(2+) currents in differentiated...
Patch clamp experiments were conducted to study the effects of basal lamina (basement membrane) of chicken ovarian follicle on membrane Ca(2+) currents in differentiated chicken granulosa cells in a homologous system. The whole cell patch clamp technique was used to simultaneously monitor membrane capacitance (an indirect measure of total cell surface area) and currents flowing through voltage-dependent Ca(2+) channels (using Ba(2+) as the charge carrier). Membrane capacitance was smaller in cells incubated on intact basal lamina than in control cells (incubated on tissue culture-treated plastic substratum). Granulosa cells expressed both T- and L-type Ca(2+) currents, and the amplitudes of the currents in cells incubated on intact basal lamina were significantly lower than those of control cells. Also, granulosa cells incubated on intact basal lamina were found to have significantly lower T- or L-type Ca(2+) current densities than control cells. Intact basal lamina that had been stored for 12 mo produced effects on T- and L-type Ca(2+) currents similar to those caused by freshly isolated basal lamina. The basal lamina was solubilized completely in one step and used to coat glass coverslips (uncoated glass coverslips served as controls). Granulosa cells incubated on coverslips precoated with solubilized basal lamina assumed spherical shape similar to those incubated on intact basal lamina. Similar to the observations made for intact basal lamina, the solubilized basal lamina suppressed T- and L-type Ca(2+) currents in the differentiated granulosa cells. Moreover, fibronectin, laminin, and type IV collagen, obtained from commercial sources, attenuated T- and L-type Ca(2+) currents in the differentiated granulosa cells. This interplay between basal lamina and Ca(2+) currents may be one mechanism that subserves the effects of the matrix material on metabolic functions of granulosa cells.
Topics: Animals; Basement Membrane; Calcium Channels, L-Type; Calcium Channels, T-Type; Cell Size; Chickens; Cycloheximide; Dactinomycin; Electric Capacitance; Electric Conductivity; Female; Granulosa Cells; Nucleic Acid Synthesis Inhibitors; Ovarian Follicle; Preservation, Biological; Protein Synthesis Inhibitors; Time Factors
PubMed: 11739100
DOI: 10.1152/ajpendo.2002.282.1.E184 -
Cell Adhesion & Migration 2013Basement membranes (BMs) evolved together with the first metazoan species approximately 500 million years ago. Main functions of BMs are stabilizing epithelial cell... (Review)
Review
Basement membranes (BMs) evolved together with the first metazoan species approximately 500 million years ago. Main functions of BMs are stabilizing epithelial cell layers and connecting different types of tissues to functional, multicellular organisms. Mutations of BM proteins from worms to humans are either embryonic lethal or result in severe diseases, including muscular dystrophy, blindness, deafness, kidney defects, cardio-vascular abnormalities or retinal and cortical malformations. In vivo-derived BMs are difficult to come by; they are very thin and sticky and, therefore, difficult to handle and probe. In addition, BMs are difficult to solubilize complicating their biochemical analysis. For these reasons, most of our knowledge of BM biology is based on studies of the BM-like extracellular matrix (ECM) of mouse yolk sac tumors or from studies of the lens capsule, an unusually thick BM. Recently, isolation procedures for a variety of BMs have been described, and new techniques have been developed to directly analyze the protein compositions, the biomechanical properties and the biological functions of BMs. New findings show that native BMs consist of approximately 20 proteins. BMs are four times thicker than previously recorded, and proteoglycans are mainly responsible to determine the thickness of BMs by binding large quantities of water to the matrix. The mechanical stiffness of BMs is similar to that of articular cartilage. In mice with mutation of BM proteins, the stiffness of BMs is often reduced. As a consequence, these BMs rupture due to mechanical instability explaining many of the pathological phenotypes. Finally, the morphology and protein composition of human BMs changes with age, thus BMs are dynamic in their structure, composition and biomechanical properties.
Topics: Aging; Animals; Basement Membrane; Biomechanical Phenomena; Cell Adhesion; Cell Culture Techniques; Cell Shape; Collagen Type IV; Endothelium, Vascular; Extracellular Matrix; Humans; Mice; Microscopy, Electron, Transmission; Proteome
PubMed: 23154404
DOI: 10.4161/cam.22479 -
Developmental Biology Nov 1993We and other investigators have repeatedly observed that, although purified populations of Schwann cells cultured in the absence of neurons immunostain for some basal...
We and other investigators have repeatedly observed that, although purified populations of Schwann cells cultured in the absence of neurons immunostain for some basal lamina constituents, assembled basal lamina is not seen ultrastructurally. In this study we show that purified rat Schwann cells cultured with either fibroblasts or diffusible substances from fibroblasts acquire basal lamina; this basal lamina is most robust and continuous when Schwann cells and fibroblasts are cultured together. The diffusible fibroblast factor(s) is ascorbate-dependent and heat-sensitive and exhibits a molecular weight greater than 30-50,000. The addition of either a combination of basal lamina components or purified laminin also results in the deposition of lengths of basal lamina. Extracellular matrix elaboration promoted by fibroblast factors is linked to dramatic changes in the morphology of Schwann cells; the cells become elongated and aligned with respect to each other. The addition of purified laminin partly mimics this effect. These changes may represent an early response of the Schwann cell to the acquisition of basal lamina preceding further differentiation in vivo. Our observations resemble those reported for other epithelial cell-fibroblast interactions and thus reaffirm the identity of the Schwann cell as an epithelial cell sensitive to the influence of mesenchymally derived factors. We propose that fibroblast stimulation of Schwann cell extracellular matrix deposition probably occurs in normal development with axons and in abnormal situations without axons, such as peripheral nerve injury and tumor formation.
Topics: Animals; Basement Membrane; Cell Differentiation; Cell Separation; Cells, Cultured; Diffusion; Extracellular Matrix; Fibroblasts; Immunohistochemistry; Mesoderm; Microscopy, Electron; Neurons; Rats; Schwann Cells
PubMed: 8224529
DOI: 10.1006/dbio.1993.1291