Bone morphogenetic protein 1 is an extracellular processing enzyme of the laminin 5 gamma 2 chain

PCPE-2 (procollagen C-proteinase enhancer-2): the NON-IDENTICAL twin of PCPE-1

PCPE-2 was discovered at the beginning of this century, and was soon identified as a close homolog of PCPE-1 (procollagen C-proteinase enhancer 1). After the demonstration that it could also stimulate the proteolytic maturation of fibrillar procollagens by BMP-1/tolloid-like proteinases (BTPs), PCPE-2 did not attract much attention as it was thought to fulfill the same functions as PCPE-1 which was already well-described. However, the tissue distribution of PCPE-2 shows both common points and significant differences with PCPE-1, suggesting that their activities are not fully overlapping. Also, the recently established connections between PCPE-2 (gene name PCOLCE2) and several important diseases such as atherosclerosis, inflammatory diseases and cancer have highlighted the need for a thorough reappraisal of the in vivo roles of this regulatory protein. In this context, the recent finding that, while retaining the ability to bind fibrillar procollagens and to activate their C-terminal maturation, PCPE-2 can also bind BTPs and inhibit their activity has substantially extended its potential functions. In this review, we describe the current knowledge about PCPE-2 with a focus on collagen fibrillogenesis, lipid metabolism and inflammation, and discuss how we could further advance our understanding of PCPE-2-dependent biological processes.

Roles for epithelial integrin α3β1 in regulation of the microenvironment during normal and pathological tissue remodeling

Integrin receptors for the extracellular matrix activate intracellular signaling pathways that are critical for tissue development, homeostasis, and regeneration/repair, and their loss or dysregulation contributes to many developmental defects and tissue pathologies. This review will focus on tissue remodeling roles for integrin α3β1, a receptor for laminins found in the basement membranes (BMs) that underlie epithelial cell layers. As a paradigm, we will discuss literature that supports a role for α3β1 in promoting ability of epidermal keratinocytes to modify their tissue microenvironment during skin development, wound healing, or tumorigenesis. Preclinical and clinical studies have shown that this role depends largely on ability of α3β1 to govern the keratinocyte's repertoire of secreted proteins, or the "secretome," including 1) matrix proteins and proteases involved in matrix remodeling and 2) paracrine-acting growth factors/cytokines that stimulate other cells with important tissue remodeling functions (e.g., endothelial cells, fibroblasts, inflammatory cells). Moreover, α3β1 signaling controls gene expression that helps epithelial cells carry out these functions, including genes that encode secreted matrix proteins, proteases, growth factors, or cytokines. We will review what is known about α3β1-dependent gene regulation through both transcription and posttranscriptional mRNA stability. Regarding the latter, we will discuss examples of α3β1-dependent alternative splicing (AS) or alternative polyadenylation (APA) that prevents inclusion of cis-acting mRNA sequences that would otherwise target the transcript for degradation via nonsense-mediated decay or destabilizing AU-rich elements (AREs) in the 3'-untranslated region (3'-UTR). Finally, we will discuss prospects and anticipated challenges of exploiting α3β1 as a clinical target for the treatment of cancer or wound healing.

Observing Dynamic Conformational Changes within the Coiled-Coil Domain of Different Laminin Isoforms Using High-Speed Atomic Force Microscopy

Laminins are trimeric glycoproteins with important roles in cell-matrix adhesion and tissue organization. The laminin α, ß, and γ-chains have short N-terminal arms, while their C-termini are connected via a triple coiled-coil domain, giving the laminin molecule a well-characterized cross-shaped morphology as a result. The C-terminus of laminin alpha chains contains additional globular laminin G-like (LG) domains with important roles in mediating cell adhesion. Dynamic conformational changes of different laminin domains have been implicated in regulating laminin function, but so far have not been analyzed at the single-molecule level. High-speed atomic force microscopy (HS-AFM) is a unique tool for visualizing such dynamic conformational changes under physiological conditions at sub-second temporal resolution. After optimizing surface immobilization and imaging conditions, we characterized the ultrastructure of laminin-111 and laminin-332 using HS-AFM timelapse imaging. While laminin-111 features a stable S-shaped coiled-coil domain displaying little conformational rearrangement, laminin-332 coiled-coil domains undergo rapid switching between straight and bent conformations around a defined central molecular hinge. Complementing the experimental AFM data with AlphaFold-based coiled-coil structure prediction enabled us to pinpoint the position of the hinge region, as well as to identify potential molecular rearrangement processes permitting hinge flexibility. Coarse-grained molecular dynamics simulations provide further support for a spatially defined kinking mechanism in the laminin-332 coiled-coil domain. Finally, we observed the dynamic rearrangement of the C-terminal LG domains of laminin-111 and laminin-332, switching them between compact and open conformations. Thus, HS-AFM can directly visualize molecular rearrangement processes within different laminin isoforms and provide dynamic structural insight not available from other microscopy techniques.

Proteolytic modulation of tumor microenvironment signals during cancer progression

Under normal conditions, the cellular microenvironment is optimized for the proper functioning of the tissues and organs. Cells recognize and communicate with the surrounding cells and extracellular matrix to maintain homeostasis. When cancer arises, the cellular microenvironment is modified to optimize its malignant growth, evading the host immune system and finding ways to invade and metastasize to other organs. One means is a proteolytic modification of the microenvironment and the signaling molecules. It is now well accepted that cancer progression relies on not only the performance of cancer cells but also the surrounding microenvironment. This mini-review discusses the current understanding of the proteolytic modification of the microenvironment signals during cancer progression.

Distinct contributions of meprins to skin regeneration after injury - Meprin α a physiological processer of pro-collagen VII

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Meprins subtly support epidermal and dermal skin wound healing.

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Loss of both meprins reduces re-epithelialization and wound macrophage abundance.

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Meprin α is a physiological maturing proteinase of collagen VII.

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Meprins are reduced in recessive dystrophic epidermolysis bullosa skin.

Astacin-like proteinases (ALPs) are regulators of tissue and extracellular matrix (ECM) homeostasis. They convey this property through their ability to convert ECM protein pro-forms to functional mature proteins and by regulating the bioavailability of growth factors that stimulate ECM synthesis. The most studied ALPs in this context are the BMP-1/tolloid-like proteinases. The other subclass of ALPs in vertebrates – the meprins, comprised of meprin α and meprin β – are emerging as regulators of tissue and ECM homeostasis but have so far been only limitedly investigated. Here, we functionally assessed the roles of meprins in skin wound healing using mice genetically deficient in one or both meprins. Meprin deficiency did not change the course of macroscopic wound closure. However, subtle but distinct contributions of meprins to the healing process and dermal homeostasis were observed. Loss of both meprins delayed re-epithelialization and reduced macrophage infiltration. Abnormal dermal healing and ECM regeneration was observed in meprin deficient wounds. Our analyses also revealed meprin α as one proteinase responsible for maturation of pro-collagen VII to anchoring fibril-forming-competent collagen VII in vivo. Collectively, our study identifies meprins as subtle players in skin wound healing.

Effects of bone morphogenetic proteins on epithelial repair

Epithelial tissue has important functions such as protection, secretion, and sensation. Epithelial damage is involved in various pathological processes. Bone morphogenetic proteins (BMPs) are a class of growth factors with multiple functions. They play important roles in epithelial cells, including in differentiation, proliferation, and migration during the repair of the epithelium. This article reviews the functions and mechanisms of the most profoundly studied BMPs in the process of epithelial damage repair and their clinical significance.

Loss of the laminin subunit alpha-3 induces cell invasion and macrophage infiltration in cutaneous squamous cell carcinoma

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is a common cancer that invades the dermis through the basement membrane. The role of the basement membrane in poorly differentiated cSCC is not well understood.

OBJECTIVES

To study the effect that loss of the laminin subunit alpha-3 (α3) chain from the tumour microenvironment has on tumour invasion and inflammatory cell recruitment.

METHODS

We examined the role of the basement membrane proteins laminin subunits α3, β3 and γ2 in SCC invasion and inflammatory cell recruitment using immunohistochemistry, short hairpin RNA knockdown, RNA-Seq, mouse xenograft models and patient tumour samples.

RESULTS

Analysis of SCC tumours and cell lines using antibodies specific to laminin chains α3, β3 and γ2 identified a link between poorly differentiated SCC and reduced expression of laminin α3 but not the other laminin subunits investigated. Knockdown of laminin α3 increased tumour invasion both in vitro and in vivo. Western blot and immunohistochemical staining identified increased phosphorylated myosin light chain with loss of laminin α3. Inhibition of ROCK (rho-associated protein kinase) but not Rac1 significantly reduced the invasive potential of laminin α3 knockdown cells. Knockdown of laminin subunits α3 and γ2 increased monocyte recruitment to the tumour microenvironment. However, only the loss of laminin α3 correlated with increased tumour-associated macrophages both in xenografted tumours and in patient tumour samples.

CONCLUSIONS

These data provide evidence that loss of the laminin α3 chain in cSCC has an effect on both the epithelial and immune components of cSCC, resulting in an aggressive tumour microenvironment.

Expression profile analysis to predict potential biomarkers for glaucoma: BMP1, DMD and GEM

Purpose

Glaucoma is the second commonest cause of blindness. We assessed the gene expression profile of astrocytes in the optic nerve head to identify possible prognostic biomarkers for glaucoma.

Method

A total of 20 patient and nine normal control subject samples were derived from the GSE9944 (six normal samples and 13 patient samples) and GSE2378 (three normal samples and seven patient samples) datasets, screened by microarray-tested optic nerve head tissues, were obtained from the Gene Expression Omnibus (GEO) database. We used a weighted gene coexpression network analysis (WGCNA) to identify coexpressed gene modules. We also performed a functional enrichment analysis and least absolute shrinkage and selection operator (LASSO) regression analysis. Genes expression was represented by boxplots, functional geneset enrichment analyses (GSEA) were used to profile the expression patterns of all the key genes. Then the key genes were validated by the external dataset.

Results

A total 8,606 genes and 19 human optic nerve head samples taken from glaucoma patients in the GSE9944 were compared with normal control samples to construct the co-expression gene modules. After selecting the most common clinical traits of glaucoma, their association with gene expression was established, which sorted two modules showing greatest correlations. One with the correlation coefficient is 0.56 (P = 0.01) and the other with the correlation coefficient is −0.56 (P = 0.01). Hub genes of these modules were identified using scatterplots of gene significance versus module membership. A functional enrichment analysis showed that the former module was mainly enriched in genes involved in cellular inflammation and injury, whereas the latter was mainly enriched in genes involved in tissue homeostasis and physiological processes. This suggests that genes in the green–yellow module may play critical roles in the onset and development of glaucoma. A LASSO regression analysis identified three hub genes: Recombinant Bone Morphogenetic Protein 1 gene (BMP1), Duchenne muscular dystrophy gene (DMD) and mitogens induced GTP-binding protein gene (GEM). The expression levels of the three genes in the glaucoma group were significantly lower than those in the normal group. GSEA further illuminated that BMP1, DMD and GEM participated in the occurrence and development of some important metabolic progresses. Using the GSE2378 dataset, we confirmed the high validity of the model, with an area under the receiver operator characteristic curve of 85%.

Conclusion

We identified several key genes, including BMP1, DMD and GEM, that may be involved in the pathogenesis of glaucoma. Our results may help to determine the prognosis of glaucoma and/or to design gene- or molecule-targeted drugs.

Bone morphogenetic protein 1 cleaves the linker region between ligand-binding repeats 4 and 5 of the LDL receptor and makes the LDL receptor non-functional

The cell-surface low-density lipoprotein receptor (LDLR) internalizes low-density lipoprotein (LDL) by receptor-mediated endocytosis and plays a key role in the regulation of plasma cholesterol levels. The ligand-binding domain of the LDLR contains seven ligand-binding repeats of approximately 40 residues each. Between ligand-binding repeats 4 and 5, there is a 10-residue linker region that is subject to enzymatic cleavage. The cleaved LDLR is unable to bind LDL. In this study, we have screened a series of enzyme inhibitors in order to identify the enzyme that cleaves the linker region. These studies have identified bone morphogenetic protein 1 (BMP1) as being the cleavage enzyme. This conclusion is based upon the use of the specific BMP1 inhibitor UK 383367, silencing of the BMP1 gene by the use of siRNA or CRISPR/Cas9 technology and overexpression of wild-type BMP1 or the loss-of-function mutant E214A-BMP1. We have also shown that the propeptide of BMP1 has to be cleaved at RSRR120↓ by furin-like proprotein convertases for BMP1 to have an activity towards the LDLR. Targeting BMP1 could represent a novel strategy to increase the number of functioning LDLRs in order to lower plasma LDL cholesterol levels. However, a concern by using BMP1 inhibitors as cholesterol-lowering drugs could be the risk of side effects based on the important role of BMP1 in collagen assembly.

Expression of Laminin γ2 Proteolytic Fragments in Murine Skin Following Exposure to Sulfur Mustard

Laminin-332 is a basement membrane protein composed of three genetically distinct polypeptide chains that actively promote both skin epidermal cell adhesion and migration. Proteolytic fragments of the laminin γ2 chain stimulate migration and scattering of keratinocytes and cancer cells. Sulfur mustard (SM) is a bifunctional alkylating agent that induces separation of basal keratinocytes from the dermal-epidermal junction and invokes a strong inflammatory response leading to delayed wound repair. In the present studies, the role of laminin γ2 in SM-induced skin injury and wound repair was investigated using the mouse ear vesicant model. We found that laminin γ2 chain mRNA was preferentially upregulated in mouse ear skin exposed to SM. In situ hybridization confirmed overexpression of laminin γ2 transcript. Western blot analysis showed increased protein expression of the full-length proform of laminin γ2 and smaller processed fragments of laminin γ2 in skin exposed to SM. Dual immunofluorescence labeling indicated that laminin γ2 fragments are prevalent in suprabasal keratinocytes behind the leading edge in areas of hyperplasia in injured skin. In addition, co-expression of laminin γ2 and the senescent marker, p16^-INK4a was found to overlap with the hyperplastic migratory epithelial sheet. This observation is similar to hypermotile keratinocytes reported in invasive carcinoma cells. Overall, our studies indicate that laminin γ2 is preferentially expressed in skin post SM exposure and that protein expression appears to become progressively more fragmented. The laminin γ2 fragments may play a role in regulating SM-induced skin wound repair. Anat Rec, 2020. © 2020 American Association for Anatomy.

Anti-human serum albumin autoantibody may be involved in the pathogenesis of autoimmune bullous skin diseases

Although effective immunological diagnostic systems for autoimmune bullous skin diseases (AIBD) have been established, there are still unidentified cutaneous autoantigens. The purpose of this study is to investigative whether anti-human serum albumin (HSA) autoantibodies exist in AIBD sera and their potential pathogenesis. By immunoprecipitation-immunoblotting, immunofluorescence assay, anti-HSA autoantibodies could be detected in AIBD sera; by ELISAs, positive rates of AIBD sera for IgG and IgA anti-HSA autoantibodies were 29% and 34%, respectively. The IgG anti-HSA autoantibodies in ABID sera recognized a number of HSA antigen epitopes and therefore a polyclonal antibody against HSA were next employed to study its pathogenesis. In vitro cell and tissue culture models, anti-HSA antibody could influence DNA damage-related signaling proteins, via activation of phospho-p38 signaling pathway. This is the first report that an autoantibody may influence DNA damage-related signaling proteins. Statistical analyses also proved that anti-HSA autoantibodies were positively correlated with various known autoantibodies and clinical features of ABID patients. In summary, IgG and IgA autoantibodies to HSA may have diagnosis values for AIBD. DNA damage-related signaling proteins might be involved in the pathogenic role of anti-HSA autoantibodies in AIBD. Phospho-p38 signaling pathway is a potential target for treatment of AIBD positive for serum anti-HSA autoantibodies.

Laminin 332 in cancer: When the extracellular matrix turns signals from cell anchorage to cell movement

Laminin 332 is crucial in the biology of epithelia. This large extracellular matrix protein consists of the heterotrimeric assembly of three subunits - α3, β3, and γ2 - and its multifunctionality relies on a number of extracellular proteolytic processing events. Laminin 332 is central to normal epithelium homeostasis by sustaining cell adhesion, polarity, proliferation, and differentiation. It also supports a major function in epithelial tissue formation, repair, and regeneration by buttressing cell migration and survival and basement membrane assembly. Interest in this protein increased after the discovery that its expression is perturbed in tumor cells, cancer-associated fibroblasts, and the tumor microenvironment. This review summarizes current knowledge regarding the established involvement of the laminin 332 γ2 chain in tumor invasiveness and discusses the role of its α3 and β3 subunits.

Zebrafish and medaka as models for biomedical research of bone diseases

The identification of disease-causing mutations has in recent years progressed immensely due to whole genome sequencing approaches using patient material. The task accordingly is shifting from gene identification to functional analysis of putative disease-causing genes, preferably in an in vivo setting which also allows testing of drug candidates or biotherapeutics in whole animal disease models. In this review, we highlight the advances made in the field of bone diseases using small laboratory fish, focusing on zebrafish and medaka. We particularly highlight those human conditions where teleost models are available.

Upregulation of bone morphogenetic protein 1 is associated with poor prognosis of late-stage gastric Cancer patients

Background

Gastric cancer is the eighth most common cancer in Taiwan, with a 40% 5-year survival rate. Approximately 40% of patients are refractory to chemotherapy. Currently, the anti-HER2 therapy is the only clinically employed targeted therapy. However, only 7% patients in Taiwan are HER2-positive. Identifying candidate target genes will facilitate the development of adjuvant targeted therapy to increase the efficacy of gastric cancer treatment.

Methods

Clinical specimens were analyzed by targeted RNA sequencing to assess the expression levels of target genes. Statistical significance of differential expression and correlation between specimens was evaluated. The correlation with patient survival was analyzed as well. In vitro cell mobility was determined using wound-healing and transwell mobility assays.

Results

Expression of BMP1, COL1A1, STAT3, SOX2, FOXA2, and GATA6 was progressively dysregulated through the stages of gastric oncogenesis. The expression profile of these six genes forms an ubiquitously biomarker signature that is sufficient to differentiate cancer from non-cancerous specimens. High expression status of BMP1 correlates with poor long-term survival of late-stage patients. In vitro, suppression of BMP1 inhibits the mobility of the gastric cancer cell lines, indicating a role of BMP1 in metastasis.

Conclusions

BMP1 is upregulated in gastric cancer and is correlated with poor patient survival. Suppression of BMP1 reduced gastric cancer mobility in vitro. Our finding suggests that anti-BMP1 therapy will likely augment the efficacy of standard chemotherapy and improve the treatment outcome.

Cancer Invasion: Watch Your Neighbourhood!

The critical event in neoplastic diseases is the invasion of surrounding tissue by cancer cells. This event greatly reduces treatment options, and makes cancer a lethal disease. Factors that initiate cancer invasion are not well understood, neither do we have mechanistic insights in the process itself. Recently, a new concept has emerged: the tissue surrounding tumor cells, ie, the tumor microenvironment, may play an important, if not decisive role in triggering invasion. This concept is based on data from many laboratories working on the cell biology of cancer invasion. In this review, we survey several components of the tumor microenvironment, including extracellular matrix macromolecules, metalloproteinases and soluble factors, and discuss their potential involvement in stimulating cancer cell motility. These novel views may have far-reaching consequences, since “normal” tissue microenvironment components, rather than the traditional tumor cells themselves, may eventually become targets for devising new treatments that prevent, inhibit or block cancer invasion and metastasis.

Opposing Roles of Epidermal Integrins α3β1 and α9β1 in Regulation of mTLD/BMP-1-Mediated Laminin-γ2 Processing during Wound Healing

Proteolytic processing of the laminin-γ2 chain is a hallmark of basement membrane maturation in the skin. Integrin α3β1, a major receptor for epidermal adhesion to laminin-332, is critical for proper basement membrane organization during skin development and wound healing. Previously, we identified a role for α3β1 in promoting the processing of laminin-γ2 in cultured keratinocytes in vitro and in wound epidermis in vivo. In this study we identify the Bmp1 gene, which encodes variants of the mTLD/BMP-1 metalloproteases, as a critical regulator of α3β1-dependent laminin-γ2 processing, thereby expanding the role of this integrin in controlling the secretion by the epidermis of factors that modulate the tissue microenvironment. Because our previous studies identified another epidermal integrin, α9β1, as a suppressive regulator of α3β1-dependent wound angiogenesis, we investigated whether α9β1 has a similar cross-suppressive effect on the ability of α3β1 to promote basement membrane organization. Here, we show that, rather than a cross-suppressive role, α9β1 has an opposing role in basement membrane assembly/maturation through reduced laminin-γ2 processing via mTLD/BMP-1. Although α3β1 promotes this process during wound healing, α9β1 has an inhibitory role, suggesting that regulation of basement membrane assembly requires a complex interplay between these distinct epidermal integrins.

A slow-cycling subpopulation of melanoma cells with highly invasive properties

Melanoma is a heterogeneous tumor with different subpopulations showing different proliferation rates. Slow-cycling cells were previously identified in melanoma, but not fully biologically characterized. Using the label-retention method, we identified a subpopulation of slow-cycling cells, defined as label-retaining cells (LRC), with strong invasive properties. We demonstrate through live imaging that LRC are leaving the primary tumor mass at a very early stage and disseminate to peripheral organs. Through global proteome analyses, we identified the secreted protein SerpinE2/protease nexin-1 as causative for the highly invasive potential of LRC in melanomas.

Structural proteins of the dermal-epidermal junction targeted by autoantibodies in pemphigoid diseases

The dermal-epidermal junction consists of a network of several interacting structural proteins that strengthen adhesion and mediate signalling events. This structural network consists of hemidesmosomal-anchoring filament complexes connecting the basal keratinocytes to the basement membrane. The anchoring filaments in turn interact with the anchoring fibrils to attach the basement membrane to the underlying dermis. Several of these structural proteins are recognized by autoantibodies in pemphigoid diseases, a heterogeneous group of clinically and immunopathologically diverse entities. Targeted proteins include the two intracellular plakins, plectin isoform 1a and BP230 (also called bullous pemphigoid antigen (BPAG) 1 isoform e (BPAG1e)). Plectin 1a and BP230 are connected to the intermediate filaments and to the cell surface receptor α6β4 integrin, which in turn is connected to laminin 332, a component of the anchoring filaments. Further essential adhesion proteins are BP180, a transmembrane protein, laminin γ1 and type VII collagen. Latter protein is the major constituent of the anchoring fibrils. Mutations in the corresponding genes of these adhesion molecules lead to inherited epidermolysis bullosa emphasizing the importance of these proteins for the integrity of the dermal-epidermal junction. This review will provide an overview on the structure and function of the proteins situated in the dermal-epidermal junction targeted by autoantibodies.

BMP1-like proteinases are essential to the structure and wound healing of skin

Closely related extracellular metalloproteinases bone morphogenetic protein 1 (BMP1) and mammalian Tolloid-like 1 (mTLL1) are co-expressed in various tissues and have been suggested to have overlapping roles in the biosynthetic processing of extracellular matrix components. Early lethality of mice null for the BMP1 gene Bmp1 or the mTLL1 gene Tll1 has impaired in vivo studies of these proteinases. To overcome issues of early lethality and functional redundancy we developed the novel BT^KO mouse strain, with floxed Bmp1 and Tll1 alleles, for induction of postnatal, simultaneous ablation of the two genes. We previously showed these mice to have a skeletal phenotype that includes elements of osteogenesis imperfecta (OI), osteomalacia, and deficient osteocyte maturation, observations validated by the finding of BMP1 mutations in a subset of human patients with OI-like phenotypes. However, the roles of BMP1-like proteinase in non-skeletal tissues have yet to be explored, despite the supposed importance of putative substrates of these proteinases in such tissues. Here, we employ BT^KO mice to investigate potential roles for these proteinases in skin. Loss of BMP1-like proteinase activity is shown to result in markedly thinned and fragile skin with unusually densely packed collagen fibrils and delayed wound healing. We demonstrate deficits in the processing of collagens I and III, decorin, biglycan, and laminin 332 in skin, which indicate mechanisms whereby BMP1-like proteinases affect the biology of this tissue. In contrast, lack of effects on collagen VII processing or deposition indicates this putative substrate to be biosynthetically processed by non-BMP1-like proteinases.

Collagen VI deficiency reduces muscle pathology, but does not improve muscle function, in the γ-sarcoglycan-null mouse

Muscular dystrophy is characterized by progressive skeletal muscle weakness and dystrophic muscle exhibits degeneration and regeneration of muscle cells, inflammation and fibrosis. Skeletal muscle fibrosis is an excessive deposition of components of the extracellular matrix including an accumulation of Collagen VI. We hypothesized that a reduction of Collagen VI in a muscular dystrophy model that presents with fibrosis would result in reduced muscle pathology and improved muscle function. To test this hypothesis, we crossed γ-sarcoglycan-null mice, a model of limb-girdle muscular dystrophy type 2C, with a Col6a2-deficient mouse model. We found that the resulting γ-sarcoglycan-null/Col6a2Δex5 mice indeed exhibit reduced muscle pathology compared with γ-sarcoglycan-null mice. Specifically, fewer muscle fibers are degenerating, fiber size varies less, Evans blue dye uptake is reduced and serum creatine kinase levels are lower. Surprisingly, in spite of this reduction in muscle pathology, muscle function is not significantly improved. In fact, grip strength and maximum isometric tetanic force are even lower in γ-sarcoglycan-null/Col6a2Δex5 mice than in γ-sarcoglycan-null mice. In conclusion, our results reveal that Collagen VI-mediated fibrosis contributes to skeletal muscle pathology in γ-sarcoglycan-null mice. Importantly, however, our data also demonstrate that a reduction in skeletal muscle pathology does not necessarily lead to an improvement of skeletal muscle function, and this should be considered in future translational studies.

Epidermal Basement Membrane in Health and Disease

Skin, as the organ protecting the individual from environmental aggressions, constantly meets external insults and is dependent on mechanical toughness for its preserved function. Accordingly, the epidermal basement membrane (BM) zone has adapted to enforce tissue integrity. It harbors anchoring structures created through unique organization of common BM components and expression of proteins exclusive to the epidermal BM zone. Evidence for the importance of its correct assembly and the nonredundancy of its components for skin integrity is apparent from the multiple skin blistering disorders caused by mutations in genes coding for proteins associated with the epidermal BM and from autoimmune disorders in which autoantibodies target these molecules. However, it has become clear that these proteins not only provide mechanical support but are also critically involved in tissue homeostasis, repair, and regeneration. In this chapter, we provide an overview of the unique organization and components of the epidermal BM. A special focus will be given to its function during regeneration, and in inherited and acquired diseases.

Proteolytic control of TGF-β co-receptor activity by BMP-1/tolloid-like proteases revealed by quantitative iTRAQ proteomics

The metalloproteinase BMP-1 (bone morphogenetic protein-1) plays a major role in the control of extracellular matrix (ECM) assembly and growth factor activation. Most of the growth factors activated by BMP-1 are members of the TGF-β superfamily known to regulate multiple biological processes including embryonic development, wound healing, inflammation and tumor progression. In this study, we used an iTRAQ (isobaric tags for relative and absolute quantification)-based quantitative proteomic approach to reveal the release of proteolytic fragments from the cell surface or the ECM by BMP-1. Thirty-eight extracellular proteins were found in significantly higher or lower amounts in the conditioned medium of HT1080 cells overexpressing BMP-1 and thus, could be considered as candidate substrates. Strikingly, three of these new candidates (betaglycan, CD109 and neuropilin-1) were TGF-β co-receptors, also acting as antagonists when released from the cell surface, and were chosen for further substrate validation. Betaglycan and CD109 proved to be directly cleaved by BMP-1 and the corresponding cleavage sites were extensively characterized using a new mass spectrometry approach. Furthermore, we could show that the ability of betaglycan and CD109 to interact with TGF-β was altered after cleavage by BMP-1, leading to increased and prolonged SMAD2 phosphorylation in BMP-1-overexpressing cells. Betaglycan processing was also observed in primary corneal keratocytes, indicating a general and novel mechanism by which BMP-1 directly affects signaling by controlling TGF-β co-receptor activity. The proteomic data have been submitted to ProteomeXchange with the identifier PXD000786 and doi: 10.6019/PXD000786 .

Clinicopathological significance of MMP-7, laminin γ2 and EGFR expression at the invasive front of gastric carcinoma

BACKGROUND

For several types of cancer, including gastric cancer (GC), tumor cells at the invasive front are considered to have a more aggressive behavior compared with those in the more central region. The aim of the present study was to analyze the expression of MMP-7, laminin γ2 and EGFR in a large number of GCs and to investigate how these expression patterns correlate with clinicopathologic parameters, infiltrative patterns, histology or mucin phenotype.

METHODS

We immunohistochemically examined the expression of MMP-7, laminin γ2 and EGFR using a tissue microarray analysis of 790 GCs, and evaluated their clinicopathological significance.

RESULTS

MMP-7, cytoplasmic laminin γ2, extracellular laminin γ2 and EGFR expression were observed in 25, 25, 8 and 21 % of the 790 GC cases, respectively. Expression of MMP-7, cytoplasmic laminin γ2 and EGFR was associated with advanced T grade, N grade and tumor stage. Extracellular laminin γ2 expression was not associated with any clinicopathologic parameters, infiltrative patterns, histology or mucin phenotype. Furthermore, we investigated the correlations of MMP-7, laminin γ2 and EGFR expression. MMP-7 expression was significantly more frequent in positive expression of cytoplasmic laminin γ2 than negative cases, and EGFR expression was significantly more frequent in positive expression of cytoplasmic laminin γ2 and MMP-7.

CONCLUSIONS

Molecular expression of MMP-7, laminin γ2 or EGFR, and their combinations, may be associated with GC tumor aggressiveness. Assessment of expression of these molecules at the invasive front of primary tumors is clinically significant in predicting the malignant behavior of GC.

Human papillomavirus species-specific interaction with the basement membrane-resident non-heparan sulfate receptor

Using a cell culture model where virus is bound to the extracellular matrix (ECM) prior to cell surface binding, we determined that human papillomavirus type 16 (HPV16) utilizes ECM resident laminin (LN) 332 as an attachment receptor for infectious entry. In presence of LN332, soluble heparin can function as ligand activator rather than competitive inhibitor of HPV16 infection. We also show that the ability to use LN332 binding as a productive attachment step for infectious entry is not conserved amongst HPV types. In the alpha genus, species 9 members (HPV16) attach to ECM via LN332, while members of species 7 (HPV18) are completely inhibited by heparin pre-incubation due to an inability to use LN332. Since HPV species 7 and 9 are preferentially associated with adenocarcinoma and squamous cell carcinoma of the cervix, respectively, our data provide first evidence that pre-entry events may contribute to the anatomical-site preference of HPV species.

Possible target for preventing fibrotic scar formation following acute myocardial infarction

Bone morphogenetic protein 1 (BMP1) was originally isolated from bone with other BMPs due to its affinity for heparin. While all other BMPs are members of the Transforming Growth Factor β (TGFβ) superfamily of growth factors, BMP1 is not an authentic member of the BMP protein family. Together with mammalian Tolloid Like protein 1 (mTLL-1) and mTLL-2, BMP1 comprise a small group of zinc- and calcium-dependent proteinases. Acute myocardial infarction (AMI) is the leading cause of death in developed countries which accounts for 13% of deaths worldwide. It was recently shown that inhibition of BMP1-3 reduces progression of fibrosis in chronic kidney disease and suggested that BMP1-3 is an important molecule for fibrogenesis. We hypothesize that inhibition of BMP1-3 represents future of therapeutic interventions in the heart tissue fibrosis following AMI. This novel approach aims to acquire the first candidate specific treatment for recuperating the heart function in patients with AMI.

Isolation of a hemidesmosome-rich fraction from a human squamous cell carcinoma cell line

Hemidesmosomes are cell-to-matrix adhesion complexes anchoring keratinocytes to basement membranes. For the first time, we present a method to prepare a fraction from human cultured cells that are highly enriched in hemidesmosomal proteins. Using DJM-1 cells derived from human squamous cell carcinoma, accumulation of hemidesmosomes was observed when these cells were cultured for more than 10 days in a commercial serum-free medium without supplemental calcium. Electron microscopy demonstrated that numerous electron-dense adhesion structures were present along the basal cell membranes of DJM-1 cells cultured under the aforementioned conditions. After removing cellular materials using an ammonia solution, hemidesmosomal proteins and deposited extracellular matrix were collected and separated by electrophoresis. There were eight major polypeptides, which were determined to be plectin, BP230, BP180, integrin α6 and β4 subunits, and laminin-332 by immunoblotting and mass spectrometry. Therefore, we designated this preparation as a hemidesmosome-rich fraction. This fraction contained laminin-332 exclusively in its unprocessed form, which may account for the promotion of laminin deposition, and minimal amounts of Lutheran blood group protein, a nonhemidesmosomal transmembrane protein. This hemidesmosome-rich fraction would be useful not only for biological research on hemidesmosomes but also for developing a serum test for patients with blistering skin diseases.

Reduced fibulin-2 contributes to loss of basement membrane integrity and skin blistering in mice lacking integrin α3β1 in the epidermis

Deficient epidermal adhesion is a hallmark of blistering skin disorders and chronic wounds, implicating integrins as potential therapeutic targets. Integrin α3β1, a major receptor in the epidermis for adhesion to laminin-332 (LN-332), has critical roles in basement membrane (BM) organization during skin development. In the current study we identify a role for α3β1 in promoting stability of nascent epidermal BMs through induction of fibulin-2, a matrix-associated protein that binds LN-332. We demonstrate that mice lacking α3β1 in the epidermis display ruptured BM beneath neo-epidermis of wounds, characterized by extensive blistering. This junctional blistering phenocopies defects reported in newborn α3-null mice, as well as in human patients with α3 gene mutations, indicating that the developmental role of α3β1 in BM organization is recapitulated during wound healing. Mice lacking epidermal α3β1 also have reduced fibulin-2 expression, and fibulin-2-null mice display perinatal skin blisters similar to those in α3β1-deficient mice. Interestingly, α3-null wound epidermis or keratinocytes also show impaired processing of the LN-332 γ2 chain, although this defect was independent of reduced fibulin-2 and did not appear to cause blistering. Our findings indicate a role for integrin α3β1 in BM stability through fibulin-2 induction, both in neonatal skin and in adult wounds.

A truncating mutation in the laminin-332α chain highlights the role of the LG45 proteolytic domain in regulating keratinocyte adhesion and migration

BACKGROUND

Altered function of laminin-332 (α3β3γ2) consequent to mutations in the LAMA3, LAMB3 and LAMC2 genes causes junctional epidermolysis bullosa non-Herlitz (JEB-nH). JEB-nH patients suffer from skin blistering and have an increased risk of developing aggressive skin carcinomas in adulthood. Laminin-332 is proteolytically processed and its extracellular mature form lacks the α3 chain C-terminal globules 4 and 5 (LG45). The LG45 tandem has cell adhesion and protumorigenic properties. However, mutations that affect this domain are very rare and their functional effects in patients have not been explored to date.

OBJECTIVE

To characterize molecularly an adult patient with JEB-nH and altered laminin-332 expression presenting multiple skin carcinomas, and to analyse LG45-mediated biological functions using keratinocytes from the patient.

METHODS

A mutational search in laminin-332 genes was performed by hetero-duplex analysis. LAMA3 mRNA and laminin-332 protein levels in patient keratinocytes were investigated by real-time reverse transcriptase polymerase chain reaction and radioimmunoprecipitation assay, respectively. Keratinocyte migration was examined by scratch and Boyden chamber assays.

RESULTS

We identified a homozygous LAMA3 mutation, p.Leu1648TrpfsX32, which truncates the last 45 amino acids of the carboxyl terminal LG5 subdomain. Gene expression studies revealed that the mutant transcripts were stable and even increased, precursor laminin-332 molecules were retained intracellularly and the amount of mature extracellular heterotrimers was reduced to about 50%. Finally, the patient's keratinocytes migrated faster than normal keratinocytes.

CONCLUSIONS

Structural disruption of LG5 highlights the critical functions of the LG45 proteolytic region in precursor laminin-332 secretion and keratinocyte adhesion and migration. Perturbation of LG45 function might explain the non-aggressive behaviour of carcinomas in this patient.

Surgical correction of microstomia in a patient with antilaminin 332 mucous membrane pemphigoid

Microstomia is a term used to describe a small oral aperture. Most of the reported cases are caused by scar contracture after facial trauma, burn injury, and tumor excision. We experienced a rare case of microstomia in a patient with antilaminin 332 mucous membrane pemphigoid, which was an acquired autoimmune disease and showed blisters and erosive lesions mainly on the mucous membranes. The patient had recurrent aphthous stomatitis and presented microstomia caused by scar contracture of oral mucosa. We surgically corrected microstomia by 5-flap Z-plasty for commissuroplasty and 2 Z-plasty of both upper and lower lips for an enlargement of oral aperture. The patient could achieve an enough oral aperture and was satisfied with the result. There was no recurrence of microstomia for 2 years.

Integrin Regulation of Epidermal Functions in Wounds

Significance: Integrins are bidirectional signaling receptors for extracellular matrix that regulate both inside-out signaling that controls keratinocyte-mediated changes to the wound microenvironment and outside-in signaling that controls keratinocyte responses to microenvironmental changes. As such, integrins represent attractive therapeutic targets for treatment of chronic wounds or general promotion of wound healing. Advances in wound management are particularly important as the elderly and diabetic populations within the United States continue to grow. Recent Advances: Although integrins are best known for mediating cell adhesion and migration, integrins in wound epidermis also control cell survival, proliferation, matrix remodeling, and paracrine crosstalk to other cellular compartments of the wound. Importantly, the concept of targeting integrins in the clinic has been established for treatment of certain cancers and other diseases, laying the groundwork for similar exploitation of integrins as targets to treat chronic wounds. Critical Issues: Despite their attractiveness as therapeutic targets, integrins have complex roles in wound healing that are impacted by both their own expression and a highly dynamic wound microenvironment that determines ligand availability. Therefore, identifying relevant integrin ligands in the wound and understanding both distinct and overlapping functions that different integrins play in the epidermis will be critical to determine their precise roles in wound healing. Future Directions: Future research should focus on gaining a thorough understanding of the highly coordinated functions of different integrins in wound epidermis, and on determining which of these functions go awry in pathological wounds. This focus should facilitate development of integrin-targeting therapeutics for treating chronic wounds.

The influence of substrate topography on the migration of corneal epithelial wound borders

Currently available artificial corneas can develop post-implant complications including epithelial downgrowth, infection, and stromal melting. The likelihood of developing these disastrous complications could be minimized through improved formation and maintenance of a healthy epithelium covering the implant. We hypothesize that this epithelial formation may be enhanced through the incorporation of native corneal basement membrane biomimetic chemical and physical cues onto the surface of the keratoprosthesis. We fabricated hydrogel substrates molded with topographic features containing specific bio-ligands and developed an in vitro wound healing assay. In our experiments, the rate of corneal epithelial wound healing was significantly increased by 50% in hydrogel surfaces containing topographic features, compared to flat surfaces with the same chemical attributes. We determined that this increased healing is not due to enhanced proliferation or increased spreading of the epithelial cells, but to an increased active migration of the epithelial cells. These results show the potential benefit of restructuring and improving the surface of artificial corneas to enhance epithelial coverage and more rapidly restore the formation of a functional epithelium.

Osseous metaplasia with mature bone formation of the thyroid gland: Three case reports

Nodular hyperplasia (nodular or multinodular goiter) is the most common form of thyroid disease. These nodules may undergo secondary changes in the form of hemorrhages, calcification and cystic degeneration. However, osseous metaplasia with mature bone formation rarely occurs. The present study reports the cases of three female patients with thyroid nodules diagnosed as nodular hyperplasia with osseous metaplasia and mature bone formation. The patients underwent right lobectomy, near total thyroidectomy and total thyroidectomy, respectively. The clinical course of the patients following resection were unremarkable.

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. Depletion or functional deficiencies of any BM component are lethal at some stage of development or around birth, though BM defects vary between organs and tissues. Lethality problems were overcome by developmental stage- and skin-specific gene targeting or by cell grafting and organotypic (3D) cocultures of normal or defective cells, which allows recapitulating BM formation de novo. Thus, evidence is accumulating that BM assembly and turnover rely on mechanical properties and composition of the adjacent ECM and the dynamics of molecular assembly, including further "minor" local components, nidogens largely functioning as catalysts or molecular adaptors and perlecan as bridging stabilizer. Collectively, orchestration of BM assembly, remodeling, and the role of individual players herein are determined by the developmental, tissue-specific, or functional context.

Laminin 332 processing impacts cellular behavior

Laminin 332, composed of the α3, β3 and γ2 chains, is an epithelial-basement membrane specific laminin variant. Its main role in normal tissues is the maintenance of epithelial-mesenchymal cohesion in tissues exposed to external forces, including skin and stratified squamous mucosa. After being secreted and deposited in the extracellular matrix, laminin 332 undergoes physiological maturation processes consisting in the proteolytic processing of domains located within the α3 and the γ2 chains. These maturation events are essential for laminin 332 integration into the basement membrane where it plays an important function in the nucleation and maintenance of anchoring structures. Studies in normal and pathological situations have revealed that laminin 332 can trigger distinct cellular events depending on the level of its proteolytic cleavages. In this review, the biological and structural characteristics of laminin 332 domains are presented and we discuss whether they trigger specific functions.

Functional significance of periostin in excisional skin repair: is the devil in the detail?

In the past year, three papers have been published exploring the role of the matricellular protein periostin in excisional skin repair. These papers all show a delay in wound closure and the kinetics of this delay are strikingly similar across the three reports. The similarities between these papers end, however, when each investigates the mechanism through which periostin influences skin repair. Three proposed mechanisms have been identified: (1) myofibroblast differentiation, (2) keratinocyte proliferation and (3) fibroblast proliferation and migration. The aim of this commentary is to compare and contrast the three studies performed to date in an attempt to decipher the role of periostin in the repair of full-thickness skin wounds.

Selective cleavage of human sex hormone-binding globulin by kallikrein-related peptidases and effects on androgen action in LNCaP prostate cancer cells

Stimulation of the androgen receptor via bioavailable androgens, including testosterone and testosterone metabolites, is a key driver of prostate development and the early stages of prostate cancer. Androgens are hydrophobic and as such require carrier proteins, including sex hormone-binding globulin (SHBG), to enable efficient distribution from sites of biosynthesis to target tissues. The similarly hydrophobic corticosteroids also require a carrier protein whose affinity for steroid is modulated by proteolysis. However, proteolytic mechanisms regulating the SHBG/androgen complex have not been reported. Here, we show that the cancer-associated serine proteases, kallikrein-related peptidase (KLK)4 and KLK14, bind strongly to SHBG in glutathione S-transferase interaction analyses. Further, we demonstrate that active KLK4 and KLK14 cleave human SHBG at unique sites and in an androgen-dependent manner. KLK4 separated androgen-free SHBG into its two laminin G-like (LG) domains that were subsequently proteolytically stable even after prolonged digestion, whereas a catalytically equivalent amount of KLK14 reduced SHBG to small peptide fragments over the same period. Conversely, proteolysis of 5α-dihydrotestosterone (DHT)-bound SHBG was similar for both KLKs and left the steroid binding LG4 domain intact. Characterization of this proteolysis fragment by [(3)H]-labeled DHT binding assays revealed that it retained identical affinity for androgen compared with full-length SHBG (dissociation constant = 1.92 nM). Consistent with this, both full-length SHBG and SHBG-LG4 significantly increased DHT-mediated transcriptional activity of the androgen receptor compared with DHT delivered without carrier protein. Collectively, these data provide the first evidence that SHBG is a target for proteolysis and demonstrate that a stable fragment derived from proteolysis of steroid-bound SHBG retains binding function in vitro.

Inhibition of collagen fibril formation

Background

The overall aim of presented study is to test the inhibition of the formation of collagen fibrils as the novel approach to reduce accumulation of pathological fibrotic deposits. The main hypothesis is that by interfering with the initial steps of the extracellular process of collagen fibril formation, it is possible to reduce the formation of fibrotic tissue.

Methods

The experimental model includes antibody-based inhibitors that specifically bind to the sites that participate in the collagen/collagen interaction.

Results

Employed antibody-based inhibitors effectively limit the amount of collagen fibrils formed in vitro and in engineered tissue models of localized fibrosis.

Conclusions

(i) Inhibition of collagen formation is an attractive target to reduce excessive formation of fibrotic tissue.

(ii) Antibody-based inhibitors of collagen fibril formation are promising therapeutic agents with a potential to limit localized fibrosis in a number of tissues.

Interaction of the retinoic acid signaling pathway with spicule formation in the marine sponge Suberites domuncula through activation of bone morphogenetic protein-1

BACKGROUND

The formation of the spicules in siliceous sponges involves the formation of cylinder-like structures in the extraspicular space, composed of the enzyme silicatein and the calcium-dependent lectin.

SCOPE OF REVIEW

Molecular cloning of the cDNAs (carotene dioxygenase, retinal dehydrogenase, and BMB-1 [bone morphogenic protein-1]) from the demosponge Suberites domuncula was performed. These tools were used to understand the retinoid metabolism in the animal by qRT-PCR, immunoblotting and TEM.

MAJOR CONCLUSIONS

We demonstrate that silintaphin-2, a silicatein-interacting protein, is processed from a longer-sized 15-kDa precursor to a truncated, shorter-sized 13kDa calcium-binding protein via proteolytic cleavage at the dipeptide Ala↓Asp, mediated by BMP-1. The expression of this protease as well as the expression of two key enzymes of the carotinoid metabolism, the β,β-carotene-15,15'-dioxygenase and the retinal dehydrogenase/reductase, were found to be strongly up-regulated by retinoic acid. Hence retinoic acid turned out to be a key factor in skeletogenesis in the most ancient still existing metazoans, the sponges.

GENERAL SIGNIFICANCE

It is shown that retinoic acid regulates the formation of the organic cylinder that surrounds the axis of the spicules and enables, as a scaffold, the radial apposition of new silica layers and hence the growth of the spicules.

Laminin-332 coordinates mechanotransduction and growth cone bifurcation in sensory neurons

Laminin-332 is a major component of the dermo-epidermal skin basement membrane and maintains skin integrity. The transduction of mechanical force into electrical signals by sensory endings in the skin requires mechanosensitive channels. We found that mouse epidermal keratinocytes produce a matrix that is inhibitory for sensory mechanotransduction and that the active molecular component is laminin-332. Substrate-bound laminin-332 specifically suppressed one type of mechanosensitive current (rapidly adapting) independently of integrin-receptor activation. This mechanotransduction suppression could be exerted locally and was mediated by preventing the formation of protein tethers necessary for current activation. We also found that laminin-332 could locally control sensory axon branching behavior. Loss of laminin-332 in humans led to increased sensory terminal branching and may lead to a de-repression of mechanosensitive currents. These previously unknown functions for this matrix molecule may explain some of the extreme pain experienced by individuals with epidermolysis bullosa who are deficient in laminin-332.

Molecular organization of the basement membrane zone

The dermal-epidermal basement membrane is a complex assembly of proteins that provide adhesion and regulate many important processes such as development, wound healing, and cancer progression. This contribution focuses on the structure and function of individual components of the basement membrane, how they assemble together, and how they participate in human tissues and diseases, with an emphasis on skin involvement. Understanding the composition and structure of the basement membrane provides insight into the pathophysiology of inherited blistering disorders, such as epidermolysis bullosa, and acquired bullous diseases, such as the pemphigoid group of autoimmune diseases and epidermolysis bullosa acquisita.

The timeline of lamellar basement membrane changes during equine laminitis development

REASONS FOR PERFORMING STUDY

The timing of lamellar basement membrane (BM) changes occurring during laminitis development is incompletely understood.

OBJECTIVES

To determine the temporal progression of lamellar BM changes and whether laminin-332 (Ln-332) γ2 cleavage products are generated during laminitis development.

METHODS

Eight clinically normal Standardbred horses were allocated into treatment (n = 5) or sham (n = 3) groups. The treatment group received, via nasogastric intubation, an oligofructose (OF) bolus (10 g/kg bwt) while the sham group was given water. Laminitis induction proceeded for 48 h followed by euthanasia. Lamellar biopsies were obtained prior to dosing and at intervals during the treatment period for analysis (at 12, 18, 24, 30 and 36 h and at 48 h following euthanasia).

RESULTS

Changes in lamellar collagen type IV and Ln-332 were first observed at 12 h post dosing. A unique pattern of reactivity for the Ln-332 γ2 antibody D4B5 occurred, in which reactivity was observed only in lamellar tissue affected by laminitis. No bioactive Ln-332 γ2 proteolytic fragments were detected in lamellar samples.

CONCLUSIONS

Basement membrane changes occurred early during the laminitis process. Direct Ln-332 γ2 cleavage to release biologically active products did not appear to occur. Thus loss of stability or protein interaction of the BM is probably responsible for the γ2 specific reactivity observed.

POTENTIAL RELEVANCE

Basement membrane changes may a first step in lamellar failure occurring prior to detection with conventional methods. Thus, more sensitive detection methods of BM changes are required to study laminitis development.

Delayed re-epithelialization in periostin-deficient mice during cutaneous wound healing

Background

Matricellular proteins, including periostin, are important for tissue regeneration.

Methods and Findings

Presently we investigated the function of periostin in cutaneous wound healing by using periostin-deficient (−/−) mice. Periostin mRNA was expressed in both the epidermis and hair follicles, and periostin protein was located at the basement membrane in the hair follicles together with fibronectin and laminin γ2. Periostin was associated with laminin γ2, and this association enhanced the proteolytic cleavage of the laminin γ2 long form to produce its short form. To address the role of periostin in wound healing, we employed a wound healing model using WT and periostin−/− mice and the scratch wound assay in vitro. We found that the wound closure was delayed in the periostin−/− mice coupled with a delay in re-epithelialization and with reduced proliferation of keratinocytes. Furthermore, keratinocyte proliferation was enhanced in periostin-overexpressing HaCaT cells along with up-regulation of phosphorylated NF-κB.

Conclusion

These results indicate that periostin was essential for keratinocyte proliferation for re-epithelialization during cutaneous wound healing.

Bone morphogenetic protein (BMP)1-3 enhances bone repair

Members of the astacin family of metalloproteinases such as human bone morphogenetic protein 1 (BMP-1) regulate morphogenesis by processing precursors to mature functional extracellular matrix (ECM) proteins and several growth factors including TGFβ, BMP2, BMP4 and GFD8. We have recently discovered that BMP1-3 isoform of the Bmp-1 gene circulates in the human plasma and is significantly increased in patients with acute bone fracture. We hypothesized that circulating BMP1-3 might have an important role in bone repair and serve as a novel bone biomarker. When administered systemically to rats with a long bone fracture and locally to rabbits with a critical size defect of the ulna, recombinant human BMP1-3 enhanced bone healing. In contrast, neutralization of the endogenous BMP1-3 by a specific polyclonal antibody delayed the bone union. Invitro BMP1-3 increased the expression of collagen type I and osteocalcin in MC3T3-E(1) osteoblast like cells, and enhanced the formation of mineralized bone nodules from bone marrow mesenchymal stem cells. We suggest that BMP1-3 is a novel systemic regulator of bone repair.

Laminin-332 cleavage by matriptase alters motility parameters of prostate cancer cells

BACKGROUND

Matriptase, a type II transmembrane serine protease, has been linked to initiation and promotion of epidermal carcinogenesis in a murine model, suggesting that deregulation of its role in epithelia contributes to transformation. In human prostate cancer, matriptase expression correlates with progression. It is therefore of interest to determine how matriptase may contribute to epithelial neoplastic progression. One approach for studying this is to identify potential matriptase substrates involved in epithelial integrity and/or transformation like the extracellular matrix macromolecule, laminin-332 (Ln-332), which is found in the basement membrane of many epithelia, including prostate. Proteolytic processing of Ln-332 regulates cell motility of both normal and transformed cells, which has implications in cancer progression.

METHODS

In vitro cleavage experiments were performed with purified Ln-332 protein and matriptase. Western blotting, enzyme inhibition assays, and mass spectrometry were used to confirm cleavage events. Matriptase overexpressing LNCaP prostate cancer cells were generated and included in Transwell migration assays and single cell motility assays, along with other prostate cells.

RESULTS

We report that matriptase proteolytically cleaves Ln-332 in the β3 chain. Substrate specificity was confirmed by blocking cleavage with the matriptase inhibitor, Kunitz domain-1. Transwell migration assays showed that DU145 cell motility was significantly enhanced when plated on matriptase-cleaved Ln-332. Similarly, Transwell migration of matriptase-overexpressing LNCaP cells was significantly increased on Ln-332 and, as determined by live single-cell microscopy, two motility parameters of this cell line, speed and directional persistence, were also higher.

CONCLUSIONS

Proteolytic processing of Ln-332 by matriptase enhances speed and directional persistence of prostate cancer cells.