Repression of multiple CYP2D genes in mouse primary hepatocytes with a single siRNA construct

Development of Resistance to Endoplasmic Reticulum Stress-Inducing Agents in Mouse Leukemic L1210 Cells

Four new variants of L1210 cells resistant to endoplasmic reticulum (ER) stressors, tunicamycin (S_Tun), thapsigargin (S_Thap), bortezomib (S_Bor), and MG-132 (S_MG-132), were developed via an 18-month periodic cultivation in culture medium with a gradual increase in substance concentration. Multidrug resistance was generated for S_Tun (to tunicamycin, bortezomib and MG-132), S_Thap (to tunicamycin, thapsigargin and MG-132), S_Bor (to bortezomib and MG-132), and S_MG-132 (to bortezomib and MG-132). These cells were compared to the original L1210 cells and another two variants, which expressed P-gp due to induction with vincristine or transfection with the gene encoding P-gp, in terms of the following properties: sensitivity to either vincristine or the ER stressors listed above, proliferative activity, expression of resistance markers and proteins involved in the ER stress response, and proteasome activity. The resistance of the new cell variants to ER stressors was accompanied by a decreased proliferation rate and increased proteasome activity. The most consistent change in protein expression was the elevation of GRP78/BiP at the mRNA and protein levels in all resistant variants of L1210 cells. In conclusion, the mechanisms of resistance to these stressors have certain common features, but there are also specific differences.

Coordinated cytochrome P450 expression in mouse liver and intestine under different dietary conditions during liver regeneration after partial hepatectomy

Liver resection is performed to remove tumors in patients with liver cancer, but the procedure's suitability depends on the regenerative ability of the liver. It is important to consider the effects of exogenous factors, such as diets, on liver regeneration for the recovery of function. The evaluation of drug metabolism during liver regeneration is also necessary because liver dysfunction is generally observed after the operation. Here, we investigated the influence of a purified diet (AIN-93G) on liver regeneration and changes in the mRNA expression of several cytochrome P450 (CYP) isoforms in the liver and small intestine using a two-thirds partial hepatectomy (PH) mouse model fed with a standard diet (MF) and a purified diet. Liver regeneration was significantly delayed in the purified diet group relative to that in the standard diet group. The liver Cyp2c55 and Cyp3a11 expression was increased at 3 day after PH especially in the purified diet group. Bile acid may partly cause the differences in liver regeneration and CYP expression between two types of diets. On the other hand, Cyp3a13 expression in the small intestine was transiently increased at day 1 after PH in both diet groups. The findings suggest that compensatory induction of the CYP expression occurred in the small intestine after attenuation of drug metabolism potential in the liver. The present results highlight the importance of the relationship between liver regeneration, drug metabolism, and exogenous factors for the effective treatment, including surgery and medication, in patients after liver resection or transplantation.

Transcriptomic analysis and plasma metabolomics in Aldh16a1-null mice reveals a potential role of ALDH16A1 in renal function

ALDH16A1 is a novel member of the ALDH superfamily that is enzymatically-inactive and highly expressed in the kidney. Recent studies identified an association between a rare missense single nucleotide variant (SNV) in the ALDH16A1 gene and elevated serum uric acid levels and gout. The present study explores the mechanisms by which ALDH16A1 influences uric acid homeostasis in the kidney. We generated and validated a mouse line with global disruption of the Aldh16a1 gene through gene targeting and performed RNA-seq analyses in the kidney of wild-type (WT) and Aldh16a1 knockout (KO) mice, along with plasma metabolomics. We found that ALDH16A1 is expressed in proximal and distal convoluted tubule cells in the cortex of the kidney and in zone 3 hepatocytes. RNA-seq and gene ontology enrichment analyses showed that cellular lipid and lipid metabolic processes are up-regulated. Three transporters localized in the apical membrane of the proximal convoluted tubule of the kidney known to influence urate/uric acid homeostasis were found to be up-regulated (Abcc4, Slc16a9) or down-regulated (Slc17a3). An initial metabolomics analysis in plasma revealed an altered lipid profile in KO mice that is in agreement with our RNA-seq analysis. This is the first study demonstrating a functional role of ALDH16A1 in the kidney.