RESUMO
The expression and function of some xenobiotic transporters varies according to the time of day, causing the dosing time-dependent changes in drug disposition and toxicity. Multidrug resistance-associated protein-4 (MRP4), an ATP-binding cassette (ABC) efflux transporter encoded by the Abcc4 gene, is highly expressed in bone marrow cells (BMCs) and protects them against xenobiotics, including chemotherapeutic drugs. In this study, we demonstrated that MRP4 was responsible for the extrusion of oxaliplatin (L-OHP), a platinum (Pt)-based chemotherapeutic drug, from BMCs of mice, and that the efflux transporter expression exhibited significant diurnal variation. Therefore, we investigated the relevance of the diurnal expression of MRP4 in BMCs for L-OHP-induced myelotoxicity in mice maintained under standardized light/dark cycle conditions. After intravenous injection of L-OHP, the Pt content in BMCs varied according to the injection time. Lower Pt accumulation in BMCs was detected in mice after injection of L-OHP at the mid-dark phase, during which the expression levels of MRP4 increased. Consistent with these observations, the myelotoxic effects of L-OHP were attenuated when mice were injected with L-OHP during the dark phase. This dosing schedule also alleviated the L-OHP-induced reduction of the peripheral white blood cell count. The present results suggest that the myelotoxicity of L-OHP is attenuated by optimizing the dosing schedule. Diurnal expression of MRP4 in BMCs is associated with the dosing time-dependent changes in L-OHP-induced myelotoxicity.
Assuntos
Ritmo Circadiano/genética , Regulação Neoplásica da Expressão Gênica/genética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Antineoplásicos/farmacologia , Células da Medula Óssea/metabolismo , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Expressão Gênica/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos ICR , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Compostos Organoplatínicos/farmacologia , Oxaliplatina/farmacologiaRESUMO
A number of diverse cell-surface proteins are anchored to the cytoskeleton via scaffold proteins. Na+/H+ exchanger regulatory factor-1 (NHERF1), encoded by the Slc9a3r1 gene, functions as a scaffold protein, which is implicated in the regulation of membrane expression of various cell-surface proteins. Here, we demonstrate that the circadian clock component PERIOD2 (PER2) modulates transcription of the mouse Slc9a3r1 gene, generating diurnal accumulation of NHERF1 in the mouse liver. Basal expression of Slc9a3r1 was dependent on transcriptional activation by p65/p50. PER2 bound to p65 protein and prevented p65/p50-mediated transactivation of Slc9a3r1. The time-dependent interaction between PER2 and p65 underlay diurnal oscillation in the hepatic expression of Slc9a3r1/NHERF1. The results of immunoprecipitation experiments and liquid chromatography-mass spectrometry analysis of mouse liver revealed that NHERF1 time-dependently interacted with fatty acid transport protein-5 (FATP5). Temporary accumulation of NHERF1 protein stabilized plasmalemmal localization of FATP5, thereby enhancing hepatic uptake of fatty acids at certain times of the day. Our results suggest an unacknowledged role for PER2 in regulating the diurnal expression of NHERF1 in mouse liver. This machinery also contributed to diurnal changes in the ability of hepatic cells to uptake fatty acids.
Assuntos
Relógios Circadianos/genética , Ritmo Circadiano/genética , Proteínas Circadianas Period/genética , Fosfoproteínas/genética , Trocadores de Sódio-Hidrogênio/genética , Animais , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Células Cultivadas , Proteínas de Transporte de Ácido Graxo/genética , Proteínas de Transporte de Ácido Graxo/metabolismo , Regulação da Expressão Gênica , Fígado/citologia , Fígado/metabolismo , Camundongos , Camundongos Knockout , Células NIH 3T3 , Proteínas Circadianas Period/metabolismo , Fosfoproteínas/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismoRESUMO
Cisplatin, cis-diamminedichloro-platinum (CDDP), is a widely used anticancer agent, the clinical applications of which have been limited by severe nephrotoxicity. Although dosing time-dependent differences in CDDP-induced nephrotoxicity have been reported in both humans and laboratory animals, the underlying mechanism remains unknown. In the present study, we investigated the molecular mechanism for the dosing-time dependency of the nephrotoxic effect of CDDP in mice. CDDP-induced nephrotoxicity was significantly attenuated by injecting CDDP at times of the day when its renal clearance was enhanced. The dosing-time dependency of the nephrotoxic effect was parallel to that of CDDP incorporation into renal DNA. Two types of transporters, organic cation transporter 2 (OCT2, encoded by Slc22a2) and multidrug and toxin extrusion 1 (MATE1, encoded by Slc47a1), are responsible for the renal excretion of CDDP. The expression of OCT2, but not MATE1, exhibited a significant time-dependent oscillation in the kidneys of mice. The circadian expression of OCT2 was closely related to the dosing-time dependency of CDDP incorporation into renal DNA. Molecular components of the circadian clock regulated the renal expression of Slc22a2 mRNA by mediating peroxisome proliferator-activated receptor-α, which resulted in rhythmic oscillations in OCT2 protein levels. These findings indicate a clock-regulated mechanism of dosing time-dependent changes in CDDP-induced nephrotoxicity and also suggest a molecular link between the circadian clock and renal xenobiotic excretion.