Dual role of laminin‑511 in regulating melanocyte migration and differentiation.

Laminins are the major basement membrane (BM) components and are heterotrimers composed of an α, a β and a γ chain. In skin, laminins are present in basement membranes surrounding vascular structures, nerves, adipose tissue and in the specialized junctional BM between the epidermis and dermis. The main laminin isoforms in the dermo-epidermal BM are laminin‑332, laminin‑511 and laminin‑211, the latter being restricted to hair follicles (HFs).

Deletion of the epidermis derived laminin γ1 chain leads to defects in the regulation of late hair morphogenesis.

Laminins are the most abundant non-collagenous basement membrane (BM) components, composed of an α, β and γ chain. The laminin γ1 chain, encoded by LAMC1, is the most abundant γ chain. The main laminin isoforms in the dermo-epidermal junction (DEJ) are laminin-332, laminin-511 and laminin-211, the latter being restricted to the lower part of hair follicles (HFs).

Laminin α5 in the keratinocyte basement membrane is required for epidermal-dermal intercommunication.

Laminin α5 is broadly expressed in the epidermal basement membrane (BM) of mature mice and its elimination at this site (Lama5 mouse) results in hyperproliferation of basal keratinocytes and a delay in hair follicle development, which correlated with upregulation of the dermally-derived laminin α2 and laminin α4 chains in the epidermal BM and of tenascin-C subjacent to the BM. In vitro studies revealed laminin 511 to be strongly adhesive for primary keratinocytes and that loss of laminin α5 does not result in cell autonomous defects in proliferation. Flow cytometry reveals that the loss of laminin α5 resulted in increased numbers of CD45, CD4 and CD11b immune cells in the skin, which temporo-spatial analyses revealed were detectable only subsequent to the loss of laminin α5 and the appearance of the hyperproliferative keratinocyte phenotype.

Tetanus toxin entry. Nidogens are therapeutic targets for the prevention of tetanus.

Tetanus neurotoxin (TeNT) is among the most poisonous substances on Earth and a major cause of neonatal death in nonvaccinated areas. TeNT targets the neuromuscular junction (NMJ) with high affinity, yet the nature of the TeNT receptor complex remains unknown. Here, we show that the presence of nidogens (also known as entactins) at the NMJ is the main determinant for TeNT binding.

Anti-angiogenic effect of the basement membrane protein nidogen-1 in a mouse model of choroidal neovascularization.

In patients with age-related macular degeneration disruption of the integrity of the retinal pigment epithelium (RPE) and Bruch's membrane (BrM), precedes choroidal neovascularization (CNV). We investigated the role of the basement membrane (BM) proteins nidogen-1 and nidogen-2 for the development of experimental CNV. Laser-induced CNV was studied in Nid1(-/-) and Nid2(-/-) mice and wild type (WT) controls by fluorescein angiography, by immune histochemistry of flat-mounts or paraffin sections to analyze expression pattern of nidogen-1 and -2 and nidogen binding BM proteins, and by western blotting.

Skin basement membrane: the foundation of epidermal integrity--BM functions and diverse roles of bridging molecules nidogen and perlecan.

The epidermis functions in skin as first defense line or barrier against environmental impacts, resting on extracellular matrix (ECM) of the dermis underneath. Both compartments are connected by the basement membrane (BM), composed of a set of distinct glycoproteins and proteoglycans. Herein we are reviewing molecular aspects of BM structure, composition, and function regarding not only (i) the dermoepidermal interface but also (ii) the resident microvasculature, primarily focusing on the per se nonscaffold forming components perlecan and nidogen-1 and nidogen-2.

Loss of epidermal MMP-14 expression interferes with angiogenesis but not with re-epithelialization.

Synthesis and activation of matrix metalloproteinases during wound healing are important for remodeling the extracellular matrix and modulating various cellular functions. The membrane-type 1 matrix metalloproteinase (MMP-14) has been shown to play a key role during these processes. To analyze the function of epidermal-derived MMP-14 during skin repair we generated mice lacking MMP-14 expression in the epidermis (MMP-14(ep-/-)).

Different domains in nidogen-1 and nidogen-2 drive basement membrane formation in skin organotypic cocultures.

Nidogen-1 and nidogen-2 are homologous proteins found in all basement membranes (BMs). They show comparable binding activities in vitro and partially redundant functions in vivo. Previously, we showed that in skin organotypic cocultures, BM formation was prevented in the absence of nidogens and that either nidogen was able to rescue this failure.

Expression of platelet-derived growth factor-C and insulin-like growth factor I in hepatic stellate cells is inhibited by miR-29.

MicroRNAs are short noncoding, endogenous RNA species that posttranscriptionally inhibit gene expression by targeting the untranslated region (UTR) of mRNAs. Recently, it was shown that miR-29 inhibits expression of extracellular matrix proteins such as collagens, suggesting an antifibrotic function of miR-29. In the present study, we now investigated the role of miR-29 in profibrogenic growth factor expression as a further central mechanism of fibrosis.

Epidermal transglutaminase (TGase 3) is required for proper hair development, but not the formation of the epidermal barrier.

Transglutaminases (TGase), a family of cross-linking enzymes present in most cell types, are important in events as diverse as cell-signaling and matrix stabilization. Transglutaminase 1 is crucial in developing the epidermal barrier, however the skin also contains other family members, in particular TGase 3. This isoform is highly expressed in the cornified layer, where it is believed to stabilize the epidermis and its reduction is implicated in psoriasis.

Absence of the basement membrane component nidogen 2, but not of nidogen 1, results in increased lung metastasis in mice.

Nidogen 1 and 2 are ubiquitous basement membrane (BM) components. They show a divergent expression pattern in certain adult tissues with a prominent localization of nidogen 2 in blood vessel BMs. Deletion of either nidogen 1 or 2 in mice had no effect on BM formation, suggesting complementary functions.

Hepatocyte growth factor (HGF) inhibits collagen I and IV synthesis in hepatic stellate cells by miRNA-29 induction.

Background: In chronic liver disease, hepatic stellate cells (HSC) transdifferentiate into myofibroblasts, promoting extracellular matrix (ECM) synthesis and deposition. Stimulation of HSC by transforming growth factor-β (TGF-β) is a crucial event in liver fibrogenesis due to its impact on myofibroblastic transition and ECM induction. In contrast, hepatocyte growth factor (HGF), exerts antifibrotic activities.

The disintegrin-like and cysteine-rich domains of ADAM-9 mediate interactions between melanoma cells and fibroblasts.

A characteristic of malignant cells is their capacity to invade their surrounding and to metastasize to distant organs. During these processes, proteolytic activities of tumor and stromal cells modify the extracellular matrix to produce a microenvironment suitable for their growth and migration. In recent years the family of ADAM proteases has been ascribed important roles in these processes.

Basement membrane deposition of nidogen 1 but not nidogen 2 requires the nidogen binding module of the laminin gamma1 chain.

The nidogen-laminin interaction is proposed to play a key role in basement membrane (BM) assembly. However, though there are similarities, the phenotypes in mice lacking nidogen 1 and 2 (nidogen double null) differ to those of mice lacking the nidogen binding module (γ1III4) of the laminin γ1 chain. This indicates different cell- and tissue-specific functions for nidogens and their interaction with laminin and poses the question of whether the phenotypes in nidogen double null mice are caused by the loss of the laminin-nidogen interaction or rather by other unknown nidogen functions.

Combined paracrine and endocrine AAV9 mediated expression of hepatocyte growth factor for the treatment of renal fibrosis.

In chronic renal disease, tubulointerstitial fibrosis is a leading cause of renal failure. Here, we made use of one of the most promising gene therapy vector platforms, the adeno-associated viral (AAV) vector system, and the COL4A3-deficient mice, a genetic mouse model of renal tubulointerstitial fibrosis, to develop a novel bidirectional treatment strategy to prevent renal fibrosis. By comparing different AAV serotypes in reporter studies, we identified AAV9 as the most suitable delivery vector to simultaneously target liver parenchyma for endocrine and renal tubular epithelium for paracrine therapeutic expression of the antifibrogenic cytokine human hepatocyte growth factor (hHGF).

Cell-matrix interactions in dermal repair and scarring.

Regulation of cellular functions during dermal repair following injury is complex and critically dependent on the interaction of cells with the surrounding extracellular matrix (ECM). The ECM comprises various families of macromolecules that form the structural scaffold of the tissue, but also carry distinct biological activities. After injury to the skin, the defect is filled by a provisional matrix that is invaded by inflammatory cells, sprouting blood vessels and fibroblasts.

Impaired wound healing in mice lacking the basement membrane protein nidogen 1.

Nidogens 1 and 2 are ubiquitous basement membrane (BM) components, whose interactions in particular with laminin, collagen IV and perlecan have been considered important for BM formation. Genetic deletion of either NID gene does not reveal BM alterations suggesting compensatory roles for nidogens 1 and 2. However, neurological deficits in nidogen 1 null mice, not seen in the absence of nidogen 2, also suggest isoform specific functions.

Basement membrane protein nidogen-1 shapes hippocampal synaptic plasticity and excitability.

The basement membrane (BM) is a specialized form of extracellular matrix (ECM) underlying epithelia and endothelia and surrounding many types of mesenchymal cells. Nidogen, along with collagen IV and laminin, is a major component of BMs. Although certain ECM proteins such as laminin or reelin influence neuronal function via interactions with cell-surface receptors such as integrins, behavioral neurological impairments due to deficits of BM components have been recognized only recently.

Profiling of anti-fibrotic signaling by hepatocyte growth factor in renal fibroblasts.

Hepatocyte growth factor (HGF) is a multifunctional growth factor affecting cell proliferation and differentiation. Due to its mitogenic potential, HGF plays an important role in tubular repair and regeneration after acute renal injury. However, recent reports have shown that HGF also acts as an anti-inflammatory and anti-fibrotic factor, affecting various cell types such as renal fibroblasts and triggering tubulointerstitial fibrosis of the kidney.

Basement membranes in skin: unique matrix structures with diverse functions?

The view of extracellular matrix (ECM) has evolved from a merely scaffolding and space filling tissue element to an interface actively controlling cellular activities and tissue functions. A highly specialized form of ECM is the basement membrane (BM), an ubiquitous sheet-like polymeric structure composed of a set of distinct glycoproteins and proteoglycans. In this review we are largely focusing on function and assembly of BM in skin (1) at the dermo-epidermal interface and (2) in the resident micro-vasculature.

Basement membranes in skin are differently affected by lack of nidogen 1 and 2.

Nidogens have been proposed to play a key role in basement membrane (BM) formation. However, recent findings using genetic approaches and organotypic coculture models demonstrated distinct tissue requirements thus changing the classical view of BM assembly. Toward this end, we have analyzed the dermo-epidermal junction and the microvasculature in skin of nidogen-deficient mice for their BM composition and structural assembly.

Nidogens-Extracellular matrix linker molecules.

Nidogens/entactins are a family of highly conserved, sulfated glycoproteins. Biochemical studies have implicated them as having a major structural role in the basement membrane. However despite being ubiquitous components of this specialized extracellular matrix and having a wide spectrum of binding partners, genetic analysis has shown that they are not required for the overall architecture of the basement membrane.

Role of ADAM-9 disintegrin-cysteine-rich domains in human keratinocyte migration.

ADAM-9 belongs to a family of transmembrane, disintegrin-containing metalloproteinases involved in protein ectodomain shedding and cell-cell and cell-matrix interactions. The aim of this study was to analyze the expression of ADAM-9 in skin and to assess the role of this proteolytic/adhesive protein in skin physiology. In normal skin, ADAM-9 expression was detected in both the epidermis and dermis and in vitro in keratinocytes and fibroblasts.

The autoantigen in anti-p200 pemphigoid is synthesized by keratinocytes and fibroblasts and is distinct from nidogen-2.

Anti-p200 pemphigoid is a subepidermal immunobullous disorder associated with tissue-bound and circulating autoantibodies reactive with a 200 kDa protein on the dermal side of salt-split-skin. The autoantigen, named p200, is a non-collagenous glycoprotein located at the lamina lucida-lamina densa border of the epidermal basement membrane. However, its identity and cellular origin remain elusive.

Morphometric analysis of murine skin wound healing: standardization of experimental procedures and impact of an advanced multitissue array technique.

Morphometric data based on skin wounding offer important information for the characterization of the phenotype of transgenic mouse models. The goal of this study was the comparison of technical procedures concerning wounding, processing, and evaluation of samples in different mouse strains. The multitissue array technique was used to estimate its adaptability for standardized analysis in wound healing.