Identification and characterization of multiple osmotic response sequences in the human aldose reductase gene

Aldose reductase (AR) has been implicated in osmoregulation in the kidney because it reduces glucose to sorbitol, which can serve as an osmolite. Under hyperosmotic stress, transcription of this gene is induced to increase the enzyme level. This mode of osmotic regulation of AR gene expression has been observed in a number of nonrenal cells as well, suggesting that this is a common response to hyperosmotic stress. We have identified a 132-base pair sequence 1 kilobase pairs upstream of the transcription start site of the human AR gene that enhances the transcription activity of the AR promoter as well as that of the SV40 promoter when the cells are under hyperosmotic stress. Within this 132-base pair sequence, there are three sequences that resemble TonE, the tonicity response element of the canine betaine transporter gene, and the osmotic response element of the rabbit AR gene, suggesting that the mechanism of osmotic regulation of gene expression in these animals is similar. These three sequences are designated as OreA, OreB, and OreC respectively, Analysis of the mouse AR gene also revealed that these three sequences are highly conserved between the mouse and human. Results from site-directed mutagenesis and gel mobility shift assays suggested that the OreC is the most important element for the osmotic response and cooperative interaction among the three elements in the human AR gene is essential for their enhancer function. The human aldose reductase gene osmotic response elements are the first osmotic response elements characterized in human.published_or_final_versio

Tetrandrine, an activator of autophagy, induces autophagic cell death via PKC-α inhibition and mTOR-dependent mechanisms.

Emerging evidence suggests the therapeutic role of autophagic modulators in cancer therapy. This study aims to identify novel traditional Chinese medicinal herbs as potential anti-tumor agents through autophagic induction, which finally lead to autophagy mediated-cell death in apoptosis-resistant cancer cells. Using bioactivity-guided purification, we identified tetrandrine (Tet) from herbal plant, Radix stephaniae tetrandrae, as an inducer of autophagy. Across a number of cancer cell lines, we found that breast cancer cells treated with tetrandrine show an increase autophagic flux and formation of autophagosomes. In addition, tetrandrine induces cell death in a panel of apoptosis-resistant cell lines that are deficient for caspase 3, caspase 7, caspase 3 and 7, or Bax-Bak respectively. We also showed that tetrandrine-induced cell death is independent of necrotic cell death. Mechanistically, tetrandrine induces autophagy that depends on mTOR inactivation. Furthermore, tetrandrine induces autophagy in a calcium/calmodulin-dependent protein kinase kinase-β (CaMKK-β), 5′ AMP-activated protein kinase (AMPK) independent manner. Finally, by kinase profiling against 300 WT kinases and computational molecular docking analysis, we showed that tetrandrine is a novel PKC-α inhibitor, which lead to autophagic induction through PKC-α inactivation. This study provides detailed insights into the novel cytotoxic mechanism of an anti-tumor compound originated from the herbal plant, which may be useful in promoting autophagy mediated- cell death in cancer cell that is resistant to apoptosis.published_or_final_versio

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Methanogen population in a marine biofilm corrosive to mild steel

This study was conducted to analyze the methanogen population in a corrosive marine biofilm based on 16S rDNA analysis, using a PCR-cloning-sequencing approach. There were 80 methanogen clones developed from the PCR-amplified DNA extracted from the biofilm on the mild steel surface. All clones were categorized into one of five operational taxonomy units (OTUs). Two OTUs (comprising 57 clones) were affiliated with the acetotrophic Methanosaeta genus; the remaining three OTUs (23 clones) were affiliated with the hydrogenotrophic genera of Methanogenium, Methanoplanus and Methanocalculus. The hydrogenotrophic methanogens could directly cause metal corrosion through cathodic depolarization, whereas the acetotrophic methanogens grew syntrophically with corrosion-causing sulfate-reducing bacteria, as observed by fluorescent in situ hybridization, and thus contribute indirectly to metal corrosion.link_to_subscribed_fulltex

Pseudolaric acids: Isolation, bioactivity and synthetic studies

The pseudolaric acids are diterpenoids isolated from the root bark of Pseudolarix amabilis, or the golden larch. Pseudolaric acids A and B are the major antifungal and anti-angiogenic congeners of this family of compounds. This review presents the results of the isolation, biological and synthetic studies of these natural products. © 2010 The Royal Society of Chemistry.link_to_subscribed_fulltex

Depletion of sirtuin 1 (SIRT1) leads to epigenetic modifications of telomerase (TERT) gene in hepatocellular carcinoma cells

201812 bcrcVersion of RecordRGC467210Publishe

An (A-C)(n) dinucleotide repeat polymorphic marker at the 5' end of the aldose reductase gene is associated with early-onset diabetic retinopathy in NIDDM patients

To study the relationship between the aldose reductase gene and diabetic complications, an (A-C)(n) dinucleotide repeat sequence 2.1 kb upstream of the transcription start site of this gene was identified and studied. There are seven alleles at this locus with a polymorphism information content of 0.73 and a heterozygosity of 0.77 among the Chinese population in Hong Kong. One of the alleles (Z-2) was found to be associated with early onset of retinopathy in patients with non-insulin-dependent diabetes (P = 0.007), suggesting that aldose reductase or a gene in the close vicinity may be involved in the pathogenesis of this diabetic complication.link_to_subscribed_fulltex

Overexpression of aldose reductase in liver cancers may contribute to drug resistance

We previously found that about 29% of human liver cancers overexpressed aldose reductase (AR) and about 54% of them overexpressed an AR-like gene called ARL-1 that has similar enzymatic activities to AR. Since these aldo-keto reductases can reduce a broad spectrum of substrates including cytotoxic aldehydes, we were interested to find out if these enzymes can contribute to the resistance of liver cancer chemotherapy by inactivating some of the anticancer drugs. HepG2 cells, a stable line of liver cells, were induced to overexpress AR by hypertonicity. Cells that were cultured in hypertonic medium became more resistant to daunorubicin, suggesting that ovarexpression of AR made the cells more resistant to this drug. This is confirmed by the fact that addition of AR inhibitor sensitizes the cells to this drug again. This information may be important for designing new drugs to treat this deadly disease. © 2001 Lippincott Williams & Wilkins.link_to_subscribed_fulltex

Diabetic nephropathy is associated with the 5′-end dinucleotide repeat polymorphism of the aldose reductase gene in Chinese subjects with Type 2 diabetes

Aims: We investigated whether the promoter dinucleotide repeat polymorphism of the aldose reductase gene (5′-ALR2), implicated in the development of nephropathy in Type 1 diabetes, was associated with diabetic nephropathy in Type 2 diabetes. Methods: In 265 Southern Chinese with Type 2 diabetes the 5′-ALR2 polymorphism was identified in genomic DNA using polymerase chain reaction and automated fluorescent scanning. They were classified as normoalbuminuric (n = 128), microalbuminuric (n = 85) or albuminuric (n = 52) according to the mean albumin excretion rate of two 12-h overnight collections. Results: The 5′-ALR2 allele and genotype distributions differed significantly among the three groups of patients (P < 0.003 and P < 0.01, respectively). Normoalbuminuric patients had the lowest Z - 2 allele frequency: 17.6% vs. 28.2% and 23.1% for microalbuminuric and albuminuric patients, respectively, and the highest Z + 2 allele frequency: 36.7% vs. 21.2% and 23.1% in microalbuminuric and albuminuric patients, respectively. They also had the lowest Z - 2/X genotype frequency (X = any allele other than Z + 2): 18.8% vs. 36.5% in microalbuminuric (P < 0.01) and 38.5% in albuminuric patients (P < 0.02), respectively, but the highest Z + 2/Y genotype frequency (Y = any allele other than Z - 2): 50.7% vs. 27.0% and 34.6% in microalbuminuric (P < 0.001) and albuminuric patients, respectively. In a multiple logistic regression model, the Z - 2/X genotype (odds ratio 3.10; P < 0.025) was an independent risk factor of diabetic nephropathy, microalbuminuria or albuminuria, together with age, mean arterial pressure and body mass index. Conclusions: The 5′-ALR2 dinucleotide repeat polymorphism is associated with the development of diabetic nephropathy in Southern Chinese with Type 2 diabetes.link_to_subscribed_fulltex