The physiological roles of insulin and insulin-like growth factors (IGFs) are distinct, with insulin acting to regulate cellular uptake and metabolism of fuels, whereas IGFs promote cell growth, survival and differentiation. The only components of signalling pathways known to be unique to insulin and IGFs are their respective receptors, and even these display substantial structural and functional similarity. Specificity of action in vivo must in part reflect relative levels of receptor expression in different tissues. The extent to which the receptors differ in intrinsic signalling capacity remains unclear, but specificity might in principle arise from differences in ligand-binding mechanism or properties of intracellular domains. To identify ligand binding determinants we expressed receptor fragments as soluble proteins. Both N-terminal domains and a C-terminal peptide sequence from the alpha-subunit are essential for ligand binding with moderate affinity. However, binding of ligand with high affinity and specificity requires higher-order structure. To compare signalling capacities, we constructed chimaeras containing intracellular domains of insulin or IGF receptors fused to the extracellular portion of TrkC. Expression and activation of these chimaeras in cell lines reveals subtle differences in signalling and end-point responses, which may depend on cell background.

Covid-19 crisis showed us that rapid massive virus detection campaign is a key element in SARS-CoV-2 pandemic response. The classical RT-PCR laboratory platforms must be complemented with rapid and simplified technologies to enhance efficiency of large testing strategies. To this aim, we developed EasyCoV, a direct saliva RT-LAMP based SARS-CoV-2 virus detection assay that do not requires any RNA extraction step. It allows robust and rapid response under safe and easy conditions for healthcare workers and patients. EasyCov test was assessed under double blind clinical conditions (93 asymptomatic healthcare worker volonteers, 10 actively infected patients, 20 former infected patients tested during late control visit). EasyCov results were compared with classical laboratory RT-PCR performed on nasopharyngeal samples. Our results show that compared with nasopharyngeal laboratory RT-PCR, EasyCov SARS-CoV-2 detection test has a sensitivity of 72.7%. Measured on healthcare worker population the specificity was 95.7%. LAMP technology on saliva is clearly able to identify subjects with infectivity profile. Among healthcare worker population Easycov test detected one presymptomatic subject. Because it is simple, rapid and painless for patients, EasyCov saliva SARS-Cov-2 detection test may be useful for large screening of general population.

Summary. Originating from a post-switch memory B cell or plasma cell compartment in peripheral lymphoid tissues, malignant multiple myeloma (MM) cells accumulate in the bone marrow of patients with MM. In this favourable microenvironment, their growth and survival are dependent upon both soluble factors and physical cell-to-cell and cell-to-extracellular-matrix contacts. In this study, hyaluronan (HA), a major non-protein glycosaminoglycan component of the extracellular matrix in mammalian bone marrow, acted as a survival factor against dexamethasone (Dex)-induced apoptosis in MM cell lines. These effects were mediated through an interleukin 6 (IL-6) autocrine pathway, involving signal transducers and activators of transcription-3 phosphorylation on IL-6-dependent XG-1 and XG-6 cell lines. HA promoted accumulation of IL-6 in the culture medium without affecting IL-6 gene expression, suggesting that HA protects, stabilizes and concentrates IL-6 close to its site of secretion, thus favouring its autocrine activity. In contrast, in the IL-6-independent RPMI8226 cell line, HA survival effect was mediated through a gp80-IL-6 receptor-independent pathway, resulting in the upregulation of Bcl-2 anti-apoptotic protein expression and nuclear factor-jB activation. Taken together, these data suggest that HA antagonizes Dex-induced apoptosis of MM cells by favouring the autocrine activity of different cytokines or growth factors. As HA is a major component of the bone marrow extracellular matrix, these findings support the idea that HA could play a major role in the survival of MM cells in vivo, and could explain why MM cells accumulate in the bone marrow of patients with MM and escape conventional chemotherapy.