Dataset Information

MTOR-Dependent and Independent Survival Signaling by PI3K in B Lymphocytes.

ABSTRACT: Peripheral B lymphocyte survival requires the B cell receptor (BCR) and B cell activating factor (BAFF) binding to its receptor (BAFF-R). Deletion of the BCR, or its signal transducing chaperone Ig?, leads to rapid loss of mature B cells, indicating that signals initiated at the BCR are crucial for B cell survival. BAFF or BAFF-R deficiency also significantly reduces the numbers of mature B cells despite normal BCR expression. Together, these observations indicate that continued BCR and BAFF-R signaling are essential for the survival of mature resting B cells in the periphery. Here we demonstrate that tonic BCR signals up-regulate p100 (Nfkb2) as well as Mcl-1 protein expression at a post-transcriptional level via a PI3K-dependent pathway. p100 expression is mTOR-independent, whereas Mcl-1 expression is mTOR-dependent. BAFF treatment further elevated Mcl-1 levels by an mTOR-independent pathway, while consuming p100. Accordingly, Mcl-1 induction by BAFF is abrogated in Nfkb2-/- B cells. We propose that the cumulative effects of the BCR and BAFF-R signaling pathways increase Mcl-1 levels beyond the threshold required for B cell survival.

SUBMITTER: Kaileh M

PROVIDER: S-EPMC4718598 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

mTOR-Dependent and Independent Survival Signaling by PI3K in B Lymphocytes.

Kaileh Mary M Vazquez Estefania E MacFarlane Alexander W AW Campbell Kerry K Kurosaki Tomohiro T Siebenlist Ulrich U Sen Ranjan R

PloS one 20160119 1

Peripheral B lymphocyte survival requires the B cell receptor (BCR) and B cell activating factor (BAFF) binding to its receptor (BAFF-R). Deletion of the BCR, or its signal transducing chaperone Igβ, leads to rapid loss of mature B cells, indicating that signals initiated at the BCR are crucial for B cell survival. BAFF or BAFF-R deficiency also significantly reduces the numbers of mature B cells despite normal BCR expression. Together, these observations indicate that continued BCR and BAFF-R s ...[more]

PMID: 26785352

Similar Datasets

Project description:Glioblastoma is a high-grade glioma with poor prognosis even after surgery and standard therapy. Here, we asked whether carnosine (β-alanyl-L-histidine), a naturally occurring dipeptide, exert its anti-neoplastic effect on glioblastoma cells via PI3K/Akt/mTOR signaling. Therefore, glioblastoma cells from the lines U87 and T98G were exposed to carnosine, to the mTOR inhibitor rapamycin and to the PI3K inhibitor Ly-294,002. Pyruvate dehydrogenase kinase (PDK4) expression, known to be a target of PI3K/Akt/mTOR, and which is also affected by carnosine, was analyzed by RT-qPCR, and reporter gene assays with the human PDK4 promoter were performed. Cell viability was assessed by cell-based assays and mTOR and Akt phosphorylation by Western blotting. Rapamycin and Ly-294,002 increased PDK4 mRNA expression in both cell lines but significance was only reached in U87. Carnosine significantly increased expression in both lines. A significant combinatorial effect of carnosine was only detected in U87 when the dipeptide was combined with Ly-294,002. Reporter gene assays revealed no specific effect of carnosine on the human PDK4 promoter, whereas both inhibitors increased reporter gene expression. Rapamycin reduced phosphorylation of mTOR, and Ly-294,002 that of Akt. A significant reduction of Akt phosphorylation was observed in the presence of carnosine in U87 but not in T98G, and carnosine had no effect on mTOR phosphorylation. Cell viability as determined by ATP in cell lysates was reduced only in the presence of carnosine. We conclude that carnosine's anti-neoplastic effect is independent from PI3K/Akt/mTOR signaling. As the dipeptide reduced viability in tumor cells that do not respond to PI3K or mTOR inhibitors, it appears to be worth to further investigate the mechanisms by which carnosine exerts its anti-tumor effect and to consider it for therapy, especially as it is a naturally occurring compound that has already been used for the treatment of other diseases without indication of side-effects.

Project description:Prostatic branching morphogenesis is an intricate event requiring precise temporal and spatial integration of numerous hormonal and growth factor-regulated inputs, yet relatively little is known about the downstream signaling pathways that orchestrate this process. In this study, we use a novel mesenchyme-free embryonic prostate culture system, newly available mTOR inhibitors and a conditional PTEN loss-of-function model to investigate the role of the interconnected PI3K and mTOR signaling pathways in prostatic organogenesis. We demonstrate that PI3K levels and PI3K/mTOR activity are robustly induced by androgen during murine prostatic development and that PI3K/mTOR signaling is necessary for prostatic epithelial bud invasion of surrounding mesenchyme. To elucidate the cellular mechanism by which PI3K/mTOR signaling regulates prostatic branching, we show that PI3K/mTOR inhibition does not significantly alter epithelial proliferation or apoptosis, but rather decreases the efficiency and speed with which the developing prostatic epithelial cells migrate. Using mTOR kinase inhibitors to tease out the independent effects of mTOR signaling downstream of PI3K, we find that simultaneous inhibition of mTORC1 and mTORC2 activity attenuates prostatic branching and is sufficient to phenocopy combined PI3K/mTOR inhibition. Surprisingly, however, mTORC1 inhibition alone has the reverse effect, increasing the number and length of prostatic branches. Finally, simultaneous activation of PI3K and downstream mTORC1/C2 via epithelial PTEN loss-of-function also results in decreased budding reversible by mTORC1 inhibition, suggesting that the effect of mTORC1 on branching is not primarily mediated by negative feedback on PI3K/mTORC2 signaling. Taken together, our data point to an important role for PI3K/mTOR signaling in prostatic epithelial invasion and migration and implicates the balance of PI3K and downstream mTORC1/C2 activity as a critical regulator of prostatic epithelial morphogenesis.

Project description:BackgroundAtherosclerosis is one of the most common cardiovascular disorders. The dysfunction of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) are 2 key factors in the formation of atherosclerosis. This study aims to find strategies to prevent VSMCs and ECs dysfunction for the treatment of atherosclerosis.MethodsWe investigated the expression patterns of long noncoding RNAs (lncRNAs) in 2 pairs of serum samples from both atherosclerosis patients and healthy volunteers through microarray analysis. Then we selected the most up-regulated lncRNA ENAST00113 (lnc00113) to further verify its roles in atherosclerosis. VSMCs, and human umbilical vein endothelial cells (HUVECs) transfected with small interfering RNA (siRNAs) (si-00113-1, si-00113-1) and a negative control (si-NC) were cultured. MTT assay, Caspase 3 enzyme-linked immunosorbent assay (ELISA) assay, and wound healing assay were performed to evaluate whether lnc00113 had an effect on proliferation, apoptosis, and migration ability. Further, the correlation between lnc00113 and PI3K/Akt/mTOR signaling pathway was explored.ResultsMicroarray results indicated that 243 lncRNAs were up-regulated and 187 lncRNAs were down-regulated. Therefore, we chose the most up-regulated lncRNA ENST (lnc00113) to further explore its roles in atherosclerosis. Real-time polymerase chain reaction (RT-qPCR) results showed that the expression of lnc00113 was highly increased in atherosclerosis patients. In vitro experiment demonstrated that lnc00113 down-regulation significantly suppressed VSMCs and HUVECs proliferation, survival, and migration. Furthermore, we found that the protein expressions of phosphorylated-PI3K (p-PI3K), phosphorylated-Akt (p-Akt), phosphorylated-mTOR (p-mTOR), and bcl-2 in HUVECs cells transfected with si-00113-1 or si-00113-2 were dramatically decreased compared with si-NC-transfected cells and control cells. However, the total- PI3K (t-PI3K), total-Akt (t-Akt), and total-mTOR (t-mTOR) protein expressions were not changed, indicating that lnc00113 could activate PI3K/Akt/mTOR signaling pathway in atherosclerosis.ConclusionsThis finding identified an important role of lnc00113 in VSMCs and HUVECs that promotes cell proliferation, survival, and migration by activating PI3K/Akt/mTOR signaling pathway, which could probably serve as a promising therapeutic target for atherosclerosis.

Dataset Information

MTOR-Dependent and Independent Survival Signaling by PI3K in B Lymphocytes.

Publications

mTOR-Dependent and Independent Survival Signaling by PI3K in B Lymphocytes.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets