phosphatidylinositol-3-OH Kinase Research Articles

Modulation of gene expression profile following consumption of high-dairy products in subjects with hyperinsulinemia

Background and aimDysregulation of gene expression is associated to a higher risk of type 2 diabetes (T2D). Further, research indicates that dairy consumption may potentially affect gene expression.The aim of this study was to examine if genes and pathways associated with T2D are differentially changed in subjects with hyperinsulinemia after high dairy (HD) diet. Methods and resultsTen obese patients with hyperinsulinemia who consumed HD (4 servings/day according to the Canadian Food Guide (2007)) for six weeks participated in this study. Before and after HD consumption, fasting blood samples were collected. Blood was taken in PAX-gene tubes and RNA was extracted and analyzed using Clariom S microarrays. Results indicated that 236 genes (137 up-regulated and 99 down-regulated; fold change (FC) ≥ ±1.2; p < 0.05) were expressed differentially between before and after HD intake. Genes related to pathways associated with insulin signaling and inflammation, such as olfactory receptor activity, G-protein-coupled receptors (GPCR), phosphatidylinositol-3-OHKinase (PI3K)/AKT2 (PI3K-AKT2), Ras signaling, Mitogen-Activated Protein Kinase (MAPK) were altered following HD. ConclusionOverall, results suggest a potential protective effect of HD intake in individuals at risk of T2D through modification of gene expression profiles. Registration number for clinical studiesNCT02961179.

Phosphatidylinositol-3-OH kinase signalling is spatially organized at endosomal compartments by microtubule-associated protein 4.

The canonical model of agonist-stimulated phosphatidylinositol-3-OH kinase (PI3K)-Akt signalling proposes that PI3K is activated at the plasma membrane, where receptors are activated and phosphatidylinositol-4,5-bisphosphate is concentrated. Here we show that phosphatidylinositol-3,4,5-trisphosphate generation and activated Akt are instead largely confined to intracellular membranes upon receptor tyrosine kinase activation. Microtubule-associated protein 4 (MAP4) interacts with and controls localization of membrane vesicle-associated PI3Kα to microtubules. The microtubule-binding domain of MAP4 binds directly to the C2 domain of the p110α catalytic subunit. MAP4 controls the interaction of PI3Kα with activated receptors at endosomal compartments along microtubules. Loss of MAP4 results in the loss of PI3Kα targeting and loss of PI3K-Akt signalling downstream of multiple agonists. The MAP4-PI3Kα assembly defines a mechanism for spatial control of agonist-stimulated PI3K-Akt signalling at internal membrane compartments linked to the microtubule network.

NF-κB-Induced Upregulation of miR-548as-3p Increases Invasion of NSCLC by Targeting PTEN.

Non-Small Cell Lung Cancer (NSCLC) is an aggressive cancer type due to high metastatic capacity. Nuclear Factor Kappa B (NF-κB) is a consistently active transcription factor in malignant lung cancer cells and has crucial significance in NSCLC progression. It is also implicated in the transcriptional regulation of many genes including microRNAs (miRNAs) that function as tumor suppressor or oncogene. It has been increasingly reported that several miRNAs defined as gene members are induced by NF-κB. The present study aimed to find novel miRNAs that are regulated by NF-κB. Chromatin İmmunoprecipitation Sequencing (ChIP-Seq) experiment and bioinformatic analysis were used to determine NF-κB-dependent miRNAs. Western blot analysis, quantitative real-time polymerase chain reaction (qRT-PCR), luciferase reporter gene assays were carried out to investigate the target genes of miRNAs. To determine biologic activity, transwell invasion and MTT assay were carried out on H1299 NSCLC cell line. miRNA expression level was evaluated in metastatic and non-metastatic tissue samples of NSCLC patients. ChIP-Seq and qRT-PCR experiments showed that miR-548as-3p is transcriptionally regulated by NF- κB in response to Tumor Necrosis Factor-α (TNF-α) treatment. Then, we found that tumor suppressor Phosphatase and Tension homolog (PTEN) is a direct target of miR-548as-3p. Furthermore, miR-548as-3p mediates phosphatidylinositol-3-OH kinase (PI3K)/Akt pathway and NF-κB-implicated genes including Matrix Metalloproteinases 9 (MMP9), Slug and Zeb1. We further showed that miR-548as-3p increased invasiveness of NSCLC cells and was upregulated in metastatic tumor tissues compared to non-metastatic ones. All these findings provide a miRNAs-mediated novel mechanism for NF-κB signaling and that miR-548as-3p could be a biomarker for NSCLC metastasis.

Acylglycerol Kinase Maintains Metabolic State and Immune Responses of CD8+ T Cells

CD8+ Tcell expansions and functions rely on glycolysis, but the mechanisms underlying CD8+ Tcell glycolytic metabolism remain elusive. Here, we show that acylglycerol kinase (AGK) is required for the establishment and maintenance of CD8+ Tcell metabolic and functional fitness. AGK deficiency dampens CD8+ Tcell antitumor functions invivo and perturbs CD8+ Tcell proliferation invitro. Activation of phosphatidylinositol-3-OH kinase (PI3K)-mammalian target of rapamycin (mTOR) signaling, which mediates elevated CD8+ Tcell glycolysis, is tightly dependent on AGK kinase activity. Mechanistically, Tcell antigen receptor (TCR)- and CD28-stimulated recruitment of PTEN to the plasma membrane facilitates AGK-PTEN interaction and AGK-triggered PTEN phosphorylation, thereby restricting PTEN phosphatase activity in CD8+ Tcells. Collectively, these results demonstrate that AGK maintains CD8+ Tcell metabolic and functional state by restraining PTEN activity and highlight a critical role for AGK in CD8+ Tcell metabolic programming and effector function.

MicroRNA‐181a and microRNA‐155 are involved in the regulation of the differentiation and function of regulatory T cells in allergic rhinitis children

Regulatory T cells (Tregs) play central roles in limiting airway allergic inflammation and preventing inappropriate Th2 responses to environmental allergens. This study aims to evaluate the role of miR-181a and miR-155 in the regulation of the differentiation and function of Tregs through both in vivo and in vitro studies. The CD4+ T cells and Tregs were purified from peripheral blood mononuclear cells (PBMCs) in allergic rhinitis (AR) children, respectively. The miR-155/181a mimics and inhibitors were transfected into CD4+ T cells and Tregs. The differentiation and function of Tregs were evaluated by flow cytometry and enzyme-linked immunosorbent assay. AR mice models were established, and miR-155/181a mimics or inhibitors were injected through tail vein. The Treg percentage and function from mice were compared among different groups. The miR-181a up-regulated the release of interleukin (IL)-10 and TGF-β, whereas the miR-155 promoted Treg differentiation in CD4+ T cells. Similarly, we also found that miR-155 promoted Treg proliferation directly through suppressor of cytokine signaling 1 (SOCS1) and sirtuin1 (SIRT1) signaling pathway, whereas miR-181a up-regulated mRNA expression of IL-10 and TGF-β through phosphatidylinositol 3-OH kinase (PI3K)/Akt pathway. We also found that miR-155/181a affect Treg percentage and function in mice model. Our findings suggest that miR-181a and miR-155 were closely correlated with the proliferation and function of Tregs in AR, providing new potential treatment target.

The KLF6 splice variant KLF6-SV1 promotes proliferation and invasion of non-small cell lung cancer by up-regultating PI3K-AKT signaling pathway.

Non-small cell lung cancer (NSCLC) is an aggressive type of lung malignancy. Most of the patients have poor prognosis. Increasing evidence has revealed an association between KLF6-SV1, known as an oncogenic splice variant of KLF6, and metastatic potential or poor prognosis in many cancers. We previously demonstrated the increased KLF6-SV1 expression in NSCLC samples. There was a significant association between increased expression of KLF6-SV1 with the pN and pTNM stages and poor survival in NSCLC patients. In the present study, we aimed to further investigate the functional role of KLF6-SV1 in the progression of NSCLC. SK-MES-1 cells were infected with Lenti-virus containing KLF6-SV1 to up-regulate its expression, and the small interfering RNA (siRNA) was designed to knock down KLF6-SV1 transcript level in A549 cells. CCK8, colony formation, wound-healing, and transwell assays were performed to examine cell proliferation, migration, and invasion respectively. Western blot assay was used to detect the expression or phosphorylation of related proteins. We found that in vitro silencing of KLF6-SV1 by siRNA inhibited A549 cell proliferation, migration, and invasion through changes in E-cadherin, N-cadherin, Vimentin, Snail1 and Snail2 expression. Furthermore, KLF6-SV1 isoform knockdown triggered caspase-dependent apoptosis of A549 cells through downregulation of the phosphatidylinositol 3-OH kinase (PI3K)/Akt signaling pathway and apoptosis-related protein expression. Overexpression of KLF6-SV1 transcript induced significant increase in proliferation, migration, invasion and changes in expression of related proteins. Our study support KLF6-SV1 might be an important player in modulating the growth, migration, invasion, and survival of NSCLC cells, and that silencing KLF6-SV1 siRNA has the potential to be a powerful gene therapy strategy for NSCLC.

Securidaca-saponins are natural inhibitors of AKT, MCL-1, and BCL2L1 in cervical cancer cells.

IntroductionScientific research is beginning to prove the connection between claims by African traditional medicine and the natural chemical specifics contained in medicinal plant Securidaca longipedunculata. Our previous studies showed that two natural saponin fractions (4A3 and 4A4) identified in the plant as triterpenoid glycosides are capable of activating apoptosis on cervical tumor cell lines. Considering this and some critical roles of human papillomavirus (HPV) E6 oncogene on cervical cells, by promoting carcinogenesis and cell survival, it became necessary to investigate the possible pathways for apoptosis transmission.MethodsTests conducted on relevant cervical tumor cell lines such as Caski and Bu25TK included the following: MTT assay; scratch assay (to determine cell migration/invasion); fluorescence microscopy with Annexin V–fluorescein isothiocyanate, muscle progenitor cell) and propidium iodide staining; and finally reverse transcriptase quantitative PCR (RT-qPCR) for gene analysis.ResultsReduced cell proliferation was observed due to activities of 4A3 and 4A4 fractions, with half-maximal inhibitory concentration (IC50) of 7.03 and 16.39 μg/mL, respectively, on Caski cell line. A significant reduction in cell migration occurred within 48 and 72 hours, respectively, for Caski and Bu25TK cell lines. Late apoptosis was activated by 4A3, staining both Annexin V and PI, in contrast to 4A4’s early apoptosis. RT-qPCR data revealed a fold change (FC) inhibition of antiapoptotic proteins such as MCL-1 and BCL2L1, with diminished level of AKT-3, VEGFA, MALAT1, etc. The expression of p53, proapoptotic BAD, and caspase-8 was nonsignificant.ConclusionThe low expression of AKT-3 and antiapoptotic proteins (MCL-1 and BCL2L1), as well as VEGFA, could simply be an indication for possible suppression of cell survival mechanisms via multiple channels. We therefore conclude that 4A3 and 4A4 fractions mediate activity via the inhibition of phosphatidylinositol-3-OH kinase (PI3K)-AKT/mTOR/NF-kB-dependent antiapoptotic stimuli. Further studies are ongoing to reveal the chemical structures and compositions of these two fractions.

Role of Leptin/Osteopontin Axis in the Function of Eosinophils in Allergic Rhinitis with Obesity.

Background Allergic rhinitis (AR) is characterized by tissue and blood eosinophilia. Previous studies showed enhanced eosinophilia in allergic rhinitis patients with obesity, suggesting an association between obesity and eosinophilia. However, the interaction and mechanism between obesity and eosinophilia is still unclear. Methods We recruited thirty AR children and 30 controls in this study. Expression of leptin and osteopontin (OPN) proteins in serum was detected, and correlation analysis with eosinophilia was performed. The effect of leptin or OPN on eosinophil apoptosis, adhesion, migration, and activation of eosinophil was examined. Ovalbumin-sensitized mice were established to prove the role of obesity on eosinophil regulation by leptin and OPN. Results We found that upregulated serum and nasal leptin and OPN expression in AR were positively correlated with eosinophilia and eosinophil cationic protein levels. Leptin or OPN inhibited eosinophil apoptosis, demonstrated as inhibited DNA fragmentation and phosphatidylserine (PS) redistribution (P < 0.05). Leptin and OPN promote expression of cluster of differentiation 18 (CD-18) and intercellular adhesion molecule 1 (ICAM-1) and inhibit expression of ICAM-1 and L-selectin by eosinophils, which contribute to the adhesion of eosinophils. Leptin and OPN mediated migration and activation of eosinophil through phosphatidylinositol-3-OH kinase (PI3K) pathway. Obese AR mice presented with more severe eosinophilia and symptoms compared with nonobese AR mice or control mice. Immunochemistry staining of leptin and OPN of nasal turbinate in obese AR mice was also stronger than those in nonobese AR mice or control mice. Anti-OPN, anti-leptin, and anti-α4 treatments reduce nasal eosinophilia inflammation and clinical symptoms in model mice. Conclusion Our results suggested that in an obese state, upregulation of leptin and OPN regulates apoptosis, adhesion, migration, and activation of eosinophils, and this process may be mediated by the PI3K and anti-α4 pathways.

Downregulation of microRNA‑182 inhibits cell viability, invasion and angiogenesis in retinoblastoma through inhibition of the PI3K/AKT pathway and CADM2 upregulation.

Retinoblastoma (RB) is a well‑vascularized tumor dependent on angiogenesis. The present study aimed to explore whether microRNA (miR)‑182 regulates cell viability, invasion and angiogenesis in RB via the phosphatidylinositol‑3‑OH kinase (PI3K)/protein kinase B (AKT) signaling pathway and by targeting cell adhesion molecule 2 (CADM2). The expression levels of miR‑182 and CADM2 were initially detected in RB tissues from patients with RB who underwent ophthalmectomy, and normal retinal tissues collected from other trauma patients who underwent eye enucleation. To determine whether CADM2 was targeted by miR‑182, a dual luciferase reporter assay was conducted. Subsequently, Y79 and WERI‑Rb‑1 RB cells were transfected with a miR‑182 mimic or miR‑182 inhibitor, or small interfering RNA against CADM2, in order to investigate the effects of miR‑182 on viability and invasion, which were detected using MTT and Transwell assays, respectively. In addition, to determine whether the regulatory mechanism underlying the effects of miR‑182 was associated with the PI3K/AKT signaling pathway, the expression levels of associated genes were detected by reverse transcription‑quantitative polymerase chain reaction and western blot analysis. A xenograft tumor model in nude mice was also established, in order to evaluate the effects of miR‑182 on tumor growth and angiogenesis. The results indicated that miR‑182 expression was increased and CADM2 expression was reduced in RB tissues; CADM2 was confirmed to be targeted and negatively regulated by miR‑182. When the expression of miR‑182 was downregulated, cell viability, invasion, tumor volume and angiogenesis were significantly decreased. Furthermore, the expression levels of PI3K/AKT signaling pathway‑associated genes were increased in response to miR‑182 overexpression or CADM2 silencing. Taken together, these results suggested that inhibition of miR‑182 may suppress cell viability, invasion and angiogenesis in RB through inactivation of the PI3K/AKT pathway and CADM2 upregulation. This mechanism may reveal a novel potential therapeutic target.

PTEN inhibits replicative senescence-induced MMP-1 expression by regulating NOX4-mediated ROS in human dermal fibroblasts.

The biological function of NADPH oxidase (NOX) is the generation of reactive oxygen species (ROS). ROS, primarily arising from oxidative cell metabolism, play a major role in both chronological ageing and photoageing. ROS in extrinsic and intrinsic skin ageing may be assumed to induce the expression of matrix metalloproteinases. NADPH oxidase is closely linked with phosphatidylinositol 3‐OH kinase (PI3K) signalling. Protein kinase C (PKC), a downstream molecule of PI3K, is essential for superoxide generation by NADPH oxidase. However, the effect of PTEN and NOX4 in replicative‐aged MMPs expression has not been determined. In this study, we confirmed that inhibition of the PI3K signalling pathway by PTEN gene transfer abolished the NOX‐4 and MMP‐1 expression. Also, NOX‐4 down‐expression of replicative‐aged skin cells abolished the MMP‐1 expression and ROS generation. These results suggest that increase of MMP‐1 expression by replicative‐induced ROS is related to the change in the PTEN and NOX expression.

Thyroid Hormone Controls Breast Cancer Cell Movement via Integrin αV/β3/SRC/FAK/PI3-Kinases.

Thyroid hormones (TH) play a fundamental role in diverse processes, including cellular movement. Cell migration requires the integration of events that induce changes in cell structure towards the direction of migration. These actions are driven by actin remodeling and stabilized by the development of adhesion sites to extracellular matrix via transmembrane receptors linked to the actin cytoskeleton. Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that promotes cell migration and invasion through the control of focal adhesion turnover. In this work, we demonstrate that the thyroid hormone triiodothyronine (T3) regulates actin remodeling and cell movement in breast cancer T-47D cells through the recruitment of FAK. T3 controls FAK phosphorylation and translocation at sites where focal adhesion complexes are assembled. This process is triggered via rapid signaling to integrin αV/β3, Src, phosphatidylinositol 3-OH kinase (PI3K), and FAK. In addition, we established a cellular model with different concentration of T3 levels: normal, absence, and excess in T-47D breast cancer cells. We found that the expression of Src, FAK, and PI3K remained at normal levels in the excess of T3 model, while it was significantly reduced in the absence model. In conclusion, these results suggest a novel role for T3 as an important modulator of cell migration, providing a starting point for the development of new therapeutic strategies for breast cancer treatment.

MiR-21 inhibitor suppressed the progression of retinoblastoma via the modulation of PTEN/PI3K/AKT pathway.

MicroRNA-21 (miR-21) was reported to act as an oncogene during the development of many human tumors. However, little was revealed about the function of miR-21 in retinoblastoma (RB). In this study, we examined the expression of miR-21 in RB tissues and explored the relationship between miR-21 and phosphatase and tensin homolog (PTEN)/phosphatidylinositol-3-OH kinase (PI3K)/AKT signal. Quantitative real-time PCR (qRT-PCR) results showed that the level of miR-21 in RB tissues was higher than that in retinal normal tissues. In Weri-Rb-1 cells, miR-21 inhibitor suppressed the expression of miR-21 and cell viability, but improved cell apoptotic rates by modulating the levels of PDCD4, Bax, and Bcl-2. Meanwhile, miR-21 inhibitor suppressed cell migration and invasion via inhibiting the protein levels of MMP2 and MMP9 and significantly affected the expression of PTEN, PI3K, and p-AKT. Taken together, miR-21 inhibitor suppressed cell proliferation, migration, and invasion via the PTEN/PI3K/AKT signal. These findings revealed the molecular basis of miR-21 functioning in the progression of RB and provided a new means for cell therapy in RB.

PI3 kinases p110α and PI3K-C2β negatively regulate cAMP via PDE3/8 to control insulin secretion in mouse and human islets.

ObjectivesPhosphatidylinositol-3-OH kinase (PI3K) signalling in the endocrine pancreas contributes to glycaemic control. However, the mechanism by which PI3K modulates insulin secretion from the pancreatic beta cell is poorly understood. Thus, our objective was two-fold; to determine the signalling pathway by which acute PI3K inhibition enhances glucose-stimulated insulin secretion (GSIS) and to examine the role of this pathway in islets from type-2 diabetic (T2D) donors.MethodsIsolated islets from mice and non-diabetic or T2D human donors, or INS 832/13 cells, were treated with inhibitors of PI3K and/or phosphodiesterases (PDEs). The expression of PI3K-C2β was knocked down using siRNA. We measured insulin release, single-cell exocytosis, intracellular Ca2+ responses ([Ca2+]i) and Ca2+ channel currents, intracellular cAMP concentrations ([cAMP]i), and activation of cAMP-dependent protein kinase A (PKA) and protein kinase B (PKB/AKT).ResultsThe non-specific PI3K inhibitor wortmannin amplifies GSIS, raises [cAMP]i and activates PKA, but is without effect in T2D islets. Direct inhibition of specific PDE isoforms demonstrates a role for PDE3 (in humans and mice) and PDE8 (in mice) downstream of PI3K, and restores glucose-responsiveness of T2D islets. We implicate a role for the Class II PI3K catalytic isoform PI3K-C2β in this effect by limiting beta cell exocytosis.ConclusionsPI3K limits GSIS via PDE3 in human islets. While inhibition of p110α or PIK-C2β signalling per se, may promote nutrient-stimulated insulin release, we now suggest that this signalling pathway is perturbed in islets from T2D donors.

Pl3K/Akt/NF-κB Signalling Pathway on NSCLC Invasion

Invasion is a crucial step of metastasis process that has a complex mechanism and inducible various cellular signalling pathway (SMADs, JAK/STATs, PI3K/Akt and MAP kinases). In among these pathways, Pl3K (phosphatidylinositol-3-OH kinase)/Akt/NF-A¸B (nuclear factor-A¸B) signalling pathway is an important on cellular invasion and its constitutively active in various human cancer, including non-small cell lung cancer (NSCLC). PI3K/Akt/NF-A¸B pathway has been associated with multiple cellular function; migration, apoptosis, proliferation, survival, and also differentiation. Thus, this signalling pathway plays a major role not only in tumorigenesis but also in a potential target for cancer treatment. It has been investigated that there are lots of observation about Pl3K/Akt signalling pathway on many cancers, especially NSCLC. But, it is not enough to completely understanding the molecular mechanism of NSCLC invasion. In this review, we will briefly discuss the molecular mechanism of PI3K/Akt/NF-A¸B signalling pathway in NSCLC invasion.

Skin Aging-Dependent Activation of the PI3K Signaling Pathway via Downregulation of PTEN Increases Intracellular ROS in Human Dermal Fibroblasts.

Reactive oxygen species (ROS) play a major role in both chronological aging and photoaging. ROS induce skin aging through their damaging effect on cellular constituents. However, the origins of ROS have not been fully elucidated. We investigated that ROS generation of replicative senescent fibroblasts is generated by the modulation of phosphatidylinositol 3,4,5-triphosphate (PIP3) metabolism. Reduction of the PTEN protein, which dephosphorylates PIP3, was responsible for maintaining a high level of PIP3 in replicative cells and consequently mediated the activation of the phosphatidylinositol-3-OH kinase (PI3K)/Akt pathway. Increased ROS production was blocked by inhibition of PI3K or protein kinase C (PKC) or by NADPH oxidase activating in replicative senescent cells. These data indicate that the signal pathway to ROS generation in replicative aged skin cells can be stimulated by reduced PTEN level. Our results provide new insights into skin aging-associated modification of the PI3K/NADPH oxidase signaling pathway and its relationship with a skin aging-dependent increase of ROS in human dermal fibroblasts.

MicroRNA-519a promotes tumor growth by targeting PTEN/PI3K/AKT signaling in hepatocellular carcinoma.

MicroRNAs (miRNAs) have been found to play fundamental roles in the pathogenesis of hepatocellular carcinoma (HCC). Previous miRNA array data showed that miR-519a was upregulated in HCC tissues compared to adjacent non-tumor tissues. However, the functional role of miR-519a in HCC remains unexplored. In this study, we demonstrated that the expression of miR-519a was elevated in both HCC tissues and cell lines. Clinical association analysis revealed that high expression of miR-519a was correlated with adverse clinicopathological characteristics including large tumor size, high Edmondson-Steiner grading, advanced tumor-node-metastasis (TNM) tumor stage and venous infiltration. Furthermore, high expression of miR-519a conferred a reduced 5-year overall survival and disease-free survival of HCC patients. Moreover, we disclosed that miR-519a overexpression promoted, but miR-519a silencing reduced, HCC cell proliferation and cell cycle progression in vitro. Notably, we identified phosphatase and tensin homolog (PTEN) as a direct downstream target and functional mediator of miR-519a in HCC cells. Mechanistically, phosphatidylinositol-3-OH kinase (PI3K)/AKT pathway, downstream of PTEN, is essential for the functional roles of miR-519a in HCC cells. In conclusion, our results indicate that miR-519a promotes tumor growth of HCC by targeting PTEN-mediated PI3K/AKT pathway, and potentially serves as a novel prognostic biomarker and therapeutic target for HCC.

PI3 Kinase and FOXO1 Transcription Factor Activity Differentially Control B Cells in the Germinal Center Light and Dark Zones

Phosphatidylinositol 3' OH kinase (PI3K) signaling and FOXO transcription factors play opposing roles at several B cell developmental stages. We show here abundant nuclear FOXO1 expression in the proliferative compartment of the germinal center (GC), its dark zone (DZ), and PI3K activity, downregulating FOXO1, in the light zone (LZ), where cells are selected for further differentiation. In the LZ, however, FOXO1 was expressed in a fraction of cells destined for DZ reentry. Upon FOXO1 ablation or induction of PI3K activity, GCs lost their DZ, owing at least partly to downregulation of the chemokine receptor CXCR4. Although this prevented proper cyclic selection of cells in GCs, somatic hypermutation and proliferation were maintained. Class switch recombination was partly lost due to a failure of switch region targeting by activation-induced deaminase (AID).

PTEN signaling is required for the maintenance of spermatogonial stem cells in mouse, by regulating the expressions of PLZF and UTF1

BackgroundPten plays a crucial role in the stem cell maintenance in a few organs. Pten defect also causes the premature oocytes and ovary aging. We and other groups have found that the phosphatidylinositol-3-OH kinase (PI3K)-Akt signaling regulates the proliferation and differentiation of spermatogonial stem cells (SSCs). PTEN functions as a negative regulator of the PI3K pathway. Thus, we thought that the fate of SSCs might be controlled by Pten.ResultsWe report that promyelocytic leukaemia zinc finger (PLZF) and undifferentiated embryonic cell transcription factor 1 (UTF1), both of which are germ cell-specific transcriptional factors, are regulated by Pten. Conditional deletion of Pten leads to reduction in PLZF expression but induction of UTF1, which is associated with SSCs depletion and infertility in males with age.ConclusionOur data demonstrate that Pten is required for the long-term maintenance of SSCs and precise regulation of spermatogenesis in mouse. The finding of a Pten-regulated GFRα1+/PLZF−/UTF1+ progenitor population provides a new insight into the precise mechanisms controlling SSC fate.Electronic supplementary materialThe online version of this article (doi:10.1186/s13578-015-0034-x) contains supplementary material, which is available to authorized users.

The rLrp of Mycobacterium tuberculosis inhibits proinflammatory cytokine production and downregulates APC function in mouse macrophages via a TLR2-mediated PI3K/Akt pathway activation-dependent mechanism.

We demonstrate that Mycobacterium tuberculosis recombinant leucine-responsive regulatory protein (rLrp) inhibits lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-α), interleukin-6, and interleukin-12 production and blocks the nuclear translocation of subunits of the nuclear-receptor transcription factor NF-κB (Nuclear factor-kappa B). Moreover, rLrp attenuated LPS-induced DNA binding and NF-κB transcriptional activity, which was accompanied by the degradation of inhibitory IκBα and a consequent decrease in the nuclear translocation of the NF-κB p65 subunit. RLrp interfered with the LPS-induced clustering of TNF receptor-associated factor 6 and with interleukin-1 receptor-associated kinase 1 binding to TAK1. Furthermore, rLrp did not attenuate proinflammatory cytokines or the expression of CD86 and major histocompatibility complex class-II induced by interferon-gamma in the macrophages of Toll-like receptor 2 deletion (TLR2-/-) mice and in protein kinase b (Akt)-depleted mouse cells, indicating that the inhibitory effects of rLrp were dependent on TLR2-mediated activation of the phosphatidylinositol 3-OH kinase (PI3K)/Akt pathway. RLrp could also activate the PI3K/Akt pathway by stimulating the rapid phosphorylation of PI3K, Akt, and glycogen synthase kinase 3 beta in macrophages. In addition, 19 amino acid residues in the N-terminus of rLrp were determined to be important and required for the inhibitory effects mediated by TLR2. The inhibitory function of these 19 amino acids of rLrp raises the possibility that mimetic inhibitory peptides could be used to restrict innate immune responses in situations in which prolonged TLR signaling has deleterious effects. Our study offers new insight into the inhibitory mechanisms by which the TLR2-mediated PI3K/Akt pathway ensures the transient expression of potent inflammatory mediators.

Functional compensation between Myc and PI3K signaling supports self-renewal of embryonic stem cells.

c-Myc and phosphatidylinositol 3-OH kinase (PI3K) both participate in diverse cellular processes, including cell cycle control and tumorigenic transformation. They also contribute to preserving embryonic stem cell (ESC) characteristics. However, in spite of the vast knowledge, the molecular relationship between c-Myc and PI3K in ESCs is not known. Herein, we demonstrate that c-Myc and PI3K function cooperatively but independently to support ESC self-renewal when murine ESCs are cultured under conventional culture condition. Interestingly, culture of ESCs in 2i-condition including a GSK3β and MEK inhibitor renders both PI3K and Myc signaling dispensable for the maintenance of pluripotent properties. These results suggest that the requirement for an oncogenic proliferation-dependent mechanism sustained by Myc and PI3K is context dependent and that the 2i-condition liberates ESCs from the dependence of this mechanism.