Differential expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta actin and hypoxanthine phosphoribosyltransferase (HPRT) in postnatal rabbit sclera

Reference gene identification and validation for quantitative real-time PCR studies in developing Xenopus laevis

Reference genes are essential for gene expression analysis when using real-time quantitative PCR (RT-qPCR). Xenopus laevis is a popular amphibian model for studying vertebrate embryogenesis and development. Further, X. laevis is ideal for studying thyroid signaling due to its thyroid dependent metamorphosis, a stage comparable to birth in humans. When using PCR based studies, a primary concern is the choice of reference genes. Commonly used references are eef1a1, odc1, rpl8, and actnB, although there is a lack of ad hoc reference genes for X. laevis. Here, we used previously published RNA-seq data on different X. laevis stages and identified the top 14 candidate genes with respect to their expression levels as a function of developmental stage and degree of variation. We further evaluated the stability of these and other candidate genes using RT-qPCR on various stages including the unfertilised eggs, whole embryos during early development and brains during late development. We used four different statistical software packages: deltaCT, geNorm, NormFinder and BestKeeper. We report optimized reference gene pair combinations for studying development (early whole embryos), brains at later stages (metamorphosis and adult), and  thyroid signalling. These reference gene pairs are suitable for studying different aspects of X. laevis development and organogenesis.

Tumor necrosis factor-α-induced nuclear factor-kappaB activation in human cardiomyocytes is mediated by NADPH oxidase

An elevated level of tumor necrosis factor (TNF)-α is implicated in several cardiovascular diseases including heart failure. Numerous reports have demonstrated that TNF-α activates nuclear factor (NF)-kappaB, resulting in the upregulation of several genes that regulate inflammation, proliferation, and apoptosis of cardiomyocytes. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, a major source of reactive oxygen species (ROS), is also activated by TNF-α and plays a crucial role in redox-sensitive signaling pathways. The present study investigated whether NADPH oxidase mediates TNF-α-induced NF-kappaB activation and NF-kappaB-mediated gene expression. Human cardiomyocytes were treated with recombinant TNF-α with or without pretreatment with diphenyleneiodonium (DPI) and apocynin, inhibitors of NADPH oxidase. TNF-α-induced ROS production was measured using 5-(and-6)-chloromethyl-2', 7'-dichlorodihydrofluorescein diacetate assay. TNF-α-induced NF-kappaB activation was also examined using immunoblot; NF-kappaB binding to its binding motif was determined using a Cignal reporter luciferase assay and an electrophoretic mobility shift assay. TNF-α-induced upregulation of interleukin (IL)-1β and vascular cell adhesion molecule (VCAM)-1 was investigated using real-time PCR and immunoblot. TNF-α-induced ROS production in cardiomyocytes was mediated by NADPH oxidase. Phosphorylation of IKK-α/β and p65, degradation of IkappaBα, binding of NF-kappaB to its binding motif, and upregulation of IL-1β and VCAM-1 induced by TNF-α were significantly attenuated by treatment with DPI and apocynin. Collectively, these findings demonstrate that NADPH oxidase plays a role in regulation of TNF-α-induced NF-kappaB activation and upregulation of proinflammatory cytokines, IL-1β and VCAM-1, in human cardiomyocytes.

Senescence is accelerated through donor cell specificity in cloned pigs

Animals cloned by somatic cell nuclear transfer (SCNT) sometimes have abnormalities that result in large offspring syndrome or early death during gestation due to respiratory and metabolic defects. We cloned pigs using two sources of donor cells and observed phenotypic anomalies in three pigs cloned from one type of cell, s-pig fetal fibroblasts. These animals had many wrinkles on their faces and bodies and looked older than age-matched normal pigs. We performed the present study to examine whether the wrinkled phenotype in the cloned pigs was due to senescence, a genetic problem with donor specificity, or epigenetic problems with reprogramming. To address this issue, we investigated biomarkers of senescence, including telomere length and the expression of senescence-associated β-galactosidase (SA-β-gal), glyceraldehyde phosphate dehydrogenase (GAPDH) and β-actin. We also assessed the methylation status of euchromatic PRE-1 repetitive sequences and centromeric satellite DNA, and measured the mRNA levels of six imprinted genes, Copg2, Mest, Igf2R, GNAS, SNRPN and Ube3a. The telomeres of the wrinkled cloned pigs were much shorter than those of the normal cloned pigs and age-matched normal pigs. In the wrinkled cloned pigs, SA-β-gal activity was detected and GAPDH and β-actin were repressed. The mRNA levels of Mest, GNAS and Ube3a were reduced in the wrinkled cloned pigs, although there was no difference between the normal cloned pigs and normal controls. This gene expression analysis indicates that the wrinkled abnormality of our pigs originates from genetic abnormalities in the donor cells used for SCNT.

Nox2 and Nox4 mediate tumour necrosis factor-α-induced ventricular remodelling in mice

Reactive oxygen species (ROS) and pro-inflammatory cytokines are crucial in ventricular remodelling, such as inflammation-associated myocarditis. We previously reported that tumour necrosis factor-α (TNF-α)-induced ROS in human aortic smooth muscle cells is mediated by NADPH oxidase subunit Nox4. In this study, we investigated whether TNF-α-induced ventricular remodelling was mediated by Nox2 and/or Nox4. An intravenous injection of murine TNF-α was administered to a group of mice and saline injection was administered to controls. Echocardiography was performed on days 1, 7 and 28 post-injection. Ventricular tissue was used to determine gene and protein expression of Nox2, Nox4, ANP, interleukin (IL)-1β, IL-2, IL-6, TNF-α and to measure ROS. Nox2 and Nox4 siRNA were used to determine whether or not Nox2 and Nox4 mediated TNF-α-induced ROS and upregulation of IL-1β and IL-6 in adult human cardiomyocytes. Echocardiography showed a significant increase in left ventricular end-diastolic and left ventricular end-systolic diameters, and a significant decrease in the ejection fraction and fractional shortening in mice 7 and 28 days after TNF-α injection. These two groups of mice showed a significant increase in ventricular ROS, ANP, IL-1β, IL-2, IL-6 and TNF-α proteins. Nox2 and Nox4 mRNA and protein levels were also sequentially increased. ROS was significantly decreased by inhibitors of NADPH oxidase, but not by inhibitors of other ROS production systems. Nox2 and Nox4 siRNA significantly attenuated TNF-α-induced ROS and upregulation of IL-1β and IL-6 in cardiomyocytes. Our study highlights a novel TNF-α-induced chronic ventricular remodelling mechanism mediated by sequential regulation of Nox2 and Nox4 subunits.

Dopamine increases L-type calcium current more in newborn than adult rabbit cardiomyocytes via D1 and β2 receptors

Dopamine is used to treat heart failure, particularly after cardiac surgery in infants, but the mechanisms of action are unclear. We investigated differences in the effect of dopamine on L-type calcium current ( ICa) between newborn (NB, 1–4 days) and adult (AD, 3–4 mo) rabbit ventricular myocytes. Myocytes were enzymatically dissociated from NB and AD rabbit hearts. ICa was recorded by using the whole cell patch-clamp technique. mRNA levels of cardiac dopamine receptor type 1 (D1), type 2 (D2), and β-adrenergic receptors (β-ARs) were measured by real-time RT-PCR. Dopamine (100 μM) increased ICa more in NB (Emax 87 ± 10%) than in AD ventricular cells (Emax 21 ± 3%). Further investigation of this difference showed that mRNA levels of the D1 receptor were significantly higher in NB, and, with β-AR blockade, dopamine increased ICa more in NB than AD cells. Additionally, SKF-38393 (selective D1 receptor agonist) significantly increased ICa by 55 ± 4% in NB ( P < 0.05, n = 4) and by 11 ± 1% in AD ( P < 0.05, n = 6). Dopamine in the presence of SCH-23390 (D1 receptor antagonist) increased ICa in NB cells by 67 ± 5% and by 22 ± 2% in AD cells, suggesting a role for β-AR stimulation. Selective blockade of β1- or β2-receptors (with block of D1 receptors) showed that the β-AR action of dopamine in the NB was largely mediated via β2-AR activation. Dopamine produces a larger increase in ICa in NB cardiomyocytes compared with ADs. The mechanism of action is not only through β2-ARs but also due to higher expression of cardiac D1 receptor in NB.

Genomic and proteomic determinants of lower extremity revascularization failure: rationale and study design

This translational research program applies a working model of advanced functional genomics/proteomics and bioinformatics to human peripheral arterial occlusive disease (PAOD). It is a multidisciplinary collaborative effort of clinicians, scientists, and statisticians with an advisory panel consisting of experts in inflammation biology, vascular biology, molecular genetics, bioinformatics, clinical trial design, and epidemiology. The proposed human initiative is designed to study 300 symptomatic patients with PAOD undergoing medical management with or without vascular intervention by lower extremity angioplasty/stenting or vein graft bypass. The study aims to test the hypothesis that the systemic inflammatory response after vascular intervention influences the local milieu responsible for vascular repair and adaptation. The expectation is that this response is not uniform in all patients but, rather, is modulated by either preoperative genetic predisposition or postprocedure differential regulation of the innate immune response to injury that promotes a maladaptive phenotype leading to intervention failure. Therefore, some of these differences may be present and detectable before intervention and amenable to class prediction and prospective treatment strategies, whereas others may be detectable in the early postprocedural period, before the onset of clinical failure, permitting interventions to prevent an adverse outcome. The combination of genomic/proteomic data together with functional and quality-of-life outcome measures to define a critical model for class prediction and analysis should lead to new knowledge about failure mechanisms of vascular intervention and new strategies to improve existing approaches to lower extremity revascularization.

Expression, microsomal and mitochondrial activities of cytochrome P450 enzymes in brain regions from control and phenobarbital-treated rabbits

Expression and monooxygenase activity of various cytochrome P450 (CYP) enzymes along with constitutive androstane (CAR) and the pregnane X (PXR) receptors were investigated in the brain of control and phenobarbital-treated rabbits (80 mg/kg for 4 days). RT-PCR analysis, using specific primers, demonstrated that in control rabbits mRNAs of CYP 2A10, 2B4/5 and 3A6 were expressed, though to a different extent, in the liver, as well as in brain cortex, midbrain, cerebellum, striatum, hippocampus and hypothalamus, whilst CYP2A11 and 4B1 were not expressed in the hypothalamus. CAR was expressed in liver and all the brain regions examined, whereas the PXR was expressed only in liver and cortex. Real time RT-PCR analysis demonstrated that in vivo treatment with phenobarbital, in contrast with what happened in liver, did not induce the expression of CYP 2B4/5 mRNA in cortex, midbrain and cerebellum. NADPH cytochrome c reductase and some other enzymatic activities markers of CYP 2A, 2B, 3A and 4B activities were studied in liver microsomes as well as in microsomes and mitochondria of brain cortex, midbrain and cerebellum of control and phenobarbital-treated rabbits. In contrast to what was observed in liver, phenobarbital treatment did not induce the aforementioned monooxygenase activities in brain. However, we cannot exclude that a longer phenobarbital treatment may lead to a significant induction of CYP activities in brain. These findings indicated that brain CYPs, despite the presence of CAR, were resistant to phenobarbital induction, indicating a possible different regulation of these enzymes between brain and liver.

Differential upregulation of Nox homologues of NADPH oxidase by tumor necrosis factor-alpha in human aortic smooth muscle and embryonic kidney cells

NADPH oxidases are important sources of vascular superoxide, which has been linked to the pathogenesis of atherosclerosis. Previously we demonstrated that the Nox4 subunit of NADPH oxidase is a critical catalytic component for superoxide production in quiescent vascular smooth muscle cells. In this study we sought to determine the role of Nox4 in superoxide production in human aortic smooth muscle cells (AoSMC) and embryonic kidney (HEK293) cells under proinflammatory conditions. Incubation with tumor necrosis factor-α (TNF-α, 10 ng/ml) for 12h increased superoxide production in both cell types, whereas angiotensin II, platelet-derived growth factor or interleukin-1β had little effects. Superoxide production was completely abolished by the NADPH oxidase inhibitors diphenyline iodonium and apocynin, but not by inhibitors of xanthine oxidase, nitric oxide synthase or mitochondrial electron transport. TNF-α upregulated the expression of Nox4 in AoSMC at both message and protein levels, while Nox1 and Nox2 were unchanged. In contrast, upregulation of Nox2 appeared to mediate the enhanced superoxide production by TNF-α in HEK293 cells. We suggest that Nox4 may be involved in increased superoxide generation in vascular smooth muscle cells under proinflammatory conditions.

Routine expression profiling of microarray gene signatures in acute leukaemia by real-time PCR of human bone marrow

Cancer subtype diagnosis using microarray signatures has the potential to transform pathological diagnosis but the routine measurement of genes signatures remains difficult. Reverse transcription polymerase chain reaction (RT-PCR) measurement of Indicator genes for acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL) was used to determine gene signatures. Bone marrow (BM) mononuclear cells were sorted into total, CD34(+) and CD34(-) fractions, and mRNAs globally amplified from each fraction using polyA PCR. The expression profile of the 17 top-ranked genes distinguishing AML and ALL were measured by RT-PCR in five ALL, 26 AML, 12 AML remission, four chronic myeloid leukaemia (CML) and nine morphologically normal BM samples. All but two of the genes measured showed similar expression in AML and ALL to that reported previously. Specifically, c-MYB (P </= 0.04) was significantly increased in ALL in the total fraction, whilst HOXA9 (P </= 0.19) and cystatin c (P </= 0.01) were increased in AML in the CD34(+) and CD34(-) fractions, respectively. c-MYB, hSNF2, RBAP48, HKRT-1, LYN, CD33, Adipsin and HOXA9 were increased in AML compared with remission AML, indicating an ability to determine disease activity. The method used is simple, sensitive and robust, enabling routine clinical use, and it can also be extended to other tumours types with gene signatures.

Developmental evolution of the delayed rectifier current IKs in canine heart appears dependent on the beta subunit minK

OBJECTIVES

We tested the hypothesis that the developmental changes occurring in I(Kr) and I(Ks) can be explained by changes in the expression of ERG encoding I(Kr), and KCNQ1, the beta subunit minK, and the recently reported subunit FHL2 encoding I(Ks).

BACKGROUND

The delayed rectifier current contributes importantly to the developmental evolution of the canine myocardial action potential. Specifically, in left ventricular epicardial myocytes, I(Ks) is absent and I(Kr) is the major repolarizing current until age 4 weeks. With subsequent development, I(Ks) density increases and I(Kr) decreases, resulting in an altered voltage-time course of repolarization.

METHODS

We used Western blotting and real-time polymerase chain reaction to compare the expression of ERG, KCNQ1, minK, and FHL2 in 1-week-old pups and adult dogs.

RESULTS

ERG levels are high at 1 week and decrease significantly with age, consistent with developmental decrease in I(Kr). Whereas expression of KCNQ1 and FHL2 is unchanged between the two age groups, minK is minimally expressed at 1 week and increases in adults, consistent with developmental increase in I(Ks).

CONCLUSIONS

A reduction in ERG explains the developmental decrease in I(Kr), whereas the accessory subunit minK appears to be the critical determinant of developmental evolution of I(Ks).