Histidine Triad Nucleotide-binding Protein 2 Research Articles

HINT2 protects against pressure overload-induced cardiac remodelling through mitochondrial pathways.

Histidine triad nucleotide-binding protein 2 (HINT2) is an enzyme found in mitochondria that functions as a nucleotide hydrolase and transferase. Prior studies have demonstrated that HINT2 plays a crucial role in ischemic heart disease, but its importance in cardiac remodelling remains unknown. Therefore, the current study intends to determine the role of HINT2 in cardiac remodelling. HINT2 expression levels were found to be lower in failing hearts and hypertrophy cardiomyocytes. The mice that overexpressed HINT2 exhibited reduced myocyte hypertrophy and cardiac dysfunction in response to stress. In contrast, the deficiency of HINT2 in the heart of mice resulted in a worsening hypertrophic phenotype. Further analysis indicated that upregulated genes were predominantly associated with the oxidative phosphorylation and mitochondrial complex I pathways in HINT2-overexpressed mice after aortic banding (AB) treatment. This suggests that HINT2 increases the expression of NADH dehydrogenase (ubiquinone) flavoprotein (NDUF) genes. In cellular studies, rotenone was used to disrupt mitochondrial complex I, and the protective effect of HINT2 overexpression was nullified. Lastly, we predicted that thyroid hormone receptor beta might regulate HINT2 transcriptional activity. To conclusion, the current study showcased that HINT2 alleviates pressure overload-induced cardiac remodelling by influencing the activity and assembly of mitochondrial complex I. Thus, targeting HINT2 could be a novel therapeutic strategy for reducing cardiac remodelling.

HINT2 deficiency deteriorates oxidative stress in a mouse model of myocardial infarction.

Myocardial infarction (MI) is one of the serious diseases with great mortality over the world. Myocardial mitochondrial oxidative stress has been implicated as a key player in MI. The histidine triad nucleotide-binding protein 2 (HINT2) is a nucleotide hydrolase and transferase located in mitochondria. HINT2 has multiple functions such as regulating mitochondrial lipid metabolism and respiration and glucose homeostasis. Although HINT2 has been shown to protect against MI, the underlying mechanisms were not fully elucidated. In this study, the effects of HINT2 on oxidative stress during MI were explored. MI mouse models in both wild-type and HINT2-deficient mice were established. The expression of HINT2 in HINT2-deficient mice was determined by quantitative real-time PCR and western blot. The levels of oxidative stress were measured, including the levels of malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), and glutathione (GSH). The myocardial functions, as indicated by left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), left ventricular ejection fraction (LVEF), and left ventricular fractional shortening (LVFS), were monitored. Both mRNA and protein expressions of HINT2 in the myocardial tissues were significantly down-regulated in MI mice starting at 6h post-MI. MI induced oxidative stress 6h post-MI in myocardial tissues of wild-type mice, as suggested by the enhanced MDA and NO levels and decreased SOD and GSH levels. The expression of HINT2 was negatively correlated to the MDA and NO levels and positively correlated to the SOD and GSH levels. HINT2-deficient MI mice had significantly elevated levels of MDA and NO and significantly decreased levels of SOD and GSH when compared with wild-type MI mice. HINT2-deficient MI mice had higher LVEDD and LVESD and lower LVEF and LVFS compared with wild-type MI mice, indicating that HINT2 deficiency exacerbated myocardial dysfunction. HINT2 deficiency causes deteriorative oxidative stress in MI mice, leading to exacerbated myocardial dysfunction.

THU326 - Histidine triad nucleotide-binding protein-2 is present at the cross-road of ER-mitochondria interactions and modulates adaptive stress response in hepatocytes

THU326 - Histidine triad nucleotide-binding protein-2 is present at the cross-road of ER-mitochondria interactions and modulates adaptive stress response in hepatocytes

Absence of histidine triad nucleotide binding protein-2 (HINT-2) triggers mitochondrial dysfunction and aggravates steatosis

Absence of histidine triad nucleotide binding protein-2 (HINT-2) triggers mitochondrial dysfunction and aggravates steatosis

Affinity Isolation and Mass Spectrometry Identification of Prostacyclin Synthase (PTGIS) Subinteractome.

Prostacyclin synthase (PTGIS; EC 5.3.99.4) catalyzes isomerization of prostaglandin H2 to prostacyclin, a potent vasodilator and inhibitor of platelet aggregation. At present, limited data exist on functional coupling and possible ways of regulating PTGIS due to insufficient information about protein–protein interactions in which this crucial enzyme is involved. The aim of this study is to isolate protein partners for PTGIS from rat tissue lysates. Using CNBr-activated Sepharose 4B with covalently immobilized PTGIS as an affinity sorbent, we confidently identified 58 unique proteins by mass spectrometry (LC-MS/MS). The participation of these proteins in lysate complex formation was characterized by SEC lysate profiling. Several potential members of the PTGIS subinteractome have been validated by surface plasmon resonance (SPR) analysis. SPR revealed that PTGIS interacted with full-length cytochrome P450 2J2 and glutathione S-transferase (GST). In addition, PTGIS was shown to bind synthetic peptides corresponding to sequences of for GSTA1, GSTM1, aldo-keto reductase (AKR1A1), glutaredoxin 3 (GLRX3) and histidine triad nucleotide binding protein 2 (HINT2). Prostacyclin synthase could potentially be involved in functional interactions with identified novel protein partners participating in iron and heme metabolism, oxidative stress, xenobiotic and drugs metabolism, glutathione and prostaglandin metabolism. The possible biological role of the recognized interaction is discussed in the context of PTGIS functioning.

The histidine triad nucleotide-binding protein 2 (HINT-2) positively regulates hepatocellular energy metabolism.

The histidine triad nucleotide-binding protein 2 (HINT-2) is a mitochondrial adenosine phosphoramidase expressed in hepatocytes. The phenotype of Hint2 knockout ( Hint2-/-) mice includes progressive hepatic steatosis and lysine hyperacetylation of mitochondrial proteins, which are features of respiratory chain malfunctions. We postulated that the absence of HINT-2 induces a defect in mitochondria bioenergetics. Isolated Hint2-/- hepatocytes produced less ATP and generated a lower mitochondrial membrane potential than did Hint2+/+ hepatocytes. In extracellular flux analyses with glucose, the basal, ATP-linked, and maximum oxygen consumption rates (OCRs) were decreased in Hint2-/- hepatocytes and in HepG2 cells lacking HINT-2. Conversely, in HINT-2 overexpressing SNU-449 and HepG2 cells, the basal, ATP-linked, and maximum OCRs were increased. Similarly, with palmitate, basal and maximum OCRs were decreased in Hint2-/- hepatocytes, but they were increased in HINT-2 overexpressing HepG2 cells. When assayed with radiolabeled substrate, palmitate oxidation was reduced by 25% in Hint2-/- mitochondria. In respirometry assays, complex I- and II-driven, coupled and uncoupled respirations and complex IV KCN-sensitive respiration were reduced in Hint2-/- mitochondria. Furthermore, HINT-2 associated with cardiolipin and glucose-regulated protein 75 kDa. Our study shows decreased electron transfer and oxidative phosphorylation capacity in the absence of HINT-2. The bioenergetics deficit accumulated over time in hepatocytes lacking HINT-2 likely leads to the secondary outcome of steatosis.-Rajasekaran, R., Felser, A., Nuoffer, J.-M., Dufour, J.-F., St-Pierre, M. V. The histidine triad nucleotide-binding protein 2 (HINT-2) positively regulates hepatocellular energy metabolism.

WITHDRAWN: Upregulation of HINT2 Inhibits Non-Small Cell Lung Cancer Cell Invasion Via COX-2/PGE₂-Mediated Activation of ß-catenin Signaling.

Histidine triad nucleotide binding protein 2 (HINT2) belongs to a HIT superfamily. It is ubiquitous and can be detectedin all forms of life. Recently, this protein has been reported to function as a tumor suppressor in some kind of cancers. However, little is known about its precise role in non-small cell lung cancer (NSCLC). In the present study, we explored the effects of HINT2 on the invasive potential of NSCLC cells. Our results showed that the expression of HINT2 was reduced in NSCLC tissues and cell lines. Up-regulation of HINT2 inhibited NSCLC cell invasion in vitro and tumor metastasis in vivo. We also found that the inhibitory effect of HINT2 on NSCLC cell invasion was associated with reduction of COX-2 expression. In addition, our further investigation on the underlying mechanisms demonstrated that up-regulation of HINT2 inhibited NSCLC cell invasion via COX-2/PGE₂-mediated activation of ß-catenin signaling. In conclusion, we presented evidence that HINT2 exerted a tumor-suppression effect on the progression of NSCLC. Thus, HINT2 might be a promising molecular target for treatment of NSCLC.

Progesterone Enhances Calcitriol Antitumor Activity by Upregulating Vitamin D Receptor Expression and Promoting Apoptosis in Endometrial Cancer Cells

Human studies suggest that progesterone and calcitriol may prove beneficial in preventing or inhibiting oncogenesis, but the underlying mechanism is not fully understood. The current study investigates the effects of progesterone, calcitriol, and their combination on immortalized human endometrial epithelial cells and endometrial cancer cells and identifies their targets of action. Combination treatment with both agents enhanced vitamin D receptor expression and inhibited cell proliferation through caspase-3 activation and induction of G0-G1 cell-cycle arrest with associated downregulation of cyclins D1 and D3 and p27 induction. We used mass spectrometry-based proteomics to measure protein abundance differences between calcitriol-, progesterone-, or combination-exposed endometrial cells. A total of 117 proteins showed differential expression among these three treatments. Four proteins were then selected for validation studies: histone H1.4 (HIST1H1E), histidine triad nucleotide-binding protein 2 (HINT2), IFN-induced, double-stranded RNA-activated protein kinase (EIF2AK2), and Bcl-2-associated X protein (BAX). Abundance levels of selected candidates were low in endometrial cancer cell lines versus the immortalized endometrial epithelial cell line. All four proteins displayed elevated expression in cancer cells upon exposure to calcitriol, progesterone, or the combination. Further BAX analysis through gain- or loss-of-function experiments revealed that upregulation of BAX decreased cell proliferation by changing the BAX:BCL-2 ratio. Knockdown of BAX attenuated progesterone- and calcitriol-induced cell growth inhibition. Our results showed that progesterone and calcitriol upregulate the expression of BAX along with other apoptosis-related proteins, which induce inhibition of endometrial cancer cell growth by apoptosis and cell-cycle arrest.

Expression, purification, crystallization and preliminary X-ray crystallographic analysis of human histidine triad nucleotide-binding protein 2 (hHINT2).

Histidine triad nucleotide-binding protein 2 (HINT2) is a mitochondrial adenosine phosphoramidase mainly expressed in the pancreas, liver and adrenal gland. HINT2 possibly plays a role in apoptosis, as well as being involved in steroid biosynthesis, hepatic lipid metabolism and regulation of hepatic mitochondria function. The expression level of HINT2 is significantly down-regulated in hepatocellular carcinoma patients. To date, endogenous substrates for this enzyme, as well as the three-dimensional structure of human HINT2, are unknown. In this study, human HINT2 was cloned, overexpressed in Escherichia coli and purified. Crystallization was performed at 278 K using PEG 4000 as the main precipitant; the crystals, which belonged to the tetragonal space group P41212 with unit-cell parameters a = b = 76.38, c = 133.25 Å, diffracted to 2.83 Å resolution. Assuming two molecules in the asymmetric unit, the Matthews coefficient and the solvent content were calculated to be 2.63 Å(3) Da(-1) and 53.27%, respectively.

Abstract 1716: Calcitriol and progesterone synergistically inhibit growth in endometrial cancer cells.

Abstract Human studies suggest that progesterone and calcitriol may prove beneficial in preventing or inhibiting oncogenesis, but the underlying mechanism is not fully understood. The current study investigates the effects of progesterone, calcitriol and their combination on immortalized human endometrial epithelial cells and endometrial cancer cells and identifies their targets of action. The combined cell treatment enhanced vitamin D receptor expression and synergistically inhibited cell proliferation through caspase-3 activation and induction of G0/G1 cell cycle arrest with associated down-regulation of cyclin D1, D3 and p27 induction. We used mass spectrometry-based proteomics to measure protein abundance differences between calcitriol-, progesterone-, or combination-exposed endometrial cells. A total of 117 proteins showed differential expression amongst these three treatments. Four proteins were then selected for validation studies: histone H1.4 (HIST1H1E), histidine triad nucleotide-binding protein 2 (HINT2), interferon-induced, double-stranded RNA-activated protein kinase (EIF2AK2), and Bcl-2-associated X protein (BAX). Abundance levels of selected candidates were low in endometrial cancer cell lines versus the immortalized endometrial epithelial cell line. All four proteins displayed elevated expression in cancer cells upon exposure to calcitriol, progesterone or the combination. Further BAX analysis through gain or loss of function experiments revealed that upregulation of BAX decreased cell proliferation by changing the BAX:Bcl2 ratio. Knock down of BAX attenuated progesterone- and calcitriol-induced cell growth inhibition. Our results showed that progesterone and calcitriol up-regulate the expression of BAX along with other apoptosis-related proteins, which induced inhibition of endometrial cancer cell growth by apoptosis and cell cycle arrest. Citation Format: Laura R. Lee, Brian L. Hood, Huyen Nguyen, Leyla Kavandi, Jane M. Turbov, Larry G. Thaete, Chad A. Hamilton, Gustavo C. Rodriguez, George L. Maxwell, Thomas P. Conrads, Viqar Syed. Calcitriol and progesterone synergistically inhibit growth in endometrial cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1716. doi:10.1158/1538-7445.AM2013-1716