Abstract Background Congenital anomalies of the kidney and urinary tract (CAKUT) refer to a diverse group of developmental malformations, which are the leading cause of chronic kidney disease and end-stage renal disease in children. The etiology and pathogenesis of CAKUT are complex. In recent years, the relationship between long noncoding RNAs and renal development and disease has attracted much attention. Our previous study established a long noncoding RNA 4933425B07Rik ( Rik ) overexpression mouse model by inserting the PB transposon and found that overexpression of Rik led to renal hypoplasia. This study aimed to explore the molecular mechanism of renal hypoplasia induced by Rik overexpression in vitro. Results In this study, by constructing Rik overexpression cell models and a Rik knockout cell model to accompany previously developed Rik PB/PB ; Hoxb7 mice and by applying RNA-seq, RT‒PCR and other experimental methods, it was found that when Rik was highly expressed, the expression of Wnt10b , Fzd8 and β-catenin decreased, while Rik was knock down, the expression of these genes increased. Conclusions The findings suggest that overexpression of Rik leads to renal hypoplasia by inactivating the Wnt/β-catenin signaling pathway. This research perspective may provide a basis for exploring new causes and mechanisms of CAKUT and provide new targets for the prevention and treatment of CAKUT.
The plasma concentrations of orally administered anti-human immunodeficiency virus protease inhibitors are significantly reduced during human and mouse pregnancy. We have shown that in the mouse, at gestational day 19, this reduction is due to increased hepatic cytochrome P450 3a (Cyp3a) protein expression and activity. In the current study, we investigated the mechanisms by which Cyp3a activity is increased by pregnancy and the time course of change in expression of Cyp3a and P-glycoprotein (P-gp) in various tissues. We found that hepatic transcripts of Cyp3a16, Cyp3a41, and Cyp3a44 were significantly increased during pregnancy, whereas those of Cyp3a11 and Cyp3a25 were significantly decreased. This resulted in a net increase in Cyp3a protein expression and activity in the liver during pregnancy. The increase in Cyp3a41 and Cyp3a44 transcripts was positively correlated (p < 0.05) with hepatocyte nuclear factor 6 and estrogen receptor-α transcripts. The pregnancy-related factors that transcriptionally activated mouse Cyp3a isoforms also activated the human CYP3A4 promoter in pregnant CYP3A4-promoter-luciferase transgenic (CYP3A4-tg) mice. In contrast, intestinal Cyp3a protein expression was not significantly affected by pregnancy. No change in P-gp protein expression was observed in the liver or kidney during pregnancy, although a significant decrease was observed in the placenta. Because hepatic CYP3A activity also seems to be induced during human pregnancy, the mouse (including CYP3A4-tg mouse) seems to be an excellent animal model to determine the molecular mechanisms for such an induction.
Oxidative stress contributes to muscle wasting in advanced chronic kidney disease (CKD) patients. Atractylenolide III (ATL-III), the major active constituent of Atractylodes rhizome, has been previously reported to function as an antioxidant. This study is aimed at investigating whether ATL-III has protective effects against CKD-induced muscle wasting by alleviating oxidative stress. The results showed that the levels of serum creatinine (SCr), blood urea nitrogen (BUN), and urinary protein significantly decreased in the ATL-III treatment group compared with the 5/6 nephrectomy (5/6 Nx) model group but were higher than those in the sham operation group. Skeletal muscle weight was increased, while inflammation was alleviated in the ATL-III administration group compared with the 5/6 Nx model group. ATL-III-treated rats also showed reduced dilation of the mitochondria, increased CAT, GSH-Px, and SOD activity, and decreased levels of MDA both in skeletal muscles and serum compared with 5/6 Nx model rats, suggesting that ATL-III alleviated mitochondrial damage and increased the activity of antioxidant enzymes, thus reducing the production of ROS. Furthermore, accumulated autophagosomes (APs) and autolysosomes (ALs) were reduced in the gastrocnemius (Gastroc) muscles of ATL-III-treated rats under transmission electron microscopy (TEM) together with the downregulation of LC3-II and upregulation of p62 according to Western blotting. This evidence indicated that ATL-III improved skeletal muscle atrophy and alleviated oxidative stress and autophagy in CKD rats. Furthermore, ATL-III could also increase the protein levels of p-PI3K, p-AKT, and p-mTOR in skeletal muscles in CKD rats. To further reveal the relevant mechanism, the oxidative stress-mediated PI3K/AKT/mTOR pathway was assessed, which showed that a reduced expression of p-PI3K, p-AKT, and p-mTOR in C2C12 myoblast atrophy induced by TNF- α could be upregulated by ATL-III; however, after the overexpression of Nox2 to increase ROS production, the attenuated effect was reversed. Our findings indicated that ATL-III is a potentially protective drug against muscle wasting via activation of the oxidative stress-mediated PI3K/AKT/mTOR pathway.
Introduction: The liver X receptors (LXRs) are members of the nuclear receptor superfamily that regulate sterol metabolism and inflammation. Knockout of LXRs in macrophages greatly accelerates the development of atherosclerosis whereas pharmacological LXR activation has potent athero-protective effects. Previous studies have shown that deletion of LXR target genes in hematopoietic cells can have opposing effects on atherosclerosis development. For example, deletion of ABCA1 using bone marrow transfer in atherogenic mouse models showed increases atherosclerotic plaque burden where as knockout studies of ABCG1 and Aim1 decreased lesion formation in bone marrow transplantation experiments owing to an increase in macrophage apoptosis. Rationale: We sought to identify previously unknown genes regulated by LXRs in macrophages and to determine their contribution to atherogenesis. Methods & Results: We demonstrate that the lipopolysaccharide binding protein (LBP), a secreted glycoprotein, is an LXR target gene in macrophages. Treatment of mouse peritoneal macrophages with modified LDL or oxysterols induces LBP expression, an effect that was lost in LXRαβ-/- macrophages, consistent with a role for LBP in the cellular response to cholesterol overload. To investigate this further, we performed bone marrow transplant studies using WT or LBP-/- donors and LDLR-/- recipients. After 18 weeks of western diet feeding atherosclerotic lesion burden was assessed by en face and aortic root section analysis. LDLR-/- mice receiving LBP-/- bone marrow had markedly smaller lesions compared to those receiving WT (P<0.0001 in en face analysis; P<.01 in root section analysis). Furthermore, loss of bone marrow LBP expression led to a strong increase in apoptosis in atherosclerotic lesions as determined by TUNEL staining. In vitro studies with isolated macrophages and stable cell lines showed that LBP expression does not affect cholesterol efflux but promotes the survival of macrophages in the setting of cholesterol loading. Conclusions: The LBP gene is a macrophage LXR target that promotes foam cell survival and atherogenesis. Our study identifies LBP as a potential diagnostic and therapeutic target in human cardiovascular disease.
Dentatorubral-pallidoluysian atrophy (DRPLA) is a progressive neurodegenerative disease caused by polyglutamine expansion within the Atrophin-1 protein. To study the mechanism of this disease and to test potential therapeutic methods, we established Atro-118Q transgenic mice, which express in neurons a mutant human Atrophin-1 protein that contains an expanded stretch of 118 glutamines. Consistent with the results from previous studies on transgenic mice that expressed mutant Atrophin-1 with 65 glutamines, Atro-118Q mice exhibited several neurodegenerative phenotypes that are commonly seen in DRPLA patients, including ataxia, tremors, and other motor defects. Overexpression of wild-type human Atrophin-1 could not rescue the motor and survival defects in Atro-118Q mice, indicating that the mutant protein with polyglutamine expansion does not simply function in a dominant negative manner. Biochemical analysis of Atro-118Q mice revealed hypoacetylation of histone H3 in brain tissues and thus suggested that global gene repression is an underlying mechanism for neurodegeneration in this mouse model. We further show that intraperitoneal administration of sodium butyrate, a histone deacetylase inhibitor, ameliorated the histone acetylation defects, significantly improved motor performance, and extended the average life span of Atro-118Q mice. These results support the hypothesis that transcription deregulation plays an important role in the pathogenesis of polyglutamine expansion diseases and suggest that reversion of transcription repression with small molecules such as sodium butyrate is a feasible approach to treating DRPLA symptoms.
Muscle mass is regulated by a wide range of hormonal and nutritional signals, such as insulin and IGF. Tuberous sclerosis complex (TSC) is an inherited hamartoma disease with tumor growth in numerous organs. TSC is caused by mutation in either TSC1 or TSC2 tumor suppressor genes that negatively regulate insulin‐induced S6K activation and cell growth. Here we report that expression of human TSC1 (hTSC1) in mouse skeletal muscle leads to reduction of muscle mass. Expression of hTSC1 stabilizes endogenous TSC2 and leads to inhibition of the mTOR signaling. The hTSC1‐mTSC2 hetero‐complex and its downstream components remain sensitive to insulin stimulation and nutrition signals. This study suggests that an increase in the steady state level of resident TSC1–TSC2 complex is sufficient to reduce muscle mass and cause atrophy.
Summary The stable genomic integration and expression of a large transgene is a major hurdle in gene therapy. We show that the modified piggyBac (PB) transposon system can be used to introduce a 207 kb genomic DNA fragment containing the RORγ/γt locus into human cells and mice. PB-mediated transgenesis results in a single copy of a stably inherited and expressed transgene. These results indicate that PB could serve as an effective high-capacity vector for functional analysis of the mammalian genome and for gene therapy in human cells.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)