The Protective Role of Calbindin-D9k on Endoplasmic Reticulum Stress-Induced Beta Cell Death.

Intracellular calcium ion content is tightly regulated for the maintenance of cellular functions and cell survival. Calbindin-D9k (CaBP-9k) is responsible for regulating the distribution of cytosolic free-calcium ions. In this study, we aimed to investigate the effect of CaBP-9k on cell survival in pancreatic beta cells. Six-month-old wildtype CaBP-9k, CaBP-28k, and CaBP-9k/28k knockout (KO) mice were used to compare the pathological phenotypes of calcium-binding protein-deleted mice. Subsequently, the endoplasmic reticulum (ER) stress reducer tauroursodeoxycholic acid (TUDCA) was administered to wildtype and CaBP-9k KO mice. In vitro assessment of the role of CaBP-9k was performed following CaBP-9k overexpression and treatment with the ER stress inducer thapsigargin. Six-month-old CaBP-9k KO mice showed reduced islet volume and up-regulation of cell death markers resulting from ER stress, which led to pancreatic beta cell death. TUDCA treatment recovered islet volume, serum insulin level, and abdominal fat storage by CaBP-9k ablation. CaBP-9k overexpression elevated insulin secretion and recovered thapsigargin-induced ER stress in the INS-1E cell line. The results of this study show that CaBP-9k can protect pancreatic beta cell survival from ER stress and contribute to glucose homeostasis, which can reduce the risk of type 1 diabetes and provide the molecular basis for calcium supplementation to diabetic patients.

S100G expression and function in fibroblasts on colitis induction.

Supplementation with interleukin (IL)-10, an important anti-inflammatory cytokine, has shown disappointing efficacy for inflammatory bowel diseases (IBD). IL-10 may down-regulate the expression of other anti-inflammatory mediators following colitis induction. We used a colitis model characterized by hapten-protein visualization, which indicates the site of hapten-protein formation after colitis induction for histological and gene expression analyses. Under IL-10 deficiency, following colitis induction inflammatory changes were reduced, and S100G expression was elevated. S100G was expressed in fibroblasts, and S100G expression was down-regulated by IL-10. S100G suppressed the production of monocyte chemotactic protein-1 (MCP-1) through the inhibition of NF-κB activation. Therefore, S100G, also known as Calbindin-D9k, may be an important anti-inflammatory mediator in fibroblasts following colitis induction, and down-regulation of S100G expression might be one reason for the insufficient performance of IL-10 supplementation.

The role of calbindin-D28k on renal calcium and magnesium handling during treatment with loop and thiazide diuretics.

Calbindin-D28k (CBD-28k) is a calcium binding protein located in the distal convoluted tubule (DCT) and plays an important role in active calcium transport in the kidney. Loop and thiazide diuretics affect renal Ca and Mg handling: both cause Mg wasting, but have opposite effects on Ca excretion as loop diuretics increase, but thiazides decrease, Ca excretion. To understand the role of CBD-28k in renal Ca and Mg handling in response to diuretics treatment, we investigated renal Ca and Mg excretion and gene expression of DCT Ca and Mg transport molecules in wild-type (WT) and CBD-28k knockout (KO) mice. Mice were treated with chlorothiazide (CTZ; 50 mg · kg(-1) · day(-1)) or furosemide (FSM; 30 mg · kg(-1) · day(-1)) for 3 days. To avoid volume depletion, salt was supplemented in the drinking water. Urine Ca excretion was reduced in WT, but not in KO mice, by CTZ. FSM induced similar hypercalciuria in both groups. DCT Ca transport molecules, including transient receptor potential vanilloid 5 (TRPV5), TRPV6, and CBD-9k, were upregulated by CTZ and FSM in WT, but not in KO mice. Urine Mg excretion was increased and transient receptor potential subfamily M, member 6 (TRPM6) was upregulated by both CTZ and FSM in WT and KO mice. In conclusion, CBD-28k plays an important role in gene expression of DCT Ca, but not Mg, transport molecules, which may be related to its being a Ca, but not a Mg, intracellular sensor. The lack of upregulation of DCT Ca transport molecules by thiazides in the KO mice indicates that the DCT Ca transport system is critical for Ca conservation by thiazides.

Regulation of tight junction gene expression in the kidney of calbindin-D9k and/or -D28k knockout mice after consumption of a calcium- or a calcium/vitamin D-deficient diet.

BACKGROUND: Calciotropic hormones were thought to facilitate calcium transfer through active transcellular or passive paracellular pathway for calcium homeostasis. While calcium transport proteins such as CaBP-28 k, TRPV5, NCX1, PMCA1b are involved in calcium reabsorption of the renal tubule using transcellular transport, tight junction proteins are known as critically related to calcium absorption through paracellular pathway. The regulation of each pathway for calcium transport was well studied but the correlation was not. It is expected that present study will provide new information about the link between transcellular and paracellular pathway within renal tubules. RESULTS: Transcripts and proteins of tight junction related genes (occludin, ZO-1, and claudins) were examined in CaBP-9 k-and/or-28 k-deficient mice as well as the effect of dietary calcium and/or vitamin D supplementation. With a normal diet, the transcriptional and translational expressions of most tight junction proteins in the kidney was not significantly changed but with a calcium- and vitamin D-deficient diet, and they were significantly increased in the kidney of the CaBP-28 k and CaBP-9 k/28 k double KO (DKO) mice. In these genotypes, the increase of tight junction related transcripts and proteins are referred to as an evidence explaining correlation between transcellular transport and paracellular pathway. CONCLUSIONS: These findings are particularly interesting in evidences that insufficient transcellular calcium transports are compensated by paracellular pathway in calcium or calcium/vitamin D deficient condition, and that both transcellular and paracellular pathways functionally cooperate for calcium reabsorption in the kidney.

Convergence of nicotine-induced and auditory-evoked neural activity activates ERK in auditory cortex.

Enhancement of sound-evoked responses in auditory cortex (ACx) following administration of systemic nicotine is known to depend on activation of extracellular-signaling regulated kinase (ERK), but the nature of this enhancement is not clear. Here, we show that systemic nicotine increases the density of cells immunolabeled for phosphorylated (activated) ERK (P-ERK) in mouse primary ACx (A1). Cortical injection of dihydro-ß-erythroidine reduced nicotine-induced P-ERK immunolabel, suggesting a role for nicotinic acetylcholine receptors located in A1 and containing α4 and ß2 subunits. P-ERK expressing cells were distributed mainly in layers 2/3 and more sparsely in lower layers, with many cells exhibiting immunolabel within pyramidal-shaped somata and proximal apical dendrites. About one-third of P-ERK positive cells also expressed calbindin. In the thalamus, P-ERK immunopositive cells were found in the nonlemniscal medial geniculate (MG) and adjacent nuclei, but were absent in the lemniscal MG. Pairing broad spectrum acoustic stimulation (white noise) with systemic nicotine increased P-ERK immunopositive cell density in ACx as well as the total amount of P-ERK protein, particularly the phosphorylated form of ERK2. However, narrow spectrum (tone) stimulation paired with nicotine increased P-ERK immunolabel preferentially at a site within A1 where the paired frequency was characteristic frequency (CF), relative to a second site with a spectrally distant CF (two octaves above or below the paired frequency). Together, these results suggest that ERK is activated optimally where nicotinic signaling and sound-evoked neural activity converge.

The prebiotic effect of Anoectochilus formosanus and its consequences on bone health.

The present study evaluated the prebiotic effect of a standardised aqueous extract of Anoectochilus formosanus (SAEAF) and its effects on osteoporosis in ovariectomised (OVX) rats. The OVX rats were randomly divided into five groups and orally treated with water, SAEAF (200 and 400 mg/kg daily) and inulin (400 mg/kg daily) for 12 weeks. The sham group was orally treated with water. The SAEAF treatment enhanced the number of faecal bifidobacteria in OVX rats. The results of a Ca-balance experiment showed that SAEAF increased apparent Ca absorption and retention. The OVX rats were killed after SAEAF treatment lasting 12 weeks. The SAEAF decreased the caecal pH values and increased the caecal wall weight, caecal mucosa calbindin-D9k mRNA expression, free-Ca concentration and levels of SCFA in the caecum. The mineral content, density and biomechanical strength of bones were lower in OVX rats than the sham group, but these bone losses were prevented by SAEAF administration. Microtomography scanning showed that the SAEAF-treated rats had higher trabecular bone volume than the OVX rats. These results suggest that SAEAF prevented bone loss associated with ovarian hormone deficiency in the rats.

Effects of octylphenol and bisphenol A on the expression of calcium transport genes in the mouse duodenum and kidney during pregnancy.

Octylphenol (OP) is the degradative product of alkylphenol ethoxylates that are widely used to produce rubber, pesticides, and paints. Bisphenol A (BPA) is an organic compound with two functional phenol groups, and used for manufacturing polycarbonate plastic and epoxy resins, as well as other applications. OP and BPA are known as endocrine disruptors (EDs) with estrogenic activities, and may disturb natural calcium (Ca) metabolism. In the present study, the effects of OP and BPA on Ca levels in the serum and expression of Ca transport genes in the duodenum, and kidney were investigated in pregnant mice. Calbindin refers to several Ca-binding proteins originally described as vitamin D-dependent Ca-binding factors in the intestine, and kidney of birds and mammals. Transient receptor potential cation channel, subfamily V, member 6 (TRPV6) and transient receptor potential cation channel, subfamily V, member 5 (TRPV5) are Ca entry channels responsible for Ca absorption in the kidney and intestine, respectively. From 6.5 to 16.5 day post coitus (dpc), pregnant mice were given oral doses of 17α-ethynylestradiol (EE, 0.2mg/kg/day), BPA (5 or 50mg/kg/day), or OP (3, 12, or 48 mg/kg/day) dissolved in corn oil. Samples of the duodenum, kidney, and blood were obtained from the mice on day 17.5 of pregnancy. Serum Ca levels were decreased in the groups treated with OP and BPA. The expression levels of Ca transport genes, TRPV5 and calbindin-D9k (CaBP-9k), in the kidney were decreased after treatment with OP and BPA. Duodenal expression of TRPV6 was also reduced by BPA and OP administration. CaBP-9k expression was differentially regulated by BPA and OP. Transcriptional and translational levels of CaBP-9k were decreased by EE and BPA but increased by a high dose of OP. Taken together, our findings demonstrate that OP and BPA regulated the expression of genes associated with Ca transport in the pregnant mice, which may result in the decreased serum Ca levels.

Novel ß-catenin target genes identified in thalamic neurons encode modulators of neuronal excitability.

BACKGROUND: LEF1/TCF transcription factors and their activator ß-catenin are effectors of the canonical Wnt pathway. Although Wnt/ß-catenin signaling has been implicated in neurodegenerative and psychiatric disorders, its possible role in the adult brain remains enigmatic. To address this issue, we sought to identify the genetic program activated by ß-catenin in neurons. We recently showed that ß-catenin accumulates specifically in thalamic neurons where it activates Cacna1g gene expression. In the present study, we combined bioinformatics and experimental approaches to find new ß-catenin targets in the adult thalamus. RESULTS: We first selected the genes with at least two conserved LEF/TCF motifs within the regulatory elements. The resulting list of 428 putative LEF1/TCF targets was significantly enriched in known Wnt targets, validating our approach. Functional annotation of the presumed targets also revealed a group of 41 genes, heretofore not associated with Wnt pathway activity, that encode proteins involved in neuronal signal transmission. Using custom polymerase chain reaction arrays, we profiled the expression of these genes in the rat forebrain. We found that nine of the analyzed genes were highly expressed in the thalamus compared with the cortex and hippocampus. Removal of nuclear ß-catenin from thalamic neurons in vitro by introducing its negative regulator Axin2 reduced the expression of six of the nine genes. Immunoprecipitation of chromatin from the brain tissues confirmed the interaction between ß-catenin and some of the predicted LEF1/TCF motifs. The results of these experiments validated four genes as authentic and direct targets of ß-catenin: Gabra3 for the receptor of GABA neurotransmitter, Calb2 for the Ca(2+)-binding protein calretinin, and the Cacna1g and Kcna6 genes for voltage-gated ion channels. Two other genes from the latter cluster, Cacna2d2 and Kcnh8, appeared to be regulated by ß-catenin, although the binding of ß-catenin to the regulatory sequences of these genes could not be confirmed. CONCLUSIONS: In the thalamus, ß-catenin regulates the expression of a novel group of genes that encode proteins involved in neuronal excitation. This implies that the transcriptional activity of ß-catenin is necessary for the proper excitability of thalamic neurons, may influence activity in the thalamocortical circuit, and may contribute to thalamic pathologies.

Effects of coumestrol administration to maternal mice during pregnancy and lactation on renal Ca metabolism in neonatal mice.

The present study was conducted to clarify the effects of coumestrol administration to maternal mice during pregnancy and lactation on serum Ca and Ca metabolism in their neonatal mice. From 6.5 to 16.5 days post coitus and from 3 to 10 days after parturition, maternal mice were administered at 200 µg/kg body weight/day of coumestrol. Coumestrol administration did not affect weight gains, serum Ca and the expression of vitamin D receptor (VDR) protein in the kidney of neonatal mice, but weight gains of maternal mice were decreased by coumestrol administration. Coumestrol administration increased the messenger RNA (mRNA) expressions of epithelial Ca channels 1 (ECaC1) and VDR in the kidney of neonatal mice, and also increased the mRNA expressions of ECaC2 in the kidney and small intestine of male neonatal mice. The mRNA expressions of ECaC1, ECaC2, calbindin-D(9k) (CaBP-9k) and estrogen receptor (ER)α in the kidney and VDR in the small intestine of male neonatal mice were higher than those of female mice. Thus, coumestrol administration to maternal mice during pregnancy and lactation may affect renal Ca metabolism in neonatal mice, especially male neonatal mice via maternal milk.

In vitro studies on intestinal calcium and phosphate transport in horses.

Transepithelial transport mechanisms play a key role in regulating the absorption and secretion of calcium (Ca(2+)) and inorganic phosphate (P(i)) in the gastrointestinal tract. Although intestinal disorders with imbalances in macromineral homeostasis are frequently observed in horses, available data on intestinal Ca(2+) and P(i) transport are limited. The aim of the present study was to characterize the intestinal Ca(2+) and P(i) transport functionally by using the in vitro radioisotope tracer technique with Ussing chambers and to identify components involved in Ca(2+) transport at both mRNA and protein level. Among the different intestinal segments, the duodenum showed significant and highest active Ca(2+) absorption. The findings from RT-PCR and Western blot analysis suggest that the epithelial Ca(2+) channel TRPV6, the cytosolic calcium binding protein calbindin-D(9K) and the plasma membrane calcium ATPase PMCA may be involved in active transcellular Ca(2+) transport. Regarding the P(i) transport, the results indicate significant active P(i) secretion in the jejunum, but the contributing mechanisms remain unclear. A significant inhibiting effect of ouabain as an antagonist of the basolateral Na(+)/K(+)-ATPase on the serosal-to-mucosal P(i) transport suggests a pivotal role of Na(+) in jejunal P(i) transport in the horse.

Synergistic effects of octylphenol and isobutyl paraben on the expression of calbindin-D9k in GH3 rat pituitary cells.

Endocrine disruptors (EDs) have estrogenic activity and can cause physiological estrogenic responses. Octylphenol (OP) is one of the alkylphenolic compounds known as environmental xenoestrogens because they strongly compete with endogenous estrogens to bind to estrogen receptors (ERs). Isobutyl paraben (IBP), a widely used preservative, also exhibits estrogenic activity. Calbindin-D9k (CaBP-9k) is a novel biomarker for the detection of EDs used in our previous studies. In this study, the CaBP-9k gene was utilized as a marker for the estrogenic activity of combined OP and IBP to investigate possible additive, synergistic or antagonistic effects of these compounds in GH3 rat pituitary cells. GH3 cells were treated with different individual or combined doses of OP and IBP. In addition, the antiestrogen ICI 182,780 was used to examine the potential involvement of ERs in the induction of CaBP-9k expression by EDs. It was found that CaBP-9k expression was significantly increased at a high-dose of OP (1 µM) combined with each dose of IBP (0.1, 1 or 10 µM) compared to all single doses of IBP and OP. A synergistic increase in luciferase activity and CaBP-9k expression was observed following combination treatment with OP and IBP. Expression of the progesterone receptor (PR) gene was similarly induced by combined treatment with OP and IBP. In addition, pre-treatment with ICI 182,780, an estrogen antagonist, significantly blunted ED-induced CaBP-9k and PR expression. In summary, the expression of CaBP-9k and PR was induced more potently by combined OP and IBP than by treatment with either ED alone. ICI 182,780 treatment reversed ED-induced CaBP-9k and PR expression in these cells. Taken together, these results indicate that combined exposure to OP and IBP has a synergistic effect on the induction of CaBP-9k and PR gene expression via an ER-dependent pathway in GH3 cells.

Sex differences in the cerebellum and frontal cortex: roles of estrogen receptor alpha and sex chromosome genes.

Most neurobehavioral diseases are sexually dimorphic in their incidence, and sex differences in the brain may be key for understanding and treating these diseases. Calbindin (Calb) D28K is used as a biomarker for the well-studied sexually dimorphic nucleus, a hypothalamic structure that is larger in males than in females. In the current study weanling C56BL/6J mice were used to examine sex differences in the Calb protein and message focusing on regions outside of the hypothalamus. A robust sex difference was found in Calb in the frontal cortex (FC) and cerebellum (CB; specifically in Purkinje cells); mRNA and protein were higher in females than in males. Using 2 mouse lines, i.e. one with a complete deletion of estrogen receptor alpha (ERα) and the other with uncoupled gonads and sex chromosomes, we probed the mechanisms that underlie sexual dimorphisms. In the FC, deletion of ERα reduced Calb1 mRNA in females compared to males. In addition, females with XY sex chromosomes had levels of Calb1 equal to those of males. Thus, both ERα and the sex chromosome complement regulate Calb1 in the FC. In the CB, ERα knockout mice of both sexes had reduced Calb1 mRNA, yet sex differences were retained. However, the sex chromosome complement, regardless of gonadal sex, dictated Calb1 mRNA levels. Mice with XX chromosomes had significantly greater Calb1 than did XY mice. This is the first study demonstrating that sex chromosome genes are a driving force producing sex differences in the CB and FC, which are neuoranatomical regions involved in many normal functions and in neurobehavioral diseases.

Paeoniflorin protects against NMDA-induced neurotoxicity in PC12 cells via Ca2+ antagonism.

Preclinical and clinical investigation has shown that hippocampal neuronal atrophy and destruction can be observed in patients with depression, and this can be ameliorated with antidepressant medication. Neuroprotection has therefore been proposed as one of the mechanisms of action of antidepressants. Paeoniflorin, a monoterpene glycoside, has been reported to display antidepressant-like effects in animal models of behavioral despair. The present study aimed to examine the protective effect of paeoniflorin treatment on N-methyl-D-aspartate (NMDA)-induced neurotoxicity in cultured rat pheochromocytoma (PC12) cells. Paeoniflorin was shown to elevate cell viability, decrease lactate dehydrogenase (LDH) release in NMDA-treated PC12 cells. Paeoniflorin also reversed the increased intracellular calcium (Ca(2+)) concentration and the reduced Calbindin-D28K mRNA level caused by NMDA in PC12 cells. These results suggest that paeoniflorin exerts a neuroprotective effect on NMDA-induced neurotoxicity in PC12 cells, at least in part, via Ca(2+) antagonism.

1,25-Dihydroxyvitamin D3-induced aortic calcifications in experimental uremia: up-regulation of osteoblast markers, calcium-transporting proteins and osterix.

BACKGROUND AND OBJECTIVE: Whether treatment with vitamin D receptor activators contributes to cardiovascular disease in patients with chronic kidney disease is a matter of debate. We studied mechanisms involved in vitamin D-related vascular calcifications in vivo and in vitro. METHODS: Aortic calcifications were induced in subtotally nephrectomized (SNX) rats by treatment with a high dose (0.25 µg/kg per day) of 1,25-dihydroxyvitamin D3 (calcitriol) given for 6 weeks. Likewise, primary rat vascular smooth muscle cells (VSMCs) were incubated with calcitriol at concentrations ranging from 10 to 10 mol/l. Immunohistochemistry revealed that the aortic expression of osteopontin, osteocalcin and bone sialoprotein was significantly increased in calcitriol-treated SNX rats compared to untreated SNX controls. In addition, aortic expression of the transient receptor potential vanilloid calcium channel 6 (TRPV6) and calbindin D9k was significantly up-regulated by treatment with calcitriol. Furthermore, calcitriol significantly increased expression of the osteogenic transcription factor osterix. In-vitro studies showed similar results, confirming that these effects could be attributed to treatment with calcitriol. CONCLUSIONS: High-dose calcitriol treatment induces an osteoblastic phenotype in VSMC both in SNX rats and in vitro, associated with up-regulation of proteins regulating mineralization and calcium transport, and of the osteogenic transcription factor osterix.

Effects of duodenal redox status on calcium absorption and related genes expression in high-fat diet-fed mice.

OBJECTIVE: This study investigated whether duodenal redox imbalance induced by high-fat diet (HFD) influenced expression of genes involved in transcellular calcium absorption, thus leading to reduced intestinal calcium absorption. METHODS: Male C57BL/6 mice were randomly assigned to one of four groups with eight mice in each group. The control group consumed an ordinary diet (4.9% fat, w/w). The other three groups were fed a HFD (21.2% fat), the HFD plus 0.1% lipoic acid, or the HFD plus an additional 0.9% calcium supplement. After 9 wk, plasma and duodenal oxidative stress biomarkers including malondialdehyde, superoxide dismutase, catalase, total antioxidant capacity, reduced glutathione/oxidized glutathione ratio, and reactive oxygen species were examined. The intestinal calcium absorption state was evaluated through examining the calcium balance, bone mineral density, and calcium metabolism biomarkers. Furthermore, quantitative reverse transcription-polymerase chain reaction was carried out to analyze the changes in expression of transcellular calcium absorption-related genes. RESULTS: The HFD induced marked decreases in intestinal calcium absorption and bone mineral density of the whole body, accompanied by redox imbalance and increased oxidative damage in duodenum; duodenal expression of calbindin-D(9K), plasma membrane calcium ATPase (PMCA(1b)), and sodium-calcium exchanger was significantly down-regulated by 1.9-, 2.7-, and 1.5-fold, respectively. Furthermore, duodenal glutathione and oxidized glutathione (GSH/GSSG) ratios were strongly positively correlated with the apparent calcium absorption rate and the expression of PMCA(1b) and Calbindin-D(9K), whereas reactive oxygen species levels were negatively correlated with them. CONCLUSION: Our results demonstrated that a HFD-induced duodenal oxidation state could significantly down-regulate expression of calbindin-D(9K), PMCA(1b), and sodium-calcium exchanger, thus causing an inhibitory effect on intestinal calcium absorption.

[Effect of electroacupuncture on the expression of hippocampal calbindin-D 28 K in hyperlipemia rats with concurrent cerebral ischemia].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on Calbindin D28 K(CB) expression and apoptosis in hippocampus in hyperlipemia rats with concomitant cerebral ischemia (CI). METHODS: Forty male SD rats were randomized into control, hyperlipemia+ CI (model), acupuncture I, and acupuncture II groups, with 10 cases in each. Hyperlipemia model was established by feeding the animals with high fat forage for 6 weeks and CI model established by occlusion of the unilateral middle cerebral artery. For rats of acupuncture I group, EA (1-3 mA, 15 Hz) was applied to bilateral "Sanyinjiao" (SP 6) and "Fenglong" (ST 40) for 20 min every time, once daily for 10 days before CI. For rats of both acupuncture I and II groups, after CI, EA was applied to SP 6, ST 40, "Baihui" (GV 20) and "Shuigou" (GV 26) were punctured with filiform needles and stimulated by twirled the needle with hand continuously for 1 min, once daily for 7 days. The apoptotic cells of hippocampal CA 3 area were displayed by TUNEL (terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling) method. CB antibody staining with immunohistochemistry was used to show CB-positive cells which were observed by optic microscope. RESULTS: In comparison with control group, the percentage of apoptotic cells of the hippocampal CA 3 area in model group increased considerably (P < 0.01), while the number of CB immunoreaction (IR)-positive cells in the same area decreased significantly (P < 0.05). Compared with model group, the percentages of apoptotic cells of CA 3 area in acupuncture I and acupuncture II groups lowered remarkably (P < 0.01), while the numbers of CB IR-positive cells in the later two groups increased significantly (P < 0.01). The therapeutic effect of acupuncture I group was apparently superior to that of acupuncture II group in lowering the percentage of apoptotic cells and upregulating CB IR-positive cell number (P < 0.05). CONCLUSION: Acupuncture can effectively lessen neuronal apoptosis of the hippocampus CA 3 area which may be closely related to its effect in upregulating the expression of CB in hyperlipemia + CI rats. Moreover, the cerebral ischemia injury degree may be lightened by acupuncture-lowering hyperlipemia first.

Calreticulin maintains the low threshold of peptide required for efficient antigen presentation.

Calreticulin (CRT) plays a critical role in MHC class I antigen processing and elicits peptide-specific CD8(+) T cell responses against tumours when administered with peptides. However, how CRT contributes to class I antigen processing and the mechanism of its adjuvant effect in anti-tumour responses, remain to be elucidated. Here we show that reduced class I expression in CRT deficient cells can be restored by the direct delivery of peptides into the ER or by incubation at low temperature. CRT deficient cells exhibited a TAP-deficient phenotype in terms of class I assembly, without loss of TAP expression or functionality. Furthermore, a higher concentration of antigen in the cytosol is required for specific T cell stimulation, suggesting that CRT has a functional role in the maintenance of the low peptide concentration threshold required in the ER for efficient antigen presentation. In the absence of CRT, ERp57 is up-regulated, which indicates that they collaborate with each other in class I antigen processing.

Improvement of impaired calcium and skeletal homeostasis in vitamin D receptor knockout mice by a high dose of calcitriol and maxacalcitol.

Vitamin D plays a major role in mineral and skeletal homeostasis through interaction with the nuclear vitamin D receptor (VDR) of target cells. Recent reports have indicated that some cellular effects of vitamin D may occur via alternative signaling pathways, but concrete evidence for mineral homeostasis has not been shown in vivo. To investigate this issue, the actions of calcitriol (1,25D) and maxacalcitol (OCT), which were developed for treatment of uremia-induced secondary hyperparathyroidism, were analyzed in VDR knockout (VDR(-/-)) mice. The VDR(-/-) mice were fed a rescue diet immediately after weaning. 1,25D, OCT or a control solution was administered intraperitoneally to these mice three times a week for eight weeks. Biological markers and bone growth were measured and bone histomorphometric analysis of the calcein-labeled tibia was performed 24 h after the final administration. Significantly higher levels of serum Ca(2+) were observed in 1,25D- and OCT-treated mice, but the serum parathyroid hormone level was unchanged by both agents. Impaired bone growth, enlarged and distorted cartilaginous growth plates, morphological abnormalities of cancellous and cortical bones; a morbid osteoid increase, lack of calcein labeling, and thinning of cortical bone, were all significantly improved by 1,25D and OCT. The significance of these effects was confirmed by bone histomorphometrical analysis. Upregulation of the calbindin D(9k) mRNA expression level in the duodenum may explain these findings, since this protein is a major modulator of Ca transport in the small intestine. We conclude that 1,25D and OCT both at a high dose exert significant effects on Ca and skeletal homeostasis with the principal improvement of Ca status in VDR(-/-) mice, and some of these effects may occur through an alternative vitamin D signaling pathway.

Reproductive and developmental effects of transovarian exposure to o,p'-DDT in Japanese quails.

Avian species have the possible risk of embryonic exposure to persistent, lipophilic environmental contaminants, such as dichlorodiphenyltrichloroethane (DDT), by transfer of chemicals accumulated in mother birds to eggs. To model developmental and reproductive disorders of wild birds living in contaminated areas, we exposed Japanese quails in ovo to o,p'-DDT prior to incubation. A positive estrogenic substance diethylstilbestrol (DES; 1 and 10 ng/g of egg) and o,p'-DDT (1-100 microg/g of egg) were injected into the yolk before incubation. Treatment with o,p'-DDT (10 or 100 microg/g) but not with DES significantly reduced the hatchability of eggs. After sexual maturation, o,p'-DDT affected eggshell formation in female quails but had little influence on laying; high doses of o,p'-DDT significantly reduced eggshell strength, shell weight, and shell thickness, and several females treated with 100 microg o,p'-DDT/g laid eggs lacking shells. Diethylstilbestrol decreased egg production itself but had little effect on the eggshell. Both o,p'-DDT and DES caused dose-dependent shortening of the left oviduct and abnormal development of the right oviduct in females, while testis asymmetry was observed in males treated with a high dose of DES. In the uterus of the oviduct, the mRNAs for calcium-regulating factors osteopontin and calbindin D28K were reduced by both treatments, particularly that with o,p'-DDT. The results indicated that transovarian exposure to o,p'-DDT could bring about population declines in avian species through loss of fecundity caused by depression of hatchability and dysfunction of the reproductive tract.

Attenuated BDNF-induced upregulation of GABAergic markers in neurons lacking Xbp1.

XBP1 is a transcription factor induced by unconventional splicing associated with endoplasmic reticulum stress and plays a role in development. Brain-derived neurotrophic factor (BDNF) causes splicing of Xbp1 mRNA in neurites, and Xbp1 is required for BDNF-induced neurite extension and branching. To search for the molecular mechanisms of how Xbp1 plays a role in neural development, comprehensive gene expression analysis was performed in primary telencephalic neurons obtained from Xbp1 knockout mice at embryonic day 12.5. By searching for the genes induced by BDNF in wild type neurons but not in Xbp1 knockout mice, we found that upregulation of three GABAergic markers, somatostatin (Sst), neuropeptide Y (Npy), and calbindin (Calb1), were compromised in Xbp1 knockout neurons. Attenuated upregulation of Npy and Calb1 in Xbp1 knockout neurons was confirmed by quantitative RT-PCR. This finding may be relevant to impaired BDNF-induced neurite extension in Xbp1 knockout neurons.