Paracanthocobitis putaoensis, a new loach species (Cypriniformes: Nemacheilidae) from the Irrawaddy basin in northern Myanmar.

Paracanthocobitis putaoensis sp. nov. is described based on analysis of morphological and molecular data (cytochrome c oxidase subunit I-COI). The new species was collected from the Mali Hka River, a tributary of the Irrawaddy River near Putao in Kachin State in northern Myanmar. It can be easily distinguished from all other species of the genus Paracanthocobitis by an incomplete lateral line, a suborbital groove in adult males, and a well-developed axillary pelvic lobe. Phylogenetic relationships of the genus Paracanthocobitis based on the mitochondrial COI locus are revealed for the first time. Maximum likelihood and Bayesian inference phylogenetic analyses indicate that the new species forms an independent clade. Both morphological and molecular phylogenetic analyses suggest that P. putaoensis is a new species.

Two new species of loaches from the Irrawaddy River basin, Chin State, Myanmar (Teleostei: Cypriniformes: Nemacheilidae).

Schistura falamensis, a new species of nemacheilid loach, is described from the main channel of the Manipur River in the Irrawaddy River basin, Chin State, western Myanmar. It differs from other congeners of the genus Schistura by a combination of the following characters: 5-8 vertical bars on body; indistinct bars in front of dorsal-fin origin; bars on posterior part of body regular, twice as wide as interspace; black caudal basal bar dissociated, short, not reaching ventral extremity; males with suborbital flap; lateral line complete; and processus dentiformis weak. Schistura altuscauda is a new species described from the Htin stream, Mindat Town, Chin State, Myanmar. It can be distinguished from other congeners by a combination of the following characters: high caudal peduncle (14.0-20.3% SL), strong processus dentiformis on upper jaw; 7-19 bars on flank of body, bars in front of dorsal fin obviously thinner than those behind, sometimes fused in front of dorsal fin; lateral line complete; males with prominent suborbital flap; and pelvic lobe present.

Short-chain aldehyde-derived ligands for RAGE and their actions on endothelial cells.

The formation and accumulation of advanced glycation endproducts (AGE) have been implicated in the development of diabetic vascular complications. Their biological responses are known to be mediated by the receptor for AGE (RAGE). Recently, AGE have been proposed to be derived not only from the classical Maillard reaction but also from other pathways of sugar autoxidation and metabolism. Here, we report the identification of glyceraldehydes (Gcer)- and glycolaldehyde (Gcol)-derived AGE as RAGE ligands and their presence in vivo. The apparent dissociation constants assessed by surface-plasmon resonance (SPR) analysis with purified human RAGE proteins were 360 nM for Gcer-AGE and 1.35 microM for Gcol-AGE. The radiolabeled-ligand binding assay with RAGE-expressing COS-7 cells revealed similar association kinetics. Competitive SPR assay with antibodies specific to the respective AGE fractions demonstrated abundant existence of both Gcer- and Gcol-AGE in RAGE affinity-purified proteins from human sera. The serum contents of Gcer- and Gcol-AGE in a diabetic patient were about twice as high as those in a healthy control. Functionally, Gcer- and Gcol-AGE upregulated the endothelial cell levels of mRNA for vascular endothelial growth factor (VEGF) and the secretion of its protein product into the culture media and DNA synthesis in a dose-dependent manner. Further, these endothelial responses were augmented by RAGE overexpression. The results suggest that RAGE engagement of Gcer- and Gcol-AGE may elicit angiogenesis through the induction of autocrine VEGF, thereby contributing to the development and progression of diabetic angiopathies.

RAGE control of diabetic nephropathy in a mouse model: effects of RAGE gene disruption and administration of low-molecular weight heparin.

Diabetic nephropathy is a major microvascular complication in long-standing diabetic patients who eventually undergo renal dialysis or transplantation. To prevent development of this disease and to improve advanced kidney injury, effective therapies directed toward the key molecular target are required. In this study, we examined whether inhibition of the receptor for advanced glycation end products (RAGE) could attenuate changes in the diabetic kidney. Here, we show that inactivation of the RAGE gene in a mouse model of diabetic nephropathy results in significant suppression of kidney changes, including kidney enlargement, increased glomerular cell number, mesangial expansion, advanced glomerulosclerosis, increased albuminuria, and increased serum creatinine compared with wild-type diabetic mice. The degree of kidney injury was proportional to RAGE gene dosage. Furthermore, we show that low-molecular weight heparin (LMWH) can bind RAGE at a mean equilibrium dissociation constant (K(d)) value of approximately 17 nmol/l and act as an antagonist to RAGE. LMWH treatment of mice significantly prevented albuminuria and increased glomerular cell number, mesangial expansion, and glomerulosclerosis in a dose-dependent manner; it also significantly improved the indexes of advanced-stage diabetic nephropathy. This study provides insight into the pathological role of RAGE in both early- and advanced-phase diabetic nephropathy and suggests that RAGE antagonists will be a useful remedy in the treatment of diabetic nephropathy.

Identification of mouse orthologue of endogenous secretory receptor for advanced glycation end-products: structure, function and expression.

The cell-surface RAGE [receptor for AGE (advanced glycation end-products)] is associated with the development of diabetic vascular complications, neurodegenerative disorders and inflammation. Recently, we isolated a human RAGE splice variant, which can work as a decoy receptor for RAGE ligands, and named it esRAGE (endogenous secretory RAGE). In the present study, we have isolated the murine equivalent of esRAGE from brain polysomal poly(A)+ (polyadenylated) RNA by RT (reverse transcription)-PCR cloning. The mRNA was generated by alternative splicing, and it encoded a 334-amino-acid protein with a signal sequence, but lacking the transmembrane domain. A transfection experiment revealed that the mRNA was actually translated as deduced to yield the secretory protein working as a decoy in AGE-induced NF-kappaB (nuclear factor kappaB) activation. RT-PCR and immunoblotting detected esRAGE mRNA and protein in the brain, lung, kidney and small intestine of wild-type mice, but not of RAGE-null mice. The esRAGE expression was increased in the kidney of diabetic wild-type mice. The present study has thus provided an animal orthologue of esRAGE for clarification of its roles in health and disease.

Blockade of diabetic vascular injury by controlling of AGE-RAGE system.

Vascular complications result in disabilities and short life expectancy in diabetic patients. During prolonged hyperglycemic exposure, non-enzymatically glycated protein derivatives termed advanced glycation endproducts (AGE) are formed at an accelerated rate and accumulated in blood and in tissues. Studies performed in vitro and in vivo revealed AGE and their receptor RAGE as the major accounts for vascular cell derangement characteristic of diabetes. The AGE-RAGE system would thus be considered as a candidate molecular target for overcoming diabetic vascular complications. Potential preventive and therapeutic approaches toward it include inhibition of AGE formation, breakage of preformed AGE-proteins crosslinks, blockade of AGE-RAGE interactions with RAGE competitors or antagonists and RAGE-specific signaling inhibition.

The AGE-RAGE system and diabetic nephropathy.

As is diabetes itself, diabetic vasculopathy is a multifactor disease. Studies revealed advanced glycation end products (AGE) as the major environmental account for vascular cell derangement characteristic of diabetes and the receptor for AGE (RAGE) as the major genic factor that responds to them. AGE fractions that caused the vascular derangement were proved to be RAGE ligands. When made diabetic, RAGE transgenic mice exhibited the exacerbation of the indices of nephropathy and retinopathy, and this was prevented by the inhibition of AGE formation. Extracellular signals and nuclear factors that induce the transcription of human RAGE gene were also identified, which would be regarded as risk factors of diabetic complications. Through an analysis of vascular polysomal poly(A)(+)RNA, a novel splice variant coding for a soluble RAGE protein was found and was named endogenous secretory RAGE. Endogenous secretory RAGE was able to capture AGE ligands and to neutralize the AGE action on endothelial cells, suggesting that this variant has a potential to protect blood vessels from diabetes-induced injury. The AGE-RAGE system, therefore, should be a candidate molecular target for overcoming this life- and quality-of-life-threatening disease.