TIGAR Enhanced Free Ca2+ Concentration in Hepatocellular Carcinoma Cells to Accelerate the Sustained Proliferation and Drug Resistance

Background: To study the role of TP53-induced glycolysis and apoptosis regulator (TIGAR) in hepatocellular carcinoma (HCC) and drug resistance.Methods: HCC cells (HepG2 and SMMC7721) were used in this study. Fura 2-AM was used to assess cytosolic free Ca2+ concentrations ([Ca2+]i) within the two HCC cell lines. Nimodipine (NMDP), a Ca2+ antagonist, was used to reduce cytosolic [Ca2+]i level. Proliferation of HCC was measured using cell counting kit-8 (CCK-8). The roles of TIGAR and Ca2+ in drug resistance of HCC cells were assessed using epirubicin (Epi), 5-fluorouracil (5-FU), or cisplatinum (DDP).Results: Knockdown of TIGAR significantly suppressed cell viability, reduced [Ca2+]i, restrained protein expression of Ca2+-activated cysteine proteinases (Calpain1 and 2), as well as blocked the activation of nuclear factor kappa B (NF-κB) through an increase of cytoplasmic NF-κB and reduction of nuclear NF-κB. However, overexpression of TIGAR (oeTIGAR) resulted in the opposite. Evidence also shows that oeTIGAR suppressed the sensitivity of HCC to Epi, which was retarded by NMDP as an additional treatment. TIGAR interference could enhance the sensitivity of HCCs with high TIGAR expression to drugs.Conclusions: TIGAR promoted HCC progression and induced drug resistance, and the mechanism involved was [Ca2+]i-mediated activation of Calpain 1 and 2 and NF-κB signaling.

Entamoeba histolytica activation of caspase-1 degrades cullin that attenuates NF-κB dependent signaling from macrophages

While Entamoeba histolytica (Eh)-induced pro-inflammatory responses are critical in disease pathogenesis, the downstream signaling pathways that subsequently dampens inflammation and the immune response remains unclear. Eh in contact with macrophages suppresses NF-κB signaling while favoring NLRP3-dependent pro-inflammatory cytokine production by an unknown mechanism. Cullin-1 and cullin-5 (cullin-1/5) assembled into a multi-subunit RING E3 ubiquitin ligase complex are substrates for neddylation that regulates the ubiquitination pathway important in NF-κB activity and pro-inflammatory cytokine production. In this study, we showed that upon live Eh contact with human macrophages, cullin-1/4A/4B/5 but not cullin-2/3, were degraded within 10 minutes. Similar degradation of cullin-1/5 were observed from colonic epithelial cells and proximal colonic loops tissues of mice inoculated with live Eh. Degradation of cullin-1/5 was dependent on Eh-induced activation of caspase-1 via the NLRP3 inflammasome. Unlike cullin-4B, the degradation of cullin-4A was partially dependent on caspase-1 and was inhibited with a pan caspase inhibitor. Cullin-1/5 degradation was dependent on Eh cysteine proteinases EhCP-A1 and EhCP-A4, but not EhCP-A5, based on pharmacological inhibition of the cysteine proteinases and EhCP-A5 deficient parasites. siRNA silencing of cullin-1/5 decreased the phosphorylation of pIκ-Bα in response to Eh and LPS stimulation and downregulated NF-κB-dependent TNF-α mRNA expression and TNF-α and MCP-1 pro-inflammatory cytokine production. These results unravel a unique outside-in strategy employed by Eh to attenuate NF-κB-dependent pro-inflammatory responses via NLRP3 activation of caspase-1 that degraded cullin-1/5 from macrophages.

The effects of plant cysteine proteinases on the nematode cuticle

Background Plant-derived cysteine proteinases of the papain family (CPs) attack nematodes by digesting the cuticle, leading to rupture and death of the worm. The nematode cuticle is composed of collagens and cuticlins, but the specific molecular target(s) for the proteinases have yet to be identified. Methods This study followed the course of nematode cuticle disruption using immunohistochemistry, scanning electron microscopy and proteomics, using a free-living nematode, Caenorhabditis elegans and the murine GI nematode Heligmosomoides bakeri (H. polygyrus) as target organisms. Results Immunohistochemistry indicated that DPY-7 collagen is a target for CPs on the cuticle of C. elegans. The time course of loss of DPY-7 from the cuticle allowed us to use it to visualise the process of cuticle disruption. There was a marked difference in the time course of damage to the cuticles of the two species of nematode, with H. bakeri being more rapidly hydrolysed. In general, the CPs’ mode of attack on the nematode cuticle was by degrading the structural proteins, leading to loss of integrity of the cuticle, and finally death of the nematode. Proteomic analysis failed conclusively to identify structural targets for CPs, but preliminary data suggested that COL-87 and CUT-19 may be important targets for the CPs, the digestion of which may contribute to cuticle disruption and death of the worm. Cuticle globin was also identified as a cuticular target. The presence of more than one target protein may slow the development of resistance against this new class of anthelmintic. Conclusions Scanning electron microscopy and immunohistochemistry allowed the process of disruption of the cuticle to be followed with time. Cuticle collagens and cuticlins are molecular targets for plant cysteine proteinases. However, the presence of tyrosine cross-links in nematode cuticle proteins seriously impeded protein identification by proteomic analyses. Multiple cuticle targets exist, probably making resistance to this new anthelmintic slow to develop. Graphic Abstract

Differential Pathogenic Gene Expression of E. histolytica in Patients with Different Clinical Forms of Amoebiasis

The etiological agent of human amoebiasis is the protozoan parasite E. histolytica; the disease is still an endemic infection in some countries and the outcome of infection in the host infection can range from asymptomatic intestinal infection to intestinal or liver invasive forms of the disease. The invasive character of this parasite is multifactorial and mainly due to the differential expression of multiple pathogenic genes. The aim of the present work was to measure the differential expression of some genes in different specimens of patients with amoebic liver abscess (ALA) and specimens of genital amoebiasis (AG) by RT-qPCR. Results show that the expression of genes is different in both types of samples. Almost all studied genes were over expressed in both sets of patients; however, superoxide dismutase (Ehsod), serine threonine isoleucine rich protein (Ehstirp), peroxiredoxin (Ehprd) and heat shock protein 70 and 90 (Ehhsp-70, EHhsp-90) were higher in AG biopsies tissue. Furthermore, cysteine proteinases 5 and 2 (Ehcp5, Ehcp2), lectin (Ehgal/galnaclectin) and calreticulin (Ehcrt) genes directly associate with pathogenic mechanisms of E. histolytica had similar over expression in both AG and ALA samples. In summary the results obtained show that trophozoites can regulate the expression of their genes depending on stimuli or environmental conditions, in order to regulate their pathogenicity and ensure their survival in the host.

Antifungal potential of some proteins agricultural plants

The results of studies on the presence in the seeds of legumes and cereals of protein inhibitors that are active against animal proteinases (trypsin) and exogenous peptidases of phytopathogenic microorganisms are presented. It has been shown that secreted proteolytic enzymes of the studied phytopathogens are mainly represented by cysteine proteinases, to a lesser extent, serine and aspartane proteinases are present. It has been established that a close positive correlation between plant resistance to pathogens is observed not with well-known and widespread trypsin inhibitors, but with the activity of inhibitors directed against exogenous peptidases secreted by fungal pathogens of the genus Fusarium, Colletotrichum and Helminthosporium. The results obtained in the course of the work can be used in breeding and genetic studies on the creation of varieties and types of crops with increased resistance to pathogenic microflora and insect pests, as well as to create protective preparations.