ß-Lapachone ameliorates lipotoxic cardiomyopathy in acyl CoA synthase transgenic mice.

Lipotoxic cardiomyopathy is caused by myocardial lipid accumulation and often occurs in patients with diabetes and obesity. This study investigated the effects of ß-lapachone (ß-lap), a natural compound that activates Sirt1 through elevation of the intracellular NAD+ level, on acyl CoA synthase (ACS) transgenic (Tg) mice, which have lipotoxic cardiomyopathy. Oral administration of ß-lap to ACS Tg mice significantly attenuated heart failure and inhibited myocardial accumulation of triacylglycerol. Electron microscopy and measurement of mitochondrial complex II protein and mitochondrial DNA revealed that administration of ß-lap restored mitochondrial integrity and biogenesis in ACS Tg hearts. Accordingly, ß-lap administration significantly increased the expression of genes associated with mitochondrial biogenesis and fatty acid metabolism that were down-regulated in ACS Tg hearts. ß-lap also restored the activities of Sirt1 and AMP-activated protein kinase (AMPK), the two key regulators of metabolism, which were suppressed in ACS Tg hearts. In H9C2 cells, ß-lap-mediated elevation of AMPK activity was retarded when the level of Sirt1 was reduced by transfection of siRNA against Sirt1. Taken together, these results indicate that ß-lap exerts cardioprotective effects against cardiac lipotoxicity through the activation of Sirt1 and AMPK. ß-lap may be a novel therapeutic agent for the treatment of lipotoxic cardiomyopathy.

Developmental expression of Pitx2c in Xenopus trigeminal and profundal placodes.

Cranial placodes are thickenings of the embryonic head ectoderm that contribute to the paired sense organs and to the cephalic peripheral nervous system. Here we report the spatiotemporal expression pattern of transcription factor Pitx2c during Xenopus laevis cranial placode formation, focusing more specifically on key stages of trigeminal and profundal placode development. We also compare its expression to five genes that have been associated with development of these sensory placodes, namely Foxi1c, Islet1, NeuroD, Pax3, and Six1. We show that while initially expressed in both the trigeminal and profundal placodes, Pitx2c is later restricted to the prospective profundal ganglion, where it is co-expressed with Islet1, NeuroD and Pax3. This combination of factors defines a molecular signature for the characterization of the profundal versus trigeminal ganglia in Xenopus.

PICOT is a critical regulator of cardiac hypertrophy and cardiomyocyte contractility.

PICOT (PKC-interacting cousin of thioredoxin) was previously shown to inhibit the development of cardiac hypertrophy, concomitant with an increase in cardiomyocyte contractility. To explore the physiological function of PICOT in the hearts, we generated a PICOT-deficient mouse line by using a gene trap approach. PICOT(-/-) mice were embryonic lethal indicating that PICOT plays an essential role during embryogenesis, whereas PICOT(+/-) mice were viable with no apparent morphological defects. The PICOT protein levels were reduced by about 50% in the hearts of PICOT(+/-) mice. Significantly exacerbated cardiac hypertrophy was induced by pressure overload in PICOT(+/-) mice relative to that seen in wild type littermates. In line with this observation, calcineurin-NFAT signaling was greatly enhanced by pressure overload in the hearts of PICOT(+/-) mice. Cardiomyocytes from PICOT(+/-) mice exhibited significantly reduced contractility, which may be due in part to hypophosphorylation of phospholamban and reduced SERCA activity. These data indicate that the precise PICOT protein level significantly affects the process of cardiac hypertrophy and cardiomyocyte contractility. We suggest that PICOT plays as a critical negative regulator of cardiac hypertrophy and a positive inotropic regulator.

Flavonoids purified from Rhus verniciflua Stokes actively inhibit cell growth and induce apoptosis in human osteosarcoma cells.

Many studies have suggested that dietary flavonoids are anticancer agents that induce the apoptosis of cancer cells. However, the effects of flavonoids on the induction of apoptosis in osteosarcoma cells are unclear. Previously, a flavonoid fraction, consisting mainly of protocatechuic acid, fustin, fisetin, sulfuretin, and butein, herein named RCMF (the RVS chloroform-methanol fraction), was prepared from a crude acetone extract of Rhus verniciflua Stokes (RVS). This study evaluated the effects of RCMF on the proliferation and apoptosis using human osteosarcoma (HOS) cells. The mechanism of growth inhibition of the HOS cells by the flavonoid fraction, RCMF, was also assessed. The results demonstrated that RCMF exhibited sensitive growth inhibition and induced apoptosis in HOS cells. PARP cleavage was closely associated with the RCMF-induced apoptosis of the HOS cells. Furthermore, the activation of caspase 8 and Bax, the inhibition of Bcl-2 expression, and the release of cytochrome c are believed to be involved in the RCMF-mediated apoptosis. Collectively, these findings suggest that RCMF is an agent which may be capable of inducing sensitive growth inhibition and apoptosis in HOS cells.

Regulatory roles of conserved intergenic domains in vertebrate Dlx bigene clusters.

Dlx homeobox genes of vertebrates are generally arranged as three bigene clusters on distinct chromosomes. The Dlx1/Dlx2, Dlx5/Dlx6, and Dlx3/Dlx7 clusters likely originate from duplications of an ancestral Dlx gene pair. Overlaps in expression are often observed between genes from the different clusters. To determine if the overlaps are a result of the conservation of enhancer sequences between paralogous clusters, we compared the Dlx1/2 and the Dlx5/Dlx6 intergenic regions from human, mouse, zebrafish, and from two pufferfish, Spheroides nephelus and Takifugu rubripes. Conservation between all five vertebrates is limited to four sequences, two in Dlx1/Dlx2 and two in Dlx5/Dlx6. These noncoding sequences are >75% identical over a few hundred base pairs, even in distant vertebrates. However, when compared to each other, the four intergenic sequences show a much more limited similarity. Each intergenic sequence acts as an enhancer when tested in transgenic animals. Three of them are active in the forebrain with overlapping patterns despite their limited sequence similarity. The lack of sequence similarity between paralogous intergenic regions and the high degree of sequence conservation of orthologous enhancers suggest a rapid divergence of Dlx intergenic regions early in chordate/vertebrate evolution followed by fixation of cis-acting regulatory elements.