Localization and structure of the asparagine-linked oligosaccharides of type IV collagen from glomerular basement membrane and lens capsule

Nayak, BL; Spiro, Robert G.

doi:10.1016/s0021-9258(18)92799-7

Cited by 30 publications

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“…In the 7S domain at the amino terminus, there are numerous hydroxylysine-linked disaccharide units and an asparagine-linked oligosaccharide unit. These carbohydrate units play an important role in the formation and stabilization of the tetramer [29,30]. It is not clear whether the recombinant a(IV) chains in this study were glycosylated or not.…”

Section: Discussionmentioning

confidence: 78%

Characterization of assembly of recombinant type IV collagen α3, α4, and α5 chains in transfected cell strains

Kobayashi

Uchiyama

2003

Kidney International

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Section: Discussionmentioning

confidence: 78%

Characterization of assembly of recombinant type IV collagen α3, α4, and α5 chains in transfected cell strains

Kobayashi

Uchiyama

2003

Kidney International

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“…Thus, these residual anionic sites could reflect negatively charged particles other than HS-GAGs. For example, collagen type IV, which is one of the primary constituents of the GBM, contains negatively charged sialic acid residues (27). Therefore, we cannot exclude the possibility that the residual negatively charged sites in the GBM are sufficient for conferring charge selectivity.…”

Section: Discussionmentioning

confidence: 99%

Glomerular permeability is not affected by heparan sulfate glycosaminoglycan deficiency in zebrafish embryos

Khalil

Lalai

Wiweger

et al. 2019

American Journal of Physiology-Renal Physiology

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Proteinuria develops when specific components in the glomerular filtration barrier have impaired function. Although the precise components involved in maintaining this barrier have not been fully identified, heparan sulfate proteoglycans are believed to play an essential role in maintaining glomerular filtration. Although in situ studies have shown that a loss of heparan sulfate glycosaminoglycans increases the permeability of the glomerular filtration barrier, recent studies using experimental models have shown that podocyte-specific deletion of heparan sulfate glycosaminoglycan assembly does not lead to proteinuria. However, tubular reabsorption of leaked proteins might have masked an increase in glomerular permeability in these models. Furthermore, not only podocytes but also glomerular endothelial cells are involved in heparan sulfate synthesis in the glomerular filtration barrier. Therefore, we investigated the effect of a global heparan sulfate glycosaminoglycan deficiency on glomerular permeability. We used a zebrafish embryo model carrying a homozygous germline mutation in the ext2 gene. Glomerular permeability was assessed with a quantitative dextran tracer injection method. In this model, we accounted for tubular reabsorption. Loss of anionic sites in the glomerular basement membrane was measured using polyethyleneimine staining. Although mutant animals had significantly fewer negatively charged areas in the glomerular basement membrane, glomerular permeability was unaffected. Moreover, heparan sulfate glycosaminoglycan-deficient embryos had morphologically intact podocyte foot processes. Glomerular filtration remains fully functional despite a global reduction of heparan sulfate.

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Differential effects of ascorbate depletion and α,α′-dipyridyl treatment on the stability, but not on the secretion, of type IV collagen in differentiated F9 cells

Kim

Peterkofsky

1997

J. Cell. Biochem.

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Ascorbic acid stimulates secretion of type I collagen because of its role in 4-hydroxyproline synthesis, but there is some controversy as to whether secretion of type IV collagen is similarly affected. This question was examined in differentiated F9 cells, which produce only type IV collagen, by labeling proteins with [14C]proline and measuring collagen synthesis and secretion. Hydroxylation of proline residues in collagen was inhibited to a greater extent in cells treated with the iron chelator alpha,alpha'-dipyridyl (97.7%) than in cells incubated without ascorbate (63.1%), but both conditions completely inhibited the rate of collagen secretion after 2-4 h, respectively. Neither treatment affected laminin secretion. Collagen synthesis was not stimulated by ascorbate even after treatment for 2 days. On SDS polyacrylamide gels, collagen produced by alpha,alpha'-dipyridyl-treated cells consisted mainly of a single band that migrated faster than either fully (+ ascorbate) or partially (- ascorbate) hydroxylated alpha 1(IV) or alpha 2(IV) chains. It did not contain interchain disulfide bonds or asn-linked glycosyl groups, and was completely digested by pepsin at 15 degrees C. These results suggested that it was a degraded product lacking the 7 S domain and that it could not form a triple helical structure. In contrast, the partially hydroxylated molecule contained interchain disulfide bonds and it was cleaved by pepsin to collagenous fragments similar in size to those obtained from the fully hydroxylated molecule, but at a faster rate. Kinetic experiments and monensin treatment suggested that completely unhydroxylated type IV collagen was degraded intracellularly in the endoplasmic reticulum or cis Golgi. These studies indicate that partial hydroxylation of type IV collagen confers sufficient helical structure to allow interchain disulfide bond formation and resistance to pepsin and intracellular degradation, but not sufficient for optimal secretion.

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Localization and structure of the asparagine-linked oligosaccharides of type IV collagen from glomerular basement membrane and lens capsule

Cited by 30 publications

References 0 publications

Characterization of assembly of recombinant type IV collagen α3, α4, and α5 chains in transfected cell strains

Characterization of assembly of recombinant type IV collagen α3, α4, and α5 chains in transfected cell strains

Glomerular permeability is not affected by heparan sulfate glycosaminoglycan deficiency in zebrafish embryos

Differential effects of ascorbate depletion and α,α′-dipyridyl treatment on the stability, but not on the secretion, of type IV collagen in differentiated F9 cells

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