Hexose-6-phosphate dehydrogenase in the endoplasmic reticulum

2010 ◽  
Vol 391 (1) ◽  
Author(s):  
Silvia Senesi ◽  
Miklos Csala ◽  
Paola Marcolongo ◽  
Rosella Fulceri ◽  
Jozsef Mandl ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Endoplasmic Reticulum ◽  
Pentose Phosphate Pathway ◽  
Hydroxysteroid Dehydrogenase ◽  
Pyridine Nucleotide ◽  
Pentose Phosphate ◽  
The Metabolic Syndrome ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract Hexose-6-phosphate dehydrogenase (H6PD) is a luminal enzyme of the endoplasmic reticulum that is distinguished from cytosolic glucose-6-phosphate dehydrogenase by several features. H6PD converts glucose-6-phosphate and NADP+ to 6-phosphogluconate and NADPH, thereby catalyzing the first two reactions of the pentose-phosphate pathway. Because the endoplasmic reticulum has a separate pyridine nucleotide pool, H6PD provides NADPH for luminal reductases. One of these enzymes, 11β-hydroxysteroid dehydrogenase type 1 responsible for prereceptorial activation of glucocorticoids, has been the focus of much attention as a probable factor in the pathomechanism of several human diseases including insulin resistance and the metabolic syndrome. This review summarizes recent advances related to the functions of H6PD.

scholarly journals Minireview: Hexose-6-Phosphate Dehydrogenase and Redox Control of 11β-Hydroxysteroid Dehydrogenase Type 1 Activity

Endocrinology ◽  
2005 ◽  
Vol 146 (6) ◽  
pp. 2539-2543 ◽  
Author(s):  
Kylie N. Hewitt ◽  
Elizabeth A. Walker ◽  
Paul M. Stewart
Keyword(s):  
Reductase Activity ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Hydroxysteroid Dehydrogenase ◽  
Pentose Phosphate ◽  
Intact Cells ◽  
The Metabolic Syndrome ◽  
Reduced Nicotinamide Adenine Dinucleotide ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract Hexose-6-phosphate dehydrogenase (H6PDH) is a microsomal enzyme that is able to catalyze the first two reactions of an endoluminal pentose phosphate pathway, thereby generating reduced nicotinamide adenine dinucleotide phosphate (NADPH) within the endoplasmic reticulum. It is distinct from the cytosolic enzyme, glucose-6-phosphate dehydrogenase (G6PDH), using a separate pool of NAD(P)+ and capable of oxidizing several phosphorylated hexoses. It has been proposed to be a NADPH regenerating system for steroid hormone and drug metabolism, specifically in determining the set point of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activity, the enzyme responsible for the activation and inactivation of glucocorticoids. 11β-HSD1 is a bidirectional enzyme, but in intact cells displays predominately oxo-reductase activity, a reaction requiring NADPH and leading to activation of glucocorticoids. However, in cellular homogenates or in purified preparations, 11β-HSD1 is exclusively a dehydrogenase. Because H6PDH and 11β-HSD1 are coexpressed in the inner microsomal compartment of cells, we hypothesized that H6PDH may provide 11β-HSD1 with NADPH, thus promoting oxo-reductase activity in vivo. Recently, several studies have confirmed this functional cooperation, indicating the importance of intracellular redox mechanisms for the prereceptor control of glucocorticoid availability. With the increased interest in 11β-HSD1 oxo-reductase activity in the pathogenesis and treatment of several human diseases including insulin resistance and the metabolic syndrome, H6PDH represents an additional novel candidate for intervention.

scholarly journals 11β-Hydroxysteroid Dehydrogenase Type 1 and the Metabolic Syndrome

10.5772/28641 ◽  
2011 ◽  
Author(s):  
Cidalia D. ◽  
Maria J. ◽  
Isabel Azevedo ◽  
Rosario Monteiro
Keyword(s):  
Metabolic Syndrome ◽  
Hydroxysteroid Dehydrogenase ◽  
The Metabolic Syndrome

Suppression of 11beta-hydroxysteroid dehydrogenase type 1 activity diminish insulin resistance and hypertriglyceridemia in metabolic syndrome

2010 ◽  
Vol 34 (8) ◽  
pp. S30-S30
Author(s):  
Jianqi Cui ◽  
Christine G. Schnackenberg ◽  
Melissa H. Costell ◽  
Daniel J. Krosky ◽  
Charlene W. Wu ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Hydroxysteroid Dehydrogenase

scholarly journals 11β-Hydroxysteroid dehydrogenase type 1 shRNA ameliorates glucocorticoid-induced insulin resistance and lipolysis in mouse abdominal adipose tissue

2015 ◽  
Vol 308 (1) ◽  
pp. E84-E95 ◽  
Author(s):  
Ying Wang ◽  
Chaoying Yan ◽  
Limei Liu ◽  
Wei Wang ◽  
Hanze Du ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Insulin Signaling ◽  
Hydroxysteroid Dehydrogenase ◽  
Target Tissue ◽  
The Metabolic Syndrome ◽  
Lipid Metabolism Genes

Long-term glucocorticoid exposure increases the risk for developing type 2 diabetes. Prereceptor activation of glucocorticoid availability in target tissue by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) coupled with hexose-6-phosphate dehydrogenase (H6PDH) is an important mediator of the metabolic syndrome. We explored whether the tissue-specific modulation of 11β-HSD1 and H6PDH in adipose tissue mediates glucocorticoid-induced insulin resistance and lipolysis and analyzed the effects of 11β-HSD1 inhibition on the key lipid metabolism genes and insulin-signaling cascade. We observed that corticosterone (CORT) treatment increased expression of 11β-HSD1 and H6PDH and induced lipase HSL and ATGL with suppression of p-Thr172 AMPK in adipose tissue of C57BL/6J mice. In contrast, CORT induced adipose insulin resistance, as reflected by a marked decrease in IR and IRS-1 gene expression with a reduction in p-Thr308 Akt/PKB. Furthermore, 11β-HSD1 shRNA attenuated CORT-induced 11β-HSD1 and lipase expression and improved insulin sensitivity with a concomitant stimulation of pThr308 Akt/PKB and p-Thr172 AMPK within adipose tissue. Addition of CORT to 3T3-L1 adipocytes enhanced 11β-HSD1 and H6PDH and impaired p-Thr308 Akt/PKB, leading to lipolysis. Knockdown of 11β-HSD1 by shRNA attenuated CORT-induced lipolysis and reversed CORT-mediated inhibition of pThr172 AMPK, which was accompanied by a parallel improvement of insulin signaling response in these cells. These findings suggest that elevated adipose 11β-HSD1 expression may contribute to glucocorticoid-induced insulin resistance and adipolysis.

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