Osmoadaptation-related genes in inner medulla of mouse kidney using microarray

To distinguish biological molecular processes of osmotic stress occurring in inner medulla, we utilized microarrays to monitor expression profiles. RNAs from three segments (cortex, outer medulla, and inner medulla) of mouse kidney were isolated and applied to microarrays. We found 35 genes expressed highly in inner medulla. Next, microarrays for the RNAs from mouse medullary collecting duct cell line (mIMCD) cells and osmotically adapted mIMCD cells (HT cells) were performed (designed as resistant to 1270mOsm/H(2)O). Of 35 genes highly expressed in inner medulla, 6 genes such as; B-cell translocation gene protein (BTG), myc-basic motif homologue, gelsolin, cell surface glycoprotein, laminin beta2, and tubulo-interstitial nephritis antigen, were also expressed highly in HT cells. Using real-time PCR, we confirmed the expression of six genes. Additionally acute osmotic stress induced the BTG. By comparing the inner medulla to a mIMCD3, we identified genes which respond to acute and chronic hyperosmotic stress.     

Fibronectin gene expression in proliferating, quiescent, and SV40-infected mouse kidney cells

To study alterations in cellular gene expression in mouse kidney cell cultures infected with simian virus 40 (SV40) or polyomavirus, we performed a differential screening of a mouse kidney cDNA library with probes prepared from mRNAs of virus-infected and mock-infected cells. We isolated and characterized cDNA recombinant pKT13 which detected increased mRNA levels in infected cells. Sequence analysis of pKT13 revealed close to 100% homology with the 3'-end of mouse fibronectin (FN) mRNA. Since primary cultures of baby mouse kidney cells have been extensively characterized in our laboratories, we studied FN gene expression at different stages of uninfected and virus-infected cultures. High levels of FN and of its mRNA were found in the kidneys of suckling mice, while in primary cultures of proliferating epithelial kidney cells the expression of FN was very low until the cultures became confluent. Thereafter FN increased and reached high levels in cells which were irreversibly arrested in phase Go and which had apparently exhausted their finite division potential. Infection of confluent cultures with polyomavirus or SV40 resulted in a further stimulation of FN gene expression. However, during abortive infection with SV40, FN mRNA and FN levels decreased with emergence of transformed cells and were low in an established SV40-transformed mouse kidney cell line. These changes in FN gene expression suggest that high levels of FN might be indicative in vivo for terminal differentiation and in vitro for cellular senescence.     

胰腺发育相关maf基因在胰腺导管和胰岛的表达

为探讨胰岛功能和发育相关maf基因在胰腺导管上皮中的表达情况,对新鲜小鼠胰腺组织切片进行显微切割,分离纯化胰腺组织中的导管和胰岛,以及外分泌腺组织细胞作为对照,利用荧光实时定量PCR的方法完成对目的基因的相对定量.结果显示,mafa mRNA,mafb mRNA水平在胰岛及导管中非常接近,无统计学差异.而c-maf在导管的表达高于胰岛(P<0.05),外分泌腺则无上述基因的表达.胰腺导管中mafa,mafb,cmaf均有表达,肯定了导管上皮细胞向内分泌细胞分化的潜能,而c-maf在导管中的表达高于胰岛,提示导管上皮c-maf的下调可能有助于导管上皮细胞向内分泌细胞的分化成熟.     

Dysregulation of adipose glutathione peroxidase 3 in obesity contributes to local and systemic oxidative stress

Glutathione peroxidase 3 (GPx3) accounts for the major antioxidant activity in the plasma. Here, we demonstrate that down-regulation of GPx3 in the plasma of obese subjects is associated with adipose GPx3 dysregulation, resulting from the increase of inflammatory signals and oxidative stress. Although GPx3 was abundantly expressed in kidney, lung, and adipose tissue, we observed that GPx3 expression was reduced selectively in the adipose tissue of several obese animal models as decreasing plasma GPx3 level. Adipose GPx3 expression was greatly suppressed by prooxidative conditions such as high levels of TNFalpha and hypoxia. In contrast, the antioxidant N-acetyl cysteine and the antidiabetic drug rosiglitazone increased adipose GPx3 expression in obese and diabetic db/db mice. Moreover, GPx3 overexpression in adipocytes improved high glucose-induced insulin resistance and attenuated inflammatory gene expression whereas GPx3 neutralization in adipocytes promoted expression of proinflammatory genes. Taken together, these data suggest that suppression of GPx3 expression in the adipose tissue of obese subjects might constitute a vicious cycle to expand local reactive oxygen species accumulation in adipose tissue potentially into systemic oxidative stress and obesity-related metabolic complications.     

Selenium Alleviates Porcine Nephrotoxicity of Ochratoxin A by Improving Selenoenzyme Expression In Vitro

Ochratoxin A (OTA), a mycotoxin, is a potent nephrotoxin in humans and animals. Selenium (Se) is an essential micronutrient for humans and animals, and plays a key role in antioxidant defense. To date, little is known about the effect of Se on OTA-induced nephrotoxicity. In this study, the protective effects of selenomethionine against OTA-induced nephrotoxicity were investigated using the porcine kidney 15 (PK15) cells as a model. The results showed that OTA induced nephrotoxicity in a dose-dependent manner. Se at 0.5, 1, 2 and 4 μM had significant protective effects against OTA-induced nephrotoxicity. Furthermore, selenomethionine enhanced the activity and mRNA and protein expression of glutathione peroxidase 1 (GPx1), mRNA expression of GPx4, and mRNA expression of thioredoxin reductase 1 in the presence and absence of OTA. Among them, promoting effect of selenomethionine on GPx1 was maximal. Knock-down of GPx1 by using a GPx1-specific siRNA eliminated the protective effects of selenomethionine against OTA-induced nephrotoxicity. The results suggest that selenomethionine alleviates OTA-induced nephrotoxicity by improving selenoenzyme expression in PK15 cells. Therefore, selenomethionine supplementation may be an attractive strategy for protecting humans and animals from the risk of kidney damage induced by OTA.