Isthmin: A multifunctional secretion protein.

Isthmin is a polypeptide secreted by adipocytes that was first detected in Xenopus gastrula embryos. Recent studies have focused on the biological functions of isthmin in growth and development, angiogenesis, and metabolism. Distinct spatiotemporal expression of isthmin-1 (ISM-1) was observed during growth and development. ISM-1 plays an important role in the occurrence and development of cancer by regulating cell proliferation, migration, angiogenesis, and immune microenvironments. Moreover, ISM-1, as a newly identified insulin-like adipokine, increases adipocyte glucose uptake and inhibits hepatic lipid synthesis. However, the biological function of ISM-1 remains largely unknown. In this review, we highlight the structure and physiological functions of isthmin and explore its application potential, contributing to a better understanding of its function and providing prevention and treatment strategies for various diseases.

Identification of adhesion-associated extracellular matrix component thrombospondin 3 as a prognostic signature for clear cell renal cell carcinoma.

PURPOSE: Clear cell renal cell carcinoma (ccRCC) is a highly aggressive disease, and approximately 30% of patients are diagnosed at the metastatic stage. Even with targeted therapies, the prognosis of advanced ccRCC is poor. The aim of this study was to investigate clinical prognosis signatures by analyzing the ccRCC datasets in The Cancer Genome Atlas (TCGA) and the Clinical Proteomic Tumor Analysis Consortium (CPTAC) and the function of thrombospondin 3 (THBS3) in ccRCC. MATERIALS AND METHODS: We analyzed the ccRCC datasets in TCGA and CPTAC to search for extracellular matrix (ECM)-related and adhesion-associated genes, and conducted overall survival, Cox, and receiver operating characteristic analyses. We also performed CCK8, colony formation, and transwell assays to compared the proliferation and migration ability of THBS3 knockout cells with those of cells without THBS3 knockout. RESULTS: Comprehensive bioinformatics analysis revealed that THBS3 is a novel candidate oncogene that is overexpressed in ccRCC tumor tissue and that its elevated expression indicates poor prognosis. Our study also showed that knockdown of THBS3 inhibits proliferation, colony formation, and migration of ccRCC cells. CONCLUSIONS: In summary, our data have revealed that THBS3 is upregulated in cancer tissues and could be used as a novel prognostic marker for ccRCC. Our findings thus offer theoretical support with bioinformatics analyses to the study of ECM and adhesion proteins in ccRCC, which may provide a new perspective for the clinical management of ccRCC.

Functions of Matricellular Proteins in Dental Tissues and Their Emerging Roles in Orofacial Tissue Development, Maintenance, and Disease.

Matricellular proteins (MCPs) are defined as extracellular matrix (ECM) associated proteins that are important regulators and integrators of microenvironmental signals, contributing to the dynamic nature of ECM signalling. There is a growing understanding of the role of matricellular proteins in cellular processes governing tissue development as well as in disease pathogenesis. In this review, the expression and functions of different MP family members (periostin, CCNs, TSPs, SIBLINGs and others) are presented, specifically in relation to craniofacial development and the maintenance of orofacial tissues, including bone, gingiva, oral mucosa, palate and the dental pulp. As will be discussed, each MP family member has been shown to have non-redundant roles in development, tissue homeostasis, wound healing, pathology and tumorigenesis of orofacial and dental tissues.

Contribution of Thrombospondin-1 and -2 to Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome.

Thrombospondin (TSP) proteins have been shown to impact T-cell adhesion, migration, differentiation, and apoptosis. Thrombospondin-1 (TSP-1) is specifically upregulated in several inflammatory diseases and can effectively promote lipopolysaccharide- (LPS-) induced inflammation. In contrast, thrombospondin-2 (TSP-2) has been associated with activation of "anti-inflammatory" T-regulatory cells (Tregs). In this study, we investigated the effects of both TSP-1 and TSP-2 overexpression on macrophage polarization and activation in vitro and in vivo. We analyzed the effects of TSP-1 and TSP-2 on inflammation, vascular endothelial permeability, edema, ultrastructural morphology, and apoptosis in lung tissues of an ARDS mouse model and cultured macrophages. Our results demonstrated that TSP-2 overexpression effectively attenuated LPS-induced ARDS in vivo and promoted M2 macrophage phenotype polarization in vitro. Furthermore, TSP-2 played a role in regulating pulmonary vascular barrier leakage by activating the PI3K/Akt pathway. Overall, our findings indicate that TSP-2 can modulate inflammation and could therefore be a potential therapeutic target against LPS-induced ARDS.

Circ-AK2 is associated with preeclampsia and regulates biological behaviors of trophoblast cells through miR-454-3p/THBS2.

INTRODUCTION: Circ-AK2 has been found to be differentially expressed in PE placenta tissues, however, the role and the underlying molecular mechanisms of circ-AK2 in PE remain poorly known. METHODS: The expression of circ-AK2, miR-454-3p, and THBS2 mRNA was detected using quantitative real-time polymerase chain reaction. Protein levels of CyclinD1, MMP-9 and THBS2 were measured using Western blot. Cell proliferation, migration, and invasion were analyzed by 3-(4, 5)-dimethylthiahiazo (-z-y1)-3, 5-di-phenytetrazoliumromide (MTT) assay and transwell assay. The interaction between miR-454-3p and circ-AK2 or THBS2 was analyzed by the dual-luciferase reporter assay. RESULTS: Circ-AK2 was highly expressed in placental tissues of PE, and overexpression of circ-AK2 inhibited trophoblast cell proliferation, migration and invasion. Circ-AK2 directly bound to miR-454-3p, and miR-454-3p overexpression reversed the inhibitory action of circ-AK2 in biological functions of trophoblast cells. MiR-454-3p was lowly expressed in placental tissues of PE, and directly regulated THBS2 expression in a targeted manner. Silencing miR-454-3p suppressed the proliferating, migratory, and invasive abilities of trophoblast cells, while this condition was abolished by THBS2 knockdown. Besides, we also proved circ-AK2 could regulate THBS2 expression via miR-454-3p. DISCUSSION: Circ-AK2 inhibited the proliferation, migration and invasion of trophoblast cells via targeting miR-454-3p/THBS2 axis, suggesting a novel insight into the etiology of PE and a potential therapeutic target for PE treatment.

R-spondin signalling is essential for the maintenance and differentiation of mouse nephron progenitors.

During kidney development, WNT/ß-catenin signalling has to be tightly controlled to ensure proliferation and differentiation of nephron progenitor cells. Here, we show in mice that the signalling molecules RSPO1 and RSPO3 act in a functionally redundant manner to permit WNT/ß-catenin signalling and their genetic deletion leads to a rapid decline of nephron progenitors. By contrast, tissue specific deletion in cap mesenchymal cells abolishes mesenchyme to epithelial transition (MET) that is linked to a loss of Bmp7 expression, absence of SMAD1/5 phosphorylation and a concomitant failure to activate Lef1, Fgf8 and Wnt4, thus explaining the observed phenotype on a molecular level. Surprisingly, the full knockout of LGR4/5/6, the cognate receptors of R-spondins, only mildly affects progenitor numbers, but does not interfere with MET. Taken together our data demonstrate key roles for R-spondins in permitting stem cell maintenance and differentiation and reveal Lgr-dependent and independent functions for these ligands during kidney formation.

Kidneys filter waste out of the bloodstream to produce urine. Each kidney contains many structures called nephrons which separate the waste from the blood. The number of nephrons in a kidney varies between people, and those with low numbers have a higher risk of chronic kidney disease. Nephrons are formed before birth from a specific group of so-called progenitor cells. Each of these cells can either divide to make others like itself, or it can specialize to make nephron cells. At the end of embryonic kidney development, all the progenitor cells become nephron cells. Cells that specialize to become part of a nephron first go through a change called a mesenchyme-to-epithelial transition. Epithelial cells move less than mesenchymal cells, and also develop a clear structure where the two ends of the cell adapt to different roles. Evidence suggests that a cell communication process called WNT/ß-catenin signaling controls this transition. Yet the details of how this transition is controlled are not fully understood. One way to activate WNT/ß-catenin signaling is with R-spondin proteins, which have been found in developing kidneys. Vidal et al. studied R-spondins during the embryonic development of kidneys in mice. Removing R-spondins stopped the progenitor cells from producing more of themselves and increased the number that died. The R-spondins were also needed for the progenitor cells to specialize as nephron cells through the mesenchyme-to-epithelial transition. Further results revealed that R-spondins activate WNT/ß-catenin signaling in these cells, even though the proteins that usually act as R-spondin receptors (called LGR4/5/6) could be removed without affecting the results. This suggests that R-spondins interact with different receptor proteins during kidney development. These findings highlight the role of R-spondins and WNT/ß-catenin signaling in kidney development. Future studies will seek the receptor proteins that R-spondins interact with in kidneys. They may also look to understand how R-spondins balance their different roles in progenitor cells and during cell specialization. These results in mice could also be extended to determine their relevance in human health and disease, including chronic kidney disease, which is responsible for more deaths than breast or prostate cancer.

R-spondin2 signaling is required for oocyte-driven intercellular communication and follicular growth.

R-spondin2 (RSPO2) is a member of the R-spondin family, which are secreted activators of the WNT/ß-catenin (CTNNB1) signaling pathway. In the mouse postnatal ovary, WNT/CTNNB1 signaling is active in the oocyte and in the neighboring supporting cells, the granulosa cells. Although the role of Rspo2 has been previously studied using in vitro experiments, the results are conflicting and the in vivo ovarian function of Rspo2 remains unclear. In the present study, we found that RSPO2/Rspo2 expression is restricted to the oocyte of developing follicles in both human and mouse ovaries from the beginning of the follicular growth. In mice, genetic deletion of Rspo2 does not impair oocyte growth, but instead prevents cell cycle progression of neighboring granulosa cells, thus resulting in an arrest of follicular growth. We further show this cell cycle arrest to be independent of growth promoting GDF9 signaling, but rather associated with a downregulation of WNT/CTNNB1 signaling in granulosa cells. To confirm the contribution of WNT/CTNNB1 signaling in granulosa cell proliferation, we induced cell type specific deletion of Ctnnb1 postnatally. Strikingly, follicles lacking Ctnnb1 failed to develop beyond the primary stage. These results show that RSPO2 acts in a paracrine manner to sustain granulosa cell proliferation in early developing follicles. Taken together, our data demonstrate that the activation of WNT/CTNNB1 signaling by RSPO2 is essential for oocyte-granulosa cell interactions that drive maturation of the ovarian follicles and eventually female fertility.

Targeting the Wnt signaling pathway through R-spondin 3 identifies an anti-fibrosis treatment strategy for multiple organs.

The Wnt/ß-catenin signaling pathway has been implicated in human proliferative diseases such as cancer and fibrosis. The functions of ß-catenin and several other components of this pathway have been investigated in fibrosis. However, the potential role of R-spondin proteins (RSPOs), enhancers of the Wnt/ß-catenin signaling, has not been described. A specific interventional strategy targeting this pathway for fibrosis remains to be defined. We developed monoclonal antibodies against members of the RSPO family (RSPO1, 2, and 3) and probed their potential function in fibrosis in vivo. We demonstrated that RSPO3 plays a critical role in the development of fibrosis in multiple organs. Specifically, an anti-RSPO3 antibody, OMP-131R10, when dosed therapeutically, attenuated fibrosis in carbon tetrachloride (CCl4)-induced liver fibrosis, bleomycin-induced pulmonary and skin fibrosis models. Mechanistically, we showed that RSPO3 induces multiple pro-fibrotic chemokines and cytokines in Kupffer cells and hepatocytes. We found that the anti-fibrotic activity of OMP-131R10 is associated with its inhibition of ß-catenin activation in vivo. Finally, RSPO3 was found to be highly elevated in the active lesions of fibrotic tissues in mouse models of fibrosis and in patients with idiopathic pulmonary fibrosis (IPF) and nonalcoholic steatohepatitis (NASH). Together these data provide an anti-fibrotic strategy for targeting the Wnt/ß-catenin pathway through RSPO3 blockade and support that OMP-131R10 could be an important therapeutic agent for fibrosis.

Extracellular matrix: the gatekeeper of tumor angiogenesis.

The extracellular matrix is a network of secreted macromolecules that provides a harmonious meshwork for the growth and homeostatic development of organisms. It conveys multiple signaling cascades affecting specific surface receptors that impact cell behavior. During cancer growth, this bioactive meshwork is remodeled and enriched in newly formed blood vessels, which provide nutrients and oxygen to the growing tumor cells. Remodeling of the tumor microenvironment leads to the formation of bioactive fragments that may have a distinct function from their parent molecules, and the balance among these factors directly influence cell viability and metastatic progression. Indeed, the matrix acts as a gatekeeper by regulating the access of cancer cells to nutrients. Here, we will critically evaluate the role of selected matrix constituents in regulating tumor angiogenesis and provide up-to-date information concerning their primary mechanisms of action.

A Plasmodium falciparum C-mannosyltransferase is dispensable for parasite asexual blood stage development.

C-mannosylation was recently identified in the thrombospondin-related anonymous protein (TRAP) from Plasmodium falciparum salivary gland sporozoites. A candidate P. falciparum C-mannosyltransferase (PfDPY-19) was demonstrated to modify thrombospondin type 1 repeat (TSR) domains in vitro, exhibiting a different acceptor specificity than their mammalian counterparts. According to the described minimal acceptor of PfDPY19, several TSR domain-containing proteins of P. falciparum could be C-mannosylated in vivo. However, the relevance of this protein modification for the parasite viability remains unknown. In the present study, we used CRISPR/Cas9 technology to generate a PfDPY19 null mutant, demonstrating that this glycosyltransferase is not essential for the asexual blood development of the parasite. PfDPY19 gene disruption was not associated with a growth phenotype, not even under endoplasmic reticulum-stressing conditions that could impair protein folding. The data presented in this work strongly suggest that PfDPY19 is unlikely to play a critical role in the asexual blood stages of the parasite, at least under in vitro conditions.

Specific factors in blood from young but not old mice directly promote synapse formation and NMDA-receptor recruitment.

Aging drives a progressive decline in cognition and decreases synapse numbers and synaptic function in the brain, thereby increasing the risk for neurodegenerative disease. Pioneering studies showed that introduction of blood from young mice into aged mice reversed age-associated cognitive impairments and increased synaptic connectivity in brain, suggesting that young blood contains specific factors that remediate age-associated decreases in brain function. However, whether such factors in blood from young animals act directly on neurons to enhance synaptic connectivity, or whether they act by an indirect mechanism remains unknown. Moreover, which factors in young blood mediate cognitive improvements in old mice is incompletely understood. Here, we show that serum extracted from the blood of young but not old mice, when applied to neurons transdifferentiated from human embryonic stem cells, directly increased dendritic arborization, augmented synapse numbers, doubled dendritic spine-like structures, and elevated synaptic N-methyl-d-aspartate (NMDA) receptors, thereby increasing synaptic connectivity. Mass spectrometry revealed that thrombospondin-4 (THBS4) and SPARC-like protein 1 (SPARCL1) were enriched in serum from young mice. Strikingly, recombinant THBS4 and SPARCL1 both increased dendritic arborization and doubled synapse numbers in cultured neurons. In addition, SPARCL1 but not THBS4 tripled NMDA receptor-mediated synaptic responses. Thus, at least two proteins enriched in young blood, THBS4 and SPARCL1, directly act on neurons as synaptogenic factors. These proteins may represent rejuvenation factors that enhance synaptic connectivity by increasing dendritic arborization, synapse formation, and synaptic transmission.

Molecular classification of membranous nephropathy.

PURPOSE OF REVIEW: Continuous expansion of our knowledge in the pathogenesis of membranous nephropathy possible by the identification of antibodies recognized specific podocytes antigens results in unprecedent patient management strategy. RECENT FINDINGS: Circulating anti-phospholipase A2 receptor (PLA2R) and anti-thrombospondin domain 7A (THSD7A) antibodies strongly relate with the modifications of podocytes biology leading to the new molecular diagnosis of membranous nephropathy. Immunization against THSD7A involves extra-renal mechanism. However, the pathway of anti-PLA2R immunization still remains unresolved. Experimental data highlight the crucial role of THSD7A in the attachment of podocytes to the glomerular basement membrane, rewarding the THSD7A pathogenicity, whereas the third of Koch's postulates is still not fulfilled for anti-PLA2R antibodies. The anti-PLA2R antibodies epitope spreading will possibly be even more specific marker improving the molecular classification of membranous nephropathy. Two immune epitopes have been identified in the N-terminal tail of THSD7A but without evidence of epitope spreading as for anti-PLA2R. SUMMARY: In 2019, the Kidney Diseases: Improving Global Outcomes guidelines recognized anti-PLA2R antibodies (but not anti-THSD7A antibodies) as a valuable molecular risk factor for the pejorative evolution of kidney function and recommended their monitoring for the diagnosis and the assessment of membranous nephropathy immune activity. Screening for malignancy is particularly advised in THSD7A-mediated membranous nephropathy.

Intracranial Aneurysms: Pathology, Genetics, and Molecular Mechanisms.

Intracranial aneurysms (IA) are local dilatations in cerebral arteries that predominantly affect the circle of Willis. Occurring in approximately 2-5% of adults, these weakened areas are susceptible to rupture, leading to subarachnoid hemorrhage (SAH), a type of hemorrhagic stroke. Due to its early age of onset and poor prognosis, SAH accounts for > 25% of years lost for all stroke victims under the age of 65. In this review, we describe the cerebrovascular pathology associated with intracranial aneurysms. To understand IA genetics, we summarize syndromes with elevated incidence, genome-wide association studies (GWAS), whole exome studies on IA-affected families, and recent research that established definitive roles for Thsd1 (Thrombospondin Type 1 Domain Containing Protein 1) and Sox17 (SRY-box 17) in IA using genetically engineered mouse models. Lastly, we discuss the underlying molecular mechanisms of IA, including defects in vascular endothelial and smooth muscle cells caused by dysfunction in mechanotransduction, Thsd1/FAK (Focal Adhesion Kinase) signaling, and the Transforming Growth Factor ß (TGF-ß) pathway. As illustrated by THSD1 research, cell adhesion may play a significant role in IA.

MiR-222 inhibits apoptosis in porcine follicular granulosa cells by targeting the THBS1 gene.

Apoptosis of granulosa cells affects follicular atresia and reproduction and is regulated by miRNAs and the expression of certain genes. For the present study, we investigated the regulatory relationship between microRNA-222 (miR-222) and THBS1 in porcine follicular granulosa cells (pGCs) and its effects on apoptosis to provide empirical data for developing methods to improve pig fecundity. Results revealed that miR-222 promotes the proliferation of pGCs. MiRNA mimics and luciferase reporter assays revealed that miR-222 functions as an anti-apoptotic factor in pGCs. MiR-222 mimics in pGCs result in the upregulation of the anti-apoptotic BCL-2 gene, down-regulation of the proapoptotic caspase-3 gene, and inhibition of apoptosis. MiR-222 inhibitors reduced BCL-2 and had no significant effect on caspase-3. MiR-222 mimics promoted estrogen levels. Inhibition of THBS1 inhibited pGC apoptosis. Transfection of THBS1-siRNA reduced the proapoptotic BAX gene. MiR-222 can directly target the 3'-untranslated region of the THBS1 gene. MiR-222 mimics suppressed THBS1 mRNA and proteins, but these were upregulated by the miR-222 inhibitor. Transfection of THBS1-siRNA resulted in the inhibition of the miR-222 inhibitor, which suggests that miR-222 inhibits pGC apoptosis by targeting THBS1. These findings suggest that miR-222 and THBS1 play important roles in follicular atresia, ovarian development, and female reproduction.

LGR4 is essential for R-spondin1-mediated suppression of food intake via pro-opiomelanocortin.

Leucine-rich repeat-containing G-protein coupled receptor 4 (LGR4) suppresses food intake after its activation by binding of its ligands, R-spondins. We investigated the mechanism of food intake suppression by R-spondin1 in a region-specific Lgr4 gene knockout (LGR4 cKO) mouse model, generated by deletion of the Lgr4 gene in arcuate nucleus (ARC) using Lgr4fx/fx mice combined with infection of an AAV-Cre vector. After R-spondin1 administration, LGR4 cKO mice didn't exhibit a suppressed appetite, compared to that in control mice, which received a vehicle. In ARC of LGR4 cKO mice, Pomc mRNA expression was reduced, leading to suppressed food intake. On the other hand, neurons-specific LGR4 KO mice exhibited no differences in Pomc expression, and no structural differences were observed in the ARC of mutant mice. These results suggest that LGR4 is an essential part of the mechanism, inducing Pomc gene expression with R-spondin1 in ARC neurons in mice, thereby regulating feeding behavior. Abbreviations: LGR4: Leucine-rich repeat-containing G-protein coupled receptor 4; RSPOs: roof plate-specific spondins; ARC: arcuate nucleus; AAV: adeno associated virus; POMC: pro-opiomelanocortin; CART: cocaine and amphetamine-regulated transcript; NPY: neuropeptide Y; AgRP: agouti-related peptide; Axin2: axis inhibition protein 2; Lef1: lymphoid enhancer binding factor 1; ccnd1: cyclin D1.

The role of R-spondin 1 through activating Wnt/ß-catenin in the growth, survival and migration of ovarian cancer cells.

Aberrant activation of the Wnt/ß-catenin has been shown to promote progression in various cancers, including ovarian cancer. However, the molecular mechanisms involved in Wnt/ß-catenin activation are not well elucidated. In the work, we identify that R-spondin 1 is an upstream regulator in Wnt/ß-catenin pathway to promote growth, survival and migration in ovarian cancer cells. We observe the upregulation of transcript and protein levels of R-spondin 1 in ovarian cancer cell lines and tissues compared to normal counterparts. R-spondin 1 upregulation via genetic (overexpression) and pharmacological (recombinant protein) approaches facilitates growth and migration of normal ovarian cells. R-spondin 1 downregulation via siRNA knockdown decreases proliferation and migration, and induces apoptosis in ovarian cancer cells. In addition, recombinant R-spondin 1 protects ovarian cancer cell against chemotherapy whereas R-spondin 1 knockdown sensitizes ovarian cancer cell response to chemotherapy. Importantly, increased ß-catenin activities and mRNA expression levels of Wnt/ß-catenin-targeted genes are detected in normal ovarian cells overexpressing R-spondin 1. In contrast, R-spondin 1 inhibition suppresses Wnt/ß-catenin signaling in ovarian cancer cells. We further identify that R-spondin 1 regulates ovarian cancer biological activities via activating Wnt/ß-catenin. Our work is the first to highlight the critical roles of R-spondin 1 in ovarian cancer progression and chemoresistance. Our work also provides a proper understanding on the regulation of Wnt/ß-catenin pathway in ovarian cancer.

Recent advances in understanding the roles of matrix metalloproteinases in tumour invasion and metastasis.

This review aims to provide an overview of recent developments regarding the roles of MMPs in tumour invasion and metastasis. Much of the mortality burden belonging to cancer relates to its ability to invade adjacent tissue and form metastases at distant sites. This would not be possible without remodelling of the ECM, a process which is enabled by the functions of MMPs. Recent studies provide a better understanding of the importance of the biophysical nature of the ECM, how this influences cancer cell motility, and how MMPs act to modify matrix stiffness. The regulation of MMPs and the role of immune cell generated MMPs has also become better understood. All of this provides a framework for the therapeutic targeting of MMPs and recent advances in the development of selective MMPs inhibitors are also reviewed. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

RSPO3 impairs barrier function of human vascular endothelial monolayers and synergizes with pro-inflammatory IL-1.

BACKGROUND: Endothelial barrier dysfunction characterized by hyperpermeability of the vascular endothelium is a key factor in the pathogenesis of chronic inflammatory diseases and affects clinical outcomes. In states of chronic inflammation, mediators secreted by activated immune cells or vascular endothelium may affect the barrier function and permeability of the vascular endothelium. The matricellular R-spondin family member RSPO3 is produced by inflammatory-activated human monocytes and vascular endothelial cells, but its effects in the regulation of vascular endothelial barrier function remains elusive. METHODS: The present study investigates the effects of RSPO3 on the barrier function of adult human primary macro- and micro- vascular endothelial monolayers. Tight monolayers of primary endothelial cells from human coronary and pulmonary arteries, and cardiac, brain, and dermal microvascular beds were treated with RSPO3 either alone or in combination with pro-inflammatory mediator IL-1ß. Endothelial barrier function was assessed non-invasively in real-time using Electric Cell-substrate Impedance Sensing. RESULTS: RSPO3 treatment critically affected barrier function by enhancing the permeability of all vascular endothelial monolayers investigated. To confer hyperpermeable phenotype in vascular endothelial monolayers, RSPO3 induced inter-endothelial gap formation by disrupting the ß-catenin and VE-cadherin alignment at adherens junctions. RSPO3 synergistically enhanced the barrier impairing properties of the pro-inflammatory mediator IL-1ß. CONCLUSION: Here, we show that the matricellular protein RSPO3 is a mediator of endothelial hyperpermeability that can act in synergy with the inflammatory mediator IL-1ß. This finding stimulates further studies to delineate the endothelial barrier impairing properties of RSPO3 and its synergistic interaction with IL-1ß in chronic inflammatory diseases.

Human Properdin Modulates Macrophage: Mycobacterium bovis BCG Interaction via Thrombospondin Repeats 4 and 5.

Mycobacterium tuberculosis can proficiently enter macrophages and diminish complement activation on its cell surface. Within macrophages, the mycobacterium can suppress macrophage apoptosis and survive within the intracellular environment. Previously, we have shown that complement regulatory proteins such as factor H may interfere with pathogen-macrophage interactions during tuberculosis infection. In this study, we show that Mycobacterium bovis BCG binds properdin, an upregulator of the complement alternative pathway. TSR4+5, a recombinant form of thrombospondin repeats 4 and 5 of human properdin expressed in tandem, which is an inhibitor of the alternative pathway, was also able to bind to M. bovis BCG. Properdin and TSR4+5 were found to inhibit uptake of M. bovis BCG by THP-1 macrophage cells in a dose-dependent manner. Quantitative real-time PCR revealed elevated pro-inflammatory responses (TNF-α, IL-1ß, and IL-6) in the presence of properdin or TSR4+5, which gradually decreased over 6 h. Correspondingly, anti-inflammatory responses (IL-10 and TGF-ß) showed suppressed levels of expression in the presence of properdin, which gradually increased over 6 h. Multiplex cytokine array analysis also revealed that properdin and TSR4+5 significantly enhanced the pro-inflammatory response (TNF-α, IL-1ß, and IL-1α) at 24 h, which declined at 48 h, whereas the anti-inflammatory response (IL-10) was suppressed. Our results suggest that properdin may interfere with mycobacterial entry into macrophages via TSR4 and TSR5, particularly during the initial stages of infection, thus affecting the extracellular survival of the pathogen. This study offers novel insights into the non-complement related functions of properdin during host-pathogen interactions in tuberculosis.

Functions of Wnt signaling pathway in hair cell differentiation and regeneration.

Wnt signaling pathway plays important roles in the development and homeostasis of multicellular organisms. Through their bindings with the Frizzled receptors, the Wnt ligands regulate a wide range of developmental processes, such as axis patterning, cell division, and cell fate specification. Wnt signaling plays vital roles in the development of inner ear of the mouse. In the early stages of inner ear development, Wnt signaling specifies the size of the placode and the formation of the otic vesicle. In later stages, Wnt signaling mediates hair cell specification and orients the stereociliary bundles in a uniform direction. In this review, we summarize the current knowledge on the roles of Wnt signaling in hair cell differentiation and regeneration, which may provide references and insights for investigators in the field.