Localization of type IV collagen, laminin, heparan sulfate proteoglycan, and fibronectin to the basal lamina of basement membranes.

Abstract

Electron microscopic immunostaining of rat duodenum and incisor tooth was used to examine the location of four known components of the basement-membrane region: type IV collagen, laminin, heparan sulfate proteoglycan, and fibronectin. Antibodies or antisera against these substances were localized by direct or indirect peroxidase methods on 60-/~m thick slices of formaldehyde-fixed tissues.In the basement-membrane region of the duodenal epithelium, enamel-organ epithelium, and blood-vessel endothelium, immunostaining for all four components was observed in the basal lamina (also called lamina densa). The bulk of the lamina lucida (rara) was unstained, but it was traversed by narrow projections of the basal lamina that were immunostained for all four components. In the subbasement-membrane fibrous elements or reticular lamina, immunostaining was confined to occasional "bridges" extending from the epithelial basal-lamina to that of adjacent capillaries.The joint presence of type IV collagen, laminin, heparan sulfate proteoglycan, and fibronectin in the basal lamina indicates that these substances do not occur in separate layers but are integrated into a common structure.

Alteration in the distribution of type IV collagen in glomerular basal laminae in diabetic rats as revealed by immunocytochemistry and morphometrical approach

“…The labelling obtained over the basal laminae of normal animals was found to be restricted to the central laminae densa of the basal laminae and this was supported by morphometrical evaluation. These observations confirm previous results obtained by applying the immunoperoxidase and immunoferritin techniques [16][17][18][19]. However, compared with these previous studies in which diffusion is a problem [37], the localization obtained applying the protein A-gold technique appears to be of higher specificity and resolution.…”

“…These antibodies were raised in sheep using an antigen extracted from the mouse EHS tumor and purified by salt precipitation and ion exchange chromatography [33,34]; they react with basal laminae of various animal tissues and in particular with rat glomerular basal laminae [16,18], and their high specificity has been demonstrated previously using several approaches [16,18,35]. To locate type IV collagen, the protein A-gold immunocytochemical postembedding approach was applied [25].…”

“…These comprise type IV collagen, three non-collagenous glycoproteins, laminin, entactin and fibronectin as well as a heparan sulphate proteoglycan. Application of various immunocytochemical techniques has allowed for the localization of these different components in basal laminae of tissues from normal animals [16][17][18][19]. Although the distribution and three dimensional arrangement of basal lamina components may constitute the basis for the selectivity of capillary permeability [20,21], they have been little investigated in tissues from diabetic animals.…”

Topographical arrangement of basement membrane proteins in lactating rat mammary gland: comparison of the distribution of type IV collagen, laminin, fibronectin, and Thy-1 at the ultrastructural level.

“…Several protein components of basement membranes have been identified (4). Type IV collagen appears to be restricted to the lamina densa (5-7), whereas laminin, fibronectin, and heparan sulfate proteoglycan are present in either the lamina lucida or lamina densa (5,(7)(8)(9)(10)(11)(12). We have shown that antibodies to type IV collagen, laminin, and the thymocyte differentiation antigen Thy-1 stain the basement membrane in the mammary glands of both virgin and lactating rats at the light microscope level, whereas antibodies to fibronectin only stain the basement membrane in the mammary gland of lactating rats (1,13,14).…”

Structural and mechanical functions of integrins

“…chondroitin sulfate and keratan sulfate) and are secreted by cells to create their extracellular niche (Humphries et al 2006). Non-ECM ligands include counter-receptors (ICAMs and VCAMs), plasma proteins (fibrinogen and von Willebrand factor), complement factors, cytokines and pathogens (viruses, bacteria and toxins) (Laurie et al 1982;Humphries et al 2006).…”