scholarly journals Immunoelectron microscope studies of membrane-microfilament interactions: distributions of alpha-actinin, tropomyosin, and vinculin in intestinal epithelial brush border and chicken gizzard smooth muscle cells.

1981 ◽  
Vol 91 (3) ◽  
pp. 614-628 ◽  
Author(s):  
B Geiger ◽  
A H Dutton ◽  
K T Tokuyasu ◽  
S J Singer

The ultrastructural localization of three cytoskeletal proteins, alpha-actinin, tropomyosin, and vinculin, in the brush border of epithelial cells of chicken small intestine and the smooth muscle cells of chicken gizzard was studied by immunofluorescence and immunonelectron microscope labeling of frozen sections of lightly fixed, intact tissues. In the immunoelectron microscope studies, a recently described new type of electron-dense antibody conjugate, imposil-antibody, has been successfully used, along with ferritin-antibody conjugates, in single and double immunolabeling experiments. In the intestinal brush border shows that vinvulin is sharply confined to the junctional complex close to the membrane region of the zonula adherens, in distinct contrast to the more diffuse distributions of the other two proteins. In the smooth muscle cells, the labeling patterns show that vinculin is sharply confined to the membrane-associated dense plaques, closer to the membrane than the alpha-Actinin is also present in the cytoplastic dense bodies, from which vinculin is absent. Tropomyosin is present diffusely distributed in the cytoplasm, but absent from both dense plaques and dense bodies. These findings with the muscle cells demonstrate, therefore, that the dense plaques and dense bodies are chemically and structurally distinct entities. The results with both tissues, along with those in previous papers (Geiger, 1979, Cell. 18:193-205.; Geiger et al., 1980, Proc. Natl. Acad. Sci. U. S. A. 77:4127-4131), suggest that vinculin may play an important and widespread role in the linkage of actin-containing microfilament bundles to membranes.

1994 ◽  
Vol 107 (3) ◽  
pp. 445-455 ◽  
Author(s):  
A.J. North ◽  
M. Gimona ◽  
Z. Lando ◽  
J.V. Small

Differentiated smooth muscle cells typically contain a mixture of muscle (alpha and gamma) and cytoplasmic (beta and gamma) actin isoforms. Of the cytoplasmic actins the beta-isoform is the more dominant, making up from 10% to 30% of the total actin complement. Employing an antibody raised against the N-terminal peptide specific to beta-actin, which labels only the beta-isoform on two-dimensional gel immunoblots, we have shown that this isoform has a restricted localisation in smooth muscle. Using double-label immunofluorescence and immunoelectron microscopy of ultrathin sections of chicken gizzard, beta-actin was localised in the dense bodies and in longitudinal channels linking consecutive dense bodies that were also occupied by desmin. It was additionally found in the membrane-associated dense plaques, but was excluded from the actomyosin-containing regions of the contractile apparatus. Taken together with earlier results these findings identify a cytoskeletal compartment containing intermediate filaments, cytoplasmic actin and the actin cross-linking protein filamin. Using an antibody specific only for muscle actin, labelling was found generally around the myosin filaments of the contractile apparatus, but was absent from the core of the dense bodies that contained beta-actin. Thus, if dense bodies act as dual-purpose anchorage sites, for the cytoskeletal actin and the contractile actin, the thin filaments of the contractile apparatus must be anchored at the periphery of the dense bodies. A model of the structural organisation of the cell is presented and the possible roles of the cytoskeleton are discussed.


Author(s):  
J.M. Minda ◽  
E. Dessy ◽  
G. G. Pietra

Pulmonary lymphangiomyomatosis (PLAM) is a rare disease occurring exclusively in women of reproductive age. It involves the lungs, lymph nodes and lymphatic ducts. In the lungs, it is characterized by the proliferation of smooth muscle cells around lymphatics in the bronchovascular bundles, lobular septa and pleura The nature of smooth muscle proliferation in PLAM is still unclear. Recently, reactivity of the smooth muscle cells for HMB-45, a melanoma-related antigen has been reported by immunohistochemistry. The purpose of this study was the ultrastructural localization of HMB-45 immunoreactivity in these cells using gold-labeled antibodies.Lung tissue from three cases of PLAM, referred to our Institution for lung transplantation, was embedded in either Poly/Bed 812 post-fixed in 1% osmium tetroxide, or in LR White, without osmication. For the immunogold technique, thin sections were placed on Nickel grids and incubated with affinity purified, monoclonal anti-melanoma antibody HMB-45 (1:1) (Enzo Diag. Co) overnight at 4°C. After extensive washing with PBS, grids were treated with Goat-anti-mouse-IgG-Gold (5nm) (1:10) (Amersham Life Sci) for 1 hour, at room temperature.


2002 ◽  
Vol 126 (6) ◽  
pp. 692-696
Author(s):  
Laszlo Nemeth ◽  
Udo Rolle ◽  
Prem Puri

Abstract Context.—Intestinal motility is under the control of smooth muscle cells, enteric plexus, and hormonal factors. In Hirschsprung disease (HD), the aganglionic colon remains spastic or tonically enhanced and unable to relax. The smooth muscle cell's cytoskeleton consists of proteins or structures whose primary function is to link or connect protein filaments to each other or to the anchoring sites. Dystrophin is a subsarcolemmal protein with a double adhesion property, one between the membrane elements and the contractile filaments of the cytoskeleton and the other between the cytoskeletal proteins and the extracellular matrix. Desmin and vinculin are functionally related proteins that are present in the membrane-associated dense bodies in the sarcolemma of the smooth muscle cells. Objective.—To examine the distribution of the cytoskeletal proteins in the smooth muscle of the aganglionic bowel. Design.—Bowel specimens from ganglionic and aganglionic sections of the colon were collected at the time of pull-through surgery from 8 patients with HD. Colon specimens collected from 4 patients at the time of bladder augmentation acted as controls. Anti-dystrophin, anti-desmin, and anti-vinculin antibodies were used for fluorescein immunostaining using confocal laser scanning microscopy. Results.—Moderate to strong dystrophin immunoreactivity was observed at the periphery of smooth muscle fibers in normal bowel and ganglionic bowel from patients with HD, whereas dystrophin immunoreactivity was either absent or weak in the smooth muscle of aganglionic colon. Moderate to strong cytoplasmic immunostaining for vinculin and desmin was seen in the smooth muscle of normal bowel and ganglionic bowel from patients with HD, whereas vinculin and desmin staining in the aganglionic colon was absent or weak. Conclusion.—This study demonstrates that the cytoskeletal proteins are abundant in the smooth muscle of normal bowel, but are absent or markedly reduced in the aganglionic bowel of HD. As cytoskeletal proteins are required for the coordinated contraction of muscle cells, their absence may be responsible for the motility dysfunction in the aganglionic segment.


Author(s):  
Vikram Joshi ◽  
Peter R Strege ◽  
Gianrico Farrugia ◽  
Arthur Beyder

Mechanosensation, the ability to properly sense mechanical stimuli and transduce them into physiologic responses, is an essential determinant of gastrointestinal (GI) function. Abnormalities in this process result in highly prevalent GI functional and motility disorders. In the GI tract, several cell types sense mechanical forces and transduce them into electrical signals, which elicit specific cellular responses. Some mechanosensitive cells like sensory neurons act as specialized mechanosensitive cells that detect forces and transduce signals into tissue-level physiologic reactions. Non-specialized mechanosensitive cells like smooth muscle cells (SMCs) adjust their function in response to forces. Mechanosensitive cells utilize various mechanoreceptors and mechanotransducers. Mechanoreceptors detect and convert force into electrical and biochemical signals, and mechanotransducers amplify and direct mechanoreceptor responses. Mechanoreceptors and mechanotransducers include ion channels, specialized cytoskeletal proteins, cell junction molecules, and G-protein coupled receptors. SMCs are particularly important due to their role as final effectors for motor function. Myogenic reflex-the ability of smooth muscle to contract in response to stretch rapidly-is a critical smooth muscle function. Such rapid mechanotransduction responses rely on mechano-gated and -sensitive ion channels, which alter their ion pores' opening in response to force, allowing fast electrical and Ca2+ responses. Though GI SMCs express a variety of such ion channels, their identities remain unknown. Recent advancements in electrophysiological, genetic, in vivo imaging, and multi-omic technologies broaden our understanding of how SMC mechano-gated and -sensitive ion channels regulate GI functions. This review discusses GI SMC mechanosensitivity's current developments with a particular emphasis on mechano-gated and -sensitive ion channels.


1992 ◽  
Vol 58 ◽  
pp. 138
Author(s):  
Kazuhiro Ohmi ◽  
Shigeru Yamashita ◽  
Takashi Sakurai ◽  
Yoshiaki Nonomura

1975 ◽  
Vol 67 (3) ◽  
pp. 660-674 ◽  
Author(s):  
T N Wight ◽  
R Ross

Proteoglycans were identified and localized histochemically and ultrastructurally in normal and hyperplastic arterial intimas in nonhuman primates (Macaca nemestrina). These regions were consistently more alcianophilic than the adjacent medial layers and this alcianophilia was absent after treatment with glycosaminoglycan-degradative enzymes. Ultrastructurally, the intimal intercellular matrix consisted of numerous, irregularly shaped, 200-500-A diameter granules possessing 30--60-A diameter filamentous projections, and these granules were dispersed between collagen and elastic fibers. The granules exhibited a marked affinity for ruthenium red and were interconnected via their filamentous projections. The ruthenium red-positive granules were intimately associated with the plasma membrane of intimal smooth muscle cells and attached to collagen fibrils and elastic fibers. The matrix granules were completely removed after testicular hyaluronidase or chondroitinase ABC digestion but only partially removed after leech hyaluronidase treatment. These results suggest that the matrix granules contain some hyaluronic acid and one or more isomers of chondroitin sulfate. In addition to the large ruthenium red-positive matrix granules, a smaller class of ruthenium red-positive granule (100--200-A diameter) was present within the basement membranes beneath the endothelium and surrounding the smooth muscle cells. Ruthenium red also exhibited an affinity for the surface coat of the smooth muscle cells. The potential importance of proteoglycans in arterial intimal hyperplasia is discussed.


1997 ◽  
Vol 137 (4) ◽  
pp. 925-937 ◽  
Author(s):  
Jill E. Hungerford ◽  
James P. Hoeffler ◽  
Chauncey W. Bowers ◽  
Lisa M. Dahm ◽  
Rocco Falchetto ◽  
...  

The assembly of the vessel wall from its cellular and extracellular matrix components is an essential event in embryogenesis. Recently, we used the descending aorta of the embryonic quail to define the morphological events that initiate the formation of a multilayered vessel wall from a nascent endothelial cell tube (Hungerford, J.E., G.K. Owens, W.S. Argraves, and C.D. Little. 1996. Dev. Biol. 178:375–392). We generated an mAb, 1E12, that specifically labels smooth muscle cells from the early stages of development to adulthood. The goal of our present study was to characterize further the 1E12 antigen using both cytological and biochemical methods. The 1E12 antigen colocalizes with the actin cytoskeleton in smooth muscle cells grown on planar substrates in vitro; in contrast, embryonic vascular smooth muscle cells in situ contain 1E12 antigen that is distributed in threadlike filaments and in cytoplasmic rosette-like patterns. Initial biochemical analysis shows that the 1E12 mAb recognizes a protein, Mr = 100,000, in lysates of adult avian gizzard. An additional polypeptide band, Mr = 40,000, is also recognized in preparations of lysate, when stronger extraction conditions are used. We have identified the 100-kD polypeptide as smooth muscle α-actinin by tandem mass spectroscopy analysis. The 1E12 antibody is an IgM isotype. To prepare a more convenient 1E12 immunoreagent, we constructed a single chain antibody (sFv) using recombinant protein technology. The sFv recognizes a single 100-kD protein in gizzard lysates. Additionally, the recombinant antibody recognizes purified smooth muscle α-actinin. Our results suggest that the 1E12 antigen is a member of the α-actinin family of cytoskeletal proteins; furthermore, the onset of its expression defines a primordial cell restricted to the smooth muscle lineage.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mara Martín-Alonso ◽  
Sharif Iqbal ◽  
Pia M. Vornewald ◽  
Håvard T. Lindholm ◽  
Mirjam J. Damen ◽  
...  

AbstractSmooth muscle is an essential component of the intestine, both to maintain its structure and produce peristaltic and segmentation movements. However, very little is known about other putative roles that smooth muscle cells may have. Here, we show that smooth muscle cells may be the dominant suppliers of BMP antagonists, which are niche factors essential for intestinal stem cell maintenance. Furthermore, muscle-derived factors render epithelium reparative and fetal-like, which includes heightened YAP activity. Mechanistically, we find that the membrane-bound matrix metalloproteinase MMP17, which is exclusively expressed by smooth muscle cells, is required for intestinal epithelial repair after inflammation- or irradiation-induced injury. Furthermore, we propose that MMP17 affects intestinal epithelial reprogramming after damage indirectly by cleaving diffusible factor(s) such as the matricellular protein PERIOSTIN. Together, we identify an important signaling axis that establishes a role for smooth muscle cells as modulators of intestinal epithelial regeneration and the intestinal stem cell niche.


2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jennifer Claire Hoving ◽  
Roanne Keeton ◽  
Maxine A. Höft ◽  
Mumin Ozturk ◽  
Patricia Otieno-Odhiambo ◽  
...  

A hallmark of ulcerative colitis is the chronic colonic inflammation, which is the result of a dysregulated intestinal mucosal immune response. Epithelial barrier disruption which allows the entry of microorganisms eventually leads to more aggressive inflammation and potentially the removal of the colon. We have previously shown that the T helper- (Th-) type 2 cytokines, Interleukin- (IL-) 4 and IL-13, mediate CD4+ T cell- or B cell-driven inflammation in the oxazolone-induced mouse model of ulcerative colitis. In contrast, mice deficient in the shared receptor of IL-4 and IL-13, IL-4 receptor-alpha (IL-4Rα), on all cells develop an exacerbated disease phenotype. This suggests that a regulatory role of IL-4Rα is required to protect against severe colitis. However, the cell populations responsible for regulating the severity of disease onset through IL-4Rα in colitis are yet to be identified. By deleting IL-4Rα on specific cell subsets shown to play a role in mediating colitis, we determined their role in a loss of function approach. Our data demonstrated that the loss of IL-4Rα signalling on intestinal epithelial cells, smooth muscle cells, and macrophages/neutrophils had no effect on alleviating the pathology associated with colitis. These results suggest that IL-4/IL-13 signalling through IL-4Rα on nonhematopoietic intestinal epithelial or smooth muscle cells and hematopoietic macrophage/neutrophils has a redundant role in driving acute oxazolone colitis.


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