Hypoxia followed by reoxygenation induces secretion of cyclophilin A from cultured rat cardiac myocytes

We previously reported that hypoxia followed by reoxygenation (hypoxia/reoxygenation) rapidly activated intracellular signaling such as mitogen-activated protein kinases (MAPKs) including extracellular signal-regulated protein kinase (ERK) 1/2, p38MAPK, and stress-activated protein kinases (SAPKs). To investigate the humoral factors which mediate cardiac response to hypoxia/reoxygenation, we analyzed the conditioned media from cardiac myocytes subjected to hypoxia/reoxygenation by two-dimensional electrophoresis and mass spectrometry. We identified cyclophilin A (CyPA) as one of the proteins secreted from cardiac myocytes in response to hypoxia/reoxygenation. Hypoxia/reoxygenation induced the expression of CyPA and its cell surface receptor CD147 on cardiac myocytes in vitro. This was also confirmed by ischemia/reperfusion in vivo. Recombinant human (rh) CyPA activated ERK1/2, p38MAPK, SAPKs, and Akt in cultured cardiac myocytes. Furthermore, CyPA significantly increased Bcl-2 in cardiac myocytes. These data strongly suggested that CyPA is released from cardiac myocytes in response to hypoxia/reoxygenation and may protect cardiac myocytes from oxidative stress-induced apoptosis.     

Expression of zebrafish glutamate receptor delta2 in neurons with cerebellum-like wiring

Mammalian glutamate receptor (GluR) delta2 is selectively expressed in cerebellar Purkinje cells and plays key roles in cerebellar plasticity, motor learning, and neural wiring. Here, we isolated cDNA encoding the zebrafish ortholog of mammalian GluRdelta2. We found that in adult zebrafish brain, glurdelta2 mRNA was expressed not only in cerebellar Purkinje cells, but also in the crest cells of the medial octavolateral nucleus (MON) and the type I neurons of the optic tectum. Immunohistochemical analysis revealed that zebrafish GluRdelta2 proteins were selectively localized in the apical dendrites of these neurons. Interestingly, the crest cells of the MON and the type I neurons of the optic tectum receive large numbers of parallel fiber inputs at the apical dendrites and sensory inputs at the proximal or basal dendrites. These results suggest that the expression of zebrafish GluRdelta2 is selective for cerebellum-like neural wiring with large numbers of parallel fiber inputs.     

Nonylphenol induces the death of neural stem cells due to activation of the caspase cascade and regulation of the cell cycle

Endocrine disruptors (EDs) are a great concern throughout the world, because they have adverse effects on human health and wildlife. In the present study, we investigated the effects of EDs on the proliferation and survival of murine neural stem cells (NSCs). In contrast to bisphenol A, phthalic acid benzyl n-butyl ester, phthalic acid di-n-butyl ester and phthalic acid di(2-ethylhexyl) ester, the treatment of NSCs with 4-nonylphenol for 24 h inhibited cell growth in a concentration-dependent manner. In addition, treatment with 4-nonylphenol resulted in nuclear condensation and DNA fragmentation (morphological changes due to apoptosis) in NSCs after 12 h of exposure, and activated caspase-3 after 6 h and 9 h of exposure. Furthermore, an exposure to 4-nonylphenol led to the accumulation of cells at the G2/M phase interface and down-regulated the protein levels of cyclin A and B1, which are the major regulatory proteins at the G2 to M transition of the cell cycle. Together, these results indicate that, in contrast to other EDs, 4-nonylphenol may exhibit a potent cytotoxicity through apoptosis via the caspase cascade and cell cycle arrest at the G2/M phase, and suggest that 4-nonylphenol may affect neurogenesis in the CNS.     

Motor activity and gene expression in rats with neonatal 6-hydroxydopamine lesions

A rat model of a hyperkinetic disorder was used to investigate the mechanisms underlying motor hyperactivity. Rats received an intracisternal injection of 6-hydroxydopamine on post-natal day 5. At 4 weeks of age, the animals showed significant motor hyperactivity during the dark phase, which was attenuated by methamphetamine injection. Gene expression profiling was carried out in the striatum and midbrain using a DNA macroarray. In the striatum at 4 weeks, there was increased gene expression of the NMDA receptor 1 and tachykinins, and decreased expression of a GABA transporter. At 8 weeks, expression of the NMDA receptor 1 in the striatum was attenuated, with enhanced expression of the glial glutamate/aspartate transporter. In the midbrain, a number of genes, including the GABA transporter gene, showed decreased expression at 4 weeks. At 8 weeks, gene expression was augmented for the dopamine transporter, D4 receptor, and several genes encoding peptides, such as tachykinins and their receptors. These results suggest that in the striatum the neurotransmitters glutamate, GABA and tachykinin may play crucial roles in motor hyperactivity during the juvenile period. Several classes of neurotransmitters, including dopamine and peptides, may be involved in compensatory mechanisms during early adulthood. These data may prompt further neurochemical investigations in hyperkinetic disorders.     

Ald6p is a preferred target for autophagy in yeast, Saccharomyces cerevisiae

Macroautophagy is the process of intracellular bulk protein degradation induced by nutrient starvation and is generally considered to be a nonselective degradation of cytosolic enzymes and organelles. However, it remains a possibility that some proteins may be preferentially degraded by autophagy. In this study, we have performed a systematic analysis on the substrate selectivity of autophagy in yeast, Saccharomyces cerevisiae, using two-dimensional PAGE. We performed a differential screen on wild-type and Deltaatg7/apg7 autophagy-deficient cells and found that cytosolic acetaldehyde dehydrogenase (Ald6p) decreased under nitrogen starvation. As assessed by immunoblot, Ald6p was reduced by greater than 82% after 24 h of nitrogen starvation. This reduction was dependent on Atg/Apg proteins and vacuolar proteases but was not dependent on the proteasome or the cytoplasm to vacuole targetting (Cvt) pathway. Using pulse-chase and subcellular fractionation, we have also demonstrated that Ald6p was preferentially transported to vacuoles via autophagosomes. Deltaatg7 Deltaald6 double mutant cells were able to maintain higher rates of viability than Deltaatg7 cells under nitrogen starvation, and Ald6p-overexpressing cells were not able to maintain high rates of viability. Furthermore, the Ald6p(C306S) mutant, which lacks enzymatic activity, had viability rates similar to Deltaald6 cells. Ald6p enzymatic activity may be disadvantageous for survival under nitrogen starvation; therefore, yeast cells may preferentially eliminate Ald6p via autophagy.     

Allocation to defense or growth in dipterocarp forest seedlings in Borneo

We quantified the allocation of net production to plant secondary metabolites (especially condensed tannins and lignins) to evaluate the investment into defense mechanisms of three tropical forest canopy species in Borneo vis-à-vis the resource availability hypothesis. In particular, we focused on Borneo ironwood (Eusideroxylon zwageri, Lauraceae), which seemed to employ an extreme defensive strategy. The wood of this species is extremely durable and has a high specific gravity with a very slow growth rate. The allocation to defense by Borneo ironwood was compared to two emergent species of Dipterocarpaceae, the dominant family in this forest community. We conducted shade-house experiments on seedlings under four controlled conditions (two light levels × two nutrient levels) and showed that the growth rate of E. zwageri was much lower than those of the other two species, and it allocated more of its net production to leaves and roots than to stems. The concentrations of condensed tannins and lignins were very high in the leaves and stems of this species, at about 20 and 30%, respectively. In total, E. zwageri allocated a maximum of about 35% of its net production to defensive substances (i.e., condensed tannins + lignins). In contrast, the two dipterocarp species allocated about 20–25% of their net production to defensive substances. The condensed tannins in E. zwageri help to prolong the lifespan of the leaves, and the lignins in the stems enhance the durability of the wood. Thus, although E. zwageri grows very slowly, the allocation to defensive substances seems to be an advantageous strategy for survival under dark conditions.An erratum to this article can be found at     

Cyclic azaphilones daldinins E and F from the ascomycete fungus Hypoxylon fuscum (Xylariaceae)

Phytochemical examination of the methanolic extract of fruit bodies of the Xylariaceous ascomycete fungus Hypoxylon fuscum led to the isolation of two azaphilone derivatives named daldinins E and F together with two known compounds daldinin C and 4,5,4',5'-tetrahydroxy-1:1'-binaphthyl using a combination of reversed phase HPLC and high performance gel permeation chromatography. Their structures were determined by 2D NMR, MS, IR, UV, and CD spectroscopy. Their antioxidative activities were also estimated by an indication of a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging effect. The chemosystematics of Hypoxylon is discussed.     

Thelephantins I-N; p-terphenyl derivatives from the inedible mushroom Hydnellum caeruleum

Phytochemical investigation of the methanolic extract of the fruiting bodies of the inedible mushroom Hydnellum caeruleum resulted in the isolation of six p-terphenyl derivatives named thelephantins I-N (1-6), together with a known compound, dihydroaurantiacin dibenzoate (7). These structures were determined by high-resolution MS, 2D NMR, IR and UV spectroscopic analysis, and by the chemical reactions.