Background Asthma in the mouse model spontaneously resolves after cessation of allergen exposure. We developed a mouse model where asthma features persisted for 6 months after cessation of allergen exposure. Objective To elucidate factors contributing to the persistence of asthma. Methods We utilized a combination of immunologic, genetic, microarray and pharmacologic approaches to dissect the mechanism of persistence of asthma. Results Elimination of T cells though antibody-mediated depletion or lethal irradiation and transplantation of Rag1−/− bone marrow in mice with chronic asthma resulted in resolution of airway inflammation but not airway hyperreactivity or remodeling. Elimination of T cells and ILC2 through lethal irradiation and transplantation of Rag2−/−γc−/− bone marrow or blockade of IL33 resulted in resolution of airway inflammation and hyperreactivity. Persistence of asthma required multiple interconnected feedback and feed forward circuits between ILC2 and epithelial cells. Epithelial IL33 induced ILC2, a rich source of IL13. The latter directly induced epithelial IL33 establishing a positive feedback circuit. IL33 auto-induced, generating another feedback circuit. IL13 upregulated IL33 receptors and facilitated IL33 auto-induction, thus establishing a feed forward circuit. Elimination of any component of these circuits resulted in resolution of chronic asthma. In agreement with the foregoing, IL33 and ILC2 were increased in the airways from asthmatic patients. IL33 correlated with disease severity. Conclusions We present a critical network of feedback and feed forward interactions between epithelial cells and ILC2 involved in maintaining chronic asthma. Although T cells contributed to the severity of chronic asthma they were redundant in maintaining airway hyperreactivity and remodeling.

Summary The mammalian target of rapamycin (mTOR) is a key regulator of cell growth and metabolism. It associates with multiple proteins and forms two distinct signaling complexes, mTORC1 and mTORC2. Accumulating evidence has revealed critical roles for intact mTOR signaling during T cell activation and responses to microbial infection. However, the importance of mTOR regulation in T cells has yet to be explored. The TSC1/TSC2 complex has been shown to inhibit mTORC1 signaling in cell line models. We show here that deletion of TSC1 in the murine T cell lineage resulted in a dramatic reduction of the peripheral T cell pool, correlating with increased cell death. While mTORC1 is constitutively activated, mTORC2 signaling, reflected by Akt phosphorylation and activity, is decreased in TSC1-deficient T cells. Furthermore, TSC1-deficient T cells contain elevated reactive oxygen species and exhibit decreased mitochondrial content and membrane potential, which is correlated with the activation of the intrinsic death pathway. Together, our results demonstrate that TSC1 differentially regulates mTORC1 and mTORC2 activity, promotes T cell survival, and is critical for normal mitochondrial homeostasis in T cells.

The engagement of TCR induces T-cell activation, which initiates multiple characteristic changes such as increase in cell size, cell division, and the production of cytokines and other effector molecules. The mammalian target of rapamycin (mTOR) regulates protein synthesis, transcription, cell survival, and autophagy. Critical roles of mTOR in T-cell activation and effector/memory differentiation have been revealed using chemical inhibitors or by genetic ablation of mTOR in T cells. However, the connection between mTOR signaling and other signaling cascades downstream of TCR is unclear. We demonstrate that diacylglycerol (DAG) and TCR engagement activate signaling in both mTOR complexes 1 and 2 through the activation of the Ras-mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 (Mek1/2)-extracellular signal-regulated kinase 1/2 (Erk1/2)-activator protein 1 (AP-1), known collectively as the Ras-Mek1/2-Erk1/2-AP-1 pathway. Deficiency of RasGRP1 or inhibition of Mek1/2 activity drastically decreases TCR-induced mTOR activation, whereas constitutively active Ras or Mek1 promotes mTOR activation. Although constitutively active Akt promotes TCR-induced mTOR activation, such activation is attenuated by Mek1/2 inhibition. We demonstrated further that DAG kinases (DGKs) α and ζ, which terminate DAG-mediated signaling, synergistically inhibit TCR-induced mTOR activation by inhibiting the Ras-Mek1/2-Erk/12 pathway. These observations provide novel insights into the regulation of mTOR activation.

Phosphorylation of the dopamine transporter (DAT) on N-terminal serines and unidentified threonines occurs concomitantly with PKC-and substrate-induced alterations in transporter activity, subcellular distribution, and dopamine efflux, but the residues phosphorylated and identities of protein kinases and phosphatases involved are not known. As one approach to investigating these issues we recombinantly expressed the N-terminal tail of rat DAT (NDAT) and examined its phosphorylation and dephosphorylation properties in vitro. We found that NDAT could be phosphorylated to significant levels by PKCα, PKA, PKG, and CaMKII, which catalyzed serine phosphorylation, and ERK1, JNK, and p38, which catalyzed threonine phosphorylation. We identified Thr53, present in a membrane proximal proline-directed kinase motif as the NDAT site phosphorylated in vitro by ERK1, JNK and p38, and confirmed by peptide mapping and mutagenesis that Thr53 is phosphorylated in vivo. Dephosphorylation studies showed that protein phosphatase 1 catalyzed near-complete in vitro dephosphorylation of PKCα-phosphorylated NDAT, similar to its in vivo and in vitro effects on native DAT. These findings demonstrate the ability of multiple enzymes to directly recognize the DAT N-terminal domain and for kinases to act at multiple distinct sites. The strong correspondence between NDAT and rDAT phosphorylation characteristics suggests the potential for the enzymes that are active on NDAT in vitro to act on DAT in vivo and indicates the usefulness of NDAT for guiding future DAT phosphorylation analyses.The dopamine transporter (DAT) is a plasma membrane phosphoprotein expressed in dopaminergic neurons that clears synaptic dopamine (DA) by Na + -Cl − dependent reuptake. This activity controls the availability of extracellular DA for binding to receptors and thus regulates the dynamics of dopaminergic neurotransmission (1). Processes controlled by DA include motor activity, emotion, and reward, and agents such as cocaine that inhibit DAT cause elevations in DA levels that lead to motor stimulation and addiction (2). DA levels are also increased by amphetamine (AMPH) and methamphetamine (METH), which are carried by DAT and induce DA efflux by the process of reverse transport (3,4). It is thought that dopaminergic disorders such as depression, schizophrenia, ADHD and Parkinson's disease may be linked to dysregulation of DAT activity and resulting imbalances in DA clearance (5-9).Various properties of DAT are acutely regulated by protein kinases, protein phosphatases, and substrate pretreatments (10-12), indicating the ability of DAT to rapidly respond to physiological demands. Regulation of DA transport occurs in response to modulation of protein kinase C (PKC), extracellular-signal regulated protein kinase (ERK), protein kinase B (Akt), and protein phosphatases 1 and 2A (PP1/2A) (13)(14)(15)(16), and PKC activity is required for substrate induced transport down-regulation (17)(18)(19). Kinase-and substrate-induced DA transport down- NIH Public Access Aut...

Lung cancer is the leading cause of cancer-related deaths worldwide, and lung squamous carcinomas (LUSC) represent about 30% of cases. Molecular aberrations in lung adenocarcinomas have allowed for effective targeted treatments, but corresponding therapeutic advances in LUSC have not materialized. However, immune checkpoint inhibitors in sub-populations of LUSC patients have led to exciting responses. Using computational analyses of The Cancer Genome Atlas, we identified a subset of LUSC tumors characterized by dense infiltration of inflammatory monocytes (IMs) and poor survival. With novel, immunocompetent metastasis models, we demonstrated that tumor cell derived CCL2-mediated recruitment of IMs is necessary and sufficient for LUSC metastasis. Pharmacologic inhibition of IM recruitment had substantial anti-metastatic effects. Notably, we show that IMs highly express Factor XIIIA, which promotes fibrin cross-linking to create a scaffold for LUSC cell invasion and metastases. Consistently, human LUSC samples containing extensive cross-linked fibrin in the microenvironment correlated with poor survival.