Phenotype of a calbindin-D9k gene knockout is compensated for by the induction of other calcium transporter genes in a mouse model.

UNLABELLED: CaBP-9k may be involved in the active calcium absorption and embryo implantation. Although we generated CaBP-9k KO mice to explore its function, no distinct phenotypes were observed in these KO mice. It can be hypothesized that TRPV5 and 6 and plasma membrane calcium ATPase 1b may play a role in the regulation of calcium transport to compensate CaBP-9k deficiency in its KO model. INTRODUCTION: Active calcium transport in the duodenum and kidney is carried in three steps: calcium entry through epithelial Ca2+ channels (TRPV5 and TRPV6), buffering and/or transport by calbindin-D9k (CaBP-9k) and -D28k (CaBP-28k), and extrusion through the plasma membrane calcium ATPase 1b (PMCA1b) and sodium/calcium exchanger 1. Although the molecular mechanism of calcium absorption has been studied using knockouts (KOs) of the vitamin D receptor and CaBP-28k in animals, the process is not fully understood. MATERIALS AND METHODS: We generated CaBP-9k KO mice and assessed the phenotypic characterization and the molecular regulation of active calcium transporting genes when the mice were fed different calcium diets during growth. RESULTS: General phenotypes showed no distinct abnormalities. Thus, the active calcium transport of CaBP-9k-null mice proceeded normally in this study. Therefore, the compensatory molecular regulation of this mechanism was elucidated. Duodenal TRPV6 and CaBP-9k mRNA of wildtype (WT) mice increased gradually during preweaning. CaBP-9k is supposed to be an important factor in active calcium transport, but its role is probably compensated for by other calcium transporter genes (i.e., intestinal TRPV6 and PMCA1b) during preweaning and renal calcium transporters in adult mice. CONCLUSIONS: Depletion of the CaBP-9k gene in a KO mouse model had little phenotypic effect, suggesting that its depletion may be compensated for by calcium transporter genes in the intestine of young mice and in the kidney of adult mice.

Cyclic diarylheptanoids inhibit cell mediated low-density lipoprotein oxidation.

Two cyclic diarylheptanoids, garugamblin-3 (1) and acerogenin L (2), isolated from the MeOH extract of the fruits of Alnus japonica Steud., inhibited human low-density lipoprotein (LDL) oxidation in the thiobarbituric acid-reactive substance assay with IC(50) values of 2.9 and 1.7 microM, respectively, and they also inhibited cell-mediated LDL oxidation more than 5 times more strongly than that of a well-known antioxidant, probucol, at a concentration of 10 microM. Compound (1) had no effect on the anti-atherogenesis in low-density lipoprotein receptor-deficient mice.

Cyclic diarylheptanoids inhibit cell-mediated low-density lipoprotein oxidation.

Two cyclic diarylheptanoids, garugamblin-3 (1) and acerogenin L (2), isolated from the MeOH extract of the fruits of Alnus japonica Steud., inhibited human low-density lipoprotein (LDL) oxidation in the thiobarbituric acid-reactive substance assay with IC50 values of 2.9 and 1.7 microM, respectively, and they also inhibited cell-mediated LDL oxidation more than five times more strongly than that of a well-known antioxidant, probucol, at a concentration of 10 microM. 1 had no effect on the anti-atherogenesis in low-density lipoprotein receptor- deficient mice.

Comparative study of cholinergic cells in retinas of various mouse strains.

We examined cholinergic cells in the retinas of BALB/C albino, C57BL/6J black, and 129/SvJ light chinchilla mice by using immunocytochemistry with specific antisera against choline acetyltransferase (ChAT). Two types of ChAT-immunoreactive amacrine cell bodies were found in the inner nuclear layer (INL) and ganglion cell layer in the retinas of all three mouse strains. They were distributed with mirror-image symmetry and their processes ramified in strata 2 and 4 of the inner plexiform layer. A distinct type of ChAT-immunoreactive cell was found only in C57BL/6J mouse retina. The somata of this third type of ChAT-immunoreactive cell were located in the outermost part of the INL, with their processes extending toward the outer plexiform layer. Double-labeling experiments demonstrated that these were not horizontal cells and that they were GABA-immunoreactive. The results suggested that these cells were probably "misplaced" cholinergic amacrine cells showing GABA immunoreactivity. This feature of the C57BL/6J mouse retina should be taken into account in studies of mutant mice having a mixed genetic background with a C57BL/6J contribution.

KR-31378 ameliorates atherosclerosis by blocking monocyte recruitment in hypercholestrolemic mice.

The recruitment of monocytes into the artery wall is a crucial early step in atherogenesis. A novel compound, KR-31378, has been shown to be a neuroprotective agent for ischemia-reperfusion damage in rat brain via its potent antioxidant and antiapoptotic actions. Here, we report the effects of this compound on atherogenesis and possible mechanisms of action. In Ldlr knockout mice fed with a high-fat, high-cholesterol diet, treatment with KR-31378 significantly inhibited fatty streak formation and macrophage accumulation. To address the possibility that KR-31378 may influence the initial stages of atherogenesis, we examined its effect on the adhesion and migration of monocytes to endothelial cells stimulated with tumor necrosis factor-alpha. KR-31378 decreased the adhesion in a dose-dependent manner. The observed decreases in cell adhesion and migration correlated with KR-31378-mediated down-regulation of vascular cell adhesion molecule-1 (VCAM-1) and interleukin (IL)-8. Nuclear factor-kappaB (NF-kappaB) is known to regulate the expression of adhesive and chemotactic molecules including VCAM-1 and IL-8. Indeed, transient transfection experiments, electrophoretic mobility shift assay, and IkappaB degradation assay showed that KR-31378 decreased NF-kappaB activation. These results indicate that KR-31378 potently reduces fatty streak formation by inhibiting NF-kappaB-dependent cellular adhesion and chemotactic molecule expression, which are crucial to monocyte infiltration into the arterial wall during the early stages of atherogenesis.