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p38MAP kinase (MAPK) signal transduction pathways are important regulators of inflammation and the immune response; their involvement in immune cell development and function is still largely unknown. Here we analysed the role of the p38 MAPK isoforms p38γ and p38δ in B cell differentiation in bone marrow (BM) and spleen, using mice lacking p38γ and p38δ, or conditional knockout mice that lack both p38γ and p38δ specifically in the B cell compartment. We found that the B cell differentiation programme in the BM was not affected in p38γ/δ-deficient mice. Moreover, these mice had reduced numbers of peripheral B cells as well as altered marginal zone B cell differentiation in the spleen. Expression of co-stimulatory proteins and activation markers in p38γ/δ-deficient B cells are diminished in response to B cell receptor (BCR) and CD40 stimulation; p38γ and p38δ were necessary for B cell proliferation induced by BCR and CD40 but not by TLR4 signaling. Furthermore, p38γ/δ-null mice produced significantly lower antibody responses to T-dependent antigens. Our results identify unreported functions for p38γ and p38δ in B cells and in the T-dependent humoral response; and show that the combined activity of these kinases is needed for peripheral B cell differentiation and function., This work was supported by grants from the Spanish Ministry of Science and Innovation (SAF2013-45331-R and SAF2016-79792RtoAC; BFU2011-30097, BFU2013-48828-P,andRTI2018-101345-B-I00/MCIU/AEI/FEDER, UE to YC).

Microtubule (MT) dynamics are central to eukaryotic cell organization, intracellular transport, division, adhesion, polarization, and migration. Unbalanced MT stability is associated with metastasis and neurodegenerative diseases. We show that altered expression of death-inducer obliterator isoform 3 (DIDO3) restricts cell adhesion and motility. Fibroblasts with a DIDO3 C-terminal delection (DIDO3ΔCT) show i) MT bundling and looping, ii) failure to localize the tubulin plus-end binding protein CLASP2 to the membrane, iii) deregulated tubulin-actin-binding proteins EB1, GAS2L1, and DNM1 downstream of GSK3β, and iv) transcriptionally deregulated cytoskeletal- and non-cytoskeletal-coding genes (Gas2l1, Dnm1, Tubb4a, Obsl1 and Sema7a, Lgals3bp, Cct3, respectively) associated to cell migration, adhesion, immune responses, and tubulin-actin folding. DIDO3ΔCT deletion delocalizes the GSK3β-interacting protein ninein and prevents MT growth from the centrosome. DIDO3 expression in DIDO3ΔCT fibroblasts largely reestablishes the normal phenotype. Furthermore, DIDO3ΔCT B cells do not polarize the centrosome to the immunological synapse, a tubulin-dependent process. DIDO3CT overexpression induces tubulin stabilization and CLASP2 accumulation at the cell membrane. We propose a mechanism by which DIDO3 links transcriptional and posttranslational regulation of MT stability.

Bruton's tyrosine kinase (Btk) has a key role in the signaling pathways of receptors essential for the B lymphocyte response. Given its implication in B cell-related immunodeficiencies, leukemias/lymphomas and autoimmunity, Btk is studied intensely and is a target for therapy. Here, using primary B cells from distinct mouse models and the pharmacological inhibitors ibrutinib and acalabrutinib, we report distinct roles for Btk in antigen-triggered immune synapse (IS) formation. Btk recruitment to the plasma membrane regulates the B cell ability to trigger IS formation as well as its appropriate molecular assembly; Btk shuttling/scaffold activities seem more relevant than the kinase function on that. Btk-kinase activity controls antigen accumulation at the IS through the PLCγ2/Ca2+ axis. Impaired Btk membrane-recruitment or kinase function likewise alters antigen-triggered microtubule-organizing center (MTOC) polarization to the IS, B cell activation and proliferation. Data also show that, for B cell function, IS architecture is as important as the quantity of antigen that accumulates at the synapse.

Methods Twenty-eight (22±4.48 yrs, 179.22±9.04 cm, 83.41±11.95 kg, 15.90±5.07 %BF) resistance-trained males between the ages of 18 and 30 were randomly assigned by body weight to ingest either a placebo or tribulus blend (tribulus fruit extract-40% saponins) in a double-blind manner. Subjects participated in a supervised 4-day per week periodized resistance training program split into two upper and two lower extremity workout per week. At baseline (T1), 4 weeks (T2), and 8 weeks (T3), body composition (DEXA), muscular strength (1RM), muscular endurance, and anaerobic power measurements (Wingate) were determined. Venous blood samples were obtained using standard procedures at all time points. Blood analyses included serum and whole blood metabolic profile and the serum analysis of free testosterone, cortisol, and insulin were conducted using standard EIA and ELISA assay protocols. Statistical analyses utilized a two-way ANOVA with repeated measures for all dependent variables (p 0.05) indicating that supplementation had no additional benefit. A significant main effect for time was observed for serum insulin (p = 0.01), however there was no significant differences between groups. No significant main effects or interactions (p > 0.05) were noted on measures of anaerobic power, muscular endurance, RHR & BP, nutritional dietary intake, cortisol, free testosterone, or on the markers of the metabolic/CBC panel.