Structural characterization of As-MIF and hJAB1 during the inhibition of cell-cycle regulation

A secreted MIF homologue from Trichinella spiralis binds to and interacts with host monocytes

Trichinella spiralis is a very successful parasite capable of surviving in many mammal hosts and residing in muscle tissues for long periods, indicating that it must have some effective strategies to escape from or guard against the host immune attack. The functions of MIF have been studied in other parasites and demonstrated to function as a virulence factor aiding in their survival by modulating the host immune response. However, the functions of Trichinella spiralis MIF (TsMIF) have not been addressed. Here, we successfully obtained the purified recombinant TsMIF and anti-TsMIF serum. Our results showed that TsMIF was expressed in all the Trichinella spiralis developmental stages, especially highly expressed in the muscle larvae (ML) and mainly located in stichocytes, midgut, cuticle, muscle cells of ML and around intrauterine embryos of female adults. We also observed TsMIF could be secreted from ML and bind to host monocytes. Next, our data demonstrated that TsMIF not only stimulated the phosphorylation of ERK1/2 and cell proliferation by binding to the host cell surface receptor CD74, but also interacted with a host intracellular protein, Jab1, which is a coactivator of AP-1 transcription. We concluded the secreted TsMIF plays an important role in the interaction between Trichinella spiralis and its host and could be a potential drug or vaccine target molecule against Trichinella spiralis infection.

Nematode Orthologs of Macrophage Migration Inhibitory Factor (MIF) as Modulators of the Host Immune Response and Potential Therapeutic Targets

One of the adaptations of nematodes, which allows long-term survival in the host, is the production of proteins with immunomodulatory properties. The parasites secrete numerous homologs of human immune mediators, such as macrophage migration inhibitory factor (MIF), which is a substantial regulator of the inflammatory immune response. Homologs of mammalian MIF have been recognized in many species of nematode parasites, but their role has not been fully understood. The application of molecular biology and genetic engineering methods, including the production of recombinant proteins, has enabled better characterization of their structure and properties. This review provides insight into the current state of knowledge on MIF homologs produced by nematodes, as well as their structure, enzymatic activity, tissue expression pattern, impact on the host immune system, and potential use in the treatment of parasitic, inflammatory, and autoimmune diseases.

Helicobacter pylori-induced reactive oxygen species direct turnover of CSN-associated STAMBPL1 and augment apoptotic cell death

Deubiquitinylases (DUBs) are central regulators of the ubiquitin system involved in protein regulation and cell signalling and are important for a variety of physiological processes. Most DUBs are cysteine proteases, and few other proteases are metalloproteases of the JAB1/MPN +/MOV34 protease family (JAMM). STAM-binding protein like 1 (STAMBPL1), a member of the JAMM family, cleaves ubiquitin bonds and has a function in regulating cell survival, Tax-mediated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation and epithelial-mesenchymal transition. However, the molecular mechanism by which STAMBPL1 influences cell survival is not well defined, especially with regard to its deubiquitinylation function. Here, we show that reactive oxygen species (ROS) induced by chemotherapeutic agents or the human microbial pathogen Helicobacter pylori can induce cullin 1-RING ubiquitin ligase (CRL1) and 26S proteasome-dependent degradation STAMBPL1. Interestingly, STAMBPL1 has a direct interaction with the constitutive photomorphogenic 9 (COP9 or CSN) signalosome subunits CSN5 and CSN6. The interaction with the CSN is required for the stabilisation and function of the STAMBPL1 protein. In addition, STAMBPL1 deubiquitinylates the anti-apoptotic protein Survivin and thus ameliorates cell survival. In summary, our data reveal a previously unknown mechanism by which the deubiquitinylase STAMBPL1 and the E3 ligase CRL1 balance the level of Survivin degradation and thereby determine apoptotic cell death. In response to genotoxic stress, the degradation of STAMBPL1 augments apoptotic cell death. This new mechanism may be useful to develop therapeutic strategies targeting STAMBPL1 in tumours that have high STAMBPL1 and Survivin protein levels.