A phylogenetic analysis of Antrodia s.l. based on nrDNA ITS sequences, with emphasis on rhizomorphic European species

The rhizomorphic European species of Antrodia, belonging to the traditionally called Antrodia radiculosa group, are investigated. On the basis of morphological and molecular analysis, the genus Fibroporia is supported. Specimens from Central Europe previously ascribed to Antrodia radiculosa constitute a species of their own, and are herein described as Fibroporia bohemica. Moreover, a new combination, Fibroporia citrina, is proposed.     

Identification of a posttranslational mechanism for the regulation of hERG1 K+ channel expression and hERG1 current density in tumor cells

A common feature of tumor cells is the aberrant expression of ion channels on their plasma membrane. The molecular mechanisms regulating ion channel expression in cancer cells are still poorly known. K(+) channels that belong to the human ether-a-go-go-related gene 1 (herg1) family are frequently misexpressed in cancer cells compared to their healthy counterparts. We describe here a posttranslational mechanism for the regulation of hERG1 channel surface expression in cancer cells. This mechanism is based on the activity of hERG1 isoforms containing the USO exon. These isoforms (i) are frequently overexpressed in human cancers, (ii) are retained in the endoplasmic reticulum, and (iii) form heterotetramers with different proteins of the hERG family. (iv) The USO-containing heterotetramers are retained intracellularly and undergo ubiquitin-dependent degradation. This process results in decreased hERG1 current (I(hERG1)) density. We detailed such a mechanism in heterologous systems and confirmed its functioning in tumor cells that endogenously express hERG1 proteins. The silencing of USO-containing hERG1 isoforms induces a higher I(hERG1) density in tumors, an effect that apparently regulates neurite outgrowth in neuroblastoma cells and apoptosis in leukemia cells.     

IGF-I alleviates diabetes-induced RhoA activation, eNOS uncoupling, and myocardial dysfunction

IGF-I rescues diabetic heart defects and oxidative stress, although the underlying mechanism of action remains poorly understood. This study was designed to delineate the beneficial effects of IGF-I with a focus on RhoA, Akt, and eNOS coupling. Echocardiography was performed in normal or diabetic Friend Virus-B type (FVB) and IGF-I transgenic mice. Cardiomyocyte contractile properties were evaluated using peak shortening (PS), time-to-90% relengthening (TR90), and intracellular Ca2+ rise and decay. Diabetes reduced fraction shortening, PS, and intracellular Ca2+; it increased chamber size, prolonged TR90, and intracellular Ca2+ decay. Levels of RhoA mRNA, active RhoA, and O2(-) were elevated, whereas nitric oxide (NO) levels were reduced in diabetes. Diabetes-induced O2(-) accumulation was ablated by the NO synthase (NOS) inhibitor nitro-L-arginine methyl ester (L-NAME), indicating endothelial NOS (eNOS) uncoupling, all of which except heart size were negated by IGF-I. The IGF-I-elicited beneficial effects were mimicked by the Rho kinase inhibitor Y27632 and BH4. Diabetes depressed expression of Kv1.2 and dihydrofolate reductase (DHFR), increased beta-myosin heavy-chain expression, stimulated p38 MAPK, and reduced levels of total Akt and phosphorylated Akt/eNOS, all of which with the exception of myosin heavy chain were attenuated by IGF-I. In addition, Y27632 and the eNOS coupler folate abrogated glucose toxicity-induced PS decline, TR90 prolongation, while it increased O2(-) and decreased NO and Kv1.2 levels. The DHFR inhibitor methotrexate impaired myocyte function, NO/O2(-) balance, and rescued Y27632-induced cardiac protection. These results revealed that IGF-I benefits diabetic hearts via Rho inhibition and antagonism of diabetes-induced decrease in pAkt, eNOS uncoupling, and K+ channel expression.     

TGF-beta1 genotypes in cirrhosis: relationship with the occurrence of liver cancer

This study aimed to verify whether specific single nucleotide polymorphisms (SNPs) of the transforming growth factor-beta1 (TGF-beta1) may predispose to end-stage liver disease and/or hepatocellular carcinoma (HCC). One hundred eighty-eight consecutive patients transplanted for liver cirrhosis (HBV N=21, HCV N=68, alcoholic N=55 and others N=23) and a control group of 140 healthy blood donors were investigated. Four SNPs were studied by restriction fragment length assays: -800G>A, -509C>T, Leu10Pro and Arg25Pro. Patients were found to possess the -509T/ * (TT 53/188, CT 85/188, CC 50/188 vs TT 22/140, CT 61/140, CC 57/140; p<0.002) and Arg25Pro C/ * genotypes (CC 1/188, CG 31/188, GG 156/188 vs CC 0/140, CG 13/140, GG 127/140; p<0.05) more frequently than controls. Patients with cirrhosis complicated by HCC possessed more frequently the Leu10Pro T/ * genotype than patients without HCC (TT 20/54, CT 26/54, CC 8/54 vs TT 31/134, CT 69/134, CC 34/134; p<0.05). The analysis of molecular variance detected significant genotypic differentiations between controls and cirrhotics but not between cirrhotics with or without HCC. In conclusion, TGF-beta1 SNPs probably facilitate the development of liver cirrhosis, while they seem to have a limited role in predicting the occurrence of HCC.     

hERG1 Potassium Channel Expression in Colorectal Adenomas: Comparison with Other Preneoplastic Lesions of the Gastrointestinal Tract

Preneoplastic lesions represent a useful target for early diagnosis and follow-up of gastrointestinal malignancies. hERG1 channel expression was tested by immunohistochemistry (IHC) in a cohort of colorectal adenoma samples belonging to Italian subjects. Overall, hERG1 was expressed in 56.5% of cases with both high staining intensity and a high percentage of positive cells. Moreover, hERG1 was expressed in a higher percentage of dysplastic adenomas with respect to hyperplastic lesions, and the proportion of positive samples further increased in patients with high-grade dysplasia. Comparing hERG1 expression in other preneoplastic lesions of the GI tract (gastric dysplasia and Barrett’s esophagus), it emerged that in all the conditions, hERG1 was expressed with a diffused pattern, throughout the cell, with variable staining intensity within the samples. The highest expression was detected in gastric dysplasia samples and the lowest in Barrett’s esophagus at similar levels observed in colorectal adenomas. Our results show that hERG1 is aberrantly expressed in human preneoplastic lesions of the gastrointestinal tract and has a different pattern of expression and role in the different sites. Overall, the detection of hERG1 expression in preneoplastic lesions could represent a novel diagnostic or prognostic marker of progression in the gastrointestinal tract.     

Soluble or Bound Laminin Elicit in Human Neuroblastoma Cells Short- or Long-Term Potentiation of a K+ Inwardly Rectifying Current: Relevance to Neuritogenesis

Changes in the resting potential (V_rest) and in the underlying ionic conductances were measured by the patch-clamp technique in SH-SY5Y human neuroblastoma cells exposed to substrate-bound or soluble Laminin (bLN: sLN), as compared to integrin-independent substrates (polylysine (PL); bovine serum albumin (BSA)). While PL and BSA were ineffective, both forms of LN caused an early (5-15 min) activation of a peculiar type of Inwardly Rectifying K^- current (I,_ir) characterised by a voltage-dependent inactivation in the range of membrane potentials around —50/0 mV. I_ir was blocked by Cs⁺ ions and by the antiarrhythmic drug E-4031, a specific inhibitor of the HERG-codified channels. In cells adherent to bLN, I,_ir potentiation (85%) persisted for 90-120 min and was accompanied by a similar, but transient, increase in the leakage conductance (G_l). Successively, the persistence of a high I_ir conductance and the decrease of G_l progressively bring V_rest from -12 to -30 mV in about 120 min. On the other hand, in cells adherent to PL, exposure to sLN produced a similar but not persistent activation of I_ir, without any increase in G_l: this caused a rapid, transient hyperpolarisation of V_rest The effects of bLN and sLN were mimicked by antibodies raised against the integrin β₁ subunit, suggesting a specific integrin-mediated mechanism. In fact, when bound to the culture dishes, these antibodies simultaneously activated the I_ir and G_l, whereas in soluble form they only activated I_ir. Cells adherent to bLN emitted neurites, a process impaired by the block of I_ir by E-4031 and Cs⁺. On the whole data suggest that the integrin-mediated activation of I_ir plays a crucial role in the commitment to neuritogenesis of neuroblastoma cells, independently on the effects of this activation on V_rest.     

Isoleucine production in bifidobacteria

Summary About 300 strains of bifidobacteria were examined for their capacity to release L-isoleucine in the fermentation broth. A strain of the speciesBifidobacterium ruminale was selected as the best producer. After treatment of this strain with NTG a DL--aminobutyric acid-resistant mutant capable of producing about 5 mg/ml of L-isoleucine in presence of 1.5 % DL--aminobutyric acid was obtained. Cultural conditions and acetohydroxyacid synthetase activity were studied.     

Ubiquitin-Mediated Stress Response in a Rat Model of Brain Transient Ischemia/Hypoxia

Ubiquitin (Ub) is a small 76-residue protein, involved in intracellular protein degradation through a specific ATP-dependent system, which uses Ub as a tag to label proteins committed to be hydrolyzed by a specific 26 S protease. PGP-9.5 is another important component of the Ub system, i.e. a neuron-specific carboxyl-terminal hydrolase, which recycles Ub from Ub-polypeptide complexes. We have investigated the expression of Ub and PGP-9.5 in rat hippocampal neurons in an early phase of reperfusion in a model of transient global brain ischemia/hypoxia (bilateral occlusion of common carotid arteries for 10 min accompanied by mild hypoxia—15% O₂—for 20 min), by means of immunohistochemical methods using light and electron microscopy. The intensity of Ub and PGP-9.5 immunoreactivity was evaluated by image analysis. We have detected a marked increase of Ub immunoreactivity (UIR) in neurons of CA1, CA2, CA3, CA4, and dentate gyrus subfields 1 hr after ischemia/hypoxia (but not after hypoxia only), statistically significant as confirmed by image analysis. Such increase in immunoreactivity in ischemic/hypoxic rats was localized essentially in the nuclei of hippocampal neurons. There were no changes in PGP-9.5 immunoreactivity. The data suggest that in the present model of rat brain ischemia/hypoxia Ub is involved in the neuronal stress response.