Changes In Cathepsin Research Articles

Can alterations in cathepsin levels restrain the development of skin cancer?: A bidirectional multivariate Mendelian-randomization study.

Malignant skin tumors mainly include basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. There is currently observational research suggesting that changes in cathepsin (CTS) may be a factor in the development of malignant skin tumors, but no studies have yet demonstrated a causal relationship between tissue protease changes and the occurrence of malignant skin tumors. Current studies have shown that cathepsin is involved in tumor cell invasion and metastasis by regulating growth factors and cellular immune function in tumor microenvironment, decomposing extracellular matrix and basement membrane, and promoting angiogenesis. In this study, we conducted a bidirectional Mendelian-randomization study using publicly available genome-wide association study (GWAS; GWAS Catalog) data. This study applies a bidirectional multivariate Mendelian randomization (MR) approach to investigate the causal relationship between cathepsin, basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. In cases where multiple cathepsins are implicated as etiological factors in certain diseases, a multivariable analysis is conducted to assess the direct and indirect causal effects of the exposure factors. In this study, we present a comprehensive MR analysis to investigate the relationship between 9 cathepsin and basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Based on our MR analysis using the largest GWAS Catalog dataset available, we are able to draw relatively reliable conclusions. In the MR study, we found that tissue protease L2 can promote skin cancer, Cathepsin O, and Cathepsin F are associated with an increased risk of basal cell carcinoma. Cathepsin H can inhibit basal cell carcinoma and malignant melanoma. In the reverse MR study, it was found that squamous cell carcinoma may cause an increase in Cathepsin O expression. In the multivariate analysis, it was found that Cathepsin H is a direct factor in reducing the occurrence of skin cancer and melanoma, with no apparent causal relationship to non-melanoma skin cancer. Cathepsin has a dual impact on skin cancer cells, and the expression of different cathepsins at the edge of skin tumors may indicate different developmental tendencies of skin cancer. Cathepsin may serve as effective biomarkers for predicting tumors.

Investigation of conformational changes of cathepsin B as a feasibility assessment for NaCl reduction in Jinhua ham

Investigation of conformational changes of cathepsin B as a feasibility assessment for NaCl reduction in Jinhua ham

Retraction Note to: Changes in Cathepsin D and Beclin-1 mRNA and protein expression by the excitotoxin quinolinic acid in human astrocytes and neurons.

Retraction Note to: Changes in Cathepsin D and Beclin-1 mRNA and protein expression by the excitotoxin quinolinic acid in human astrocytes and neurons.

Investigation of the activity of cathepsin B in red shrimp (Solenocera crassicornis) and its relation to the quality of muscle proteins during chilled and frozen storage.

Cathepsin B is a cysteine protease that has important effects on the quality of muscle products. In this study, the changes of cathepsin B activity and its relation to muscle proteins were investigated in intact and beheaded shrimp during chilled and frozen storage. The obtained results indicated that the water holding capacity (WHC), shear force, hardness, and myofibrillar protein (MP) content all significantly decreased in both the intact and beheaded shrimp samples with increasing storage period (p<0.05). Specifically, beheading shrimp exhibited much more stable characteristics than intact shrimp samples during both chilled and frozen storage. The enzyme activity results suggested that cold temperature and storage induced the release of cathepsin B from the lysosomes to the mitochondria, sarcoplasm, and myofibrils in the muscle tissues. Furthermore, SDS-PAGE and transmission electron microscopy (TEM) analysis revealed that beheading the shrimp greatly inhibited the dissociation of shrimp muscle proteins during storage. The current findings suggest that cathepsin B located in the head of shrimp was likely transferred to the muscle through the first abdominal segment during storage, accelerating the dissociation of the muscle proteins. Therefore, beheading the shrimp was conducive to prolonging the shelf-life of stored shrimp products.

Effects of Cathepsins on Gel Strength and Water-Holding Capacity of Myofibrillar Protein Gels from Bighead Carp (Aristichthys nobilis) under a Hydroxyl Radical-Generation Oxidizing System.

This study investigates the effects of cathepsins on the gel strength and water-holding capacity (WHC) of myofibrillar protein gels from bighead carp (Aristichthys nobilis) under a hydroxyl radical-generation oxidizing system. The myofibrillar proteins were divided into control group (with cathepsins) and E64 group (without cathepsins). The changes of cathepsin B and cathepsin L activities, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), protein oxidation (total sulfhydryl and carbonyl contents), and chemical interactions (nonspecific association, ionic bonds, hydrogen bonds, hydrophobic interactions, and disulfides) of myofibrillar protein and gels, as well as the gel strength and WHC of two groups under 0–100 mM H2O2, were measured. The results indicated that mild oxidation (10 mM H2O2) made a better gel strength and WHC. Cathepsin B and L activities decreased with increasing H2O2 concentrations but their effects on myofibrillar protein degradation still existed during 0.1–50 mM H2O2, which was expressed by higher carbonyl contents and ionic bonds at 0.1 and 50 mM H2O2, higher total sulfhydryl contents at 0 mM H2O2, and a lower intensity of MHC and actin of the control group than the E64 group. Besides more protein degradation, cathepsin proteolysis also resulted in lower gel strength and WHC in control gels than E64 gels under mild oxidation, which could be explained by lower hydrophobic interaction and moderate disulfides bonds between gel protein molecules of control gels.

Influence of Cold Storage on the Quality of Muscle and the Activity of Cathepsin H in Red Shrimp( Solenocera crassicornis )

To investigate the changes of cathepsin H activity and muscle quality of shrimp (Solenocera crassicornis) under different conditions, the samples were refrigerated at 4 °C for 6 days and frozen at -18 °C for 120 days, respectively. The changes of pH, water retention, hardness, springness, myofibrillar protein content, water content, and cathepsin H activity in intact shrimp and beheaded shrimp were compared and analyzed during chilling storage. Results showed that, with the increasing of storage period, the pH of muscle from the whole shrimps and beheaded shrimps both increased continuously, while the increasing rate of beheaded shrimp was slightly lower than that of whole shrimp samples. The myofibrillar protein (MP) content of both shrimp muscle decreased gradually with the prolonging of storage time. The MP content in intact shrimp and beheaded shrimp group decreased by 38.32% and 30.88% after refrigerated for 6 days, and by 61.67% and 52.09% after frozen for 120 days, respectively. During the whole frozen storage, the hardness and springness of the two groups of shrimps increased first and then decreased, while during the cold storage, the hardness and springness of the two groups of shrimp always decreased. The changes of cathepsin H activity in different subcellular fractions were different. The activity of cathepsin H in frozen condition was lower than that in cold condition, and the activity of cathepsin H in intact shrimp group was higher than that in beheaded shrimp group. The results showed that compared with the whole shrimp, the storage of beheaded shrimp was more conducive to the protection of muscle quality, and the activity of cathepsin H enzyme was greatly affected by the storage temperature. The results would provide a theoretical basis for the changes of physicochemical properties and cathepsin activity of shrimp under different conditions.

Abstract 2007: Investigating how RIPK1-mediated mitophagy induces cell death in ECM-detached cancer cells

Abstract Lead Contact Metastasis is responsible for 90% of deaths caused by cancer. For cancer cells to begin successful metastasis, they must detach from their extracellular matrix (ECM) and evade intrinsic cell death mechanisms. Detachment from the ECM is known to induce a caspase-dependent cell death program, termed anoikis, that cancer cells have been shown to circumvent. Nonetheless, overcoming caspase-dependent cell death alone is not sufficient to promote survival during ECM-detachment, but cancer cells must also address caspase-independent cell death programs. In our recent studies, we have identified RIPK1 as a critical mediator of ECM-detachment induced caspase-independent cell death via its capacity to promote mitophagy and subsequent accumulation of mitochondrial ROS. More recently, we have begun to examine how ROS levels are elevated as a consequence of mitophagy and how these ROS ultimately promote cell death. During mitophagy, autophagosomes containing mitochondria fuse with lysosomes containing a plethora of hydrolases that could facilitate cell death. As such, we sought to examine the relationship between RIPK1-mediated mitophagy and lysosomal membrane permeabilization (LMP) Using immunoblotting, we found that not only does ECM-detachment promote the expression of the lysosomal protease cathepsin B, but also that this induction is dependent upon RIPK1 activity. Given that mitochondrial ROS (mitoROS) was shown to be a consequence of RIPK1-mediated mitophagy during ECM-detachment, we investigated if mitoROS were required for the observed changes in cathepsin B expression. Indeed, when treated with a mitochondrial ROS (mitoROS) scavenger, cathepsin B protein levels noticeably reduce. Taken together, this data suggests that RIPK1-driven mitoROS production is playing a role in regulating cathepsin B expression during ECM-detachment. Future studies will be aimed at determining whether these RIPK1-mediated alterations in cathepsin B are linked to the induction of caspase-independent cell death. Citation Format: Jordan Alexandria Cockfield, Ishan Antony, Samantha Ekanayake, Zachary T. Schafer. Investigating how RIPK1-mediated mitophagy induces cell death in ECM-detached cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2007.

Changes in Cathepsin Activity during Low-Temperature Storage and Sous Vide Processing of Beef Brisket

It is believed that two main proteolytic systems are involved in the tenderization of meat: the cathepsins and the calpains. Many researchers consider the calpain system to be the major contributor to meat tenderness during post-mortem storage. However, the role and activity of cathepsins during post-mortem storage or low temperature meat processing is unclear, particularly for the tough meat cuts like brisket. Thus, the study was designed to investigate the effects of cold (refrigerated and frozen) storage and sous vide processing on the activities of cathepsin B, H, and L in beef brisket. There were no significant changes in pH and cathepsin H activity throughout the 18 d of storage at both temperatures. However, an increase in cathepsin B activity was observed during the first 4 d at both storage temperatures, but subsequently the activity remained unchanged. Cathepsins B and L were found to be more heat stable at sous vide temperatures (50°C for 24 h, 55°C for 5 h and at 60°C and 70°C for 1 h) compared to cathepsin H. Cathepsin B+L activity was found to increase after sous vide cooking at 50°C for 1 h but decreased to about 47% relative to the uncooked control after 24 h of cooking. These results suggest that cathepsins B and L may contribute to the improved meat tenderness usually seen in sous vide cooked brisket meat.

The Effect of Fucoidan on Cellular Oxidative Stress and the CatD-Bax Signaling Axis in MN9D Cells Damaged by 1-Methyl-4-Phenypyridinium.

Background: The purpose of this study was to investigate the impact of fucoidan (FUC) on the oxidative stress response and lysosomal apoptotic pathways in the Parkinson disease (PD) cell model.Methods: The Dopaminergic nerve precursor cell line(MN9D) cells that served as a PD model in this study underwent damage induced by 100 μM 1-methyl-4-phenyl pyridine (MPP+). Cell viability was assessed after FUC treatment and intracellular SOD GSH was measured via immunofluorescence assay. Cellular changes in cathepsin D, Autophagy marker Light Chain 3-II (LC3-II), and apoptotic protein Bax were assessed by Western blot. The expression of Cat D, LC3-II, and B cell lymphoma-2-associated x protein (Bax) was also measured after addition of the cathepsin inhibitor, pepstatin A.Results: The results indicated that MN9D cell viability decreased by 50% within 24 h after 100 μM MPP+ induced toxicity. Pretreatment with 100 μM Fucoidan reduced cellular expression of LC3-II and CatD in 3 h and suppressed the induction of Bax protein. After pepstatin A treatment, Bax expression was significantly downregulated.FUC reversed the reduction of superoxide dismutase (SOD) L-Glutathione(GSH), decreased cell viability, and apoptosis induced by MPP+ in 6 h, suggesting that Fucoidan can attenuate damage to MN9D cells induced by MPP+.Conclusions: Fucoidan protected lysosomes, reduced the expression of LC3-II, inhibited the expression of CatD-Bax and the oxidative stress response, suppressed apoptosis, and thus conferred protective effects for dopaminergic neural cells. FUC may have neuroprotective effects on PD and further research is needed.

Effect of Metabolic Stress on Lysosomal Proteolysis in the Liver and Brain of Rats Receiving Q10-Enriched Ration.

Activation of lysosomal proteolysis and increased coenzyme Q10 level were revealed in the liver and brain of rats with individual typological features under conditions of food deprivation. Changes in cathepsin B activity in these tissues were different in behaviorally active and passive animals. We observed indirect modulating effect of coenzyme Q10 in the regulation of activity of lysosomal endopeptidases in the brain of animals with different behavior during adaptation to metabolic stress.

Circulating cathepsin B and D in pregnancy

The purpose of this prospective study was to investigate the changes in the circulating levels of cathepsin B and D in pregnancy. We obtained longitudinal cathepsin B and D levels in 76 healthy pregnant women in the first and third trimesters and compared these levels with 20 non-pregnant controls. The plasma levels of soluble cathepsin B and D were measured using an enzyme-linked immunosorbent assay kit. The cathepsin D concentrations in the third trimester were significantly higher than that in the first trimester (p < .001), and the cathepsin D levels in the first trimester were significantly lower than that in the non-pregnant controls (p = .002). However, there was no significant difference in the cathepsin B level throughout pregnancy compared to the non-pregnant controls. Our study is unique in evaluating the longitudinal changes in the cathepsin B and D levels in pregnancies without obstetric complications. The results implicate that changes in the levels of cathepsins might be essential in placentation. Therefore, molecular and genetic studies on cathepsin B and D are needed to understand the roles of these enzymes in pregnancy, thereby contributing to the understanding of placentation.Impact statementWhat is already known? Matrix metalloproteinases (MMP) have been widely studied, and their function is very important in the normal implantation process. The level of MMP-9 is known to increase throughout pregnancy, while the level of MMP-2 decreases in the first trimester. In addition to MMPs, other proteases are important for placental development; cathepsins B and D are two of the proteases that are involved in the normal placentation process. The function of cathepsin D is related to MMPs because this protease can activate MMPs either directly or indirectly. Nevertheless, the role of circulating cathepsins in pregnancy has not yet been fully elucidated.What do these results add? This study provides evidence, for the first time, that there are fluctuations of plasma cathepsin D level and there are no changes in the plasma cathepsin B level in a normal pregnancy. Moreover, we demonstrated that a cathepsin D level is significantly decreased in the first trimester compared to the non-pregnant controls, and that the level is markedly elevated in the third trimester.What are the implications of these findings for clinical practice and/or further research? Cathepsins B and D should be further studied locally in the placenta to explain the differences in the concentration of cathepsin D and no changes in cathepsin B, thereby exploring their exact roles.

Interferon-γ treatment in vitro elicits some of the changes in cathepsin S and antigen presentation characteristic of lacrimal glands and corneas from the NOD mouse model of Sjögren's Syndrome.

Inflammation and impaired secretion by lacrimal and salivary glands are hallmarks of the autoimmune disease, Sjögren’s Syndrome. These changes in the lacrimal gland promote dryness and inflammation of the ocular surface, causing pain, irritation and corneal damage. The changes that initiate and sustain autoimmune inflammation in the lacrimal gland are not well-established. Here we demonstrate that interferon-γ (IFN-γ) is significantly elevated in lacrimal gland and tears of the male NOD mouse, a model of autoimmune dacryoadenitis which exhibits many ocular characteristics of Sjögren’s Syndrome, by 12 weeks of age early in lacrimal gland inflammation. Working either with primary cultured lacrimal gland acinar cells from BALB/c mice and/or rabbits, in vitro IFN-γ treatment for 48 hr decreased expression of Rab3D concurrent with increased expression of cathepsin S. Although total cellular cathepsin S activity was not commensurately increased, IFN-γ treated lacrimal gland acinar cells showed a significant increase in carbachol-stimulated secretion of cathepsin S similar to the lacrimal gland in disease. In vitro IFN-γ treatment did not increase the expression of most components of major histocompatibility complex (MHC) class II-mediated antigen presentation although antigen presentation was slightly but significantly stimulated in primary cultured lacrimal gland acinar cells. However, exposure of cultured human corneal epithelial cells to IFN-γ more robustly increased expression and activity of cathepsin S in parallel with increased expression and function of MHC class II-mediated antigen presentation. We propose that early elevations in IFN-γ contribute to specific features of ocular disease pathology in Sjögren’s Syndrome.

Синдром ендогенної інтоксикації в щурів із гострим поширеним перитонітом на тлі мерказоліл-індукованого гіпотиреозу

Introduction. The growth of endogenous toxicosis occurs when the admission intensity of toxic metabolic products increased sharply, or when the activity of antitoxic systems or elimination of toxic metabolites inhibits. The syndrome of endogenous intoxication develops at various pathological conditions, when the number of natural waste products of the body, which appeared in large quantities in biological environments, as well as aggressive components exceeds the capacity of biotransformation. The aim of the study – to learn the effect of reduced production of thyroid hormones on the indices of endogenous intoxication of rats with acute widespread peritonitis.Research Methods. The study used white Wistar rats. Hypothyroidism was simulated by the administration of Mercazolil at a dose of 25 mg / kg for 21 days. Acute widespread peritonitis was simulated by injecting 0.5 ml of 10 % filtered fecal suspension into the abdominal cavity of the studied animals. The determination of molecules of average weight, erythrocyte and leukocyte indices of intoxication, level of circulating immune complexes and catepsin D was carried out.Results and Discussion. It was established that the presence of hypothyroidism in experimental animals to which was simulated acute widespread faecal peritonitis was accompanied by, more expressed than in euthyroid rats, increase in endotoxicosis – medium molecular weight peptides, erythrocyte and leukocyte indices of intoxication, circulating immune complexes and worse dynamics of their normalization. Phase changes in cathepsin D activity were observed.Conclusions. Deficiency of iodine-containing thyroid hormones is accompanied by a reliable increase in the indices characterizing the syndrome of endogenous intoxication in comparison with the euthyroid animals. This may be one of the reasons for the development of multiple organ failure in these conditions.

Local and Systemic Functional Responses of Mouse Macrophages to Intravaginal Infection with Type 2 Herpes Simplex Virus and Vaccination.

Activity of cathepsin D and phagocytosis of macrophages from vaginal lavage fluid, peritoneal exudation, and spleen were studied in mice of sensitive (DBA/2) and resistant (BALB/c) lines after intravaginal infection with type 2 herpes simplex virus and vaccination. Activity of cathepsin D and intensity of phagocytosis (irrespective of the macrophage source) and their ratio in BALB/c mice in early terms after infection were close to the control levels taken as a unit. In DBA/2 mice, these parameters and their balance were shifted and changes in cathepsin D activity depended on the time after challenge. Activities of cellular and extracellular cathepsin D increased sharply on day 1 postinfection under conditions of local virus interaction with the vaginal mucosa and activation of the pathological process. Later, after generalization of the infection, activity of cathepsin D decreased, while phagocytosis increased in all the studied macrophage populations. Vaccination corrected the cathepsin D/phagocytosis imbalance and created conditions for rapid elimination of the virus.

Adenosine-to-inosine RNA editing controls cathepsin S expression in atherosclerosis by enabling HuR-mediated post-transcriptional regulation.

Adenosine-to-inosine (A-to-I) RNA editing, which is catalyzed by a family of adenosine deaminase acting on RNA (ADAR) enzymes, is important in the epitranscriptomic regulation of RNA metabolism. However, the role of A-to-I RNA editing in vascular disease is unknown. Here we show that cathepsin S mRNA (CTSS), which encodes a cysteine protease associated with angiogenesis and atherosclerosis, is highly edited in human endothelial cells. The 3' untranslated region (3' UTR) of the CTSS transcript contains two inverted repeats, the AluJo and AluSx+ regions, which form a long stem-loop structure that is recognized by ADAR1 as a substrate for editing. RNA editing enables the recruitment of the stabilizing RNA-binding protein human antigen R (HuR; encoded by ELAVL1) to the 3' UTR of the CTSS transcript, thereby controlling CTSS mRNA stability and expression. In endothelial cells, ADAR1 overexpression or treatment of cells with hypoxia or with the inflammatory cytokines interferon-γ and tumor-necrosis-factor-α induces CTSS RNA editing and consequently increases cathepsin S expression. ADAR1 levels and the extent of CTSS RNA editing are associated with changes in cathepsin S levels in patients with atherosclerotic vascular diseases, including subclinical atherosclerosis, coronary artery disease, aortic aneurysms and advanced carotid atherosclerotic disease. These results reveal a previously unrecognized role of RNA editing in gene expression in human atherosclerotic vascular diseases.

Cyclosporine A induced histological changes of Cathepsin L and CD2AP expression in renal glomeruli and tubules.

Cyclosporine A (CsA) is used globally as an immunosuppressant for the treatment of immune-mediated nephrotic syndrome (NS). However, its long-term use causes nephrotoxicity characterized by tubulointerstitial injury and glomerulosclerosis. The present study aimed to investigate the associations between histomorphological findings and immunohistological expression of Cathepsin L (CatL) and CD2-associated protein (CD2AP) in patients with NS mediated with CsA. A total of 18 patients with child-onset NS were divided into two groups after treatment with CsA for 2years (group A; n=10) and more than 4years (group B; n=8), respectively. Analyses of relationships between tubulointerstitial disorders and expression of CatL and CD2AP proteins were performed using immunohistochemistry of paired renal specimens. Glomeruli with arteriole hyalinization were significantly increased in both groups depending on dosage periods, although degrees of tubule and interstitial injury did not differ between groups. CD2AP expression was significantly greater in podocytes (P=0.046) and was significantly less in proximal tubule cells (P=0.014) in patients of group B compared with those of group A. Moreover, CD2AP expression was significantly increased in lateral tubule cells in both groups (group A, P=0.02; group B, P=0.001), and CatL expression in glomeruli and tubule cells did not change with the duration of CsA treatment in either patient group. CD2AP expression in renal tubules may histologically associate with tissue hypoxia and reflected recovery from CsA-mediated renal injury in patients, even with mild histological features of tubulointerstitial disorder.

Serum levels of cathepsin D, sirtuin1, and endothelial nitric oxide synthase are correlatively reduced in elderly healthy people.

Nowadays, cathepsins have been reported to be related to aging. The aim of this study is to evaluate the association between serum levels of cathepsin D (CTSD) and human aging. In the present study, we analyzed the serum levels of CTSD and its relation with levels of sirtuin1 (SIRT1) and endothelial nitric oxide synthase (eNOS) activity, which were known having an important role in aging. This study recruited 90 healthy subjects (62 men and 28 women), which were subdivided into three groups with respect to age: young (about 19years old, n=30), middle-age (about 40years old, n=30), and aged (above 65years old, n=30). Altered serum levels of CTSD and SIRT1 were measured by enzyme-linked immunosorbent assay, and eNOS activity was assessed by the conversion of 14(C)-L-arginine to 14(C)-L-citrulline. Elderly subjects had significantly lower CTSD, SIRT1, and eNOS than younger ones. Serum levels of CTSD were negatively correlated with age. There was a statistically significant positive correlation between serum levels of CTSD, eNOS, and SIRT1. This study shows lower serum CTSD values in elderly subjects than in younger subjects. This is the first to demonstrate age-related changes in cathepsin D levels in humans and the association between SIRT1 and eNOS.

Changes in Structural-Mechanical Properties and Degradability of Collagen during Aging-associated Modifications

During aging, changes occur in the collagen network that contribute to various pathological phenotypes in the skeletal, vascular, and pulmonary systems. The aim of this study was to investigate the consequences of age-related modifications on the mechanical stability and in vitro proteolytic degradation of type I collagen. Analyzing mouse tail and bovine bone collagen, we found that collagen at both fibril and fiber levels varies in rigidity and Young's modulus due to different physiological changes, which correlate with changes in cathepsin K (CatK)-mediated degradation. A decreased susceptibility to CatK-mediated hydrolysis of fibrillar collagen was observed following mineralization and advanced glycation end product-associated modification. However, aging of bone increased CatK-mediated osteoclastic resorption by ∼27%, and negligible resorption was observed when osteoclasts were cultured on mineral-deficient bone. We observed significant differences in the excavations generated by osteoclasts and C-terminal telopeptide release during bone resorption under distinct conditions. Our data indicate that modification of collagen compromises its biomechanical integrity and affects CatK-mediated degradation both in bone and tissue, thus contributing to our understanding of extracellular matrix aging.

The Unfolded Protein Response Regulates Apoptosis of Alveolar Epithelial Cells (AECs) by Modulating Autocrine Angiotensin (ANG)II and ANG1‐7

STUDY OBJECTIVEOur prior work showed that ER stress‐induced apoptosis of AECs is regulated by the autocrine ANGII/ANG1‐7 system. MG132 or surfactant protein C (SP‐C) BRICHOS domain mutation G100S induced apoptosis in human AECs by activating cathepsin D and by decreasing the protective angiotensin‐converting enzyme 2 (ACE‐2). This study tested the hypothesis that ER stress‐induced apoptosis of human AECs might be mediated by UPR pathways that in turn modulate the autocrine ANGII/ANG1‐7 system of these cells.METHODSA549 cells were challenged with the proteasome inhibitor MG132 or the SP‐C mutant G100S. UPR markers and ANG system components were measured by Western blotting. Apoptosis was measured by caspase activation and nuclear fragmentation.RESULTSMG132‐ or G100S mutation‐induced ER stress activated the UPR pathways (phospho PERK, phospho eIF2α, ATF4, phospho IRE1, spliced XBP1, ATF6), which led to an increase of cathepsin D and a decrease of anti‐apoptotic ACE‐2. Blockade of UPR pathways with UPR chaperone 4‐PBA or siRNAs (siATF6, siIRE1, siPERK) prevented both the changes in cathepsin D and ACE‐2 and the AEC apoptosis caused by MG132 or G100S.CONCLUSIONSThese data show that ER stress induces apoptosis in human AECs through UPR‐mediated pathways that in turn modulate the autocrine ANGII/ANG1‐7 system. They also demonstrate that ER stress‐induced apoptosis of human AECs can be prevented by inhibition of UPR‐specific pathways.

Expression of cathepsin B in acutely photodamaged fibroblasts and its significance

Objective To investigate the changes in cathepsin B (CatB) expression in acutely photodamaged human dermal fibroblasts (HDFs) and their significance.Methods HDFs were isolated from the foreskin of children,and subjected to primary culture and subculture.The fourth-to eighth-passage HDFs were used in the following experiment.HDFs were divided into two groups to receive irradiation with different doses of ultraviolet A (UVA) for different durations (acutely photodamaged group) or remain unirradiated (control group).Cell counting kit-8 (CCK8) assay was conducted to evaluate the proliferative activity of HDFs after irradiation with UVA at 5,10,15,20 and 25 J/cm2 respectively.Western blot and quantitative real-time reverse transcription PCR were performed to measure the protein and mRNA expressions of CatB respectively in HDFs at 24,48 and 72 hours after exposure to UVA at 10 J/cm2,and at 48 hours after exposure to UVA at 10,15,20 and 25 J/cm2.Statistical analysis was carried out by analysis of variance and least significant difference (LSD) test using the SPSS 13.0 software.Results UVA radiation induced a decrease in the proliferative activity of HDFs.When the dose of UVA was ≤ 10 J/cm2,the survival rate of HDFs maintained higher than 85％,and significant differences were observed in cell survival rate between unirradiated and irradiated HDFs at 24,48 and 72 hours (all P ＜ 0.05).Western blot showed that the gray value of CatB protein in the acutely photodamaged group irradiated with 10 J/cm2 UVA was significantly higher than that in the control group at 24 hours (0.76 ± 0.14 vs.0.35 ± 0.01,P ＜ 0.05),48 hours (1.34 ± 0.38 vs.0.45 ± 0.12,P＜ 0.05) and 72 hours (0.82 ± 0.09 vs.0.61 ± 0.06,P＜ 0.05).Increased mRNA expressions of CatB were also observed in the acutely photodamaged group compared with the control group at 24 hours (0.149 ± 0.009 vs.0.089 ± 0.015,P ＜ 0.05),48 hous (0.173 ± 0.009 vs.0.091 ± 0.010,P ＜ 0.05) and 72 hours (0.185 ± 0.158 vs.0.111 ± 0.017,P ＜ 0.05) after UVA radiation at 10 J/cm2.The gray value of CatB protein was 0.99 ± 0.07,1.49 ± 0.14,1.89 ± 0.08,2.07 ± 0.06 in HDFs at 48 hours after exposure to UVA of 10,15,20 and 25 J/cm2,respectively,significantly higher than that in the control group (0.60 ± 0.05,all P ＜ 0.05).Similarly,the mRNA expression of CatB was up-regulated in HDFs at 48 hours after UVA radiation at 10,15,20 and 25 J/cm2 compared with the unirradiated HDFs.Conclusion The protein and mRNA expressions of CatB are up-regulated in acutely photodamaged HDFs induced by UVA radiation. Key words: Fibroblasts; Ultraviolet rays; Radiation injuries, experimental; Cathepsin B