Asn25 Deamidation as an Allosteric Tool to Increase IFNβ-1a Biological Activity

Interferon beta (IFNβ) is a well-known cytokine, belonging to the type I family, that exerts antiviral, immunomodulatory, and antiproliferative activity. It has been reported that the artificially deamidated form of recombinant IFNβ-1a at Asn25 position shows an increased biological activity. As a deepening of the previous study, the molecular mechanism underlying this biological effect was investigated in this work by combining experimental and computational techniques. Specifically, the binding to IFNAR1 and IFNAR2 receptors and the canonical pathway of artificially deamidated IFNβ-1a molecule were analyzed in comparison to the native form. As a result, a change in receptor affinity of deamidated IFNβ-1a with respect to the native form was observed, and to better explore this molecular interaction, molecular dynamics simulations were carried out. Results confirmed, as previously hypothesized, that the N25D mutation can locally change the interaction network of the mutated residue but also that this effect can be propagated throughout the molecule. In fact, many residues not involved in the interaction with IFNAR1 in the native form participate to the recognition in the deamidated molecule, enhancing the binding to IFNAR1 receptor and consequently an increase of signaling cascade activation. In particular, a higher STAT1 phosphorylation and interferon-stimulated gene expression was observed under deamidated IFNβ-1a cell treatment. In conclusion, this study increases the scientific knowledge of deamidated IFNβ-1a, deciphering its molecular mechanism, and opens new perspectives to novel therapeutic strategies.

The endocannabinoid system in renal cells: regulation of Na(+) transport by CB1 receptors through distinct cell signalling pathways

BACKGROUND AND PURPOSE

The function of the endocannabinoid system (ECS) in renal tissue is not completely understood. Kidney function is closely related to ion reabsorption in the proximal tubule, the nephron segment responsible for the re-absorption of 70-80% of the filtrate. We studied the effect of compounds modulating the activity of cannabinoid (CB) receptors on the active re-absorption of Na(+) in LLC-PK1 cells.

EXPERIMENTAL APPROACH

Changes in Na(+) /K(+) -ATPase activity were assessed after treatment with WIN55,212-2 (WIN), a non-selective lipid agonist, and haemopressin (HP), an inverse peptide agonist at CB1 receptors. Pharmacological tools were used to investigate the signalling pathways involved in the modulation of Na(+) transport.

KEY RESULTS

In addition to CB1 and CB2 receptors and TRPV1 channels, the mRNAs encoding for enzymes of the ECS were also expressed in LLC-PK1. WIN (10(-7)  M) and HP (10(-6)  M) altered Na(+) re-absorption in LLC-PK1 in a dual manner. They both acutely (after 1 min) increased Na(+) /K(+) -ATPase activity in a TRPV1 antagonist-sensitive way. WIN's stimulating effect persisted for 30 min, and this effect was partially blocked by a CB1 antagonist or a PKC inhibitor. In contrast, HP inhibited Na(+) /K(+) -ATPase after 30 min incubation, and this effect was attenuated by a CB1 antagonist or a PKA inhibitor.

CONCLUSION AND IMPLICATIONS

The ECS is expressed in LLC-PK1 cells. Both CB1 receptors and TRPV1 channels regulate Na(+) /K(+) -ATPase activity in these cells, and are modulated by lipid and peptide CB1 receptor ligands, which act via different signalling pathways.

Neuroendocrine Transdifferentiation in Human Prostate Cancer Cells: An Integrated Approach

Prostate cancer is highly sensitive to hormone therapy because androgens are essential for prostate cancer cell growth. However, with the nearly invariable progression of this disease to androgen independence, endocrine therapy ultimately fails to control prostate cancer in most patients. Androgen-independent acquisition may involve neuroendocrine transdifferentiation, but there is little knowledge about this process, which is presently controversial. In this study, we investigated this question in a novel model of human androgen-dependent LNCaP cells cultured for long periods in hormone-deprived conditions. Strikingly, characterization of the neuroendocrine phenotype by transcriptomic, metabolomic, and other statistically integrated analyses showed how hormone-deprived LNCaP cells could transdifferentiate to a nonmalignantneuroendocrine phenotype. Notably, conditioned media from neuroendocrine-like cells affected LNCaP cell proliferation. Predictive in silico models illustrated how after an initial period, when LNCaP cell survival was compromised by an arising population of neuroendocrine-like cells, a sudden trend reversal occurred in which the neuroendocrine-like cells functioned to sustain the remaining androgen-dependent LNCaP cells. Our findings provide direct biologic and molecular support for the concept that neuroendocrine transdifferentiation in prostate cancer cell populations influences the progression to androgen independence.

Nonpsychotropic plant cannabinoids, cannabidivarin (CBDV) and cannabidiol (CBD), activate and desensitize transient receptor potential vanilloid 1 (TRPV1) channels in vitro: potential for the treatment of neuronal hyperexcitability

Epilepsy is the most common neurological disorder, with over 50 million people worldwide affected. Recent evidence suggests that the transient receptor potential cation channel subfamily V member 1 (TRPV1) may contribute to the onset and progression of some forms of epilepsy. Since the two nonpsychotropic cannabinoids cannabidivarin (CBDV) and cannabidiol (CBD) exert anticonvulsant activity in vivo and produce TRPV1-mediated intracellular calcium elevation in vitro, we evaluated the effects of these two compounds on TRPV1 channel activation and desensitization and in an in vitro model of epileptiform activity. Patch clamp analysis in transfected HEK293 cells demonstrated that CBD and CBDV dose-dependently activate and rapidly desensitize TRPV1, as well as TRP channels of subfamily V type 2 (TRPV2) and subfamily A type 1 (TRPA1). TRPV1 and TRPV2 transcripts were shown to be expressed in rat hippocampal tissue. When tested on epileptiform neuronal spike activity in hippocampal brain slices exposed to a Mg(2+)-free solution using multielectrode arrays (MEAs), CBDV reduced both epileptiform burst amplitude and duration. The prototypical TRPV1 agonist, capsaicin, produced similar, although not identical effects. Capsaicin, but not CBDV, effects on burst amplitude were reversed by IRTX, a selective TRPV1 antagonist. These data suggest that CBDV antiepileptiform effects in the Mg(2+)-free model are not uniquely mediated via activation of TRPV1. However, TRPV1 was strongly phosphorylated (and hence likely sensitized) in Mg(2+)-free solution-treated hippocampal tissue, and both capsaicin and CBDV caused TRPV1 dephosphorylation, consistent with TRPV1 desensitization. We propose that CBDV effects on TRP channels should be studied further in different in vitro and in vivo models of epilepsy.

Analysis of the "endocannabinoidome" in peripheral tissues of obese Zucker rats

The endocannabinoid system (ECS) represents one of the major determinants of metabolic disorders. We investigated potential changes in the endogenous levels of anandamide (AEA), 2-arachidonoylglycerol (2-AG), N-oleoylethanolamine (OEA) and N-palmitoylethanolamine (PEA) in some peripheral organs and tissues of obese Zucker(fa/fa) and lean Zucker(fa/+) rats by qPCR, liquid chromatography mass spectrometry, western blot and enzymatic activity assays. At 10-12 weeks of age AEA levels were significantly lower in BAT, small intestine and heart and higher in soleus of Zucker(fa/fa) rats. In this tissue, also the expression of CB1 receptors was higher. By contrast in Zucker(fa/fa) rats, 2-AG levels were changed (and lower) solely in the small and large intestine. Finally, in Zucker(fa/fa), PEA levels were unchanged, whereas OEA was slightly lower in BAT, and higher in the large intestine. Interestingly, these differences were accompanied by differential alterations of the genes regulating ECS tone. In conclusion, the levels of endocannabinoids are altered during obesity in a way partly correlating with changes of the genes related to their metabolism and activity.