Contribution of the Minor Chain Type IV Collagen Network to the Mechanics of the Ocular Lens Capsule

2012 ◽  
Author(s):  
Lazarina Gyoneva ◽  
Yoav Segal ◽  
Kevin D. Dorfman ◽  
Victor H. Barocas
Keyword(s):  
Alport Syndrome ◽  
Type Iv Collagen ◽  
Dry Weight ◽  
Hereditary Disease ◽  
Collagen Iv ◽  
Lens Capsule ◽  
Basement Membranes ◽  
Ocular Lens ◽  
Ocular Manifestations ◽  
Type Iv

The ocular lens capsule (LC) is a specialized basement membrane which completely surrounds the lens. The LC serves as an attachment point for lens epithelial and fiber cells, controls lens solute and water transport, and makes accommodation possible [1]. It is primarily composed of type IV collagen (65% of dry weight), laminin, nidogen, and proteoglycans, of which type IV collagen is the main-tension resisting element [1,2]. Collagen IV monomers organize into polygonal planar networks resembling chicken wire (Fig.1) [3]. There are six different collagen IV monomers, labeled α1(IV) to α6(IV) each produced by a separate gene – COL4A1 to COL4A6. Monomers form triple helical protomers in a highly selective manner. In nature, only three monomer combinations have been discovered: the [α1(IV)]2α2(IV) protomer, referred to as the major chain, is found in all basement membranes; the α3(IV)α4(IV)α5(IV) protomer (minor chain) is found only in few basement membranes including the LC; the [α5(IV)]2α6(IV) protomer is very rare and will not be discussed further. Protomers of the same type assemble with one another to form separate networks which are known to have some differences [4]. For example, the minor chain network is more cross-linked than the major chain network. In a hereditary disease called Alport syndrome, the minor chain network is completely missing in males due to a mutation in the COL4A5 gene (located on the X chromosome) which prevents production of the α5(IV) monomer. Male Alport syndrome patients have significant ocular manifestations such as anterior lenticonus (protrusion of the lens), cataract, and even lens rupture [5] and they exhibit significant thinning of the LC. Because 1) the minor network is more cross-linked than the major network, 2) its absence affects lens shape, and 3) the LC displays pathological disruptions when it is missing, we theorize that its presence confers additional mechanical strength to the LC. Therefore, the objective of this study is to assess the contribution of the minor chain network to the mechanics of the LC.

Role of Lateral Interactions in Type IV Collagen Network Mechanics

2013 ◽  
Author(s):  
Lazarina Gyoneva ◽  
Mohammad F. Hadi ◽  
Yoav Segal ◽  
Kevin D. Dorfman ◽  
Victor H. Barocas
Keyword(s):  
Mechanical Properties ◽  
Basement Membrane ◽  
Type Iv Collagen ◽  
Type I Collagen ◽  
Hereditary Disease ◽  
Collagen Iv ◽  
Basement Membranes ◽  
Type I ◽  
Lateral Interactions ◽  
Type Iv

The basement membrane is a specialized part of the extra-cellular matrix. It is usually characterized as a scaffold for epithelial cells but in some tissues it serves other, mechanical, roles [1]. The mechanical properties of the basement membrane are mainly determined by one of its main constituents — type IV collagen. Unlike the well-known fibrous type I collagen, collagen IV assembles into planar networks (Fig. 1) [2]. The α 1(IV) and α 2(IV) collagen IV chains assemble into the so-called major chain network, present in all basement membranes. The α 3(IV), α 4(IV), α 5(IV) collagen IV chains form the minor chain network which is found only in the adult basement membranes of the kidney glomerular capillaries (GBM), ocular lens (LBM), cochlea, and the testes [3]. The minor chains have a higher number of cysteine residues, allowing them to form a higher number of lateral interactions. In the minor chain network, the greater potential to interact laterally manifests in the formation of super-coils, which are rarely observed in the major chain network [4]. Increasing the number of cross-links in a polymeric material is known to increase material stiffness; therefore, it is believed that the minor chain network confers basement membranes with additional strength and stability [5]. In the hereditary disease Alport syndrome, a mutation causes the absence of the minor chain network. The GBM and LBM of Alport patients appear weakened and unable to meet their mechanical demands, further supporting this theory [6]. The objective of this study was to evaluate the importance of cross-linking in the minor chains for the mechanical properties of type IV collagen networks, specifically in the GBM and LBM where the absence of the minor chains has an observed mechanical effect.

scholarly journals Expression of collagen type IV in human kidney during prenatal development

2020 ◽  
pp. 111-111
Author(s):  
Vladimir Petrovic ◽  
Ivan Nikolic ◽  
Marko Jovic ◽  
Vladimir Zivkovic ◽  
Miodrag Jocic ◽  
...  
Keyword(s):  
Type Iv Collagen ◽  
Collagen Type ◽  
Kidney Tissue ◽  
Volume Density ◽  
Collagen Iv ◽  
Basement Membranes ◽  
Collagen Type Iv ◽  
Type Iv ◽  
Metanephric Kidney ◽  
Collecting System

Background / Aim. Type IV collagen belongs to the group of non-fibrillar collagens and is an important component of the basement membranes where it accounts for approximately 50% of its structural elements. The aim of the paper was to describe the expression and distribution of collagen type IV in embryonic and fetal metanephric kidney, and to determine the volume density of collagen type IV in kidney tissue in each trimester of development. Methods. The material consisted of 19 human embryos/fetuses, in the gestational age from 8th to 37th week. Kidney tissue specimens were routinely processed to paraffin molds and stained with hematoxylin and eosin and immunohistochemically using polyclonal anti-collagen IV antibody. Stained slides were examined using light microscope and images of the selected areas, under different lens magnification were captured with digital camera. Volume density of collagen type IV was determined by using ImageJ 1.48v and a plugin of the software which inserted a grid system with 336 points. For the data comparison One-Way Analysis of Variance was used. Results. Strong collagen IV immunopositivity was seen in all specimens, with a distribution in the basement membranes of urinary bud, parietal leaf of Bowman?s capsule, glomerular basement membrane, basement membrane of interstitial blood vessels, and basement membranes of nephron tubules and collecting ducts. No statistically significant difference in the volume density of type IV collagen was found between the different trimesters of development. Conclusion. The synthesis and secretion of collagen type IV simultaneously follows the development of nephron structures, collecting system and blood vessels. The volume density of collagen type IV remains constant throughout all the trimesters of metanephric kidney development, indicating that it plays a crucial role in normal development of nephron and collecting system structures, as well as in maintaining the normal kidney function.

scholarly journals Developmental acquisition of basement membrane heterogeneity: type IV collagen in the avian lens capsule.

1983 ◽  
Vol 97 (3) ◽  
pp. 940-943 ◽  
Author(s):  
J M Fitch ◽  
R Mayne ◽  
T F Linsenmayer
Keyword(s):  
Basement Membrane ◽  
Type Iv Collagen ◽  
Lens Capsule ◽  
Basement Membranes ◽  
Developmentally Regulated ◽  
Membrane Heterogeneity ◽  
Domain Specific ◽  
Type Iv ◽  
Anterior Lens Capsule ◽  
Immunohistochemical Analyses

To investigate potential heterogeneity and developmental changes in basement membranes during embryogenesis, we performed immunohistochemical analyses on lens capsules in chicken embryos of different ages using domain-specific monoclonal antibodies against type IV collagen. We found that the capsule of the newly formed lens stained uniformly with antibodies against this component of basement membranes, but with increasing age and differentiation of the lens cells the anterior lens capsule remained brightly fluorescent while staining of the posterior capsule became relatively much less intense. This antero-posterior gradient of anti-type IV collagen antibody reactivity demonstrated that developmentally-regulated changes can occur within a single, continuous basement membrane.

Alport Syndrome

2021 ◽  
pp. 373-375
Author(s):  
Karpagam J. ◽  
Pandimeena. P
Keyword(s):  
Hearing Loss ◽  
Alport Syndrome ◽  
Type Iv Collagen ◽  
Hereditary Disease ◽  
Collagen Gene ◽  
Dominant Form ◽  
Type Iv ◽  
Ocular Changes

Alport syndrome (AS) is a type IV collagen hereditary disease characterized by the association of progressive Hematuric nephritis, hearing loss, and, frequently, ocular changes. Mutations in the COL4A5 collagen gene are responsible for the more common X-linked dominant form of the disease.

scholarly journals Immunogold quantitation of laminin, type IV collagen, and heparan sulfate proteoglycan in a variety of basement membranes.

1988 ◽  
Vol 36 (3) ◽  
pp. 271-283 ◽  
Author(s):  
D S Grant ◽  
C P Leblond
Keyword(s):  
Heparan Sulfate ◽  
Type Iv Collagen ◽  
Collagen Iv ◽  
Heparan Sulfate Proteoglycan ◽  
Basement Membranes ◽  
Enamel Organ ◽  
Sulfate Proteoglycan ◽  
Lamina Densa ◽  
Type Iv ◽  
Reichert's Membrane

A series of basement membranes was immunolabeled for laminin, type IV collagen, and heparan sulfate proteoglycan in the hope of comparing the content of these substances. The basement membranes, including thin ones (less than 0.3 micron) from kidney, colon, enamel organ, and vas deferens, and thick ones (greater than 2 micron), i.e., Reichert's membrane, Descemet's membrane, and EHS tumor matrix, were fixed in formaldehyde, embedded in Lowicryl, and treated with specific antisera or antibodies followed by anti-rabbit immunoglobulin bound to gold. The density of gold particles, expressed per micron2, was negligible in controls (less than or equal to 1.1), but averaged 307, 146, and 23, respectively, for laminin, collagen IV, and proteoglycan over the thick basement membranes (except for Descemet's membranes, over which the density was 16, 5, and 34, respectively) and 117, 72, and 64, respectively, over the lamina densa of the thin basement membranes. Lower but significant reactions were observed over the lamina lucida. Interpretation of the gold particle densities was based on (a) the similarity between the ultrastructure of most thick basement membranes and of the lamina densa of most thin basement membranes, and (b) the biochemical content of the three substances under study in the EHS tumor matrix (Eur J Biochem 143:145, 1984). It was proposed that thick basement membranes (except Descemet's) contained more laminin and collagen IV but less heparan sulfate proteoglycan than the lamina densa of thin basement membranes. In the latter, there was a fair variation from tissue to tissue, but a tendency towards a similar molar content of the three substances.

scholarly journals Distribution of α‐chains of type IV collagen in glomerular basement membranes with ultrastructural alterations suggestive of Alport syndrome

2001 ◽  
Vol 16 (5) ◽  
pp. 945-952 ◽  
Author(s):  
Paola Barsotti ◽  
Andrea Onetti Muda ◽  
Gianna Mazzucco ◽  
Laura Massella ◽  
Bruno Basolo ◽  
...  
Keyword(s):  
Alport Syndrome ◽  
Type Iv Collagen ◽  
Basement Membranes ◽  
Ultrastructural Alterations ◽  
Type Iv

scholarly journals Analysis of the role of Nidogen/entactin in basement membrane assembly and morphogenesis in Drosophila

2018 ◽  
Author(s):  
Jianli Dai ◽  
Beatriz Estrada ◽  
Sofie Jacobs ◽  
Besaiz J. Sánchez-Sánchez ◽  
Jia Tang ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Type Iv Collagen ◽  
Collagen Iv ◽  
Basement Membranes ◽  
Extracellular Matrices ◽  
Tissue Specific ◽  
Type Iv

AbstractBasement membranes (BMs) are thin sheet-like specialized extracellular matrices found at the basal surface of epithelia and endothelial tissues. They have been conserved across evolution and are required for proper tissue growth, organization, differentiation and maintenance. The major constituents of BMs are two independent networks of Laminin and Type IV Collagen interlinked by the proteoglycan Perlecan and the glycoprotein Nidogen/entactin (Ndg). The ability of Ndg to bind in vitro Collagen IV and Laminin, both with key functions during embryogenesis, anticipated an essential role for Ndg on morphogenesis linking the Laminin and Collagen IV networks. This was supported by results from in vitro and cultured embryonic tissues experiments. However, the fact that elimination of Ndg in C. elegans and mice did not affect survival, strongly questioned this proposed linking role. Here, we have isolated mutations in the only Ndg gene present in Drosophila. We find that while, similar to C.elegans and mice, Ndg is not essential for overall organogenesis or viability, it is required for appropriate fertility. We also find, alike in mice, tissue-specific requirements of Ndg for proper assembly and maintenance of certain BMs, namely those of the adipose tissue and flight muscles. In addition, we have performed a thorough functional analysis of the different Ndg domains in vivo. Our results support an essential requirement of the G3 domain for Ndg function and unravel a new key role for the Rod domain in regulating Ndg incorporation into BMs. Furthermore, uncoupling of the Laminin and Collagen IV networks is clearly observed in the larval adipose tissue in the absence of Ndg, indeed supporting a linking role. In light of our findings, we propose that BM assembly and/or maintenance is tissue-specific, which could explain the diverse requirements of a ubiquitous conserved BM component like Nidogen.Author SummaryBasement membranes (BMs) are thin layers of specialized extracellular matrices present in every tissue of the human body. Its main constituents are two networks of Laminin and Type IV Collagen linked by Nidogen (Ndg) and proteoglycans. They form an organized scaffold that regulates organ morphogenesis and function. Mutations affecting BM components are associated with organ dysfunction and several congenital diseases. Thus, a better comprehension of BM assembly and maintenance will not only help to learn more about organogenesis but also to a better understanding and, hopefully, treatment of these diseases. Here, we have used Drosophila to analyse the role of Ndg in BM formation in vivo. Elimination of Ndg in worms and mice does not affect survival, strongly questioning its proposed linking role, derived from in vitro experiments. Here, we show that in the fly Ndg is dispensable for BM assembly and preservation in many tissues, but absolutely required in others. Furthermore, our functional study of the different Ndg domains challenges the significance of some interactions between BM components derived from in vitro experiments, while confirming others, and reveals a new key requirement for the Rod domain in Ndg function and incorporation into BMs.

scholarly journals Abnormal Glomerular Basement Membrane Laminins in Murine, Canine, and Human Alport Syndrome: Aberrant Laminin α2 Deposition Is Species Independent

2001 ◽  
Vol 12 (2) ◽  
pp. 252-260
Author(s):  
CLIFFORD E. KASHTAN ◽  
YOUNGKI KIM ◽  
GEORGE E. LEES ◽  
PAUL S. THORNER ◽  
ISMO VIRTANEN ◽  
...  
Keyword(s):  
Alport Syndrome ◽  
Type Iv Collagen ◽  
Critical Role ◽  
Basement Membranes ◽  
Type Iv ◽  
Normal Human ◽  
Composition Structure ◽  
Type V ◽  
And Function ◽  
Laminin Α2

Abstract. Kidneys from mice, dogs, and humans with X-linked and autosomal-recessive forms of Alport syndrome were examined by immunofluorescence for expression of laminin α, β, and γ chains using monospecific antibodies. Laminin α2 chain was absent from glomerular basement membranes (GBM) in normal human, murine, and canine kidneys but was abnormally deposited in Alport GBM, regardless of species or inheritance pattern. In murine and canine Alport kidneys, laminin α2 seems to be deposited as part of both laminin-2 (α2β1γ1) and laminin-4 (α2β2γ1) but as part of only laminin-4 in human Alport kidneys. GBM laminin α2 chain deposition was not observed in a variety of non-Alport human glomerulopathies. This finding adds to the list of proteins that are aberrantly deposited in Alport GBM as a consequence of the absence of the α3, α4, and α5 chains of type IV collagen: (1) type IV collagen α1 and α2 chains, (2) type V collagen, (3) type VI collagen, and most recently (4) the laminin α2 chain and (5) the laminin α1 and β1 chains in mice and dogs. These findings emphasize further the critical role played by the α3, α4, and α5 chains of type IV collagen in establishing and maintaining the composition, structure, and function of mature GBM.

scholarly journals The Genetics, Current Research, and Future Treatment of Alport Syndrome

2017 ◽  
Vol 6 (1) ◽  
pp. 1-7
Author(s):  
Elise Alexandra Kikis ◽  
Emily Holland Williams
Keyword(s):  
Basement Membrane ◽  
End Stage Renal Disease ◽  
Alport Syndrome ◽  
Autosomal Recessive ◽  
Type Iv Collagen ◽  
Autosomal Dominant ◽  
Basement Membranes ◽  
Type Iv ◽  
Stage Renal Disease ◽  
End Stage

Alport syndrome is a type IV collagen disease that affects the glomerular basement membrane of approximately one in every 5000 people. The disease was first described by A. Cecil Alport in 1927 as “a dominantly inherited hereditary nephritis.” The three genotypes of the disease are X-linked dominant, autosomal recessive, and autosomal dominant. The X-linked dominant genotype is the most common, accounting for 80% of all cases of Alport syndrome, affecting mainly men. The autosomal recessive and autosomal dominant types affect men and women equally. Alport syndrome is caused by mutations on the COL4A3, COL4A4, and COL4A5 genes, which code the ?3, ?4, and ?5 (IV) chains that make up type IV collagen molecules, an important component of basement membranes. Thus, Alport syndrome results in malformed basement membranes, with symptoms including renal impairment, hematuria, bilateral sensorineural hearing loss, and an abnormal structure of the glomerular basement membrane. Alport syndrome also often progresses to end-stage renal disease, especially in men with X-linked Alport syndrome. At this point, there is no cure for Alport syndrome. However, there are many successful treatments for its symptoms. Angiotensin-converting enzyme (ACE) inhibitors are often given to patients in the early stages of Alport syndrome. For patients with end-stage renal disease, dialysis or kidney transplants are considered the best course of action.

Sign in / Sign up

Export Citation Format

Share Document