Vav1 Promotes T Cell Cycle Progression by Linking TCR/CD28 Costimulation to FOXO1 and p27kip1 Expression

Psoriasis is a chronic inflammatory skin disease. Recently, lysophosphatidic acid (LPA)/LPAR5 signaling has been reported to be involved in both NLRP3 inflammasome activation in macrophages and keratinocyte activation to produce inflammatory cytokines, contributing to psoriasis pathogenesis. However, the effect and molecular mechanisms of LPA/LPAR signaling in keratinocyte proliferation in psoriasis remain unclear. In this study, we investigated the effects of LPAR1/3 inhibition on imiquimod (IMQ)-induced psoriasis-like mice. Treatment with the LPAR1/3 antagonist, ki16425, alleviated skin symptoms in IMQ-induced psoriasis-like mouse models and decreased keratinocyte proliferation in the lesion. It also decreased LPA-induced cell proliferation and cell cycle progression via increased cyclin A2, cyclin D1, cyclin-dependent kinase (CDK)2, and CDK4 expression and decreased p27Kip1 expression in HaCaT cells. LPAR1 knockdown in HaCaT cells reduced LPA-induced proliferation, suppressed cyclin A2 and CDK2 expression, and restored p27Kip1 expression. LPA increased Rho-associated protein kinase 2 (ROCK2) expression and PI3K/AKT activation; moreover, the pharmacological inhibition of ROCK2 and PI3K/AKT signaling suppressed LPA-induced cell cycle progression. In conclusion, we demonstrated that LPAR1/3 antagonist alleviates IMQ-induced psoriasis-like symptoms in mice, and in particular, LPAR1 signaling is involved in cell cycle progression via ROCK2/PI3K/AKT pathways in keratinocytes.

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Casitas B-Lineage Lymphoma b Inhibits Antigen Recognition and Slows Cell Cycle Progression at Late Times during CD4+ T Cell Clonal Expansion

The Journal of Immunology ◽

10.4049/jimmunol.181.8.5331 ◽

2008 ◽

Vol 181 (8) ◽

pp. 5331-5339 ◽

Cited By ~ 13

Author(s):

Ruan Zhang ◽

Na Zhang ◽

Daniel L. Mueller

Keyword(s):

Cell Cycle ◽

T Cell ◽

Cell Cycle Progression ◽

Clonal Expansion ◽

Antigen Recognition ◽

Cd4 T Cell ◽

Cycle Progression ◽

B Lineage ◽

Cell Clonal Expansion

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Interleukin-7 promotes survival and cell cycle progression of T-cell acute lymphoblastic leukemia cells by down-regulating the cyclin-dependent kinase inhibitor p27kip1

Blood ◽

10.1182/blood.v98.5.1524 ◽

2001 ◽

Vol 98 (5) ◽

pp. 1524-1531 ◽

Cited By ~ 115

Author(s):

Joao T. Barata ◽

Angelo A. Cardoso ◽

Lee M. Nadler ◽

Vassiliki A. Boussiotis

Keyword(s):

Cell Cycle ◽

T Cell ◽

Cell Cycle Progression ◽

Lymphoblastic Leukemia ◽

Cyclin Dependent Kinase ◽

Malignant Cells ◽

Cycle Progression ◽

Interleukin 7 ◽

Cell Acute Lymphoblastic Leukemia ◽

Immature Thymocytes

In normal T-cell development interleukin-7 (IL-7) functions as an antiapoptotic factor by regulating bcl-2 expression in immature thymocytes and mature T cells. Similar to what occurs in normal immature thymocytes, prevention of spontaneous apoptosis by IL-7 in precursor T-cell acute lymphoblastic leukemia (T-ALL) cells correlates with up-regulation of bcl-2. IL-7 is also implicated in leukemogenesis because IL-7 transgenic mice develop lymphoid malignancies, suggesting that IL-7 may regulate the generation and expansion of malignant cells. This study shows that in the presence of IL-7, T-ALL cells not only up-regulated bcl-2 expression and escaped apoptosis but also progressed in the cell cycle, resulting in sequential induction of cyclin D2 and cyclin A. Down-regulation of p27kip1 was mandatory for IL-7–mediated cell cycle progression and temporally coincided with activation of cyclin-dependent kinase (cdk)4 and cdk2 and hyperphosphorylation of Rb. Strikingly, forced expression of p27kip1 in T-ALL cells not only prevented cell cycle progression but also reversed IL-7–mediated up-regulation of bcl-2 and promotion of viability. These results show for the first time that a causative link between IL-7–mediated proliferation and p27kip1 down-regulation exists in malignant T cells. Moreover, these results suggest that p27kip1 may function as a tumor suppressor gene not only because it is a negative regulator of cell cycle progression but also because it is associated with induction of apoptosis of primary malignant cells.

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HCV core/gC1qR interaction arrests T cell cycle progression through stabilization of the cell cycle inhibitor p27Kip1

Virology ◽

10.1016/s0042-6822(03)00419-7 ◽

2003 ◽

Vol 314 (1) ◽

pp. 271-282 ◽

Cited By ~ 40

Author(s):

Zhi Qiang Yao ◽

Audrey Eisen-Vandervelde ◽

Suma Ray ◽

Young S Hahn

Keyword(s):

Cell Cycle ◽

T Cell ◽

Cell Cycle Progression ◽

Cycle Progression ◽

Cell Cycle Inhibitor

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PI3K/Akt/FOXO3a Pathway Contributes to Thrombopoietin-Induced Proliferation of Primary Megakaryocytes In Vitro and In Vivo Via Modulation of p27Kip1.

Blood ◽

10.1182/blood.v106.11.202.202 ◽

2005 ◽

Vol 106 (11) ◽

pp. 202-202

Author(s):

Takafumi Nakao ◽

Amy E Geddis ◽

Norma E. Fox ◽

Kenneth Kaushansky

Keyword(s):

Cell Cycle ◽

Cell Line ◽

Cell Cycle Progression ◽

Wild Type ◽

Cycle Progression ◽

P27kip1 Expression ◽

Cell Counts ◽

Deficient Mice

Abstract Thrombopoietin (TPO), the primary regulator of megakaryocyte (MK) and platelet formation, modulates the activity of multiple signal transduction molecules, including those in the Jak/STAT, p42/p44 MAPK, and phosphatidylinositol 3-kinase (PI3K)/Akt pathways. In the previous study, we reported that PI3K and Akt are necessary for TPO-induced cell cycle progression of primary MK progenitors. The absence of PI3K activity results in a block of transition from G1 to S phase in these cells (Geddis AE et al. JBC2001276:34473–34479). However, the molecular events secondary to the activation of PI3K/Akt responsible for MK proliferation remain unclear. In this study we show that FOXO3a and its downstream target p27Kip1 play an important role in TPO-induced proliferation of MK progenitors. TPO induces phosphorylation of Akt and FOXO3a in both UT-7/TPO, a megakaryocytic cell line, and primary murine MKs in a PI3K dependent fashion. Cell cycle progression of UT-7/TPO cells is blocked in G1 phase by inhibition of PI3K. We found that TPO down-modulates p27Kip1 expression at both the mRNA and protein levels in UT-7/TPO cells and primary MKs in a PI3K dependent fashion. UT-7/TPO stably expressing constitutively active Akt or a dominant-negative form of FOXO3a failed to induce p27Kip1 expression after TPO withdrawal. Induced expression of an active form of FOXO3a resulted in increased p27Kip1 expression in this cell line. In an attempt to assess whether FOXO3a has an effect of MK proliferation in vivo, we compared the number of MKs in Foxo3a-deficient mice and in wild type controls. Although peripheral blood cell counts of erythrocytes, neutrophils, monocytes and platelets were normal in the Foxo3a-deficient mice, total nucleated marrow cell count of Foxo3a-deficient mice were 60% increased compared with wild type controls. In addition, the increase of MKs was more profound than that of total nucleated marrow cells; CD41+ MKs from Foxo3a-deficient mice increased 2.1-fold, and mature MKs with 8N and greater ploidy increased 2.5-fold, compared with wild type controls. Taken together with the previous observation that p27Kip1-deficient mice also display increased numbers of MK progenitors, our findings strongly suggest that the effect of TPO on MK proliferation is mediated by PI3K/Akt-induced FOXO3a inactivation and subsequent p27Kip1 down-regulation in vitro and in vivo.

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OSI-027, a Dual TORC1/TORC2 Inhibitor, Induces Bim- and Puma-Mediated Apoptosis In Lymphoid Malignancy

Blood ◽

10.1182/blood.v116.21.970.970 ◽

2010 ◽

Vol 116 (21) ◽

pp. 970-970 ◽

Cited By ~ 1

Author(s):

Andrea E. Wahner Hendrickson ◽

Mamta Gupta ◽

Seongseok Yun ◽

Jennifer C. Shing ◽

Paula A. Schneider ◽

...

Keyword(s):

Cell Cycle ◽

T Cell ◽

Cell Cycle Progression ◽

Mitochondrial Pathway ◽

Lymphoid Cells ◽

Jurkat Cells ◽

Lymphoid Malignancy ◽

Cycle Progression ◽

Advisory Boards ◽

Wide Range

Abstract Abstract 970 The mammalian target of rapamycin, mTOR, is a highly conserved serine/threonine kinase known to play a role in regulating mRNA translation, cell cycle progression, cell proliferation and apoptosis. As a downstream effector of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway, mTOR is a component of two distinct complexes, TORC1 and TORC2. While TORC1 facilitates cell cycle progression from G1 into S phase by phosphorylating p70S6 kinase and eukaryotic initiation factor 4E binding protein 1 (4E-BP1), TORC2 catalyzes the activating phosphorylation of Akt on Ser473, providing a feedback loop for further activation of mTOR. Phase II trials have shown activity of the TORC1-selective inhibitor rapamycin and its analogs in a wide range of lymphoma subtypes. The purpose of this study was to evaluate the anti-proliferative and pro-apoptotic effects of the dual TORC1/TORC2 inhibitor OSI-027 in human neoplastic lymphoid cells in vitro. MTS assays demonstrated that OSI-027 inhibited proliferation in a wide range of lymphoid lines, including SeAx (Sezary syndrome), DoHH2 (large cell lymphoma), RL (follicular lymphoma) and Jurkat (T cell ALL), as well as clinical lymphoma and T cell ALL samples, with IC50 values ranging from 0.078 to 10 μM. Propidium iodide staining followed by flow cytometry for subdiploid cells revealed induction of apoptosis within 48 h of treatment with OSI-027 (but not rapamycin) in SeAx, DoHH2, and Jurkat cells. Examination of Jurkat variants with alterations in key proteins involved in the death receptor versus mitochondrial pathway revealed diminished apoptotic responses to OSI-027 when Bcl-2 was overexpressed or caspase 9 was silenced, indicating involvement of the mitochondrial pathway. Immunoblotting for Bcl-2 family members revealed upregulation of Bim and Puma after a 48-hour exposure to OSI-027 but not rapamycin. This upregulation was also seen at the mRNA level, with a 12- to 20-fold increase in Puma mRNA and 4- to 12-fold induction of Bim mRNA. Small interfering RNA (siRNA)-mediated knockdown of Bim and Puma significantly diminished the apoptotic response to OSI-027. Because the Foxo3a transcription factor has been implicated in Bim and Puma expression and is known to be activated when Akt is inhibited, we next examined whether Bim and Puma induction was Foxo3a-dependent. Luciferase reporter assays showed that OSI-027 activated the full-length Puma and Bim promoters and that this activation was diminished when the Foxo3a binding sites were deleted or mutated. In addition, OSI-027 induced nuclear translocation of Foxo3a, while Foxo3a siRNA diminished OSI-027-induced apoptosis in Jurkat cells. Collectively, these results indicate that OSI-027 inhibits proliferation and induces apoptosis in a wide range of neoplastic lymphoid cells through a process that involves Foxo3a-mediated upregulation of Bim and Puma. These results also suggest that dual inhibition of TORC1 and TORC2 may be an effective treatment strategy in lymphoid malignancy. Disclosures: Barr: OSI Pharmaceuticals: Employment. Witzig:Novartis and Celgene: Patents & Royalties, Research Funding, Served on advisory boards with Novartis and Celgene – both uncompensated with compensation to Mayo Clinic.

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PD-1 Signals Inhibit Cell Cycle Progression by Mediating Upregulation of Both KIP and INK Family of Cdk Inhibitors

Blood ◽

10.1182/blood.v116.21.585.585 ◽

2010 ◽

Vol 116 (21) ◽

pp. 585-585

Author(s):

Julia Brown ◽

Nikolaos Patsoukis ◽

Vassiliki A Boussiotis

Keyword(s):

Cell Cycle ◽

T Cells ◽

T Cell ◽

Cd4 T Cells ◽

Cell Cycle Progression ◽

S Phase ◽

Cdk Inhibitors ◽

Cycle Progression ◽

Smad3 Phosphorylation ◽

Cells Cultured

Abstract Abstract 585 The PD-1 pathway plays a critical role in the inhibition of T cell activation and the maintenance of T cell tolerance. PD-1 is expressed on activated T cells and limits T cell clonal expansion and effector function upon engagement with its ligands PD-L1 and PD-L2. PD-1 signals are vital for inhibition of autoimmunity whereas PD-1 ligation by PD-L1 and PD-L2 expressed on malignant cells has a detrimental effect on tumor-specific immunity. Furthermore, PD-1 signals result in T cell exhaustion in several chronic viral infections. The mechanism via which PD-1 signals mediate inhibition of T cell expansion is currently poorly understood. Here, we sought to determine the effects of PD-1 signals on mechanistic regulation of cell cycle progression mediated via TCR/CD3 and CD28 in primary human CD4+ T cells using anti-CD3/CD28 with or without agonist anti-PD-1 mAb conjugated to magnetic beads. Cell cycle analysis by ethynyl-deoxyuridine incorporation revealed that PD-1 induced blockade of cell cycle progression at the early G1 phase. To determine the molecular mechanisms underlying the blocked cell cycle progression we examined the expression and activation of cyclins and cdks and the regulation of cdk inhibitors that counterbalance the enzymatic activation of cyclin/cdk holoenzyme complexes. Our studies revealed that PD-1 mediated signals inhibited upregulation of Skp2, the SCF ubiquitin ligase that leads p27kip1 cdk inhibitor to ubiquitin-dependent degradation, and resulted in accumulation of p27kip1. Expression of cyclin E that is induced at the G1/S phase transition, and cyclin A that is synthesized during the S phase of the cell cycle, was dramatically reduced in the presence of PD-1 signaling. Strikingly, although expression of cdk4 and cdk2 was comparable between cells cultured in the presence or in the absence of PD-1, cdk2 enzymatic activation was significantly reduced in the presence of PD-1 signaling. Smad3 is a novel critical cdk substrate. Maximum cdk-mediated Smad3 phosphorylation occurs at the G1/S phase junction and requires activation of cdk2. Phosphorylation by cdk antagonizes TGF-β-induced transcriptional activity and antiproliferative function of Smad3 whereas impaired phosphorylation on the cdk-specific sites renders Smad3 more effective in executing its antiproliferative function. Based on those findings, we examined the effects of PD-1 signaling on Smad3 phosphorylation on cdk-specific and TGF-β-specific sites using site-specific phospho-Smad3 antibodies. Compared to anti-CD3/CD28 alone, culture in the presence of PD-1 induced impaired cdk2 activity, reduced levels of Smad3 phosphorylation on the cdk-specific sites and increased Smad3 phophorylation on the TGF-b-specific site. To determine whether the differential phosphorylation of Smad3 might differentially regulate Smad3 transcriptional activity in CD4+ T cells cultured in the presence versus the absence of PD-1, we examined expression of the INK family cdk4/6 inhibitor p15, a known downstream transcriptional target of Smad3. Expression of p15 was upregulated in CD4+ T cells cultured in the presence of PD-1 but not in cells cultured in the presence of CD3/CD28-coated beads alone. These results indicate that PD-1 signals inhibit cell cycle progression by mediating upregulation of both KIP and INK family of cdk inhibitors and Smad3 is a critical component of this mechanism, regulating blockade at the early G1 phase. Disclosures: No relevant conflicts of interest to declare.

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