The peroxisome proliferator-activated receptors (PPARs) are a family of transcription factors belonging to the nuclear receptor superfamily. Until recently, the genes regulated by PPARs were those believed to be predominantly associated with lipid metabolism. Recently, an immunomodulatory role for PPARγ has been described in cells critical to the innate immune system, the monocyte/macrophage. In addition, evidence for an antiinflammatory role of the PPARγ ligand, 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2) has been found. In the present studies, we demonstrate, for the first time, that murine helper T cell clones and freshly isolated splenocytes express PPARγ 1. The PPARγ expressed is of functional significance in that two ligands for PPARγ, 15d-PGJ2 and a thiazolidinedione, ciglitazone, mediate significant inhibition of proliferative responses of both the T cell clones and the freshly isolated splenocytes. This inhibition is mediated directly at the level of the T cell and not at the level of the macrophage/APC. Finally, we demonstrate that the two ligands for PPARγ mediate inhibition of IL-2 secretion by the T cell clones while not inhibiting IL-2-induced proliferation of such clones. The demonstration of the expression and function of PPARγ in T cells reveals a new level of immunoregulatory control for PPARs and significantly increases the role and importance of PPARγ in immunoregulation.

FTY720, a potent immunosuppressive agent, is phosphorylated in vivo into FTY720-P, a high affinity agonist for sphingosine 1-phosphate (S1P) receptors. The effects of FTY720 on vascular cells, a major target of S1P action, have not been addressed. We now report the metabolic activation of FTY720 by sphingosine kinase-2 and potent activation of vascular endothelial cell functions in vitro and in vivo by phosphorylated FTY720 (FTY720-P). Incubation of endothelial cells with FTY720 resulted in phosphorylation by sphingosine kinase activity and formation of FTY720-P. Sphingosine kinase-2 effectively phosphorylated FTY720 in the human embryonic kidney 293T heterologous expression system. FTY720-P treatment of endothelial cells stimulated extracellular signal-activated kinase and Akt phosphorylation and adherens junction assembly and promoted cell survival. The effects of FTY720-P were inhibited by pertussis toxin, suggesting the requirement for G i -coupled S1P receptors. Indeed, transmonolayer permeability induced by vascular endothelial cell growth factor was potently reversed by FTY720-P. Furthermore, oral FTY720 administration in mice potently blocked VEGF-induced vascular permeability in vivo. These findings suggest that FTY720 or its analogs may find utility in the therapeutic regulation of vascular permeability, an important process in angiogenesis, inflammation, and pathological conditions such as sepsis, hypoxia, and solid tumor growth.

Conventional kinesin is a major microtubule-based motor protein responsible for anterograde transport of various membrane-bounded organelles (MBO) along axons. Structurally, this molecular motor protein is a tetrameric complex composed of two heavy (kinesin-1) chains and two light chain (KLC) subunits. The products of three kinesin-1 (kinesin-1A, -1B, and -1C, formerly KIF5A, -B, and -C) and two KLC (KLC1, KLC2) genes are expressed in mammalian nervous tissue, but the functional significance of this subunit heterogeneity remains unknown. In this work, we examine all possible combinations among conventional kinesin subunits in brain tissue. In sharp contrast with previous reports, immunoprecipitation experiments here demonstrate that conventional kinesin holoenzymes are formed of kinesin-1 homodimers. Similar experiments confirmed previous findings of KLC homodimerization. Additionally, no specificity was found in the interaction between kinesin-1s and KLCs, suggesting the existence of six variant forms of conventional kinesin, as defined by their gene product composition. Subcellular fractionation studies indicate that such variants associate with biochemically different MBOs and further suggest a role of kinesin-1s in the targeting of conventional kinesin holoenzymes to specific MBO cargoes. Taken together, our data address the combination of subunits that characterize endogenous conventional kinesin. Findings on the composition and subunit organization of conventional kinesin as described here provide a molecular basis for the regulation of axonal transport and delivery of selected MBOs to discrete subcellular locations.Molecular motors of the kinesin and dynein superfamilies are responsible for microtubule-(MT-) based motility in cells. Approximately 40−45 kinesin-related polypeptides have been identified in mouse and human (1), with 25 or more being expressed in the developing nervous system (2). From these, conventional kinesin is the most abundant kinesin family member in the adult nervous system (3). Biochemical (4) and electron microscopic studies (5) indicated that the native conventional kinesin holoenzyme exists as a tetramer consisting of two kinesin light chain (KLCs) 1 and two kinesin heavy chain (kinesin-1, KHC, KIF5s) subunits (6). † This work was supported by grants from the Huntington's Disease Society of America (HDSA) and ALSA (to G.M.), grants from NINDS (NS23868, NS23320, NS41170 and NS43408), MDA, and ALSA (to S.T.B.), and the Fitz-Thyssen Foundation and DFG (to S.K.).* To whom correspondence should be addressed. Phone: (312) 996−6791. Fax: (312) 413−0354. E-mail: gmorfini@uic.edu.. ‡ These authors contributed equally to this paper. § University of Illinois at Chicago. ∥ University of Heidelberg.1 Abbreviations: KHC, kinesin heavy chain; KLC, kinesin light chain; TR, tandem repeats; PIPES, 1,4-piperazinediethanesulfonic acid; HEPES, N-(2-hydroxyethyl)piperazine-N′-2-ethanesulfonic acid; AMP-PNP, adenosine 5′-(β,γ-imino)triphosphate; GST, glutathione Stransferase; SDS-PAGE, sodium d...

Alzheimer's disease (AD) is pathologically characterized by tau-laden neurofibrillary tangles and ␤-amyloid deposits. Dysregulation of cholinergic neurotransmission has been implicated in AD pathogenesis, contributing to the associated memory impairments; yet, the exact mechanisms remain to be defined. Activating the muscarinic acetylcholine M 1 receptors (M 1 Rs) reduces AD-like pathological features and enhances cognition in AD transgenic models. To elucidate the molecular mechanisms by which M 1 Rs affect AD pathophysiological features, we crossed the 3xTgAD and transgenic mice expressing human Swedish, Dutch, and Iowa triple-mutant amyloid precursor protein (Tg-SwDI), two widely used animal models, with the M 1 R ؊/؊ mice. Our data show that M 1 R deletion in the 3xTgAD and Tg-SwDI mice exacerbates the cognitive impairment through mechanisms dependent on the transcriptional dysregulation of genes required for memory and through acceleration of AD-related synaptotoxicity. Ablating the M 1 R increased plaque and tangle levels in the brains of 3xTgAD mice and elevated cerebrovascular deposition of fibrillar A␤ in Tg-SwDI mice. Notably, tau hyperphosphorylation and potentiation of amyloidogenic processing in the mice with AD lacking M 1 R were attributed to changes in the glycogen synthase kinase 3␤ and protein kinase C activities. Alzheimer's disease (AD) is a progressive neurodegenerative disorder that leads to cognitive impairment and dementia. The neuropathological hallmarks of AD are amyloid plaques, composed of ␤-amyloid (A␤) peptides, and neurofibrillary tangles, composed of the hyperphosphorylated tau protein. The deposition of fibrillar A␤ in the cerebrovasculature, a condition known as cerebral amyloid angiopathy (CAA), is also a prominent feature of AD. Together with associated processes, such as inflammation and oxidative stress, these pathological cascades contribute to loss of synaptic integrity and progressive neurodegeneration. 1Restoring cholinergic dysfunction has been a primary means of improving the cognitive decline in AD because four of the five Food and Drug Administration-approved drugs are acetylcholinesterase inhibitors, with the notable exception of memantine.2 Acetylcholinesterase inhibitors provide mild symptomatic relief but eventually lose efficacy over time, most likely because they are not disease-modifying agents.1 Alternatively, recent evidence 3,4 indicates that stimulation of muscarinic acetylcholine receptors, in particular the M 1 receptor (M 1 R), restores cognition and attenuates AD-like pathological features in several different animal models, rendering it an attractive therapeutic approach for AD. The M 1 R is the most abundant muscarinic acetylcholine receptor subtype in the cerebral cortex and hippocampus, the two main brain reSupported by grants from the NIH (NIH/NIAMS K99AR054695 to M.K.; NIH/NIA R01AG20335 and Program Project AG00538 to F.M.L.).