Direct protein–protein interaction of 11β-hydroxysteroid dehydrogenase type 1 and hexose-6-phosphate dehydrogenase in the endoplasmic reticulum lumen

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.

Download Full-text

The Glucose-6-Phosphate Transporter-Hexose-6-Phosphate Dehydrogenase-11β-Hydroxysteroid Dehydrogenase Type 1 System of the Adipose Tissue

Endocrinology ◽

10.1210/en.2006-1472 ◽

2007 ◽

Vol 148 (5) ◽

pp. 2487-2495 ◽

Cited By ~ 27

Author(s):

Paola Marcolongo ◽

Simona Piccirella ◽

Silvia Senesi ◽

Livius Wunderlich ◽

Isabelle Gerin ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Adipose Tissue ◽

Nicotinamide Adenine Dinucleotide Phosphate ◽

Hydroxysteroid Dehydrogenase ◽

Phosphate Transporter ◽

Nicotinamide Adenine ◽

Functional Connection ◽

Pharmacological Targets ◽

Isolated Adipocytes

11β-Hydroxysteroid dehydrogenase type 1, expressed mainly in the endoplasmic reticulum of adipocytes and hepatocytes, plays an important role in the prereceptorial activation of glucocorticoids. In liver endoplasmic reticulum-derived microsomal vesicles, nicotinamide adenine dinucleotide phosphate reduced supply to the enzyme is guaranteed by a tight functional connection with hexose-6-phosphate dehydrogenase and the glucose-6-phosphate transporter (G6PT). In adipose tissue, the proteins and their activities supporting the action of 11β-hydroxysteroid dehydrogenase type 1 have not been explored yet. Here we report the occurrence of the hexose-6-phosphate dehydrogenase in rat epididymal fat, as detected at the level of mRNA, protein, and activity. In the isolated microsomes, the activity was evident only on the permeabilization of the membrane because of the poor permeability to the cofactor nicotinamide adenine dineucleotide phosphate (NADP+), which is consistent with the intralumenal compartmentation of both the enzyme and a pool of pyridine nucleotides. In fat cells, the access of the substrate, glucose-6-phosphate to the intralumenal hexose-6-phosphate dehydrogenase appeared to be mediated by the liver-type G6PT. In fact, the G6PT expression was revealed at the level of mRNA and protein. Accordingly, the transport of glucose-6-phosphate was demonstrated in microsomal vesicles, and it was inhibited by S3483, a prototypic inhibitor of G6PT. Furthermore, isolated adipocytes produced cortisol on addition of cortisone, and the production was markedly inhibited by S3483. The results show that adipocytes are equipped with a functional G6PT-hexose-6-phosphate dehydrogenase-11β-hydroxysteroid dehydrogenase type 1 system and indicate that all three components are potential pharmacological targets for modulating local glucocorticoid activation.

Download Full-text

Split-TurboID enables contact-dependent proximity labeling in cells

10.1101/2020.03.11.988022 ◽

2020 ◽

Cited By ~ 1

Author(s):

Kelvin F. Cho ◽

Tess C. Branon ◽

Sanjana Rajeev ◽

Tanya Svinkina ◽

Namrata D. Udeshi ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Protein Interaction ◽

Proteomic Analysis ◽

Protein Protein Interaction ◽

Conventional Fractionation ◽

Contact Sites ◽

Biochemical Fractionation ◽

Versatile Tool ◽

Endogenous Proteins ◽

In Cells

AbstractProximity labeling (PL) catalyzed by promiscuous enzymes such as TurboID have enabled the proteomic analysis of subcellular regions difficult or impossible to access by conventional fractionation-based approaches. Yet some cellular regions, such as organelle contact sites, remain out of reach for current PL methods. To address this limitation, we split the enzyme TurboID into two inactive fragments that recombine when driven together by a protein-protein interaction or membrane-membrane apposition. At endoplasmic reticulum (ER)-mitochondria contact sites, reconstituted TurboID catalyzed spatially-restricted biotinylation, enabling the enrichment and identification of >100 endogenous proteins, including many not previously linked to ER-mitochondria contacts. We validated eight novel candidates by biochemical fractionation and overexpression imaging. Overall, split-TurboID is a versatile tool for conditional and spatially-specific proximity labeling in cells.

Download Full-text

Comparative analysis of performance K-nearest neighbor and weighted K-nearest neighbor combined with global encoding in predicting protein-protein interaction human immunodeficiency virus type 1 with human

10.1063/5.0010738 ◽

2020 ◽

Author(s):

N. Inayah ◽

I. P. P. Lestari ◽

M. I. S. Musti

Keyword(s):

Human Immunodeficiency Virus ◽

Comparative Analysis ◽

Human Immunodeficiency Virus Type ◽

Protein Interaction ◽

Nearest Neighbor ◽

K Nearest Neighbor ◽

Protein Protein Interaction ◽

Immunodeficiency Virus ◽

Analysis Of Performance

Download Full-text

Comparison of Protein Acetyltransferase Action of CRTAase with the Prototypes of HAT

The Scientific World JOURNAL ◽

10.1155/2014/578956 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Prija Ponnan ◽

Ajit Kumar ◽

Prabhjot Singh ◽

Prachi Gupta ◽

Rini Joshi ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Protein Interaction ◽

Protein A ◽

Histone Acetyltransferases ◽

Protein Acetylation ◽

Receptor Proteins ◽

Protein Protein Interaction ◽

Acetyl Group ◽

Protein Acetyltransferase ◽

Protein Acylation

Our laboratory is credited for the discovery of enzymatic acetylation of protein, a phenomenon unknown till we identified an enzyme termed acetoxy drug: protein transacetylase (TAase), catalyzing the transfer of acetyl group from polyphenolic acetates to receptor proteins (RP). Later, TAase was identified as calreticulin (CR), an endoplasmic reticulum luminal protein. CR was termed calreticulin transacetylase (CRTAase). Our persistent study revealed that CR like other families of histone acetyltransferases (HATs) such as p300, Rtt109, PCAF, and ESA1, undergoes autoacetylation. The autoacetylated CR was characterized as a stable intermediate in CRTAase catalyzed protein acetylation, and similar was the case with ESA1. The autoacetylation of CR like that of HATs was found to enhance protein-protein interaction. CR like HAT-1, CBP, and p300 mediated the acylation of RP utilizing acetyl CoA and propionyl CoA as the substrates. The similarities between CRTAase and HATs in mediating protein acylation are highlighted in this review.

Download Full-text

Cooperativity between 11β-Hydroxysteroid Dehydrogenase Type 1 and Hexose-6-phosphate Dehydrogenase in the Lumen of the Endoplasmic Reticulum

Journal of Biological Chemistry ◽

10.1074/jbc.m404159200 ◽

2004 ◽

Vol 279 (26) ◽

pp. 27017-27021 ◽

Cited By ~ 125

Author(s):

Gábor Bánhegyi ◽

Angelo Benedetti ◽

Rosella Fulceri ◽

Silvia Senesi

Keyword(s):

Endoplasmic Reticulum ◽

Hydroxysteroid Dehydrogenase

Download Full-text

EDEM1 Drives Misfolded Protein Degradation via ERAD and Exploits ER-Phagy as Back-Up Mechanism When ERAD Is Impaired

International Journal of Molecular Sciences ◽

10.3390/ijms21103468 ◽

2020 ◽

Vol 21 (10) ◽

pp. 3468 ◽

Cited By ~ 1

Author(s):

Marioara Chiritoiu ◽

Gabriela N. Chiritoiu ◽

Cristian V. A. Munteanu ◽

Florin Pastrama ◽

N. Erwin Ivessa ◽

...

Keyword(s):

Mass Spectrometry ◽

Endoplasmic Reticulum ◽

Protein Degradation ◽

Protein Interaction ◽

Proteasomal Degradation ◽

Misfolded Proteins ◽

Misfolded Protein ◽

Protein Protein Interaction ◽

Pathological Conditions ◽

Er Homeostasis

Endoplasmic reticulum (ER)-associated degradation (ERAD) is the main mechanism of targeting ER proteins for degradation to maintain homeostasis, and perturbations of ERAD lead to pathological conditions. ER-degradation enhancing α-mannosidase-like (EDEM1) was proposed to extract terminally misfolded proteins from the calnexin folding cycle and target them for degradation by ERAD. Here, using mass-spectrometry and biochemical methods, we show that EDEM1 is found in auto-regulatory complexes with ERAD components. Moreover, the N-terminal disordered region of EDEM1 mediates protein–protein interaction with misfolded proteins, whilst the absence of this domain significantly impairs their degradation. We also determined that overexpression of EDEM1 can induce degradation, even when proteasomal activity is severely impaired, by promoting the formation of aggregates, which can be further degraded by autophagy. Therefore, we propose that EDEM1 maintains ER homeostasis and mediates ERAD client degradation via autophagy when either dislocation or proteasomal degradation are impaired.

Download Full-text