scholarly journals Fibronectin localization in the rat glomerulus.

1980 ◽  
Vol 87 (3) ◽  
pp. 691-696 ◽  
Author(s):  
P J Courtoy ◽  
Y S Kanwar ◽  
R O Hynes ◽  
M G Farquhar
Keyword(s):  
Epithelial Cells ◽  
Mesangial Cell ◽  
Cultured Cells ◽  
Mesangial Cells ◽  
Basement Membranes ◽  
Frozen Sections ◽  
Mesangial Matrix ◽  
Capillary Loop ◽  
Important Constituent

Fibronectin (FN) has been localized in the rat glomerulus using indirect immunolabeling. It was demonstrated in frozen sections by immunofluorescence, in sections of fixed kidneys by both peroxidase and ferritin-labeled antibodies, and in isolated glomerular basement membranes (GBM) with ferritin-labeled antibodies. Complementary and convergent results were obtained with these approaches. FN was most abundant in the mesangial matrix where it was especially concentrated at the interface between the endothelial and mesangial cells. In the peripheral capillary loop, FN was also detected in the laminae rarae (interna and externa) of the GBM--i.e., between the endothelial and epithelial cells, respectively, and the GBM. These findings indicate that FN is an important constituent of the glomerulus, and they are compatible with the assumption that, in the glomerulus, as in cultured cells, FN is involved in cell-to-cell (mesangial-mesangial, mesangial-endothelial) and cell-to-substrate (mesangial cell-mesangial matrix, epithelium-GBM, endothelium-GBM) attachment.

scholarly journals Ultrastructural localization of fibronectin and laminin in the basement membranes of the murine kidney.

1980 ◽  
Vol 86 (2) ◽  
pp. 682-687 ◽  
Author(s):  
J A Madri ◽  
F J Roll ◽  
H Furthmayr ◽  
J M Foidart
Keyword(s):  
Mesangial Cell ◽  
Ultrastructural Localization ◽  
Ultrastructural Level ◽  
Basement Membranes ◽  
Frozen Sections ◽  
Mesangial Matrix ◽  
Lamina Densa ◽  
Rabbit Igg ◽  
Cell Processes ◽  
Bowman's Capsule

Affinity-purified rabbit antibodies specific for two large noncollagenous gycoproteins--laminin and fibronectin--were used to study the distribution of these proteins in normal murine kidneys. Immunofluorescence staining of conventional frozen sections demonstrates fibronectin within mesangial areas of the glomerulus. Laminin is also found in mesangial areas. However, it also appears to be distributed in typical basement membranelike patterns on glomerular and tubular basement membranes and Bowman's capsule. At the ultrastructural level, by labeling 600-800-A thick frozen sections with a three-stage procedure consisting of specific antibodies, biotinyl sheep anti-rabbit IgG, and avidin-ferritin conjugates, fibronectin is present ony in the mesangial matrix and is specifically localized to areas immediately surrounding mesangial cell processes. Laminin, on the other hand, is found uniformly distributed throughout tubular basement membranes, the mesangial matrix, and Bowman's capsule. In glomerular basement membranes, laminin labeling is restricted to the lamina rara interna and adjacent regions of the lamina densa.

Vasoactive agents affect mesangial cell adhesion

1986 ◽  
Vol 251 (4) ◽  
pp. C505-C511 ◽  
Author(s):  
J. I. Kreisberg ◽  
M. A. Venkatachalam
Keyword(s):  
Cell Adhesion ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Mesangial Cell ◽  
Cultured Cells ◽  
Mesangial Cells ◽  
Stress Fibers ◽  
Vasoactive Agents ◽  
Substrate Adhesion ◽  
Adhesive Contacts

The formation and maintenance of stress fibers in cultured mesangial cells is associated with myosin light chain phosphorylation [Kreisberg et al. Am. J. Physiol. 249 (Renal Fluid Electrolyte Physiol. 18): F227-F235, 1985], a biochemical indicator for activation of actin-myosin interactions. Agents that elevate intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP) (e.g., isoproterenol) fragment stress fibers and cause myosin light chain dephosphorylation, whereas the addition of contractile agents such as arginine vasopressin (AVP) and prostaglandin E2 (PGE2) reverses these changes. Because stress fiber development in cultured cells is correlated with tight cell to substrate adhesion, we wanted to examine whether vasoactive agents have an effect on mesangial cell adhesion. Both isoproterenol and dibutyryl cAMP (DBcAMP) reduced mesangial cell adherence as measured by a trypsin assay (% detached cells: control 11 +/- 2.4%; isoproterenol plus isobutylmethylxanthine (IBMX) = 48.3 +/- 7.4%; DBcAMP = 29.3 +/- 3.7%; DBcAMP-IBMX = 73 +/- 4.4%). The areas of focal (adhesive) contacts between the cell and substratum as observed by interference-reflexion microscopy were also reduced, being replaced by areas of greater separation (% of the surface in contact with the substratum: control = 7.4 +/- 0.8%; isoproterenol-IBMX = 2.9 +/- 1.1%). Addition of PGE2 or AVP to the incubation medium containing the cAMP-elevating agents prevented the above changes. PGE2 or AVP alone increased mesangial cell adhesion (% detached cells: control 11 +/- 2.4%; PGE2 = 6.8 +/- 0.5%; AVP = 5.1 +/- 1.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of Cultured Mesangial Matrix Protein Production by the Bradford Technique

1997 ◽  
Vol 64 (3) ◽  
pp. 344-345
Author(s):  
A. Mukhtar
Keyword(s):  
Protein Production ◽  
Matrix Protein ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Extracellular Volume ◽  
Matrix Proteins ◽  
Cell Protein ◽  
Mesangial Matrix ◽  
Cell Contraction ◽  
Glomerular Diseases

It has been suggested that mesangial cell contraction can adapt the glomerular tuft in response to variations in extracellular volume, although the relevance of mesangial cell contraction for the regulation of glomerular haemodynamics appeared to be small. Mesangial matrix is an intercellular substance morphologically similar to but biochemically distinct from glomerular basement membrane. This study measures the amount of stimulated and non-stimulated mesangial cell protein production in culture using the Bradford technique. This study shows the effect of cytokines in altering extracellular matrix proteins produced by mesangial cells and it shows that IL-1 increases the amount of matrix proteins while PMA decreases them compared to the non-stimulated cells. These in turn could lead to the alteration of pore size, matrix properties and filtration, and thus influence the development and progression of glomerular diseases.

scholarly journals Codistribution of collagen types IV and AB2 in basement membranes and mesangium of the kidney. an immunoferritin study of ultrathin frozen sections.

1980 ◽  
Vol 85 (3) ◽  
pp. 597-616 ◽  
Author(s):  
F J Roll ◽  
J A Madri ◽  
J Albert ◽  
H Furthmayr
Keyword(s):  
Ultrastructural Level ◽  
Basement Membranes ◽  
Frozen Sections ◽  
Mesangial Matrix ◽  
Collagen Types ◽  
Type Iv ◽  
Collagen Antibodies ◽  
Ultrathin Frozen Sections ◽  
Bowman's Capsule ◽  
Large Vessels

Affinity-purified rabbit antibodies specific for collagen types I, III, AB2 and for a partially characterized type IV collagen derived from a murine tumor were used to study the distribution of collagens in the normal mouse kidney. Immunofluorescence staining of conventional frozen sections demonstrated that types I and III were present in bundles around large vessels and in fibers surrounding glomeruli and tubules, whereas types IV and AB2 were distributed in a linear fashion along basement membranes of tubules, glomeruli, and Bowman's capsule and in the mesangial stalk. The distribution of types IV nd AB2 was examined at the ultrastructural level by staining of 600- to 800-A thick frozen sections with a three-stage procedure employing specific collagen antibodies, biotinyl sheep antirabbit IgG, and avidin-ferritin conjugates. Labeling by this procedure demonstrated codistribution of types AB2 and the putative type IV in all three basement membranes. In addition, mesangial matrix was shown to contain both of these collagen types. These results support recent biochemical evidence of collagen heterogeneity in basement membranes, and also support the concept of a structural relationship between mesangial matrix and glomerular basement membranes.

scholarly journals Mesangial cells organize the glomerular capillaries by adhering to the G domain of laminin α5 in the glomerular basement membrane

2003 ◽  
Vol 161 (1) ◽  
pp. 187-196 ◽  
Author(s):  
Yamato Kikkawa ◽  
Ismo Virtanen ◽  
Jeffrey H. Miner
Keyword(s):  
Cell Adhesion ◽  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Basement Membranes ◽  
Domain Specific ◽  
Integrin Α3β1 ◽  
Glomerular Capillaries

In developing glomeruli, laminin α5 replaces laminin α1 in the glomerular basement membrane (GBM) at the capillary loop stage, a transition required for glomerulogenesis. To investigate domain-specific functions of laminin α5 during glomerulogenesis, we produced transgenic mice that express a chimeric laminin composed of laminin α5 domains VI through I fused to the human laminin α1 globular (G) domain, designated Mr51. Transgene-derived protein accumulated in many basement membranes, including the developing GBM. When bred onto the Lama5 −/− background, Mr51 supported GBM formation, preventing the breakdown that normally occurs in Lama5 −/− glomeruli. In addition, podocytes exhibited their typical arrangement in a single cell layer epithelium adjacent to the GBM, but convolution of glomerular capillaries did not occur. Instead, capillaries were distended and exhibited a ballooned appearance, a phenotype similar to that observed in the total absence of mesangial cells. However, here the phenotype could be attributed to the lack of mesangial cell adhesion to the GBM, suggesting that the G domain of laminin α5 is essential for this adhesion. Analysis of an additional chimeric transgene allowed us to narrow the region of the α5 G domain essential for mesangial cell adhesion to α5LG3-5. Finally, in vitro studies showed that integrin α3β1 and the Lutheran glycoprotein mediate adhesion of mesangial cells to laminin α5. Our results elucidate a mechanism whereby mesangial cells organize the glomerular capillaries by adhering to the G domain of laminin α5 in the GBM.

scholarly journals Heparin decreases mesangial matrix accumulation after selective antibody-induced mesangial cell injury.

1992 ◽  
Vol 3 (4) ◽  
pp. 921-929
Author(s):  
W W Tang ◽  
C B Wilson
Keyword(s):  
Cell Proliferation ◽  
Cell Injury ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Chronic Administration ◽  
Glomerular Mesangial Cells ◽  
Mesangial Matrix ◽  
Beneficial Effects ◽  
Mesangial Cell Proliferation ◽  
Matrix Accumulation

Anti-rat thymocyte antibody-induced injury of glomerular mesangial cells is characterized initially by lysis (1 h) and is followed by proliferation (beginning at 3 to 4 days), with resolution that can include a focal increase in mesangial matrix (by 28 days). Chronic administration (every 12 h) of heparin (anticoagulant or nonanticoagulant) resulted in a decrease in antibody-induced mesangial cell proliferation, which, in turn, was associated with a decrease in the size and number of areas of focal mesangial matrix increase. The effect could not be attributed to the effect of heparin on complement, to alterations in the small numbers of la-positive cells that characterize the lesion, or to binding of antibody to glomeruli. The beneficial effects of heparin in reducing mesangial cell proliferation, with a subsequent reduction in matrix increase, suggest that mesangial cell responses are a major element in the development of at least some forms of glomerulosclerosis. The possible mechanisms by which these effects of heparin may be achieved are discussed.

scholarly journals Species-specific properties of the glomerular mesangium.

1993 ◽  
Vol 3 (7) ◽  
pp. 1342-1350
Author(s):  
J D Sraer ◽  
C Adida ◽  
M N Peraldi ◽  
E Rondeau ◽  
A Kanfer
Keyword(s):  
Angiotensin Ii ◽  
Prostaglandin E2 ◽  
Mesangial Cell ◽  
Cultured Cells ◽  
Mesangial Cells ◽  
Human Mesangial Cells ◽  
Infiltrating Cells ◽  
Single Nephron ◽  
Species Specific

Mesangial cells play a central role in the physiology and pathophysiology of the glomerulus. To date, most of the in vitro studies have been performed in cultured rat mesangial cells, with only 10% of them performed in human mesangial cells. In this article, the major differences between results obtained with these two types of cultured cells will be reviewed. In rats and in humans, most of the mesangial cells appear to be of smooth muscle origin. In the rat, some of the cultured cells also express a phenotype suggesting a monocyte/macrophage origin. Phagocytosis and synthesis of cytokines or proinflammatory proteins that have been described in cultured rat cells seem mostly linked to this monocyte/macrophage subtype of resident mesangial cells. In humans, macrophages are only detected in pathologic conditions, suggesting that they are not resident but rather infiltrating cells. Mesangial receptors, most notably angiotensin II receptors, are clearly present on mesangial cell membranes and are linked to prostaglandin E2 synthesis and to cell contraction. In humans, spontaneous prostanoid synthesis is low and is increased by the induction of cyclooxygenase by sodium butyrate in the medium. Even so, the amount of prostaglandin E2 synthesized by human mesangial cells is quantitatively low comparatively with that in rats. In rats, accordingly, mesangial cells play a role in the regulation of single-nephron GFR. In humans, angiotensin II also exerts a control on GFR but it is more difficult to demonstrate its contractile effect on human than on rat mesangial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Proteolytic processing of endogenous and recombinant beta 4 integrin subunit.

1992 ◽  
Vol 118 (4) ◽  
pp. 951-959 ◽  
Author(s):  
F G Giancotti ◽  
M A Stepp ◽  
S Suzuki ◽  
E Engvall ◽  
E Ruoslahti
Keyword(s):  
Epithelial Cells ◽  
Cultured Cells ◽  
Cytoplasmic Domain ◽  
Basement Membranes ◽  
Proteolytic Processing ◽  
In Vitro Assays ◽  
Integrin Subunit ◽  
Calcium Dependent

The alpha 6 beta 4 integrin is a receptor involved in the interaction of epithelial cells with basement membranes. This integrin is unique among the known integrins in that its beta 4 subunit has a large cytoplasmic domain. The function of this cytoplasmic domain is not known. In this paper we show that the beta 4 subunit undergoes proteolytic processing in cultured cells and provide evidence that this also happens in tissues. Immunoprecipitation experiments indicated that the cytoplasmic domain of beta 4 is susceptible to a calcium-dependent protease present in cellular extracts. In vitro assays with purified calpain showed that this enzyme can cleave beta 4 at two distinct sites in the cytoplasmic domain, generating truncated molecules of 165 and 130 kD. Immunoblotting experiments performed on cultured epithelial cells using an antibody to a peptide modeled after the COOH-terminus of the beta 4 subunit showed 70-kD fragments and several fragments of molecular masses between 185 and 115 kD. Similar fragments were detected in CHO cells transfected with the full-length beta 4 cDNA, but not in control transfected cells or in cells transfected with a mutant cDNA lacking the epitope of the cytoplasmic peptide antibody. The sizes of the fragments indicated that both the intracellular and extracellular domains of beta 4 are proteolytically processed. To examine the processing of the beta 4 subunit in epithelial tissues in vivo, human skin frozen sections were stained with antibodies to the ectodomain or the cytoplasmic domain of beta 4. The distinct staining patterns obtained with the two types of antibodies provided evidence that beta 4 is proteolytically processed in vivo in skin. Analogous experiments performed on sections of the cornea suggested that beta 4 is not proteolytically processed at a detectable level in this tissue. Thus, cleavage of the beta 4 subunit occurs in a tissue-specific fashion. These results suggest a potential mechanism of modulating the activities of the alpha 6 beta 4 integrin.

scholarly journals Expression of Megsin mRNA, a Novel Mesangium-Predominant Gene, in the Renal Tissues of Various Glomerular Diseases

1999 ◽  
Vol 10 (12) ◽  
pp. 2606-2613
Author(s):  
DAISUKE SUZUKI ◽  
TOSHIO MIYATA ◽  
MASAOMI NANGAKU ◽  
HIDEO TAKANO ◽  
NOBORU SAOTOME ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Periodic Acid ◽  
Cell Number ◽  
Mesangial Matrix ◽  
Periodic Acid Schiff ◽  
Glomerular Diseases ◽  
Mesangial Cell Proliferation ◽  
Matrix Expansion

Abstract. Mesangial cells play an important role in maintaining a structure and function of the glomerulus and in the pathogenesis of glomerular diseases. Recently, we discovered a new mesangium-predominant gene termed “megsin.” Megsin is a novel protein that belongs to the serine protease inhibitor (serpin) superfamily. To elucidate the pathophysiologic role of megsin in the kidney, the expression and localization of megsin mRNA in renal tissues of patients with IgA nephropathy (IgA-N), diabetic nephropathy (DN), minimal change nephrotic syndrome (MCNS), membranous nephropathy (MN), and normal human kidney (NHK) was evaluated by in situ hybridization using digoxigenin-labeled oligonucleotide. Individual cells positive for megsin mRNA were observed only in glomeruli in all renal tissues. Their localization coincided with those of mesangial cells. The percentage of positive cells for megsin mRNA in total glomerular cells was significantly greater in IgA-N than in MCNS, MN, and NHK. It was also significantly greater in DN than in MCNS and NHK. In IgA-N, the percentage of megsin mRNA-positive cells was greater in tissues from those with mesangial cell proliferation and slightly mesangial matrix expansion (periodic acid-Schiff-positive area in the total glomerulus area, <30%; cell number in mesangial matrix area, >30; assessed in cross-sections through their vascular poles) than in tissues from those with severe mesangial matrix expansion (periodic acid-Schiff-positive area in total glomerulus area, >30%; cell number in mesangial matrix area, <30). In conclusion, megsin mRNA was predominantly expressed in glomerular mesangial cells in all renal tissues. The expression of megsin mRNA was upregulated in IgA-N and DN, both of which are diseases accompanied with mesangial cell proliferation and/or mesangial matrix expansion. These data suggest a link of megsin expression to the pathogenesis of IgA-N and DN, two major causes of end-stage renal failure.

scholarly journals The activated mesangial cell: a glomerular "myofibroblast"?

1992 ◽  
Vol 2 (10) ◽  
pp. S190 ◽  
Author(s):  
R J Johnson ◽  
J Floege ◽  
A Yoshimura ◽  
H Iida ◽  
W G Couser ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Mesangial Cell ◽  
De Novo ◽  
Mesangial Cells ◽  
Smooth Muscle Actin ◽  
Mesangial Matrix ◽  
Glomerular Injury ◽  
Alpha Smooth Muscle Actin ◽  
Glomerular Mesangial Cell ◽  
Structural Support

The glomerular mesangial cell may have several important beneficial functions in the normal glomerulus. These include the production of growth factors to allow normal cell turnover, the provision of structural support for the capillaries via the production of mesangial matrix, and the modulation of glomerular hemodynamics via their contractile properties. However, in various types of glomerular injury, the mesangial cell may acquire characteristics of a "myofibroblast", which may in fact be injurious to the glomerulus. These "activated" mesangial cells can be shown to be proliferating by one or more mechanisms that are mediated by platelets and that also involve the local production of platelet-derived growth factor. Like myofibroblasts in other tissues, the mesangial cell acquires smooth muscle cell-like properties, characterized by the de novo expression of alpha-smooth muscle actin, and by the development of fibroblast-like properties, characterized by the production of interstitial collagens in addition to normal mesangial matrix constituents. Identifying therapeutic strategies that prevent this phenotypic modulation of the mesangial cell may provide new ways to treat golmerular diseases.

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