PCSK6 exacerbates Alzheimer's disease pathogenesis by promoting MT5-MMP maturation

Proprotein convertase subtilisin/kexin type 6 (PCSK6) is a calcium-dependent serine proteinase that regulates the proteolytic activity of various precursor proteins and facilitates protein maturation. Dysregulation of PCSK6 expression or function has been implicated in several pathological processes including nervous system diseases. However, whether and how PCSK6 is involved in the pathogenesis of Alzheimer's disease (AD) remains unclear. In this study, we reported that the expression of PCSK6 was significantly increased in the brain tissues of postmortem AD patients and APP23/PS45 transgenic AD model mice, as well as N2AAPP cells. Genetic knockdown of PCSK6 reduced amyloidogenic processing of APP in N2AAPP cells by suppressing the activation of membrane-type 5-matrix metalloproteinase (MT5-MMP), referred to as η-secretase. We further found that PCSK6 cleaved and activated MT5-MMP by recognizing the RRRNKR sequence in its N-terminal propeptide domain in N2A cells. The mutation or knockout of this cleavage motif prevented PCSK6 from interacting with MT5-MMP and performing cleavage. Importantly, genetic knockdown of PCSK6 with adeno-associated virus (AAV) reduced Aβ production and ameliorated hippocampal long-term potentiation (LTP) and long-term spatial learning and memory in APP23/PS45 transgenic mice. Taken together, these results demonstrate that genetic knockdown of PCSK6 effectively alleviate AD-related pathology and cognitive impairments by inactivating MT5-MMP, highlighting its potential as a novel therapeutic target for AD treatment.

Proprotein convertase subtilisin/kexin type 6 (PCSK6) is a likely antigenic target in membranous nephropathy and nonsteroidal anti-inflammatory drug use

Drugs are an important secondary cause of membranous nephropathy (MN) with the most common drugs associated with MN being nonsteroidal anti-inflammatory drugs (NSAIDs). Since the target antigen in NSAID-associated MN is not known, we performed laser microdissection of glomeruli followed by mass spectrometry (MS/MS) in 250 cases of PLA2R-negative MN to identify novel antigenic targets. This was followed by immunohistochemistry to localize the target antigen along the glomerular basement membrane and western blot analyses of eluates of frozen biopsy tissue to detect binding of IgG to the novel antigenic target. MS/MS studies revealed high total spectral counts of a novel protein Proprotein Convertase Subtilisin/Kexin Type 6 (PCSK 6) in five of the 250 cases in the discovery cohort. A validation cohort using protein G immunoprecipitation, MS/MS, and immunofluorescence detected PCSK6 in eight additional cases. All cases were negative for known antigens. Ten of 13 cases had a history of heavy NSAID use with no history available in one case. The mean serum creatinine and proteinuria at kidney biopsy were 0.93 ± 0.47 mg/dL and 6.5 ± 3.3 gms/day, respectively. Immunohistochemistry/immunofluorescence showed granular staining for PCSK6 along the glomerular basement membrane, and confocal microscopy showed co-localization of IgG and PCSK6. IgG subclass analysis in three cases revealed codominance of IgG1 and IgG4. Western blot analysis using eluates from frozen tissue showed IgG binding to PCSK6 in PCSK6-associated but not in PLA2R-positive MN. Thus, PCSK6 may be a likely novel antigenic target in MN in patients with prolonged NSAID use.

PCSK6 mediates Th1 differentiation and promotes chronic colitis progression and mucosal barrier injury via STAT1

This study was aimed at investigating the expression and role of proprotein convertase subtilisin/kexin type (PCSK6) in inflammatory bowel disease (IBD). DSS induced mouse colitis and mucosal barrier injury, down-regulation of TJ proteins, improvement of permeability, and increases of the proportions of Th1 and M1 macrophages. After PCSK6 knockdown, the colitis in KO mice was improved relative to WT mice, the TJ protein levels increased, and the proportions of Th1 and M1 macrophages decreased. STAT1 inhibitor treatment also inhibited chronic colitis in mice. As revealed by in-vitro experiments, PCSK6 overexpression promoted the transformation of Th0 into Th1, while PCSK6 silencing suppressed the transfection. COPI assay results revealed the presence of targeted binding relation between PCSK6 and STAT1. PCSK6 binds to STAT1 to promote STAT1 phosphorylation and regulate Th1 cell differentiation, thus promoting the M1 polarization of macrophages and aggravating colitis progression. PCSK6 is promising as the new target for the treatment of colitis.

Circ_0002984 promotes proliferation, migration and inflammatory cytokine secretion and inhibits apoptosis of rheumatoid arthritis fibroblast-like synoviocytes by inducing PCSK6 through miR-543

BACKGROUND

Rheumatoid arthritis (RA) is inflammatory arthritic disease, and circular RNA is involved in RA development. The aim of the present work is to analyze the role of circ_0002984 in the process of RA fibroblast-like synoviocytes (RAFLSs) and the underlying mechanism.

METHODS

Circ_0002984, miR-543, and proprotein convertase subtilisin/kexin type 6 (PCSK6) expression levels were analyzed by quantitative real-time polymerase chain reaction or western blotting. Cell proliferation, migration, inflammatory response, and apoptosis were investigated through 5-Ethynyl-2'-deoxyuridine assay, wound-healing assay, enzyme-linked immunosorbent assay, and flow cytometry analysis. Dual-luciferase reporter assay and RNA immunoprecipitation assay were performed to assess the binding relationship.

RESULTS

Circ_0002984 and PCSK6 expression were increased, while miR-543 expression was decreased in the synovial tissues of RA patients and RAFLSs. Circ_0002984 introduction facilitated RAFLS cell proliferation, migration and inflammatory response and repressed apoptosis, but circ_0002984 knockdown had an opposite role. Circ_0002984 targeted miR-543, and PCSK6 was targeted by miR-543. MiR-543 downregulation or PCSK6 overexpression restored the effects of circ_0002984 interference on RAFLS phenotypes.

CONCLUSION

Circ_0002984 promoted RAFLS proliferation, migration and inflammatory cytokine secretion and inhibited apoptosis by binding to miR-543 to induce PCSK6 production, providing a potential target for RA therapy.

PCSK6 attenuates cardiac dysfunction in doxorubicin-induced cardiotoxicity by regulating autophagy

Doxorubicin (DOX) is a chemotherapeutic drug widely used in the field of cancer, but its side effects on the heart hinder its clinical application. In cardiac injury caused by DOX, apoptosis and oxidative stress are both involved in cardiac damage, and autophagy is also one of the key responses. Both apoptosis and oxidative stress interact with autophagy. Proper promotion of autophagy effectively protects the myocardium and blocks cardiac injury. DOX mainly acts downstream of the autophagic flow and hinders the degradation process of autophagolysosomes, resulting in abnormal accumulation of autophagolysosomes in cells, which can prevent the timely removal of harmful substances and disrupt the normal function of cells. Proprotein convertase subtilisin/kexin type 6 (PCSK6) is involved in the occurrence and development of various cardiovascular diseases, blood pressure regulation and the inflammatory response, but its role in DOX is still unclear. Here, we constructed cardiac PCSK6-overexpressing mice by injecting AAV9-PCSK6. Both in vivo and in vitro experiments confirmed that overexpression of PCSK6 effectively protected cardiac function, inhibited apoptosis and oxidative stress. We focused on the effect of PCSK6 overexpression on autophagy. We have detected an increase in autophagosomes production and a decrease in autophagolysosomes accumulation. This suggests that PCSK6 promotes the level of autophagy, while possibly acting on the sites where DOX inhibits degradation, so that the autophagic flux inhibited by DOX is restored and the degradation process of autophagolysosomes is restored. The effect of PCSK6 was dependent on FOXO3a, which promoted the nuclear translocation of Forkhead box O3 (FOXO3a), and Sirtuin 1 (SIRT1) regulated the expression of FOXO3a. When SIRT1 was inhibited, the protective effect of PCSK6 was diminished. In conclusion, overexpression of PCSK6 exerts a protective effect through SIRT1/FOXO3a in cardiac injury induced by DOX, suggesting that PCSK6 may be a therapeutic target for DOX cardiomyopathy.

Identification of Genes Associated with Liver Metastasis in Pancreatic Cancer Reveals PCSK6 as a Crucial Mediator

Liver metastasis occurs frequently in patients with pancreatic cancer. We analyzed the molecular profiling in liver metastatic lesions aiming to uncover novel genes responsible for tumor progression. Bioinformatics analysis was applied to identify genes directing liver metastasis. CRISPR/Cas9 technology was used to knock out the candidate gene. Proliferation assays, colony formation assays, cell cycle analysis, migration assays, wound healing assays, Immunofluorescence analysis, and the tumor xenograft model of intrasplenic injection were adopted to evaluate the effects of PCSK6 inactivation on cell growth, migration and liver metastasis. GSEA and Western blot were used to investigate the corresponding signaling pathway. PCSK6 was one of the obtained liver-metastasis-related genes in pancreatic cancer. PCSK6 inactivation inhibited cell growth and cell migration, due to G0/G1 cell cycle arrest and the remodeling of cell-cell junctions or the cell skeleton, respectively. PCSK6 inactivation led to fewer counts and lower outgrowth rates of liver metastatic niches in vivo. The Raf-MEK1/2-ERK1/2 axis was repressed by PCSK6 inactivation. Accordingly, we found PCSK6 inactivation could inhibit cell growth, cell migration, and liver metastasis, and explored the role of the Raf-MEK1/2-ERK1/2 axis in PCSK6 inactivation. PCSK6-targeted therapy might represent a novel approach for combatting liver metastasis in pancreatic cancer.

Pcsk6 Deficiency Promotes Cardiomyocyte Senescence by Modulating Ddit3-Mediated ER Stress

Cardiac aging is a critical determinant of cardiac dysfunction, which contributes to cardiovascular disease in the elderly. Proprotein convertase subtilisin/kexin 6 (PCSK6) is a proteolytic enzyme important for the maintenance of cardiac function and vascular homeostasis. To date, the involvement of PCSK6 in cardiac aging remains unknown. Here we report that PCSK6 expression decreased in the hearts of aged mice, where high levels cyclin dependent kinase inhibitor 2A (P16) and cyclin dependent kinase inhibitor 1A (P21) (senescence markers) were observed. Moreover, PCSK6 protein expression was significantly reduced in senescent rat embryonic cardiomyocytes (H9c2) induced by D-galactose. Pcsk6 knockdown in H9c2 cells increased P16 and P21 expression levels and senescence-associated beta-galactosidase activity. Pcsk6 knockdown also impaired cardiomyocyte function, as indicated by increased advanced glycation end products, reactive oxygen species level, and apoptosis. Overexpression of PCSK6 blunted the senescence phenotype and cellular dysfunction. Furthermore, RNA sequencing analysis in Pcsk6-knockdown H9c2 cells identified the up-regulated DNA-damage inducible transcript 3 (Ddit3) gene involved in endoplasmic reticulum (ER) protein processing. Additionally, DDIT3 protein levels were remarkably increased in aged mouse hearts. In the presence of tunicamycin, an ER stress inducer, DDIT3 expression increased in Pcsk6-deficient H9c2 cells but reduced in PCSK6-overexpressing cells. In conclusion, our findings indicate that PCSK6 modulates cardiomyocyte senescence possibly via DDIT3-mediated ER stress.

Distribution of Cardiac and Renal Corin and Proprotein Convertase Subtilisin/Kexin-6 in the Experimental Model of Cardio-Renal Syndrome of Various Severities

Congestive heart failure (CHF) often leads to progressive cardiac hypertrophy and salt/water retention. However, its pathogenesis remains largely unclarified. Corin, a cardiac serine protease, is responsible for converting proANP and proBNP to biologically active peptides. Although the involvement of corin in cardiac hypertrophy and heart failure was extensively studied, the alterations in corin and proprotein convertase subtilisin/kexin-6 (PCSK6), a key enzyme in the conversion of procorin to corin, has not been studied simultaneously in the cardiac and renal tissues in cardiorenal syndrome. Thus, this study aims to examine the status of PCSK6/corin in the cardiac and renal tissues of rats with CHF induced by the creation of aorto-caval fistula (ACF). We divided rats with ACF into two subgroups based on the pattern of their urinary sodium excretion, namely, compensated and decompensated. Placement of ACF led to cardiac hypertrophy, pulmonary congestion, and renal dysfunction, which were more profound in the decompensated subgroup. Corin immunoreactive peptides were detected in all heart chambers at the myocyte membranal and cytosolic localization and in the renal tissue, especially in the apical membrane of the proximal tubule, mTAL, and the collecting duct. Interestingly, the expression and abundance of corin in both the cardiac ventricles and renal tissues were significantly increased in compensated animals as compared with the decompensated state. Noteworthy, the abundance of PCSK6 in these tissues followed a similar pattern as corin. In contrast, furin expression was upregulated in the cardiac and renal tissues in correlation with CHF severity. We hypothesize that the obtained upregulation of cardiac and renal PCSK6/corin in rats with compensated CHF may represent a compensatory response aiming at maintaining normal Na⁺ balance, whereas the decline in these two enzymes may contribute to the pathogenesis of avid sodium retention, cardiac hypertrophy, and blunted atrial natriuretic peptide/brain natriuretic peptide actions in decompensated CHF.

Up-regulation of microRNA-135 or silencing of PCSK6 attenuates inflammatory response in preeclampsia by restricting NLRP3 inflammasome

OBJECTIVE

Numerous studies have confirmed the correlation of microRNAs (miRNAs) with human disease, yet few have explored the role of miR-135 in preeclampsia (PE). This study intends to discuss miR-135's function in inflammatory response in PE by modulating proprotein convertase subtilisin/kexin-6 (PCSK6) and NLR pyrin domain containing 3 (NLRP3).

METHODS

The venous blood and placental tissues were collected from PE pregnant women and 25 normal ones. The levels of miR-135, PCSK6 and NLRP3 in placenta tissues of patients were detected. Hypoxia/reoxygenation HTR-8/SVneo and HPT-8 models were established to mimic PE in vitro, and cell proliferation, colony formation, apoptosis rate, invasion, migration and inflammation were detected through gain-of and loss-of-function assays.

RESULTS

MiR-135 was down-regulated, and PCSK6 and NLRP3 were up-regulated in PE patients. Up-regulating miR-135 or silencing PCSK6 strengthened colony formation ability, viability, invasion and migration ability, and weakened apoptosis and inflammation of H/R-treated HTR-8/SVneo and HPT-8 cells. Inhibition of NLRP3 negated the effects of silenced PCSK6 in H/R-treated HTR-8/SVneo and HPT-8 cells.

CONCLUSIONS

Altogether, we demonstrate that up-regulated miR-135 or reduced PCSK6 attenuates inflammatory response in PE by restricting NLRP3 inflammasome, which provides novel therapy for PE treatment.

New susceptibility alleles associated with severe coronary artery stenosis in the Lebanese population

Background

Coronary Artery Disease (CAD) is the narrowing or blockage of the coronary arteries. It is closely associated with numerous genetics and environmental factors that have been extensively evaluated in various populations. In recent studies, severe phenotypes have been strongly linked to genetic risk factors.

Methods

This study investigated the association of clinical, demographic, and genetic factors with severe coronary artery stenosis phenotypes in our population composed of 1734 individuals with severe coronary stenosis (≥ 50% in coronary vessels) and comparing them to 757 controls with no evidence of stenosis on angiography. We performed generalized linear model (GLM) genome-wide association studies to evaluate three stratification models and their associations to characteristics of the clinical disease. In model 1, patients were not stratified. In model 2, patients were stratified based on presence or absence of CAD family history (FxCAD). In model 3, patients were stratified by young age of CAD onset.

Results

Eight SNPs (single nucleotide polymorphism) were significantly associated with severe CAD phenotypes in the various models \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left( {p < 5 \times 10^{ - 7} } \right)$$\end{document}p<5×10-7, four of these SNPs were associated with severe CAD and the four others were specifically significant for young CAD patients. While these SNPs were not previously reported for association with CAD, six of them are present in genes that have already been linked to coronary disease.

Conclusion

In conclusion, this study presents new genetic factors associated with severe stenosis and highlights different risk factors associated with a young age at diagnosis of CAD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-00942-x.

Up-regulation of PCSK6 by lipid oxidation products: A possible role in atherosclerosis

Atherosclerosis is a degenerative disease characterized by lesions that develop in the wall of large- and medium-sized arteries due to the accumulation of low-density lipoproteins (LDLs) in the intima. A growing bulk of evidence suggests that cholesterol oxidation products, known as oxysterols, and the aldehyde 4-hydroxy-2-nonenal (HNE), the major pro-atherogenic components of oxidized LDLs, significantly contribute to atherosclerotic plaque progression and destabilization, with eventual plaque rupture. The involvement of certain members of the protein convertase subtilisin/kexin proteases (PCSKs) in atherosclerosis has been recently hypothesized. Among them, PCSK6 has been associated with plaque instability, mainly thanks to its ability to stimulate the activity of matrix metalloproteinases (MMPs) involved in extracellular matrix remodeling and to enhance inflammation. In U937 promonocytic cells and in human umbilical vein endothelial cells, an oxysterol mixture and HNE were able to up-regulate the level and activity of PCSK6, resulting in MMP-9 activation as demonstrated by PCSK6 silencing. Inflammation, enhanced by these lipid oxidation products, plays a key role in the up-regulation of PCSK6 activity as demonstrated by cell pretreatment with NS-398, with epigallocatechin gallate or with acetylsalicylic acid, all with anti-inflammatory effects. For the first time, we demonstrated that both oxysterols and HNE, which substantially accumulate in the atherosclerotic plaque, up-regulate the activity of PCSK6. Of note, we also suggest a potential association between PCSK6 activity and MMP-9 activation, pointing out that PCSK6 could contribute to atherosclerotic plaque development.

Structural Asymmetry in the Frontal and Temporal Lobes Is Associated with PCSK6 VNTR Polymorphism

The nodal cascade influences the development of bodily asymmetries in humans and other vertebrates. The gene PCSK6 has shown a regulatory function during left-right axis formation and is therefore thought to influence bodily left-right asymmetries. However, it is not clear if variation in this gene is also associated with structural asymmetries in the brain. We genotyped an intronic 33bp PCSK6 variable number tandem repeat (VNTR) polymorphism that has been associated with handedness in a cohort of healthy adults. We acquired T1-weighted structural MRI images of 320 participants and defined cortical surface and thickness for each HCP region. The results demonstrate a significant association between PCSK6 VNTR genotypes and gray matter asymmetry in the superior temporal sulcus, which is involved in voice perception. Heterozygous individuals who carry a short (≤ 6 repeats) and a long (≥ 9 repeats) PCSK6 VNTR allele show stronger rightward asymmetry. Further associations were evident in the dorsolateral prefrontal cortex. Here, individuals homozygous for short alleles show a more pronounced asymmetry. This shows that PCSK6, a gene that has been implicated in the ontogenesis of bodily asymmetries by regulating the nodal cascade, is also relevant for structural asymmetries in the human brain.

Natriuretic peptides system in the pulmonary tissue of rats with heart failure: potential involvement in lung edema and inflammation

Congestive heart failure (CHF) often leads to progressive cardiac hypertrophy and salt/water retention as evident by peripheral and lung edema. Although the pathogenesis of CHF remains largely unclarified, it is widely accepted that neurohormonal changes and inflammatory processes are profoundly involved in structural and functional deterioration of vital organs including, heart, kidney and lungs. Corin, a cardiac serine protease, is responsible for converting pro-ANP and pro-BNP to biologically active natriuretic peptides (NPs). Although the involvement of corin in cardiac hypertrophy and heart failure was extensively studied, the alterations in corin and PCSK6, a key enzyme in the conversion of procorin to corin, have not been studied in the pulmonary tissue. Thus, this study aims at examining the status of PCSK6/Corin in the lung of rats with CHF induced by the creation of aorto-caval fistula (ACF) between the abdominal aorta and vena cava in SD rats. Rats with ACF were divided into 2 subgroups based on the pattern of their daily sodium excretion, compensated and decompensated CHF. Placement of ACF led to cardiac hypertrophy, pulmonary congestion, and renal dysfunction, which were more severe in the decompensated subgroup, despite remarkable elevation of circulatory ANP and BNP levels. Corin mRNA and immunoreactive peptide were detected in pulmonary tissue of all experimental groups. However, the expression and abundance of pulmonary corin significantly increased in the decompensated animals, but not in the compensated ones. Noteworthy, the expression of PCSK6 and ANP/BNP in the pulmonary tissue followed a similar pattern as corin. The upregulation of pulmonary Corin/PCSK6 and NPs were accompanied by local activation of cathepsin L and certain cytokines including IL-6. In light of the anti-inflammatory role of NPs, we postulate that the obtained upregulation of pulmonary PCSK6/Corin along NPs in rats with decompensated CHF may represent a counterbalance response to the inflammatory milieu characterizing CHF especially in severe cases.

Short-Term High-Salt Diet Increases Corin Level to Regulate the Salt-Water Balance in Humans and Rodents

BACKGROUND

Dietary sodium and potassium affect the fluctuation in blood pressure (BP) and renal function. Corin, with its enzymatic activity to convert pro-atrial natriuretic peptide (pro-ANP) to biologically active ANP, regulates BP, cardiac, and renal functions. We investigated whether corin expression responds to a high-salt (HS) diet to regulate salt and water balance.

METHODS

Forty-two volunteers followed 3 sequential diets for 7 days each: a low-salt (LS) diet (3.0 g/day NaCl), a HS diet (18.0 g/day NaCl), followed by an HS diet with K+ supplementation (HS + K+) (18.0 g/day NaCl and 4.5 g/day KCl).

RESULTS

Corin level was higher with the HS diet than the LS and HS + K+ diets and was positively correlated with systolic BP (SBP) and 24-hour urinary Na+ and microalbumin (U-mALB) excretion. In rodents, serum and renal levels of corin were transiently increased with the HS diet and were decreased if the HS diet was continued for up to 7 days. HS loading increased SBP, 24-hour urinary Na+, U-mALB excretion, and the expression of proprotein convertase subtilisin/kexin-6 (PCSK6), a corin activator. Knockdown of PCSK6 or corin in high salt-treated M1-cortical collecting duct (M1-CCD) cells increased the expression of aquaporin 2 (AQP2) and β-epithelial Na+ channel (β-ENaC).

CONCLUSIONS

Short-term HS may induce the PCSK6-corin-ANP-AQP2/β-ENaC pathway in the kidney. Enhanced serum corin level in humans and rodents is positively correlated with HS-induced SBP and 24-hour urinary Na+ and U-mALB excretion, which suggests that corin is involved in the salt-water balance in response to HS intake.

CLINICAL TRIALS REGISTRATION

Public Trials Registry Number NCT02915315.

Functional analysis of corin protein domains required for PCSK6-mediated activation

Atrial natriuretic peptide (ANP) is a cardiac hormone essential for normal blood pressure and cardiac function. Corin is a transmembrane serine protease that activates ANP. Recently, we identified proprotein convertase subtilisin/kexin-6 (PCSK6), also called PACE4, as the long-sought corin activator. Both corin and PCSK6 are expressed in cardiomyocytes, but corin activation occurs only on the cell surface. It remains unknown if cell membrane association is needed for PCSK6 to activate corin. Here we expressed corin deletion mutants in HEK293 cells to analyze the domain structures required for PCSK6-mediated activation. Our results show that soluble corin lacking the transmembrane domain was activated by PCSK6 in the conditioned medium but not intracellularly. Recombinant PCSK6 also activated the soluble corin under cell-free conditions. Moreover, PCSK6-mediated corin activation was not enhanced by cell membrane fractions. These results indicate that cell membrane association is unnecessary for PCSK6 to activate corin. Experiments with monensin that blocks PCSK6 secretion and immunostaining indicated that the soluble corin and PCSK6 were secreted via different intracellular pathways, which may explain the lack of corin activation inside the cell. We also found that the protein domains in the corin pro-peptide region were dispensable for PCSK6-mediated activation and that addition of heparan sulfate and chondroitin sulfate or treatment with heparinase or chondroitinase did not alter corin activation by PCSK6 in HEK293 cells. Together, our results provide important insights into the molecular and cellular mechanisms underlying PCSK6-mediated corin activation that is critical for cardiovascular homeostasis.

Germline DNA copy number variations as potential prognostic markers for non-muscle invasive bladder cancer progression

Accumulating evidence has suggested that germline DNA copy number variations (CNVs) affect various disorders, including human malignancies. However, the significance of CNVs in non-muscle invasive bladder cancer (NMIBC) remains unclear. The purpose of the present study was to identify the role of CNVs in NMIBC. Array comparative genomic hybridization (CGH) analysis was performed to search for candidate CNVs associated with NMIBC susceptibility. Quantitative polymerase chain reaction was carried out to evaluate CNVs associated with patient outcome in 189 NMIBC cases. In total, 11 CNVs were associated with NMIBC risk in array CGH analysis. Out of the 189 CNVs examined, family with sequence similarity 81 member A (FAM81A) and proprotein convertase subtilisin/kexin type 6 (PCSK6) CNVs exhibited a significant association with recurrence and disease progression in NMIBC. PCSK6 has been reported to regulate proliferation and tumor progression in breast and prostate malignancies. Notably, patients with pT1 stage had significantly lower PCSK6 relative copy number than those with pTa (P=0.0196). In multivariate analyses, PCSK6 copy number was an independent prognostic factor for progression-free survival (P=0.0456; risk ratio, 2.17; 95% confidence interval, 1.02-4.82). These data suggest that PCSK6 CNV is a potential new tumor marker for estimating disease progression in NMIBC.

Enhanced Proteolytic Processing of Recombinant Human Coagulation Factor VIII B-Domain Variants by Recombinant Furins

Recombinant human factor VIII (rFVIII) is used in replacement therapy for hemophilia A. Current research efforts are focused on bioengineering rFVIII molecules to improve its secretion efficiency and stability, limiting factors for its efficient production. However, high expression yield in mammalian cells of these rFVIII variants is generally associated with limited proteolytic processing. Non-processed single-chain polypeptides constitute non-natural FVIII molecule configurations with unpredictable toxicity and/or antigenicity. Our main objective was to demonstrate the feasibility of promoting full-proteolytic processing of an rFVIII variant retaining a portion of the B-domain, converting it into the smallest natural activatable form of rFVIII, while keeping its main advantage, i.e., improved secretion efficiency. We generated and employed a CHO-DG44 cell clone producing an rFVIII variant retaining a portion of the B-domain and the FVIII native cleavage site between Arg(1648) and Glu(1649). By bioengineering CHO-DG44 cells to express stably the recombinant human endoproteases PACE, PACE-SOL, PCSK5, PCSK6, or PCKS7, we were able to achieve complete intra- or extracellular proteolytic processing of this rFVIII variant. Additionally, our quantitative data indicated that removal of the B-domain segment by intracellular proteolytic processing does not interfere with this rFVIII variant secretion efficiency. This work also provides the first direct evidence of (1) intracellular cleavage at the Arg(1648) FVIII processing site promoted by wild-type PACE and PCSK7 and (2) proteolytic processing at the Arg(1648) FVIII processing site by PCSK6.

A visible light induced photoelectrochemical aptsensor constructed by aligned ZnO@CdTe core shell nanocable arrays/carboxylated g-C3N4 for the detection of Proprotein convertase subtilisin/kexin type 6 gene

It was reported that Proprotein convertase subtilisin/kexin type 6 (PCSK6) can promote the progression of rheumatoid arthritis to a higher aggressive status. In this work, a novel visible light induced photoelectrochemical (PEC) platform was designed to detect PCSK6 gene. ZnO@CdTe nanocable arrays/carboxylated g-C3N4 used as the PEC signal generator. Hexagonal ZnO nanorods grew on ITO electrode firstly. CdTe were then electrodeposited on the ZnO nanorods surface to enhance the photogenerated h(+)/e(-) separation efficiency. Carboxylated g-C3N4 was utilized to improve h(+)/e(-) separation efficiency and anchor the capture probes of PCSK6 gene by the covalent bonding effect. The 5' and 3' primers captured PCSK6 ssDNA by the specific recognition. The linear range was 10 pg/mL to 20.0 ng/mL with a detection limit of 2 pg/mL.

PCSK6 regulated by LH inhibits the apoptosis of human granulosa cells via activin A and TGFβ2

Mammalian proprotein convertases (PCs) play an important role in folliculogenesis, as they proteolytically activate a variety of substrates such as the transforming growth factor beta (TGFβ) superfamily. PC subtilism/kexin 6 (PCSK6) is a member of the PC family and is ubiquitously expressed and implicated in many physiological and pathological processes. However, in human granulosa cells, the expression of the PC family members, their hormonal regulation, and the function of PCs are not clear. In this study, we found that PCSK6 is the most highly expressed PC family member in granulosa cells. LH increased PCSK6 mRNA level and PCSK6 played an anti-apoptosis function in KGN cells. Knockdown of PCSK6 not only increased the secretion of activin A and TGFβ2 but also decreased the secretion of follistatin, estrogen, and the mRNA levels of FSH receptor (FSHR) and P450AROM (CYP19A1). We also found that, in the KGN human granulosa cell line, TGFβ2 and activin A could promote the apoptosis of KGN cells and LH could regulate the follistatin level. These data indicate that PCSK6, which is regulated by LH, is highly expressed in human primary granulosa cells of pre-ovulatory follicles and plays important roles in regulating a series of downstream molecules and apoptosis of KGN cells.

Enhanced aggressiveness of benzopyrene-induced squamous carcinomas in transgenic mice overexpressing the proprotein convertase PACE4 (PCSK6)

PACE4 (PCSK6) is a proprotein convertase (PC) capable of processing numerous substrates involved in tumor growth, invasion, and metastasis. Because of the human relevancy of the tobacco-associated carcinogen benzo[a]pyrene (B(a)P) we investigated whether transgenic mice in which this PC is targeted to the epidermis (K5-PACE4) may be more susceptible to B(a)P complete carcinogenesis than wild type (WT) mice. In an in vitro experiment, using cell lines derived from skin tumors obtained after B(a)P treatment, we observed that PACE4 overexpression and activity accounts for an increased proliferation rate, exaggerated sensitivity to the PC inhibitor CMK, and interference with IGF-1R autophosphorylation. Squamous cell carcinomas, obtained from K5-PACE4 mice subjected to complete chemical carcinogenesis, were characterized by a 50% increase in cell proliferation, when compared with similar tumors from WT mice. In addition, tumors from K5-PACE4 mice showed deeper invasion into the underlying dermis. Thus, mice overexpressing PACE4 exhibited tumors of increased growth rate and invasive potential when exposed to the human carcinogen B(a)P, further supporting the significance of PCs in tumor growth and progression.