Desmocollin Research Articles

Re-evaluating the prevalence of anti-desmocollin-1 IgA autoantibodies in canine pemphigus foliaceus

Pemphigus foliaceus (PF) is an autoimmune skin disease of dogs characterized by intraepidermal pustules containing neutrophils and dissociated keratinocytes that develop in association with circulating and tissue-bound IgG autoantibodies. A subset of IgG autoantibodies in canine PF target desmocollin-1 (DSC1), a component of intercellular adhesion complexes within the epidermis. Passive transfer of IgG autoantibodies from canine PF sera to mice was previously shown to induce skin disease in the absence of infiltrating neutrophils. In attempts to identify a mechanism responsible for neutrophil recruitment, past studies evaluated the prevalence of IgA autoantibodies in canine PF sera where they were found in <20% of affected dogs. We re-evaluated the prevalence of anti-DSC1 IgA in canine PF due to concerns regarding the sensitivity of previously used methods. We hypothesized that anti-DSC1 IgA are present in most dogs with PF but have been under-detected due to competition with concurrent anti-DSC1 IgG for binding to their mutual antigenic target. Despite removing approximately 80% of IgG from patient sera using affinity chromatography, we did not detect an increase in anti-DSC1 IgA by performing indirect immunofluorescence on canine DSC1-transfected HEK293T cells. Taken together, our results do not support a role for pathogenic IgA in canine PF.

A complex of cadherin 17 with desmocollin 1 and p120-catenin regulates colorectal cancer migration and invasion according to the cell phenotype

BackgroundCadherin-17 (CDH17), a marker of differentiation in intestinal cells, binds and activates α2β1 integrin to promote cell adhesion and proliferation in colorectal cancer (CRC) metastasis. Furthermore, CDH17 associates with p120- and β-catenin in a manner yet to be fully elucidated. In this report, we explored the molecular mediators involved in this association, their contribution to CRC dissemination and potential therapeutic implications.MethodsProteomic and confocal analyses were employed to identify and validate CDH17 interactors. Functional characterization involved the study of proliferation, migration, and invasion in cell lines representative of various phenotypes. Immunohistochemistry was conducted on CRC tissue microarrays (TMA). In vivo animal experiments were carried out for metastatic studies.ResultsWe found that desmocollin-1 (DSC1), a desmosomal cadherin, interacts with CDH17 via its extracellular domain. DSC1 depletion led to increased or decreased invasion in CRC cells displaying epithelial or mesenchymal phenotype, respectively, in a process mediated by the association with p120-catenin. Down-regulation of DSC1 resulted in an increased expression of p120-catenin isoform 1 in epithelial cells or a shift in cellular location in mesenchymal cells. Opposite results were observed after forced expression of CDH17. DSC1 is highly expressed in budding cells at the leading edge of the tumor and associates with poor prognosis in the stem-like, mesenchymal CRC subtypes, while correlates with a more favorable prognosis in the less-aggressive subtypes. In vivo experiments demonstrated that DSC1 silencing reduced tumor growth, liver homing, and metastasis in CRC mesenchymal cells. Furthermore, a synthetic peptide derived from CDH17, containing the NLV motif, effectively inhibited invasion and liver homing in vivo, opening up new possibilities for the development of novel therapies focused on desmosomal cadherins.ConclusionsThese findings shed light on the multifaceted roles of CDH17, DSC1, and p120-catenin in CRC metastasis, offering insights into potential therapeutic interventions for targeting desmosomal cadherins in poorly-differentiated carcinomas.

A novel circadian cycle-related gene signature for prognosis prediction of patients with breast cancer.

The extensive and intricate relationships between circadian rhythm and cancer have been reported in numerous studies. However, in breast cancer (BC), the potential role of circadian clock-related genes (CCRGs) in prognosis prediction has not been fully clarified. The transcriptome data and clinical information were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus databases. A CCRGs-based risk signature was established by differential expression analysis, univariate, Lasso and multivariate Cox regression analyses. we conducted a gene set enrichment analysis (GSEA) between groups. A nomogram integrating independent clinical factors and risk score was generated and evaluated by calibration curves and decision curve analysis (DCA). Differentially expression analysis revealed 80 differentially expressed CCRGs, and 27 of them were significantly associated with the overall survival (OS) of BC. BC can be classified into 4 molecular subtypes with significant differences in prognosis based on the 27 CCRGs. Three prognostic CCRGs, including desmocollin 1 (DSC1), LEF1, and protocadherin 9 (PCDH9), were identified to be independent risk factors of BC prognosis and were used to construct a risk score model. BC patients were divided into high- and low-risk groups, and there were significant differences in prognosis between the 2 groups both in the training and validation cohorts. It was found that patients in different groups of race, status, or T stage had significant levels of risk score. Furthermore, patients of different risk levels exhibit varying degrees of sensitivity to vinorelbine, lapatinib, metformin, and vinblastine. GSEA showed that in the high-risk group, immune response-related activities were dramatically repressed whereas cilium-related processes were significantly stimulated. Cox regression analysis demonstrated that age, N stage, radiotherapy and the risk score were independent prognostic risk factors of BC, and a nomogram was established based on these variables. The nomogram exerted a favorable concordance index (0.798) as well as calibration performance, which strongly supports the clinical application of the nomogram. Our study indicated the disruption of the expression of CCRGs in BC and built a favorable prognostic risk model based on 3 independent prognostic CCRGs. These genes may be applied as candidate molecular targets for the diagnosis and therapy of BC.

Docetaxel as a Model Compound to Promote HDL (High-Density Lipoprotein) Biogenesis and Reduce Atherosclerosis.

The recent identification of the cell-surface protein DSC1 (desmocollin 1) as a negative regulator of HDL (high-density lipoprotein) biogenesis has attracted us to revisit the old HDL biogenesis hypothesis: HDL biogenesis reduces atherosclerosis. The location and function of DSC1 suggest that DSC1 is a druggable target for the promotion of HDL biogenesis, and the discovery of docetaxel as a potent inhibitor of the DSC1 sequestration of apolipoprotein A-I has provided us with new opportunities to test this hypothesis. The FDA-approved chemotherapy drug docetaxel promotes HDL biogenesis at low-nanomolar concentrations that are far lower than used in chemotherapy. Docetaxel has also been shown to inhibit atherogenic proliferation of vascular smooth muscle cells. In accordance with these atheroprotective effects of docetaxel, animal studies have shown that docetaxel reduces dyslipidemia-induced atherosclerosis. In the absence of HDL-directed therapies for atherosclerosis, DSC1 constitutes an important new target for the promotion of HDL biogenesis, and the DSC1-targeting compound docetaxel serves as a model compound to prove the hypothesis. In this brief review, we discuss opportunities, challenges, and future directions for using docetaxel in the prevention and treatment of atherosclerosis.

Repurposing the anti-cancer drug docetaxel for the prevention and treatment of atherosclerosis

Background and Aims : We have identified that a negative regulator of high-density lipoprotein (HDL) biogenesis, desmocollin 1 (DSC1) contributes to cholesterol accumulation in the atherosclerotic plaque. With screening of 10 million small molecules, the FDA-approved chemotherapy drug docetaxel was identified to inhibit the DSC1 activity and promote HDL biogenesis. To test whether docetaxel reduces atherosclerosis in an animal model, apoE-null mice were fed a high-fat diet to promote dyslipidemia.

Collective mechanical responses of cadherin-based adhesive junctions as predicted by simulations

Cadherin-based adherens junctions and desmosomes help stabilize cell-cell contacts with additional function in mechano-signaling, while clustered protocadherin junctions are responsible for directing neuronal circuits assembly. Structural models for adherens junctions formed by epithelial cadherin (CDH1) proteins indicate that their long, curved ectodomains arrange to form a periodic, two-dimensional lattice stabilized by tip-to-tip trans interactions (across junction) and lateral cis contacts. Less is known about the exact architecture of desmosomes, but desmoglein (DSG) and desmocollin (DSC) cadherin proteins are also thought to form ordered junctions. In contrast, clustered protocadherin (PCDH)-based cell-cell contacts in neuronal tissues are thought to be responsible for self-recognition and avoidance, and structural models for clustered PCDH junctions show a linear arrangement in which their long and straight ectodomains form antiparallel overlapped trans complexes. Here, we report all-atom molecular dynamics simulations testing the mechanics of minimalistic adhesive junctions formed by CDH1, DSG2 coupled to DSC1, and PCDHγB4, with systems encompassing up to 3.7 million atoms. Simulations generally predict a favored shearing pathway for the adherens junction model and a two-phased elastic response to tensile forces for the adhesive adherens junction and the desmosome models. Complexes within these junctions first unbend at low tensile force and then become stiff to unbind without unfolding. However, cis interactions in both the CDH1 and DSG2-DSC1 systems dictate varied mechanical responses of individual dimers within the junctions. Conversely, the clustered protocadherin PCDHγB4 junction lacks a distinct two-phased elastic response. Instead, applied tensile force strains trans interactions directly, as there is little unbending of monomers within the junction. Transient intermediates, influenced by new cis interactions, are observed after the main rupture event. We suggest that these collective, complex mechanical responses mediated by cis contacts facilitate distinct functions in robust cell-cell adhesion for classical cadherins and in self-avoidance signaling for clustered PCDHs.

Identification of Docetaxel as a Potential Drug to Promote HDL Biogenesis.

Objective: Our recent studies showed that desmocollin 1 (DSC1) binds to apoA-I in order to inhibit apoA-I-mediated high density lipoprotein (HDL) biogenesis in atherosclerotic plaques. To promote HDL biogenesis in the plaque, here we search for small molecules that block apoA-I-DSC1 interactions. Approach and Results: We combined mutational and computational mapping methods to show that amino acid residues 442–539 in the mature DSC1 protein form an apoA-I binding site (AIBS). Using a crystal structure of the AIBS, we carried out virtual screening of 10 million small molecules to estimate their binding affinities to the AIBS, followed by the selection of 51 high-affinity binding molecules as potential inhibitors of apoA-I-DSC1 interactions. Among the 51, the chemotherapy drug docetaxel showed the highest potency in promoting apoA-I-mediated HDL biogenesis in primary human skin fibroblasts with the half-maximal effective concentration of 0.72 nM. In silico docking studies suggest that the taxane ring in docetaxel binds to the AIBS and that the carbon-13 sidechain of the taxane tightens/stabilizes the binding. The HDL biogenic effect of docetaxel was also observed in two predominant cell types in atherosclerosis, macrophages and smooth muscle cells. Importantly, docetaxel promoted HDL biogenesis at concentrations much lower than those required for inducing cytotoxicity. Conclusion: Determination of the AIBS in DSC1 and AIBS structure-based virtual screening allowed us to identify docetaxel as a strong HDL biogenic agent. With the remarkable potency in promoting HDL biogenesis, a chemotherapy drug docetaxel may be repurposed to enhance atheroprotective HDL functions.

Autoantibodies to DSC3 in Pemphigus Exclusively Recognize Calcium-Dependent Epitope in Extracellular Domain 2

Pemphigus is a group of autoimmune bullous diseases characterized by the presence of autoantibodies against adhesion molecules, desmogleins, and desmocollins (DSCs). The pathogenicity of anti-DSC3 antibodies in pemphigus has been demonstrated; however, its characteristics have not yet been elucidated. We aimed to analyze the characteristics of anti-DSC3 antibodies using DSC3 domain‒swapped desmoglein 2 molecules in which the prosequence and five extracellular (EC) domains of desmoglein 2 were replaced with the corresponding domains of human DSC3. Using these proteins, we established an ELISA and analyzed sera from 56 patients with pemphigus. In 34 pemphigus sera positive for DSC3 full-EC domains, 15 sera (44.1%) were positive for EC2 domain, whereas other domains were rarely positive. We assessed the reactivity to a calcium-dependent epitope in DSC3 by ELISA with EDTA. The reactivity with the EC2 domain was mostly compromised in the presence of EDTA. In the invitro assay, IgG from patients with paraneoplastic pemphigus preadsorbed with EC2 prevented both reduction of DSC3 and keratinocyte dissociation as compared with that with EDTA-treated EC2. This study revealed a predominant recognition of calcium-dependent epitopes in EC2 domain by anti-DSC3 antibodies and its pathogenicity on keratinocyte adhesion through DSC3 depletion.

Ovariectomized mice and postmenopausal women exhibit analogous loss of genital epithelial integrity.

ABSTRACT Roughly half of all postmenopausal women are affected by the genitourinary syndrome of menopause (GSM). Symptoms of GSM, including vaginal irritation and dyspareunia, occur as reduced estrogen (E) production elicits loss of elasticity and other changes in genital tract tissue. While the use of the injectable contraceptive depot-medroxyprogesterone acetate (DMPA) likewise lowers serum E concentrations in reproductive age women and is associated with decreased genital levels of the cell-cell adhesion molecules desmoglein-1 (DSG1) and desmocollin-1 (DSC1) and impaired genital epithelial barrier function, the relevance of these findings to women in menopause is uncertain. Exploring the impact of menopause on genital epithelial integrity herein, we detected significantly lower levels of DSG1 and DSC1 in ectocervical tissue from menopausal and postmenopausal vs premenopausal women. Using ovariectomized (OVX) mice as a menopause model, we comparably saw significantly lower vaginal tissue levels of DSG1 and DSC1 in OVX mice vs. mice in estrus. Compared to estrus-stage mice and E-treated OVX mice, DMPA-treated ovary-intact mice and OVX mice also exhibited significantly reduced genital epithelial barrier function, greater susceptibility to genital herpes simplex virus type 2 infection, and delayed clearance of genital Chlamydia trachomatis infection. Current studies thus identify analogous loss of genital epithelial integrity in OVX mice and menopausal and postmenopausal women. By showing that loss of genital epithelial integrity is associated with increased mouse susceptibility to bacterial and viral pathogens, our findings also prioritize the need to resolve if reduced genital epithelial integrity in postmenopausal women is a significant risk factor for genital infection.

Reduced Desmosomal Cadherin Levels in Genital Epithelium of Postmenopausal Women Also Develop in Ovariectomized Mice with Increased Susceptibility to Viral and Bacterial Genital Pathogens

Background: The genitourinary syndrome of menopause affects about half of all women in menopause and includes symptoms of vaginal burning, dyspareunia, and urinary urgency. These symptoms stem from lower serum estrogen levels in postmenopausal women that cause reduced tissue elasticity and other genital tract changes. While the hypoestrogenemia induced in reproductive age women using the progestin-only contraceptive depot-medroxyprogesterone acetate (DMPA) decreases genital levels of the cell-cell adhesion molecules desmoglein-1 (DSG1) and desmocollin-1 (DSC1) and impairs genital epithelial barrier function, relevance of these findings to postmenopausal women is uncertain. Methods: We compared ectocervical DSG1 and DSC1 levels in premenopausal vs. postmenopausal women. Using ovariectomized mice to model the hypoestrogenic state in postmenopausal women, we explored effects of reduced ovarian function on genital epithelial integrity barrier function and genital pathogen susceptibility. Findings: Compared to premenopausal women, ectocervical tissue from women in menopause had significantly lower levels of DSG1 and DSC1. Likewise, Dsg1 and Dsc1 levels were significantly reduced in OVX mice vs. estrus-stage mice. Consistent with these data, DMPA-treated and OVX mice displayed significant compromise of genital epithelial barrier function and compared to estrus-stage mice or OVX mice treated with estrogen, were more susceptible to genital herpes simplex virus type 2 infection and less effectively cleared genital Chlamydia trachomatis infection. Interpretation: Our studies identify analogously reduced genital epithelial integrity in postmenopausal women and OVX mice and indicate that reduced ovarian function alters host response to bacterial and viral pathogens. Our results also spotlight the need to resolve if weakened genital epithelial integrity in postmenopausal women represents an important risk factor for genital infection. Funding Statement: This work was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01HD094634) and Stanford University School of Medicine. Declaration of Interests: Authors have no conflicts of interest to declare. Ethics Approval Statement: Prior to induction, all proposed mice studies were approved by the Stanford University Institutional Animal Care and Use Committee.

Skin characteristics associated with foot callus in people with diabetes: A cross-sectional study focused on desmocollin1 in corneocytes

AimThe purpose of this study was to investigate the degradation of desmocollin-1 (DSC1), a member of the desmosomal cadherin family in patients with diabetes, as well as the factors associated with the suppression of DSC1 degradation. MethodsThis cross-sectional study included 60 cases of foot callus involving 30 patients with diabetes (DM) and 30 matched volunteers without diabetes (non-DM). DSC1 degradation in samples from debrided calluses was analysed using western blotting. Skin hydration, a factor reported to suppress DSC1 degradation, was measured using a mobile moisture device. ResultsFull-length DSC1 (approximately 100 kDa) was detected in six participants only in the DM group, and no relationship was found between the suppression of DSC1 degradation and decreased skin hydration in the DM group. There was no significant difference in skin hydration values between the DM and non-DM groups. ConclusionDSC1 degradation was suppressed in the DM group. There was no relationship between the suppression of DSC1 degradation and decreased skin hydration in the DM group. Current external force callus care would not be sufficient. This study highlights the need to develop novel callus care to enhance the degradation of DSC1.

Proteomics Identification and Validation of Desmocollin-1 and Catechol-O-Methyltransferase as Proteins Associated with Breast Cancer Cell Migration and Metastasis.

Biological treatment of many cancers currently targets membrane bound receptors located on a cell surface. To identify novel membrane proteins associated with migration and metastasis of breast cancer cells, a more migrating subpopulation of MDA-MB-231 breast cancer cell line is selected and characterized. A high-resolution quantitative mass spectrometry with SILAC labeling is applied to analyze their surfaceome and it is compared with that of parental MDA-MB-231 cells. Among 824 identified proteins (FDR<0.01), 128 differentially abundant cell surface proteins with at least one transmembrane domain are found. Of these, i) desmocollin-1 (DSC1) is validated as a protein connected with lymph node status of luminal A breast cancer, tumor grade, and Her-2 status by immunohistochemistry in the set of 96 primary breast tumors, and ii) catechol-O-methyltransferase is successfully verified as a protein associated with lymph node metastasis of triple negative breast cancer as well as with tumor grade by targeted data extraction from the SWATH-MS data of the same set of tissues. The findings indicate importance of both proteins for breast cancer development and metastasis and highlight the potential of biomarker validation strategy via targeted data extraction from SWATH-MS datasets.

Immunohistochemical staining of skin-expressed proteins to identify exfoliated epidermal cells for forensic purposes

The determination of cell type in biological casework samples would be helpful to identify the type of body fluids and interpret the DNA source in forensic laboratories. Exfoliated epidermal cells are considered to be a reasonable source of touch DNA; therefore, we developed and assessed an immunohistochemistry (IHC) procedure for identifying exfoliated epidermal cells as a screening test of touch DNA samples. Among five candidate protein markers investigated in this study, keratin 10 and kallikrein-related peptidase 5 were strongly expressed in the stratum corneum layer of the skin; however, their specificity was insufficient to identify epidermal cells. In contrast, IHC for corneodesmosin (CDSN), desmocollin 1 (DSC1), and filaggrin (FLG) was considered to be applicable because of their detectability and specificity on skin swab samples. Actually, CDSN and DSC1 could be good markers for exfoliated epidermal cells on touched contact traces that were contaminated with many unidentified impurities. Besides, positivity for FLG on mock casework samples appeared to be lower than for the other markers, which might be caused by its instability. Finally, the relationship between positivity for IHC and DNA yield was analyzed using skin swab samples. Although it was difficult to determine these correlations quantitatively because of the heterogeneous distribution of cells and the presence of cell-free DNA, the DNA-quantifiable samples analyzed in this study contained at least some of IHC-positive epidermal cells. In conclusion, IHC detection of skin-enriched proteins, especially CDSN and DSC1, could be useful for screening samples that have been handled or touched by someone before DNA analysis.

Desmocollin 3 has a tumor suppressive activity through inhibition of AKT pathway in colorectal cancer

Desmocollin 3 (DSC3) is a transmembrane adhesion protein of desmosomes and involved in carcinogenesis in various cancer types. Downregulation of DSC3 has been reported in colorectal cancer (CRC). However, the function of DSC3 in CRC has not yet been elucidated. In this study, we performed cell-based functional analysis after DSC3 overexpression by stable transfection and knockdown by siRNA in CRC cells. It turned out that overexpression of DSC3 reduced cell proliferation, colony forming ability, induced G0/G1 cell cycle arrest and promoted apoptosis. Further pathway analysis showed that overexpression of DSC3 significantly inhibited the activity of AKT pathway and increased the expression of E-cadherin as well as p53 and p21. In contrast, siRNA-mediated knockdown of DSC3 increased cell proliferation and colony formation, activated the AKT pathway and decreased the expression of E-cadherin as well as p53 and p21. Additionally, in primary CRC patient samples, the expression of DSC3 protein was significantly related to the expression of desmocollin 1 (DSC1) and desmocollin 2 (DSC2) as well as E-cadherin (p < 0.001 respectively). Taken together, our data reveal that DSC3 suppresses CRC cell growth through inhibition of AKT pathway and regulation of E-cadherin. DSC3 may serve as a novel therapeutic target for CRC.

The aberrant expression or disruption of desmocollin2 in human diseases.

The desmosome is a member of intercellular junctions that named 'anchoring junction', which contributes to the integrity and homeostasis of tissue structure and function of multicellular living organisms. As an important component of the desmosome and the most widely distributed isoform of desmocollins (DSCs), desmocollin2 (DSC2) has been demonstrated to be essential for the unity of epithelial cells, and served as a vital regulator in signaling processes such as epithelial morphogenesis, differentiation, wound healing, cell apoptosis, migration, and proliferation. Recent studies suggested that the aberrant expression or disruption of DSC2 might lead to some disorders, including heart disorders, certain cancers, and some other human diseases. The distinctions in expression and regulation mechanisms of DSC2 in different human diseases provided a potential target for diagnosis and individualized treatment. Further research is required to certify the signaling capacity of DSC2 and to shed light on the down-stream consequences of the signaling for us to understand the new area of DSC2 biology and the development of certain diseases. This review summarizes the molecular structure and dynamics of desmosome and DSC2, the relationship between the disruption or aberrant expression of DSC2 and human diseases and related molecular mechanisms, as well as the possible prospects.

HDLs and the pathogenesis of atherosclerosis.

Plasma levels of HDL cholesterol are a biomarker of cardiovascular health but not a therapeutic target, as demonstrated by the failure of pharmacological modulation of HDL cholesterol to prevent or treat atherosclerotic cardiovascular disease. In health, HDL particles exert pleiotropic effects against atherosclerosis, including cholesterol removal from foam cells, vasodilatory effects through vascular endothelial cell nitric oxide production, decreased vascular inflammation and oxidative damage, endothelial cell proliferation and antiapoptotic effects. These functional effects of HDL are independent of the cholesterol mass and are related to the proteome and lipidome. In disease states and with the ageing process, HDL components are extensively modified and may no longer play a beneficial role but are retained in the atheroma and contribute to atherosclerosis. We have recently shown that desmocollin 1 (DSC1) acts as an apolipoprotein (apo) A-I binding protein that is highly expressed in atherosclerotic plaques and inhibits atheroprotective HDL functions by retaining apoA-I. The apoA-I retention hypothesis proposes that macrophages express DSC1 in a maladaptive process that renders apoA-I inactive and contributes to atherosclerosis. HDL loses their beneficial properties in ageing and disease states. Novel pathways may present new therapeutic avenues to restore their biological functions.

Membrane microdomains and the regulation of HDL biogenesis.

The major cardio-protective function of HDL is to remove excess cellular cholesterol in the process of HDL particle formation and maturation. The HDL biogenic procedure requiring protein-lipid interactions has been incompletely understood, and here we discuss recent progress and insights into the mechanism of HDL biogenesis. The initial and rate-limiting step of HDL biogenesis is the interaction between apoA-I and plasma membrane microdomains created by ATP-binding cassette transporter A1 (ABCA1) transporter. Computer simulation of molecular dynamics suggests that ABCA1 translocates phospholipids from the inner to the outer leaflet of the plasma membrane to create a transbilayer density gradient leading to the formation of an exovesiculated plasma membrane microdomain. The cryo-electron microscopy structure of ABCA1 suggests that an elongated hydrophobic tunnel formed by the extracellular domain of ABCA1 may function as a passageway to deliver lipids to apoA-I. In contrast to ABCA1-created plasma membrane microdomains, desmocollin 1 (DSC1) contained in a cholesterol-rich plasma membrane microdomain binds apoA-I to prevent HDL biogenesis. The identification of DSC1-containing plasma membrane microdomains as a negative regulator of HDL biogenesis may offer potential therapeutic avenues. Isolation and characterization of plasma membrane microdomains involved in HDL biogenesis may lead to a better understanding of the molecular mechanism of HDL biogenesis.

Novel Approaches for HDL-Directed Therapies.

High-density lipoproteins (HDL) are thought to exert a protective role against atherosclerosis. The measurement of the cholesterol mass within HDL (HDL-C) represents a good biomarker of cardiovascular health, but HDL-C appears to be a poor therapeutic target. Here, we discuss new targets for the development of HDL-directed therapies. Among cardio-protective functions of HDL particles, the ability of HDL to remove cholesterol from cells involved in the early stages of atherosclerosis is considered one of the most important functions. This process, termed "HDL biogenesis," is initiated by the formation of highly specialized plasma membrane micro-domains by the ATP-binding cassette transporter A1 (ABCA1) and the binding of apolipoproteins (apo) such as apoA-I, the major protein moiety of HDL, to the micro-domains. Although early strategies aimed at increasing HDL biogenesis by upregulating ABCA1 or apoA-I gene expression have not met with clinical success, recent advances in understanding transcriptional, post-transcriptional, and post-translational regulatory pathways propose new targets for the promotion of HDL biogenesis. We have recently reported that a novel apoA-I-binding protein desmocollin 1 (DSC1) prevents HDL biogenesis and that inhibition of apoA-I-DSC1 interactions promotes HDL biogenesis by stabilizing ABCA1. This new HDL regulation pathway nominates DSC1 as an attractive pharmacological target. In the absence of clinically useful therapy to increase HDL biogenesis, finding novel targets to unlock the therapeutic potential of HDL is highly desired. Modulation of apoA-I-DSC1 interactions may be a viable strategy.

Desmocollin 1 is abundantly expressed in atherosclerosis and impairs high-density lipoprotein biogenesis.

The biogenesis of high-density lipoprotein (HDL) particles by cholesterol-laden foam cells in atherosclerotic lesions is crucial for the removal of excess cholesterol from the lesions. Impairment in the HDL biogenic process contributes to the progression of atherosclerosis. The aim of this study is to identify novel cellular factors regulating HDL biogenesis. HDL biogenesis is a process of apolipoprotein (apo)-mediated solubilization of specific plasma membrane (PM) microdomains generated in cholesterol-accumulated cells. We established a new method to isolate PM microdomains interacting with the major HDL protein constituent, apoA-I. Lipidomic and proteomic analyses of an isolated PM microdomain revealed that apoA-I binds to cholesterol-rich and desmocollin 1 (DSC1)-containing microdomains. In this novel apoA-I binding microdomain, DSC1 binds and prevents apoA-I from interacting with another PM microdomain created by adenosine triphosphate-binding cassette transporter A1 (ABCA1) for the formation of HDL. Inhibition of apoA-I-DSC1 binding by silencing DSC1 expression or using DSC1 blocking antibodies increases apoA-I accessibility to ABCA1-created microdomains and thus enhances HDL biogenesis. Importantly, DSC1 is abundantly expressed in macrophages and human atherosclerotic lesions, suggesting that DSC1 may contribute to cholesterol accumulation in atherosclerotic lesions by sequestering apoA-I and impairing HDL biogenesis. The binding of apoA-I to two functionally opposing PM microdomains, ABCA1 and DSC1 domains, suggests that HDL biogenesis and PM cholesterol levels may be regulated by the relative abundance of the two domains and that novel HDL biogenic therapies may be developed by targeting DSC1.

Conjunctiva derived mesenchymal stem cell (CJMSCs) as a potential platform for differentiation into corneal epithelial cells on bioengineered electrospun scaffolds.

With the aid of tissue engineering, the capability of nanofibrous scaffolds was examined for corneal epithelial differentiation of Conjunctiva mesenchymal stem cells (CJMSCs) as a new source. This study tried to provide a synthetic corneal sheet which could be applied in corneal regeneration. The hybrid arrangement of fine Silk fibers with the diameter of 93.65 nm and the polyurethane (PU) fibers with an average diameter of 575.5 makes a mat with sufficient mechanical properties and interconnected pores that could accelerate nutrient diffusion. After methanol and plasma treatment, the highest biocompatibility of Silk-PU hybrid nanofibrous scaffolds based on cell attachment and proliferation were proven using MTT assay. The differentiation morphology of cells was observed by SEM micrographs of cells seeded on the scaffold after 12 days treatment through the differentiation medium. Despite up-regulation of Cytokeratin (CK)3, CK8, CK12, Desmocollin (DSC)1, and Desmoglein (DSG)1 in the treated PU and silk hybrid nanofibrous scaffolds, the relative expression of CK3, CK8, and CK12 genes were highest among TCP, treated PU and silk nanofibrous scaffolds. Immunocytochemistry (ICC) analysis was used to characterize the protein expression of CK3 in CJ-MSCs seeded on different groups. Although, For both TCP and hybrid group, CJ-MSCs were positive for corneal epithelial-specific marker CK3, ICC data demonstrated that CJ-MSCs seeded on the hybrid group likewise PU or Silk pure nanofibrous scaffolds, could differentiate into corneal epithelial-like cells. Finally, it was inferred that the hybrid PU and silk nanofibrous scaffold has the potential for the treatment of corneal epithelium. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2703-2711, 2017.