RESUMEN
Peroxisome proliferator-activated receptors α (PPARα) are members of the nuclear receptors family and a very potent transcription factor engaged in the regulation of lipid and energy metabolism. Recent data suggest that PPARα could play an important role in the pathomechanism of Alzheimer's disease (AD) and other neuropsychiatric disorders. This study focused on the effect of a synthetic ligand of PPARα, GW7647 on the transcription of genes encoding proteins of mitochondria biogenesis and dynamics in the brain of AD mice. The experiments were carried out using 12-month-old female FVB-Tg mice with the V717I mutation of amyloid precursor protein (APP + ) and mice without the transgene (APP - ). Moreover, APP + and APP - mice were treated for 14 days with GW7647 administered subcutaneously with a dose 5 mg/kg b.w. Brain cortex was used and qRT-PCR was performed. Our data indicated that GW7647 upregulated the expression of genes encoding proteins of mitochondria biogenesis in ADTg mice. GW7647 enhanced the level of mRNA of Ppargc1, Nrf2 and Tfam in APP + as compared to APP - mice treated with GW7647. Moreover, our studies demonstrated that GW7647 had no effect on genes that regulate mitochondria fission and fusion of ADTg mice as correlated to mice without the transgene. Our results indicate that the ligand of PPARα, GW7647 may exert a promising neuroprotective effect through the regulation of transcription of genes coding proteins of mitochondria biogenesis. These data suggest that activation of PPARα at an early stage of AD could be a helpful strategy for slowing the progression of neurodegeneration.
Asunto(s)
Enfermedad de Alzheimer , Femenino , Animales , Ratones , Enfermedad de Alzheimer/genética , PPAR alfa/genética , Ligandos , Modelos Animales , MitocondriasRESUMEN
Peroxisome proliferator-activated receptor α (PPARα) is a transcriptional regulator of lipid metabolism. GW7647 is a potent PPARα agonist that must reach the nucleus to activate this receptor. In cells expressing human fatty acid-binding protein 1 (FABP1), GW7647 treatment increases FABP1's nuclear localization and potentiates GW7647-mediated PPARα activation; GW7647 is less effective in cells that do not express FABP1. To elucidate the underlying mechanism, here we substituted residues in FABP1 known to dictate lipid signaling by other intracellular lipid-binding proteins. Substitutions of Lys-20 and Lys-31 to Ala in the FABP1 helical cap affected neither its nuclear localization nor PPARα activation. In contrast, Ala substitution of Lys-57, Glu-77, and Lys-96, located in the loops adjacent to the ligand-binding portal region, abolished both FABP1 nuclear localization and GW7647-induced PPARα activation but had little effect on GW7647-FABP1 binding affinity. Using solution NMR spectroscopy, we determined the WT FABP1 structure and analyzed the dynamics in the apo and GW7647-bound structures of both the WT and the K57A/E77A/K96A triple mutant. We found that GW7647 binding causes little change in the FABP1 backbone, but solvent exposes several residues in the loops around the portal region, including Lys-57, Glu-77, and Lys-96. These residues also become more solvent-exposed upon binding of FABP1 with the endogenous PPARα agonist oleic acid. Together with previous observations, our findings suggest that GW7647 binding stabilizes a FABP1 conformation that promotes its interaction with PPARα. We conclude that full PPARα agonist activity of GW7647 requires FABP1-dependent transport and nuclear localization processes.
Asunto(s)
Butiratos/farmacología , Proteínas de Unión a Ácidos Grasos/química , Proteínas de Unión a Ácidos Grasos/metabolismo , PPAR alfa/agonistas , Compuestos de Fenilurea/farmacología , Butiratos/metabolismo , Proteínas de Unión a Ácidos Grasos/genética , Humanos , Ligandos , Modelos Moleculares , Mutación , Compuestos de Fenilurea/metabolismo , Conformación Proteica/efectos de los fármacosRESUMEN
Alzheimer's disease is a neuroinflammatory disease and is the most common cause of dementia in the elderly. Studies have shown the beneficial effects of the peroxisome proliferator-activated receptor alpha (PPAR-α) agonists on the treatment of neuroinflammatory diseases. The aim of the present study is to examine the ability of GW7647 (a PPAR-α agonist) to regulate amyloid precursor protein (APP) amyloidogenic processing in human neuroblastoma SH-SY5Y cells transfected with APPswe gene. After administration of GW7647 for 24 h, the levels of APP, soluble APPß (sAPPß), and presenilin 1 (PS-1) were assessed by Western blot. Cellular culture medium levels of amyloid-ß 42 (Aß42) were analyzed by ELISA, and the activity of beta-site APP cleaving enzyme 1 (BACE-1) was measured by fluorometric assay. We found that GW7647 decreased the expression of sAPPß and the activity of BACE-1, and also reduced Aß42 release. However, GW7647 did not modify the levels of APP and PS-1. Furthermore, LY294002, the phosphoinositide 3-kinase (PI3-K) inhibitor, reversed the effects of GW7647 on the BACE-1 activity and the levels of sAPPß and Aß42. Our data demonstrate that GW7647 may reduce Aß production via inhibiting BACE-1 activity, and this may involve in PI3-K pathway.
Asunto(s)
Secretasas de la Proteína Precursora del Amiloide/metabolismo , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Ácido Aspártico Endopeptidasas/metabolismo , Butiratos/farmacología , Neuroblastoma/metabolismo , PPAR alfa/agonistas , Fragmentos de Péptidos/metabolismo , Compuestos de Fenilurea/farmacología , Precursor de Proteína beta-Amiloide/metabolismo , Línea Celular Tumoral , Humanos , Presenilina-1/metabolismo , Transducción de Señal/efectos de los fármacos , TransfecciónRESUMEN
BACKGROUND AND PURPOSE: The nuclear hormone receptor, PPARα, and its endogenous ligands, are involved in pain modulation. PPARα is expressed in the medial prefrontal cortex (mPFC), a key brain region involved in both the cognitive-affective component of pain and in descending modulation of pain. However, the role of PPARα in the mPFC in pain responding has not been investigated. Here, we investigated the effects of pharmacological modulation of PPARα in the rat mPFC on formalin-evoked nociceptive behaviour and the impact of formalin-induced nociception on components of PPARα signalling in the mPFC. EXPERIMENTAL APPROACH: The effects of intra-mPFC microinjection of a PPARα agonist (GW7647) or a PPARα antagonist (GW6471) on formalin-evoked nociceptive behaviour in rats were studied. Quantitative real-time PCR and LC-MS/MS were used to study the effects of intraplantar injection of formalin on PPARα mRNA expression and levels of endogenous ligands, respectively, in the mPFC. KEY RESULTS: Intra-mPFC administration of GW6471, but not GW7647, resulted in delayed onset of the early second phase of formalin-evoked nociceptive behaviour. Furthermore, formalin-evoked nociceptive behaviour was associated with significant reductions in mPFC levels of endogenous PPARα ligands (N-palmitoylethanolamide and N-oleoylethanolamide) and a 70% reduction in PPARα mRNA but not protein expression. CONCLUSIONS AND IMPLICATIONS: These data suggest that endogenous ligands may act at PPARα in the mPFC to play a facilitatory/permissive role in second phase formalin-evoked nociceptive behaviour in rats. LINKED ARTICLES: This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6.