Lysosomal cathepsins: structure, role in antigen processing and presentation, and cancer

The presence of blastocyst within the uteri facilitates lumenal epithelium transformation for implantation via upregulating lysosome proteostasis activity

ABBREVIATIONS

ACTB: actin beta; AREG: amphiregulin; ATP6V0A4: ATPase, H+ transporting, lysosomal V0 subunit A4; Baf A1: bafilomycin A1; BSA: bovine serum albumin; CLDN1: claudin 1; CTSB: cathepsin B; DEGs: differentially expressed genes; E2: 17β-estradiol; ESR: estrogen receptor; GATA2: GATA binding protein 2; GLA: galactosidase, alpha; GO: gene ontology; HBEGF: heparin-binding EGF-like growth factor; IGF1R: insulin-like growth factor 1 receptor; Ihh: Indian hedgehog; ISH: in situ hybridization; LAMP1: lysosomal-associated membrane protein 1; LCM: laser capture microdissection; Le: lumenal epithelium; LGMN: legumain; LIF: leukemia inhibitory factor; LIFR: LIF receptor alpha; MSX1: msh homeobox 1; MUC1: mucin 1, transmembrane; P4: progesterone; PBS: phosphate-buffered saline; PCA: principal component analysis; PPT1: palmitoyl-protein thioesterase 1; PGR: progesterone receptor; PSP: pseudopregnancy; PTGS2/COX2: prostaglandin-endoperoxide synthase 2; qPCR: quantitative real-time polymerase chain reaction; SP: pregnancy; TFEB: transcription factor EB.

Calpeptin is a potent cathepsin inhibitor and drug candidate for SARS-CoV-2 infections

Several drug screening campaigns identified Calpeptin as a drug candidate against SARS-CoV-2. Initially reported to target the viral main protease (Mpro), its moderate activity in Mpro inhibition assays hints at a second target. Indeed, we show that Calpeptin is an extremely potent cysteine cathepsin inhibitor, a finding additionally supported by X-ray crystallography. Cell infection assays proved Calpeptin's efficacy against SARS-CoV-2. Treatment of SARS-CoV-2-infected Golden Syrian hamsters with sulfonated Calpeptin at a dose of 1 mg/kg body weight reduces the viral load in the trachea. Despite a higher risk of side effects, an intrinsic advantage in targeting host proteins is their mutational stability in contrast to highly mutable viral targets. Here we show that the inhibition of cathepsins, a protein family of the host organism, by calpeptin is a promising approach for the treatment of SARS-CoV-2 and potentially other viral infections.

Novel therapeutic opportunities for Toxoplasma gondii, Trichomonas vaginalis and Giardia intestinalis infections

INTRODUCTION

Toxoplasma gondii, Trichomonas vaginalis and Giardia intestinalis are the causative agents of Toxoplasmosis, Trichomoniasis and Giardiasis, three important infections threatening human health and affecting millions of people worldwide. Although drugs and treatment are available to fight these protozoan parasites, side-effects and increasing drug resistance, require continuous efforts for the development of novel effective drugs.

AREAS COVERED

The patents search was carried out in September/October 2022 with four official scientific databases (Espacenet, Scifinder, Reaxys, Google Patents). Treatments for Toxoplasmosis, Trichomoniasis and Giardiasis (2015-2022) have been grouped according to their chemotypes. In particular, novel chemical entities have been reported and investigated for their structure-activity relationship, when accessible. On the other hand, drug repurposing, extensively exploited to obtain novel anti-protozoal treatment, has been in-depth described. Finally, natural metabolites and extracts have also been reported.

EXPERT OPINION

T. gondii, T. vaginalis and G. intestinalis are protozoan infections usually controlled by immune system in immunocompetent patients; however, they could represent a threatening health for immunocompromised people. The needs of novel effective drugs, endowed with new mechanisms of actions arises from the increasing drug resistance affecting antibiotic as well as antiprotozoal therapies. In this review different therapeutic approaches to treat protozoan infections have been reported.

Comparative Transcriptomics in Atlantic Salmon Head Kidney and SHK-1 Cell Line Exposed to the Sea Louse Cr-Cathepsin

The development of vaccines against sea lice in salmon farming is complex, expensive, and takes several years for commercial availability. Recently, transcriptome studies in sea louse have provided valuable information for identifying relevant molecules with potential use for fish vaccines. However, the bottleneck is the in vivo testing of recombinant protein candidates, the dosage, and the polyvalent formulation strategies. This study explored a cell-based approach to prospect antigens as candidate vaccines against sea lice by comparison with immunized fish. Herein, SHK-1 cells and Atlantic salmon head kidney tissue were exposed to the antigen cathepsin identified from the sea louse Caligus rogercresseyi. The cathepsin protein was cloned and recombinantly expressed in Escherichia coli, and then SHK-1 cell lines were stimulated with 100 ng/mL cathepsin recombinant for 24 h. In addition, Atlantic salmons were vaccinated with 30 ug/mL recombinant protein, and head kidney samples were then collected 30 days post-immunization. SHK-1 cells and salmon head kidney exposed to cathepsin were analyzed by Illumina RNA sequencing. The statistical comparisons showed differences in the transcriptomic profiles between SHK-1 cells and the salmon head kidney. However, 24.15% of the differentially expressed genes were shared. Moreover, putative gene regulation through lncRNAs revealed tissue-specific transcription patterns. The top 50 up and downregulated lncRNAs were highly correlated with genes involved in immune response, iron homeostasis, pro-inflammatory cytokines, and apoptosis. Also, highly enriched pathways related to the immune system and signal transduction were shared between both tissues. These findings highlight a novel approach to evaluating candidate antigens for sea lice vaccine development, improving the antigens screening in the SHK-1 cell line model.

Harnessing protein sensing ability of electrochemical biosensors via a controlled peptide receptor-electrode interface

BACKGROUND

Cathepsin B, a cysteine protease, is considered a potential biomarker for early diagnosis of cancer and inflammatory bowel diseases. Therefore, more feasible and effective diagnostic method may be beneficial for monitoring of cancer or related diseases.

RESULTS

A phage-display library was biopanned against biotinylated cathepsin B to identify a high-affinity peptide with the sequence WDMWPSMDWKAE. The identified peptide-displaying phage clones and phage-free synthetic peptides were characterized using enzyme-linked immunosorbent assays (ELISAs) and electrochemical analyses (impedance spectroscopy, cyclic voltammetry, and square wave voltammetry). Feasibilities of phage-on-a-sensor, peptide-on-a-sensor, and peptide-on-a-AuNPs/MXene sensor were evaluated. The limit of detection and binding affinity values of the peptide-on-a-AuNPs/MXene sensor interface were two to four times lower than those of the two other sensors, indicating that the peptide-on-a-AuNPs/MXene sensor is more specific for cathepsin B (good recovery (86-102%) and %RSD (< 11%) with clinical samples, and can distinguish different stages of Crohn's disease. Furthermore, the concentration of cathepsin B measured by our sensor showed a good correlation with those estimated by the commercially available ELISA kit.

CONCLUSION

In summary, screening and rational design of high-affinity peptides specific to cathepsin B for developing peptide-based electrochemical biosensors is reported for the first time. This study could promote the development of alternative antibody-free detection methods for clinical assays to test inflammatory bowel disease and other diseases.

Human M1 macrophages express unique innate immune response genes after mycobacterial infection to defend against tuberculosis

Mycobacterium tuberculosis (Mtb) is responsible for approximately 1.5 million deaths each year. Though 10% of patients develop tuberculosis (TB) after infection, 90% of these infections are latent. Further, mice are nearly uniformly susceptible to Mtb but their M1-polarized macrophages (M1-MΦs) can inhibit Mtb in vitro, suggesting that M1-MΦs may be able to regulate anti-TB immunity. We sought to determine whether human MΦ heterogeneity contributes to TB immunity. Here we show that IFN-γ-programmed M1-MΦs degrade Mtb through increased expression of innate immunity regulatory genes (Inregs). In contrast, IL-4-programmed M2-polarized MΦs (M2-MΦs) are permissive for Mtb proliferation and exhibit reduced Inregs expression. M1-MΦs and M2-MΦs express pro- and anti-inflammatory cytokine-chemokines, respectively, and M1-MΦs show nitric oxide and autophagy-dependent degradation of Mtb, leading to increased antigen presentation to T cells through an ATG-RAB7-cathepsin pathway. Despite Mtb infection, M1-MΦs show increased histone acetylation at the ATG5 promoter and pro-autophagy phenotypes, while increased histone deacetylases lead to decreased autophagy in M2-MΦs. Finally, Mtb-infected neonatal macaques express human Inregs in their lymph nodes and macrophages, suggesting that M1 and M2 phenotypes can mediate immunity to TB in both humans and macaques. We conclude that human MФ subsets show unique patterns of gene expression that enable differential control of TB after infection. These genes could serve as targets for diagnosis and immunotherapy of TB.

Interacting Effects of Sea Louse (Lepeophtheirus salmonis) Infection and Formalin-Killed Aeromonas salmonicida on Atlantic Salmon Skin Transcriptome

Lepeophtheirus salmonis (sea lice) and bacterial co-infection threatens wild and farmed Atlantic salmon performance and welfare. In the present study, pre-adult L. salmonis-infected and non-infected salmon were intraperitoneally injected with either formalin-killed Aeromonas salmonicida bacterin (ASAL) or phosphate-buffered saline (PBS). Dorsal skin samples from each injection/infection group (PBS/no lice, PBS/lice, ASAL/no lice, and ASAL/lice) were collected at 24 h post-injection and used for transcriptome profiling using a 44K salmonid microarray platform. Microarray results showed no clear inflammation gene expression signatures and revealed extensive gene repression effects by pre-adult lice (2,189 down and 345 up-regulated probes) in the PBS-injected salmon (PBS/lice vs. PBS/no lice), which involved basic cellular (e.g., RNA and protein metabolism) processes. Lice repressive effects were not observed within the group of ASAL-injected salmon (ASAL/lice vs. ASAL/no lice); on the contrary, the observed skin transcriptome changes –albeit of lesser magnitude (82 up and 1 down-regulated probes)– suggested the activation in key immune and wound healing processes (e.g., neutrophil degranulation, keratinocyte differentiation). The molecular skin response to ASAL was more intense in the lice-infected (ASAL/lice vs. PBS/lice; 272 up and 11 down-regulated probes) than in the non-infected fish (ASAL/no lice vs. PBS/no lice; 27 up-regulated probes). Regardless of lice infection, the skin’s response to ASAL was characterized by the putative activation of both antibacterial and wound healing pathways. The transcriptomic changes prompted by ASAL+lice co-stimulation (ASAL/lice vs. PBS/no lice; 1878 up and 3120 down-regulated probes) confirmed partial mitigation of lice repressive effects on fundamental cellular processes and the activation of pathways involved in innate (e.g., neutrophil degranulation) and adaptive immunity (e.g., antibody formation), as well as endothelial cell migration. The qPCR analyses evidenced immune-relevant genes co-stimulated by ASAL and lice in an additive (e.g., mbl2b, bcl6) and synergistic (e.g., hampa, il4r) manner. These results provided insight on the physiological response of the skin of L. salmonis-infected salmon 24 h after ASAL stimulation, which revealed immunostimulatory properties by the bacterin with potential applications in anti-lice treatments for aquaculture. As a simulated co-infection model, the present study also serves as a source of candidate gene biomarkers for sea lice and bacterial co-infection.

Disease-modifying therapeutic strategies in osteoarthritis: current status and future directions

Osteoarthritis (OA) is the most common form of arthritis. It is characterized by progressive destruction of articular cartilage and the development of chronic pain and constitutes a considerable socioeconomic burden. Currently, pharmacological treatments mostly aim to relieve the OA symptoms associated with inflammation and pain. However, with increasing understanding of OA pathology, several potential therapeutic targets have been identified, enabling the development of disease-modifying OA drugs (DMOADs). By targeting inflammatory cytokines, matrix-degrading enzymes, the Wnt pathway, and OA-associated pain, DMOADs successfully modulate the degenerative changes in osteoarthritic cartilage. Moreover, regenerative approaches aim to counterbalance the loss of cartilage matrix by stimulating chondrogenesis in endogenous stem cells and matrix anabolism in chondrocytes. Emerging strategies include the development of senolytic drugs or RNA therapeutics to eliminate the cellular or molecular sources of factors driving OA. This review describes the current developmental status of DMOADs and the corresponding results from preclinical and clinical trials and discusses the potential of emerging therapeutic approaches to treat OA.

Molecular characterization and functional analysis of the lysosomal cathepsin D-like gene in red swamp crayfish, Procambarus clarkii

Aspartic proteinases are one of the four families of proteinase enzymes that are widely present in living organisms. They are involved in various physiological events, such as protein degradation, development, and host defense. However, the characterization and functional roles of aspartic proteinases remain to be elucidated in crustaceans. Here, we characterized a fragment of cathepsin D-like cDNA from red swamp crayfish, Procambarus clarkii (Pc-cathepsin D-like). The open reading frame of the Pc-cathepsin D-like gene contained 1152 bp, encoding a protein of 383 amino acid residues. We also evaluated the immunological role of the Pc-cathepsin D-like gene in vivo. Spatial distribution analysis revealed that the Pc-cathepsin D-like mRNA was high in the hepatopancreas, followed by the gut, gills, and hemocytes of P. clarkii. The expression levels of the Pc-cathepsin D-like gene increased following challenge with viral (polyinosinic: polycytidylic acid) and bacterial (lipopolysaccharides, peptidoglycan) PAMPs compared with PBS injection. The suppression of the Pc-cathepsin D-like gene by RNA interference significantly increased the expression of immune-associated genes. These results showed that the Pc-cathepsin D-like gene has an essential biological role in innate immune responses because it regulates the expression of immune-associated genes.

Transcriptome analysis in Takifugu rubripes and Dicentrarchus labrax gills during Cryptocaryon irritans infection

Takifugu rubripes and Dicentrarchus labrax are important commercial fish in China that are under serious threat from Cryptocaryon irritans. C. irritans is a ciliated obligate parasite that causes marine white spot disease and leads to heavy economic losses. We analysed the transcriptome in the gills of T. rubripes and D. labrax to compare differentially expressed genes (DEGs) and pathways during infection with C. irritans. In total, we identified 6,901 and 35,736 DEGs from T. rubripes and D. labrax, respectively. All DEGs were annotated into GO terms; 6,901 DEGs from T. rubripes were assigned into 991 sub-categories, and 35,736 DEGs from D. labrax were assigned into 8,517 sub-categories. We mapped DEGs to the KEGG database and obtained 153 and 350 KEGG signalling pathways from T. rubripes and D. labrax, respectively. Immune-related categories included Toll-like receptors, MAPK, lysosome, C-type lectin receptor and NOD-like receptor signalling pathways were significantly enriched pathways. In immune-related signalling pathways, we found that AP-1, P38, IL-1β, HSP90 and PLA were significantly up-regulated DEGs in T. rubripes, but P38 and PLA were significantly down-regulated in D. labrax. In this study, transcriptome was used to analyse the difference between scaly and non-scaly fish infection by C. irritans, which not only provided a theoretical basis for the infection mechanism of C. irritans, but also laid a foundation for effectively inhibiting the occurrence of this disease. Our work provides further insight into the immune response of host resistance to C. irritans.

A hemocyte-specific cathepsin L-like cysteine protease is involved in response to 20-hydroxyecdysone and microbial pathogens stimulation in silkworm, Bombyx mori

Cathepsin L protease belongs to the papain-like cysteine proteases family, plays indispensable roles in animals' pathological and physiological processes. However, little is known about Cathepsin L in silkworm, Bombyx mori. Herein, a novel Cathepsin L-like (Cat L-like) was cloned and identified from silkworm by the rapid amplification of cDNA ends (RACE). Cat L-like contains an intact open reading frame (ORF) of 1 668 bp and encodes 556 amino acid residues, consisting of a signal peptide, typical cathepsins' inhibitor_I29, and pept_C1 domain. Cat L-like is specifically and highly expressed in hemocytes. The cathepsin (including Cathepsin L, B, and H) crude extract from hemocytes had typical substrate specific catalytic activities and were sensitive to pH and temperature. Cat L-like up-regulated considerably after 20-hydroxyecdysone (20-E) administration, indicating that Cat L-like may be regulated by insect hormone. The responses of Cat L-like against bacterial infection suggest it may play essential roles in silkworm immunity. Overall, our studies provide a theoretical basis and insights to further investigate the functions of Cat L-like and in insects' innate immunity mechanisms.

Cathepsin A knockdown decreases the proliferation and invasion of A549 lung adenocarcinoma cells

Cathepsin A (CTSA) is a lysosomal protease that is abnormally expressed in various types of cancer; however, the function of CTSA in lung adenocarcinoma (LUAD) is unknown. The aim of the present study was to investigate the role of CTSA during LUAD development in vitro. The Cancer Genome Atlas (TCGA) database was used to analyze the expression of CTSA mRNA in LUAD tissues. CTSA was significantly upregulated in LUAD tissues compared with normal lung tissues. To explore the effect of CTSA on LUAD in vitro, LUAD A549 cells were transfected with CTSA small interfering RNA and the hallmarks of tumorigenesis were investigated using cell proliferation, cell cycle, wound healing, invasion and western blot assays. Following CTSA knockdown, proliferation of LUAD cells was decreased and an increased proportion of LUAD cells were arrested at the G₀/G₁ phase, with altered expression of critical cell cycle and proliferative marker proteins, including p53, p21 and proliferating cell nuclear antigen. Moreover, CTSA knockdown decreased the migration and invasion of A549 cells, as determined by wound healing, invasion, and western blotting assays. The expression levels of key proteins involved in epithelial-mesenchymal transition were analyzed by western blotting. CTSA knockdown enhanced the expression of E-cadherin, but decreased the expression of N-cadherin and β-catenin in A549 cells. To the best of our knowledge, the present study suggested for the first time it has been identified that CTSA may serve as a tumor promoter in LUAD, enhancing the malignant progression of LUAD cells by promoting cell proliferation, migration and invasion. The results suggested that CTSA may serve as a novel therapeutic target for LUAD.

Characterization of the immune roles of cathepsin L in turbot (Scophthalmus maximus L.) mucosal immunity

Cathepsin L (CTSL) is one of the crucial enzymes in cathepsin family, which has been widely known for its involvement in the innate immunity. However, it still remains poorly understood how CTSL modulates the immune system of teleosts. In this study, we captured three cathepsin L genes (SmCTSL, SmCTSL.1 and SmCTSL1) from turbot (Scophthalmus maximus). The coding sequences of SmCTSL, SmCTSL.1 and SmCTSL1 are 1,026 bp, 1,005 bp and 1,017 bp in length and encode 341, 334 and 338 amino acids, respectively. In details, transcripts of CTSL genes share same domains as other CTSL genes, one signal peptide, one propeptide and one papain family cysteine protease domain. Protein interaction network analysis indicated that turbot CTSL genes may play important roles in apoptotic signaling and involve in innate immune response. Evidence from subcellular localization demonstrated that the three Cathepsin L proteins were ubiquitous in nucleus and cytoplasm. The cathepsin L genes were widely expressed in all the tested tissues with the highest expression level of SmCTSL in spleen, and SmCTSL.1 and SmCTSL1 in intestine. Following Vibrio anguillarum, Edwardsiella tarda and Streptococcus iniae challenge, these cathepsin L genes were significantly regulated in mucosal tissues in all the challenges, especially significant down-regulation occurred rapidly in intestine in all the three challenges. In addition, the three cathepsin L genes showed strong binding ability to all the examined microbial ligands (LPS, PGN and LTA). Further studies should be used to analyze the specific function of these three cathepsin L genes. By then, we can use their function to maintain the integrity of the mucosal barrier, thereby promoting the disease resistance line and family selection in turbot.

Transcriptome changes for Nile tilapia (Oreochromis niloticus) in response to alkalinity stress

Nile tilapia is an important economic fish in the world because of its fast growth, high meat yield and strong adaptability. It is more adaptable to high alkalinity than common freshwater fish and provides valuable material for developing alkaline-tolerant strains and understanding the adaptation mechanism of fish to extreme environmental stress. In this study, we employed high throughput RNA sequencing to reveal the tissues (gill, kidney and liver) transcriptome differences of O. niloticus at different carbonate alkalinities (FW, AW40 and AW60). A total of 1,369,381,790 raw reads were obtained, including 496,441,232 reads in FW group, 437,907,696 reads in AW40 and 435,032,862 reads in AW60. In addition, 484,555,626 reads in gill, 451,618,224 reads in kidney and 433,207,940 reads in liver. A large number of stress-regulated changes were detected comprehensively. We focused on 3 significantly change pathways (steroid biosynthesis, drug metabolism and protein digestion/absorption) and 17 DEGs (HMG-CoA reductase, UDP-glucuronosyltransferase, and carbonic anhydrase etc.) which were shared among compared groups (AW40 vs FW, AW60 vs FW, AW40 vs 60 AW60) in gill, kidney and liver, respectively. These pathways/genes are sensitive to alkalinity stress and crucial to the alkalinity adaptation of tilapia. Overall, we found a large number of candidate genes, which encode important regulators of stress tolerance and ultimately contribute to future alkaline-tolerant fish breeding. Among these genes, lipid metabolism (involving signal transduction), detoxification and immune related genes are more prominent to the response and adaptability of fish to alkalinity stress.

Cyclopalladated compounds containing 2,6-lutidine: Synthesis, spectral and biological studies

Bridge splitting reactions between [Pd(C²,N-dmba)(μ-X)]₂ (dmba = N,N-dimethylbenzylamine; X = Cl, I, N₃, NCO) and 2,6-lutidine (lut) in the 1:2 molar ratio at room temperature afforded cyclopalladated compounds of general formulae [Pd(C²,N-dmba)(X)(lut)] {X = Cl^- (1), I^-(2), NNN^-(3), NCO^-(4)}, which were characterized by elemental analyses and infrared (IR), ¹H NMR spectroscopy. The molecular structures of all synthesized palladacycles have been solved by single-crystal X-ray crystallography. The cytotoxicity of the cyclopalladated compounds has been evaluated against a panel of murine {mammary carcinoma (4T1) and melanoma (B16F10-Nex2)} and human {melanoma (A2058, SK-MEL-110 and SK-MEL-5) tumor cell lines. All complexes were about 10 to 100-fold more active than cisplatin, depending on the tested tumor cell line. For comparison purposes, the cytotoxic effects of 1-4 towards human lung fibroblasts (MRC-5) have also been tested. The late apoptosis-inducing properties of 1-4 compounds in SK-MEL-5 cells were verified 24 h incubation using annexin V-Fluorescein isothiocyanate (FITC)/propidium iodide (PI). The binding properties of the model compound 1 on human serum albumin (HSA) and calf thymus DNA (ct-DNA) have been studied using circular dichroism and fluorescence spectroscopy. Docking simulations have been carried out to gain more information about the interaction of the palladacycle and HSA. The ability of compounds 1-4 to inhibit the activity of cathepsin B and L has also been investigated in this work.

Fluorescent probes towards selective cathepsin B detection and visualization in cancer cells and patient samples

Highly selective fluorescent activity-based probe for the visualization of cathepsin B in cancer cells.

Human cysteine cathepsins constitute an 11-membered family of proteases responsible for degradation of proteins in cellular endosomal–lysosomal compartments as such, they play important roles in antigen processing, cellular stress signaling, autophagy, and senescence. Moreover, for many years these enzymes were also linked to tumor growth, invasion, angiogenesis and metastasis when upregulated. Individual biological roles of each cathepsin are difficult to establish, because of their redundancy and similar substrate specificities. Selective chemical tools that enable imaging of individual cathepsin activities in living cells, tumors, and the tumor microenvironment may provide a better insight into their functions. In this work, we used HyCoSuL technology to profile the substrate specificity of human cathepsin B. The use of unnatural amino acids in the substrate library enabled us to uncover the broad cathepsin B preferences that we utilized to design highly-selective substrates and fluorescent activity-based probes (ABPs). We further demonstrated that Cy5-labeled MP-CB-2 probe can selectively label cathepsin B in eighteen cancer cell lines tested, making this ABP highly suitable for other biological setups. Moreover, using Cy5-labelled MP-CB-2 we were able to demonstrate by fluorescence microscopy that in cancer cells cathepsins B and L share overlapping, but not identical subcellular localization.

Ectromelia virus suppresses expression of cathepsins and cystatins in conventional dendritic cells to efficiently execute the replication process

Background

Cathepsins are a group of endosomal proteases present in many cells including dendritic cells (DCs). The activity of cathepsins is regulated by their endogenous inhibitors – cystatins. Cathepsins are crucial to antigen processing during viral and bacterial infections, and as such are a prerequisite to antigen presentation in the context of major histocompatibility complex class I and II molecules. Due to the involvement of DCs in both innate and adaptive immune responses, and the quest to understand the impact of poxvirus infection on host cells, we investigated the influence of ectromelia virus (ECTV) infection on cathepsin and cystatin levels in murine conventional DCs (cDCs). ECTV is a poxvirus that has evolved many mechanisms to avoid host immune response and is able to replicate productively in DCs.

Results

Our results showed that ECTV-infection of JAWS II DCs and primary murine GM-CSF-derived bone marrow cells down-regulated both mRNA and protein of cathepsin B, L and S, and cystatin B and C, particularly during the later stages of infection. Moreover, the activity of cathepsin B, L and S was confirmed to be diminished especially at later stages of infection in JAWS II cells. Consequently, ECTV-infected DCs had diminished ability to endocytose and process a soluble antigen. Close examination of cellular protein distribution showed that beginning from early stages of infection, the remnants of cathepsin L and cystatin B co-localized and partially co-localized with viral replication centers (viral factories), respectively. Moreover, viral yield increased in cDCs treated with siRNA against cathepsin B, L or S and subsequently infected with ECTV.

Conclusions

Taken together, our results indicate that infection of cDCs with ECTV suppresses cathepsins and cystatins, and alters their cellular distribution which impairs the cDC function. We propose this as an additional viral strategy to escape immune responses, enabling the virus to replicate effectively in infected cells.

Electronic supplementary material

The online version of this article (10.1186/s12866-019-1471-1) contains supplementary material, which is available to authorized users.

Application of nanotechnology to target and exploit tumour associated proteases

Proteases are hydrolytic enzymes fundamental for a variety of physiological processes, but the loss of their regulation leads to aberrant functions that promote onset and progression of many diseases including cancer. Proteases have been implicated in almost every hallmark of cancer and whilst widely investigated for tumour therapy, clinical adoption of protease inhibitors as drugs remains a challenge due to issues such as off-target toxicity and inability to achieve therapeutic doses at the disease site. Now, nanotechnology-based solutions and strategies are emerging to circumvent these issues. In this review, preclinical advances in approaches to enhance the delivery of protease drugs and the exploitation of tumour-derived protease activities to promote targeting of nanomedicine formulations is examined. Whilst this field is still in its infancy, innovations to date suggest that nanomedicine approaches to protease targeting or inhibition may hold much therapeutic and diagnostic potential.

Targeted Analysis of Lysosomal Directed Proteins and Their Sites of Mannose-6-phosphate Modification

Mannose-6-phosphate (M6P) is a distinctive post-translational modification critical for trafficking of lysosomal acid hydrolases into the lysosome. Improper trafficking into the lysosome, and/or lack of certain hydrolases, results in a toxic accumulation of their substrates within the lysosomes. To gain insight into the enzymes destined to the lysosome these glycoproteins can be distinctively enriched and studied using their unique M6P tag. Here we demonstrate, by adapting a protocol optimized for the enrichment of phosphopeptides using Fe3+-IMAC chromatography, that proteome-wide M6P glycopeptides can be selectively enriched and subsequently analyzed by mass spectrometry, taking advantage of exclusive phosphomannose oxonium fragment marker ions. As proof-of-concept of this protocol, applying it to HeLa cells, we identified hundreds of M6P-modified glycopeptides on 35 M6P-modified glycoproteins. We next targeted CHO cells, either wild-type or cells deficient in Acp2 and Acp5, which are acid phosphatases targeting M6P. In the KO CHO cells we observed a 20-fold increase of the abundance of the M6P-modification on endogenous CHO glycoproteins but also on the recombinantly over-expressed lysosomal human alpha-galactosidase. We conclude that our approach could thus be of general interest for characterization of M6P glycoproteomes as well as characterization of lysosomal enzymes used as treatment in enzyme replacement therapies targeting lysosomal storage diseases.

From Analysis of Ischemic Mouse Brain Proteome to Identification of Human Serum Clusterin as a Potential Biomarker for Severity of Acute Ischemic Stroke

Ischemic stroke is a devastating neurological disease that can cause permanent brain damage, but to date, few biomarkers are available to reliably assess the severity of injury during acute onset. In this study, quantitative proteomic analysis of ischemic mouse brain detected the increase in expression levels of clusterin (CLU) and cystatin C (CST3). Since CLU is a secretary protein, serum samples (n = 70) were obtained from acute ischemic stroke (AIS) patients within 24 h of stroke onset and together with 70 matched health controls. Analysis of CLU levels indicated significantly higher levels in AIS patients than healthy controls (14.91 ± 4.03 vs. 12.79 ± 2.22 ng/L; P = 0.0004). Analysis of serum CST3 also showed significant increase in AIS patients as compared with healthy controls (0.90 ± 0.19 vs. 0.84 ± 0.12 ng/L; P = 0.0064). The serum values of CLU were also positively correlated with the NIH Stroke Scale (NIHSS) scores, the time interval after stroke onset, as well as major stroke risk factors associated with lipid profile. These data demonstrate that elevated levels of serum CLU and CST3 are independently associated with AIS and may serve as peripheral biomarkers to aid clinical assessment of AIS and its severity. This pilot study thus contributes to progress toward preclinical proteomic screening by using animal models and allows translation of results from bench to bedside.

Regulating BRCA1 protein stability by cathepsin S-mediated ubiquitin degradation

Cathepsin S (CTSS) is a cysteine protease that is thought to play a role in many physiological and pathological processes including tumor growth, angiogenesis, and metastasis; it has been identified as a radiation response gene. Here, we examined the role of CTSS in regulating the DNA damage response in breast cancer cells. Activating CTSS (producing the cleavage form of the protein) by radiation induced proteolytic degradation of BRCA1, which ultimately suppressed DNA double-strand break repair activity. Depletion of CTSS by RNAi or expression of a mutant type of CTSS enhanced the protein stability of BRCA1 by inhibiting its ubiquitination. CTSS interacted with the BRCT domain of BRCA1 and facilitated ubiquitin-mediated proteolytic degradation of BRCA1, which was tightly associated with decreased BRCA1-mediated DNA repair activity. Treatment with a pharmacological CTSS inhibitor inhibited proteolytic degradation of BRCA1 and restored BRCA1 function. Depletion of CTSS by shRNA delayed tumor growth in a xenograft mouse model, only in the presence of functional BRCA1. Spontaneously uced rat mammary tumors and human breast cancer tissues with high levels of CTSS expression showed low BRCA1 expression. From these data, we suggest that CTSS inhibition is a good strategy for functional restoration of BRCA1 in breast cancers with reduced BRCA1 protein stability.

miR-106b-5p inhibits the invasion and metastasis of colorectal cancer by targeting CTSA

Background

Although miR-106b-5p has been reported to play a pivotal role in various human malignancies, its role in colorectal cancer (CRC) remains unknown. In this study, we comprehensively investigated miR-106b-5p expression and biologic functions in CRC and the molecular mechanism involved.

Patients and methods

miR-106b-5p expression was detected in CRC tissues and cell lines by quantitative reverse transcription-polymerase chain reaction. The effects of miR-106b-5p on metastasis were determined in vitro using transwell assays, and in vivo effects were evaluated using a mouse tail vein injection model. Downstream targets of miR-106b-5p were confirmed using bioinformatics programs, luciferase assays, and rescue experiments. Target gene expression and clinicopathologic parameters were also analyzed.

Results

miR-106b-5p expression was lower in CRC tissues than in corresponding nontumorous tissues (P=0.009), and miR-106b-5p downregulation was negatively associated with lymph node metastasis (P=0.006). Functional assays demonstrated that miR-106b-5p overexpression suppressed CRC cell migration and invasion in vitro and lung metastasis formation in vivo. In addition, luciferase assays confirmed that miR-106b-5p directly bound to the 3' untranslated region of cathepsin A (CTSA) and that miR-106b-5p suppressed CRC cell migration and invasion by targeting CTSA. Clinicopathologic analysis showed that CTSA was significantly upregulated in CRC, and increased CTSA was negatively associated with lymph node metastasis (P=0.012).

Conclusion

Our findings revealed that miR-106b-5p inhibits CRC metastasis by upregulating CTSA expression, which may lead to novel therapeutic strategies for CRC patients.

Cathepsins in digestive cancers

Cathepsins are lysosomal peptidases belonging to the papain family, and based on their catalytic sites, these enzymes can be divided into serine, cysteine and aspartic proteases. The studies conducted to date have identified, 15 types of cathepsins that are widely distributed in intracellular and extracellular spaces. These proteases participate in various pathological activities, including the occurrence and development of human cancers. Several recent studies suggest that cathepsins, particularly cathepsins B, D, E and L, contribute to digestive tumorigenesis. Cathepsins were found to promote the development of most digestive cancers except liver cancer, in which they might have the opposite effects. Due to their important roles in digestive tumors, cathepsins might be therapeutic targets for the treatment of digestive cancers.

Atorvastatin inhibits the apoptosis of human umbilical vein endothelial cells induced by angiotensin II via the lysosomal-mitochondrial axis

This study was aimed to evaluate lysosomes-mitochondria cross-signaling in angiotensin II (Ang II)-induced apoptosis of human umbilical vein endothelial cells (HUVECs) and whether atorvastatin played a protective role via lysosomal-mitochondrial axis. Apoptosis was detected by flow cytometry, Hoechst 33342 and AO/EB assay. The temporal relationship of lysosomal and mitochondrial permeabilization was established. Activity of Cathepsin D (CTSD) was suppressed by pharmacological and genetic approaches. Proteins production were measured by western blotting. Our study showed that Ang II could induce the apoptosis of HUVECs in a dose-depended and time-depended manner. Exposure to 1 μM Ang II for 24 h resulted in mitochondrial depolarization, cytochrome c release, and increased ROS production. Lysosomal permeabilization and CTSD redistribution into the cytoplasm occurred several hours prior to mitochondrial dysfunction. These effects were all suppressed by atorvastatin. Either pharmacological or genetic inhibition of CTSD preserved mitochondrial function and decreased apoptosis in HUVECs. Most importantly, we found that the protective effect of atorvastatin was significantly greater than pharmacological or genetic inhibition of CTSD. Finally, overexpression of CTSD without exposure to Ang II had no effect on mitochondrial function and apoptosis. Our data strongly suggested that Ang II induced apoptosis through the lysosomal-mitochondrial axis in HUVECs. Furthermore, atorvastatin played an important role in the regulation of lysosomes and mitochondria stability, resulting in an antagonistic role against Ang II on HUVECs.

iTRAQ-Based Comparative Proteomic Analysis of Adult Schistosoma japonicum from Water Buffalo and Yellow Cattle

Schistosomiasis japonicum is one of the most severe zoonotic diseases in China. Water buffalo and yellow cattle are important reservoir hosts and the main transmission sources of Schistosoma japonicum in endemic areas. The susceptibility of these two hosts to schistosome infection is different, as water buffaloes are less susceptible to S. japonicum than yellow cattle. In this study, iTRAQ-coupled LC-MS/MS was applied to compare the protein expression profiles of adult schistosomes recovered from water buffalo with those of yellow cattle. A total of 131 differentially expressed proteins (DEPs) were identified, including 46 upregulated proteins and 85 downregulated proteins. The iTRAQ results were confirmed by Western blotting and quantitative real-time PCR. Further analysis indicated that these DEPs were primarily involved in protein synthesis, transcriptional regulation, protein proteolysis, cytoskeletal structure and oxidative stress response processes. The results revealed that some of the differential expression molecules may affect the development and survival of schistosomes in these two natural hosts. Of note, this study provides useful information for understanding the interplay between schistosomes and their final hosts.

Cathepsin B, Cathepsin H, Cathepsin X and Cystatin C in Sera of Patients with Early-Stage and Inflammatory Breast Cancer

Numerous studies have linked cathepsins and their inhibitor cystatin C to tumor invasion and metastasis. We examined whether cathepsin B, cathepsin H, cathepsin X and cystatin C could be detected in sera from women with early-stage or inflammatory breast cancer and whether they correlated with clinicopathological characteristics. Preoperative serum was obtained from 176 patients with early-stage breast cancer (tumor size <5 cm, negative lymph nodes) and 31 patients with inflammatory breast cancer. Cathepsin and cystatin C levels were measured by ELISA. The patient and tumor characteristics under study were age at diagnosis, menopausal status, tumor size, tumor grade, and steroid hormone receptor status. Serum cathepsin B levels were significantly lower in patients with poorly differentiated tumors. High cystatin C levels were associated with tumor size, postmenopausal status and patient age. Interestingly, significantly lower levels of cathepsin X and H were found in patients with inflammatory breast cancer, a trend also observed for cathepsin B and cystatin C. In conclusion, our results show a limited association of cathepsins B, H, X and cystatin C with established prognostic parameters. These data are promising and encourage future analysis of the clinical outcome of our patients in order to examine the potential prognostic value of these biomarkers. Further, this study indicates a role for cathepsin X and H in inflammatory breast cancer.

Modeling of autophagy-related gene expression dynamics during long term fasting in European eel (Anguilla anguilla)

Autophagy is an evolutionary conserved cellular self-degradation process considered as a major energy mobilizing system in eukaryotes. It has long been considered as a post-translationally regulated event, and the importance of transcriptional regulation of autophagy-related genes (atg) for somatic maintenance and homeostasis during long period of stress emerged only recently. In this regard, large changes in atg transcription have been documented in several species under diverse types of prolonged catabolic situations. However, the available data primarily concern atg mRNA levels at specific times and fail to capture the dynamic relationship between transcript production over time and integrated phenotypes. Here, we present the development of a statistical model describing the dynamics of expression of several atg and lysosomal genes in European glass eel (Anguilla anguilla) during long-term fasting at two temperatures (9 °C and 12 °C) and make use of this model to infer the effect of transcripts dynamics on an integrated phenotype – here weight loss. Our analysis shows long-term non-random fluctuating atg expression dynamics and reveals for the first time a significant contribution of atg transcripts production over time to weight loss. The proposed approach thus offers a new perspective on the long-term transcriptional control of autophagy and its physiological role.

A role of cathepsin L gene in innate immune response of crayfish (Procambarus clarkii)

Cathepsin L is one of the crucial enzyme superfamilies and involved in the immune responses. In the present study, cathepsin L gene from the red crayfish Procambarus clarkii, named PcCTSL, was cloned and characterized. The cDNA fragment of PcCTSL was 1026 bp in length, which encoded a putative protein of 341 amino acid residues with a molecular weight of 37.884 kDa. The theoretical isoelectric point was 5.218. The prepro-cathepsin L was comprised of a typical signal peptide (Met₁-Ala₁₈), a prodomain proregion peptide (Trp₂₉-Phe₈₉) and a mature peptide (Leu₁₂₄-Leu₃₄₀). Homology analysis indicated that PcCTSL exhibited 53.2%-87.1% identity to other selected species. The recombinant protein of PcCTSL was successfully expressed in Escherichia coli and rabbit anti-PcCTSL polyclonal antibodies were prepared. Real-time quantitative reverse transcription-PCR (qPCR) analysis revealed that the PcCTSL was expressed in all examined tissues, while the greatest mRNA level was observed in hepatopancreas. The expression of PcCTSL mRNA was clearly up regulated in hepatopancreas after challenge by lipopolysaccharide (LPS) and polyriboinosinic polyribocytidylic acid (Poly I:C). RNA interference of PcCTSL affected the gene expression of members of the Toll pathway. Our results suggest that the PcCTSL may play an important role to defend P. clarkii against the pathogens infection.

Divergent roles of three cytochrome c in CTSB-modulating coelomocyte apoptosis in Apostichopus japonicus

Cytochrome c plays crucial roles in apoptosis and the immune response. We previously demonstrated that cathepsin B from Apostichopus japonicus (AjCTSB) induces coelomocyte apoptosis. However, the mechanistic explanation and the regulation of this process have not been investigated. In the present study, we identified three cytochrome c cDNAs from A. japonicus (designated Ajcytc1, Ajcytc-1, and Ajcytc-2) using expressed sequence tag- (EST) and RACE-based approaches. The deduced amino acid sequences of the three cytochrome isoforms contained conserved CXXCH motifs, which are involved in binding heme and maintaining proteolytic activity. Time course expression analysis in vitro and in vivo revealed that the three cytochrome isoforms were induced upon pathogen challenge and LPS exposure. More importantly, AjCTSB knockdown by siRNA dramatically increased mitochondrial membrane potential (ΔΨm) in a time-dependent manner based on JC-1 fluorescent probe staining. AjCTSB knockdown also resulted in decreased expression of these three cytochromes 24 h after siAjCTSB transfection. Functional analysis using isoform-specific siRNAs revealed that Ajcytc-1, but not Ajcytc1 or Ajcytc-2, is involved in coelomocyte apoptosis. Moreover, the transcript level of Ajcaspase-3, an apoptosis executioner, was also consistently down-regulated upon silencing of Ajcytc-1 but not Ajcytc1 or Ajcytc-2. Collectively, these results indicate that Ajcytc1, Ajcytc-1, and Ajcytc-2 play distinct roles in mediating the immune response to bacteria according to AjCTSB expression. Moreover, Ajcytc-1 could be released upon dissipation of the ΔΨm, which could further trigger coelomocyte apoptosis through the activation of Ajcaspase-3.

Molecular cloning and functional characterization of cathepsin D from sea cucumber Apostichopus japonicus

Cathepsin D (CTSD, EC 3.4.23.5) belongs to aspartic protease family, which is located in lysosomes and is distributed in diverse tissues and cells. CTSD has a wide variety of physiological functions, owing to its proteolytic activity in degradating proteins and peptides. In the current study, the full length cDNA of sea cucumber (Apostichopus japonicus) cathepsin D (AjCTSD) was firstly cloned, then the association between AjCTSD and sea cucumber autolysis was investigated. The full length cDNA of AjCTSD was 2896 bp, with an open reading frame (ORF) for 391 amino acids. AjCTSD was widely expressed in body wall, muscle and intestine; the expression level was the highest in intestine, followed by muscle and body wall. Compared to fresh tissues, AjCTSD expression levels were significantly increased in all examined autolytic tissues. The purified recombinant AjCTSD promoted the degradation of sea cucumber muscle. In conclusion, AjCTSD contributed to sea cucumber muscle autolysis.

Effects of Vacuolar H+-ATPase Inhibition on Activation of Cathepsin B and Cathepsin L Secreted from MDA-MB231 Breast Cancer Cells

Studies indicate secreted cathepsins are involved in metastasis. V-ATPases, which are necessary for activating intracellular cathepsins, also play a role in metastasis and are targeted to the plasma membrane of metastatic breast cancer cells. We are interested in a connection between cell surface V-ATPases, activation of secreted cathepsins and the metastatic phenotype of MDA-MB231 cells. We investigated whether V-ATPase inhibition would reduce the activity of secreted cathepsin B and cathepsin L. Using cell lysates and conditioned media, we measured cathepsin B and L activity within and outside of the cells. We found different forms of cathepsin B and L were secreted representing the pre-pro, pro and active forms of the proteases. Cathepsin B activity was higher than cathepsin L in conditioned media and in cell lysates. V-ATPase inhibition by concanamycin A decreased cathepsin B activity in conditioned media and significantly decreased cathepsin B activity in cell lysates. Cathepsin L activity showed a slight decrease in cell lysates. Changes in the activity of secreted and intracellular cathepsins following V-ATPase inhibition were supported by changes in the amounts of pro and active forms of cathepsin B in conditioned media and cathepsins B and L in cell lysates. Overall, our data shows that inactive forms of cathepsins B and L are secreted from the MB231 cells and V-ATPase activity is important for the activation of secreted cathepsin B. This indicates a connection between cell surface V-ATPases in metastatic breast cancer cells and the function of secreted cathepsin B.

The Function of V-ATPases in Cancer

The vacuolar ATPases (V-ATPases) are a family of proton pumps that couple ATP hydrolysis to proton transport into intracellular compartments and across the plasma membrane. They function in a wide array of normal cellular processes, including membrane traffic, protein processing and degradation, and the coupled transport of small molecules, as well as such physiological processes as urinary acidification and bone resorption. The V-ATPases have also been implicated in a number of disease processes, including viral infection, renal disease, and bone resorption defects. This review is focused on the growing evidence for the important role of V-ATPases in cancer. This includes functions in cellular signaling (particularly Wnt, Notch, and mTOR signaling), cancer cell survival in the highly acidic environment of tumors, aiding the development of drug resistance, as well as crucial roles in tumor cell invasion, migration, and metastasis. Of greatest excitement is evidence that at least some tumors express isoforms of V-ATPase subunits whose disruption is not lethal, leading to the possibility of developing anti-cancer therapeutics that selectively target V-ATPases that function in cancer cells.

Extracellular cystatin SN and cathepsin B prevent cellular senescence by inhibiting abnormal glycogen accumulation

Cystatin SN (CST1), a known inhibitor of cathepsin B (CatB), has important roles in tumor development. Paradoxically, CatB is a member of the cysteine cathepsin family that acts in cellular processes, such as tumor development and invasion. However, the relationship between CST1 and CatB, and their roles in tumor development are poorly understood. In this study, we observed that the knockdown of CST1 induced the activity of senescence-associated β-galactosidase, a marker of cellular senescence, and expression of senescence-associated secretory phenotype genes, including interleukin-6 and chemokine (C-C motif) ligand 20, in MDA-MB-231 and SW480 cancer cells. Furthermore, CST1 knockdown decreased extracellular CatB activity, and direct CatB inhibition, using specific inhibitors or shCatB, induced cellular senescence. Reconstitution of CST1 restored CatB activity and inhibited cellular senescence in CST1 knockdown cells. CST1 knockdown or CatB inhibition increased glycogen synthase (GS) kinase 3β phosphorylation at serine 9, resulting in the activation of GS and the induction of glycogen accumulation associated with cellular senescence. Importantly, CST1 knockdown suppressed cancer cell proliferation, soft agar colony growth and tumor growth in a xenograft model. These results indicate that CST1-mediated extracellular CatB activity enhances tumor development by preventing cellular senescence. Our findings suggest that antagonists of CST1 or inhibitors of CatB are potential anticancer agents.

Transcriptomic profiling analysis of tilapia (Oreochromis niloticus) following Streptococcus agalactiae challenge

Innate immune system is the primary defense mechanism against pathogen infection in teleost, which are living in pathogen-rich aquatic environment. It has been long hypothesized that the disease resistance in teleost are strongly correlated to the activities of innate immune genes. Tilapia is an important economical fish around the world, especially in China, where the production accounts for nearly half of the global production. Recently, S. agalactiae has become one of the most serious bacterial diseases in southern China, resulted in high cumulative mortality and economic loss to tilapia industry. Therefore, we sought here to characterize the expression profiles of tilapia against S. agalactiae infection at whole transcriptome level by RNA-seq technology. A total of 2822 genes were revealed significantly expressed in tilapia spleen with a general trend of induction. Notably, most of the genes were rapidly the most induced at the early timepoint. The significantly changed genes highlighted the function of pathogen attachment and recognition, antioxidant/apoptosis, cytoskeletal rearrangement, and immune activation. Collectively, the induced expression patterns suggested the strong ability of tilapia to rapidly recognize the invasive bacteria, and activation of downstream immune signaling pathways to clear the bacteria and prevent the tissue damage and bacteria triggered cell apoptosis. Our results heighted important roles of novel candidate genes which were often missed in previous tilapia studies. Further studies are needed to characterize the molecular relationships between key immune genes and disease resistance, and to identify the candidate genes for molecular-assistant selection of disease-resistant broodstock and evaluation of disease prevention and treatment measures.

Molecular cloning and functional characterization of cathepsin B from the sea cucumber Apostichopus japonicus

Cathepsin B (CTSB), a member of lysosomal cysteine protease, is involved in multiple levels of physiological and biological processes, and also plays crucial roles in host immune defense against pathogen infection in vertebrates. However, the function of CTSB within the innate immune system of invertebrates, particularly in marine echinoderms, has been poorly documented. In this study, the immune function of CTSB in Apostichopus japonicus (designated as AjCTSB), a commercially important and disease vulnerable aquaculture specie, was investigated by integrated molecular and protein approaches. A 2153 bp cDNA representing the full-length of AjCTSB was cloned via overlapping ESTs and RACE fragments. AjCTSB contained an open reading frame of 999 bp encoding a secreted protein of 332 amino acid residues with a predicted molecular mass of 36.8 kDa. The deduced amino acid of AjCTSB shared a typical activity center containing three conserved amino acid residues (Cys¹⁰⁸, His²⁷⁷ and Asn²⁹⁷). Phylogenetic tree analysis also supported that AjCTSB was a new member of CTSB family with clustering firstly with invertebrate CTSBs. Quantitative real time PCR analysis revealed that AjCTSB was ubiquitously expressed in all examined tissues with the highest levels in intestine. The Vibrio splendidus challenged sea cucumber and LPS-exposed coelomocytes could both significantly boost the expression of AjCTSB. Moreover, the purified recombinant AjCTSB exhibited dose-dependent CTSB activities at the concentration ranged from 0 to 0.24 μg μL^-1. Further functional analysis indicated that coelomocytes apoptosis was significantly inhibited by 0.16-fold in vivo and the apoptosis execution Ajcaspase 3 was extremely reduced in Apostichopus japonicus coelomocytes treated with specific AjCTSB siRNA. Collectively, all these results suggested that AjCTSB was an important immune factor and might be served as apoptosis enhancers in pathogen challenged sea cucumber.

Degradomics in Neurotrauma: Profiling Traumatic Brain Injury

Degradomics has recently emerged as a subdiscipline in the omics era with a focus on characterizing signature breakdown products implicated in various disease processes. Driven by promising experimental findings in cancer, neuroscience, and metabolomic disorders, degradomics has significantly promoted the notion of disease-specific "degradome." A degradome arises from the activation of several proteases that target specific substrates and generate signature protein fragments. Several proteases such as calpains, caspases, cathepsins, and matrix metalloproteinases (MMPs) are involved in the pathogenesis of numerous diseases that disturb the physiologic balance between protein synthesis and protein degradation. While regulated proteolytic activities are needed for development, growth, and regeneration, uncontrolled proteolysis initiated under pathological conditions ultimately culminates into apoptotic and necrotic processes. In this chapter, we aim to review the protease-substrate repertoires in neural injury concentrating on traumatic brain injury. A striking diversity of protease substrates, essential for neuronal and brain structural and functional integrity, namely, encryptic biomarker neoproteins, have been characterized in brain injury. These include cytoskeletal proteins, transcription factors, cell cycle regulatory proteins, synaptic proteins, and cell junction proteins. As these substrates are subject to proteolytic fragmentation, they are ceaselessly exposed to activated proteases. Characterization of these molecules allows for a surge of "possible" therapeutic approaches of intervention at various levels of the proteolytic cascade.

Study of the expression of cathepsins in histological material from pancreatic lesions

BACKGROUND AND AIMS

To assess the expression levels of cathepsins in malignant and premalignant lesions.

METHODS

We retrospectively included patients who underwent pancreatic surgery on pancreatic solid or cystic masses. The expression of cathepsin H, L, B and S was determined in both types of samples. Lesions were divided into three categories: malignant (pancreatic adenocarcinoma and malignant mucinous neoplasms), premalignant (mucinous neoplasms) and benign (other lesions).

RESULTS

Thirty-one surgical resection samples were studied. The expression of cathepsins was significantly higher in malignant lesions than in premalignant and benign lesions (H 75%, 27%, 37% p = 0.05; L 92%, 36%, 37% p = 0.011; B 83%, 36%, 62% p = 0.069; S 92%, 36%, 25% p = 0.004, respectively).

CONCLUSIONS

Cathepsins are overexpressed in histological samples of malignant lesions compared to premalignant and benign lesions. However, the expression of cathepsins is similar in both premalignant and benign lesions.

Characterization and function of a cathepsin B in red crayfish (Procambarus clarkii) following lipopolysaccharide challenge

Cathepsin B is a lysosomal cysteine protease of the papain-like enzyme family with multiple biological functions. In the present study, a cathepsin B gene (named PcCTSB) was cloned and characterized from the red crayfish, Procambarus clarkii. The cDNA fragments of PcCTSB was 990 bp in length. It encoded a putative protein of 329 amino acid residues with predicted molecular weight of 36.4 kDa and isoelectric point of 7.020. Sequence alignment revealed that PcCTSB protein is 53.6%-80.4% identical with those from other 10 species. The predicted tertiary structure of PcCTSB protein was highly similar to that of animals. The results of the phylogenetic analysis indicated that the PcCTSB protein could be clustered with the Eriocheir sinensis cathepsin B protein. The recombinant protein of PcCTSB was expressed successfully in Escherichia coli cells. The mRNA expressions of PcCTSB were detected in all tested tissues, particularly high in the hepatopancreas. After lipopolysaccharide (LPS) challenge, the expression levels of PcCTSB were up-regulated significantly at different time points compared with control. Our results suggested that the PcCTSB might play an important role in defending against the pathogenes infection.

Cathepsin S Activity Controls Injury-Related Vascular Repair in Mice via the TLR2-Mediated p38MAPK and PI3K-Akt/p-HDAC6 Signaling Pathway

Supplemental Digital Content is available in the text.

Objective—

Cathepsin S (CatS) participates in atherogenesis through several putative mechanisms. The ability of cathepsins to modify histone tail is likely to contribute to stem cell development. Histone deacetylase 6 (HDAC6) is required in modulating the proliferation and migration of various types of cancer cells. Here, we investigated the cross talk between CatS and HADC6 in injury-related vascular repair in mice.

Approach and Results—

Ligation injury to the carotid artery in mice increased the CatS expression, and CatS-deficient mice showed reduced neointimal formation in injured arteries. CatS deficiency decreased the phosphorylation levels of p38 mitogen-activated protein kinase, Akt, and HDAC6 and toll-like receptor 2 expression in ligated arteries. The genetic or pharmacological inhibition of CatS also alleviated the increased phosphorylation of p38 mitogen-activated protein kinase, Akt, and HDAC6 induced by platelet-derived growth factor BB in cultured vascular smooth muscle cells (VSMCs), and p38 mitogen-activated protein kinase inhibition and Akt inhibition decreased the phospho-HDAC6 levels. Moreover, CatS inhibition caused decrease in the levels of the HDAC6 activity in VSMCs in response to platelet-derived growth factor BB. The HDAC6 inhibitor tubastatin A downregulated platelet-derived growth factor–induced VSMC proliferation and migration, whereas HDAC6 overexpression exerted the opposite effect. Tubastatin A also decreased the intimal VSMC proliferation and neointimal hyperplasia in response to injury. Toll-like receptor 2 silencing decreased the phosphorylation levels of p38 mitogen-activated protein kinase, Akt, and HDAC6 and VSMC migration and proliferation.

Conclusions—

This is the first report detailing cross-interaction between toll-like receptor 2–mediated CatS and HDAC6 during injury-related vascular repair. These data suggest that CatS/HDAC6 could be a potential therapeutic target for the control of vascular diseases that are involved in neointimal lesion formation.

Regulation of V-ATPase assembly and function of V-ATPases in tumor cell invasiveness

V-ATPases are ATP-driven proton pumps that function within both intracellular compartments and the plasma membrane in a wide array of normal physiological and pathophysiological processes. V-ATPases are composed of a peripheral V(1) domain that hydrolyzes ATP and an integral V(0) domain that transports protons. Regulated assembly of the V-ATPase represents an important mechanism of regulating V-ATPase activity in response to a number of environmental cues. Our laboratory has demonstrated that glucose-dependent assembly of the V-ATPase complex in yeast is controlled by the Ras/cAMP/PKA pathway. By contrast, increased assembly of the V-ATPase during dendritic cell maturation involves the PI-3 kinase and mTORC1 pathways. Recently, we have shown that amino acids regulate V-ATPase assembly in mammalian cells, possibly as a means to maintain adequate levels of amino acids upon nutrient starvation. V-ATPases have also been implicated in cancer cell survival and invasion. V-ATPases are targeted to different cellular membranes by isoforms of subunit a, with a3 targeting V-ATPases to the plasma membrane of osteoclasts. We have shown that highly invasive human breast cancer cell lines express higher levels of the a3 isoform than poorly invasive lines and that knockdown of a3 reduces both expression of V-ATPases at the plasma membrane and in vitro invasion of breast tumor cells. Moreover, overexpression of a3 in a non-invasive breast epithelial line increases both plasma membrane V-ATPases and in vitro invasion. Finally, specific ablation of plasma membrane V-ATPases in highly invasive human breast cancer cells using either an antibody or small molecule approach inhibits both in vitro invasion and migration. These results suggest that plasma membrane and a3-containing V-ATPases represent a novel and important target in the development of therapeutics to limit breast cancer metastasis. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.

Identification and mucosal expression analysis of cathepsin B in channel catfish (Ictalurus punctatus) following bacterial challenge

The mucosal surfaces of fish (skin, gill and intestine) constitute the primary line of defense against pathogen invasion. Although the importance of fish mucosal surfaces as the first barriers against pathogens cannot be overstated, the knowledge of teleost mucosal immunity are still limited. Cathepsin B, a lysosomal cysteine protease, is involved in multiple levels of physiological and biological processes, and playing crucial roles for host immune defense against pathogen infection. In this regard, we identified the cathepsin B (ctsba) of channel catfish and investigated the expression patterns of the ctsba in mucosal tissues following Edwardsiella ictaluri and Flavobacterium columnare challenge. Here, catfish ctsba gene was widely expressed in all examined tissues with the lowest expression level in muscle, and the highest expression level in trunk kidney, followed by spleen, gill, head kidney, intestine, liver and skin. In addition, the phylogenetic analysis showed the catfish ctsba had the strongest relationship to zebrafish. Moreover, the ctsba showed a general trend of up-regulated in mucosal tissues following both Gram-negative bacterial challenge. Taken together, the increased expression of ctsba in mucosal surfaces indicated the protective function of ctsba against bacterial infection, and the requirement for effective clearance of invading bacteria. Further studies are needed, indeed, to expand functional characterization and examine whether ctsba may play additional physiological and biological roles in catfish mucosal tissues.

Expression Analysis of Cathepsin F during Embryogenesis and Early Developmental Stage in Olive Flounder (Paralichthys olivaceus)

Cathepsins are members of the multigene family of lysosomal cysteine proteinases and have regulated function in several life processes. The potential role of cathepsin F cysteine gene was expected as protease in the yolk processing mechanism during early developmental stage, but expression analysis was unknown after fertilization. The alignment analysis showed that amino acid sequence of cathepsin F from olive flounder liver expressed sequence tag (EST) homologous to cathepsin F of other known cathepsin F sequences with 87-98% identity. In this study, we examined the gene expression analysis of cathepsin F in various tissues at variety age flounder. Tissue distribution of the cathepsin F mRNA has been shown to be ubiquitous and constitutive pattern regardless of age in each group, although derived from cDNA library using liver sample. The mRNA level of cathepsin F more increased as developmental proceed during embryogenesis and early developmental stage, especially increased in the blastula, hatching stage and 3 days post hatching (dph). As a result, it may suggest that the proteolysis of yolk proteins (YPs) has been implicated as a mechanism for nutrient supply during early larval stages in olive flounder.

Deficiency for the cysteine protease cathepsin L impairs Myc-induced tumorigenesis in a mouse model of pancreatic neuroendocrine cancer

Motivated by the recent implication of cysteine protease cathepsin L as a potential target for anti-cancer drug development, we used a conditional MycERTAM;Bcl-xL model of pancreatic neuroendocrine tumorigenesis (PNET) to assess the role of cathepsin L in Myc-induced tumor progression. By employing a cysteine cathepsin activity probe in vivo and in vitro, we first established that cathepsin activity increases during the initial stages of MycERTAM;Bcl-xL tumor development. Among the cathepsin family members investigated, only cathepsin L was predominately produced by beta-tumor cells in neoplastic pancreata and, consistent with this, cathepsin L mRNA expression was rapidly upregulated following Myc activation in the beta cell compartment. By contrast, cathepsins B, S and C were highly enriched in tumor-infiltrating leukocytes. Genetic deletion of cathepsin L had no discernible effect on the initiation of neoplastic growth or concordant angiogenesis. However, the tumors that developed in the cathepsin L-deficient background were markedly reduced in size relative to their typical wild-type counterparts, indicative of a role for cathepsin L in enabling expansive tumor growth. Thus, genetic blockade of cathepsin L activity is inferred to retard Myc-driven tumor growth, encouraging the potential utility of pharmacological inhibitors of cysteine cathepsins in treating late stage tumors.

Lysosomal signaling pathways and apoptosis

The lysosome is a membranous organelle that exists in all protozoa and cells of multicellular animals. Studies have shown that lysosome metabolic pathways are closely related to cell apoptosis. This paper reviews the structure of lysosomes, lysosome membrane permeability and cell apoptosis, the main way through which lysosomes participate in cell apoptosis, and the involvement of lysosomal signaling pathways in the apoptosis of hepatic stellate cells.