Site-specific acetylation of adenine nucleotide translocase 1 at lysine 23 in human muscle.

Evidence suggests acetylation of human adenine nucleotide translocase 1 (ANT1) at lysine 23 (Lys23) reduces binding of ADP. Lys23 contributes to the positive charge that facilitates this interaction. This study was undertaken to characterize ANT1 abundance and acetylation by a novel method using small amounts of human skeletal muscle biopsies. Lysates of whole muscle or mitochondria from the same tissue were prepared from needle biopsies of vastus lateralis muscle of healthy volunteers. Lysed proteins were resolved on gels, the section containing ANT1 (surrounding 30 Kd) was excised, digested with trypsin, spiked with labeled unacetylated and acetylated synthetic standard peptides and analyzed by mass spectrometry. Natural logarithm transformation of data linearized ion intensities over a 10-fold range of peptide mass. Coefficients of variation ranged from 7 to 30% for ANT1 abundance and Lys23 acetylation. In three volunteers, ANT1 content was 8.36 ± 0.33 nmol/g wet weight muscle and 0.64 ± 0.05 nmol/mg mitochondria, so mitochondrial content was 13.3 ± 2.4 mg mitochondria per gram muscle. Acetylation of Lys23 averaged 14.3 ± 4.2% and 4.87 ± 1.84% in whole muscle and mitochondria, respectively. This assay makes it possible to assess effects of acetylation on the function of ANT1 in human muscle.

A study of PKM2, PFK-1, and ANT1 expressions in cervical biopsy tissues in China.

This present study explored the association of Pyruvate Kinase isozyme M2 (PKM2), Phosphofructokinase 1 (PFK-1) and Adenine nucleotide translocator 1 (ANT1) with cervical carcinoma. A case-control method was designed by the collected 95 cervical biopsy samples, which were divided into 30 controls and 60 cases. Cases were subdivided into mild cervical carcinoma (MCC-25), intermediate cervical carcinoma (ICC-20), and severe cervical carcinoma (SCC-20) by method of cervical pathology. The expression of PKM2, PFK-1, and ANT1 was examined by methods of immunohistochemistry and western blotting (WB). The results showed that the positive proportions of PKM2 and PFK-1 in case group were higher than that of control, and the increased positive proportions of PKM2 and PFK-1 were also revealed with the order of Control, MCC, ICC, SCC (P<0.05). Further, the results of WB confirmed the enhanced expressions of PKM2 and PFK-1 in case group and the increasing trend of PKM2 and PFK-1 expressions in Control, MCC, ICC, and SCC groups. In addition, the WB result of ANT1 showed a lower level of expression in SCC group, while the positive proportion of ANT1 was not significant between cases group and control. In conclusion, PKM2 and PFK-1 genes are associated closely with cervical carcinoma. The enhanced expressions of PKM2 and PFK-1 indicate one developing signal of cervical carcinoma.

Effect of ß-amyloid (25-35) on mitochondrial function and expression of mitochondrial permeability transition pore proteins in rat hippocampal neurons.

The aim of this study was to assess the effect of the ß-amyloid fragment Aß(25-35) on mitochondrial structure and function and on the expression of proteins associated with the mitochondrial permeability transition pore (MPTP) in rat hippocampal neurons. Ninety clean-grade Sprague-Dawley rats were randomly assigned to six groups (n = 15 per group). Aß(25-35) (1, 5, or 10 µg/rat) was injected into hippocampal area CA1. Normal saline was injected as a control. The effect of Aß(25-35) injection on hippocampal structure was assessed by transmission electron microscopy. Ca(2+) -ATPase activity, [Ca(2+) ](i) , and mitochondrial membrane potential were measured. The expression of genes associated with the MPTP, including the voltage-dependent anion channel (VDAC), adenine nucleotide translocator (ANT), and cyclophilin D (Cyp-D), were evaluated. Results showed that Aß(25-35) injection damaged the mitochondrial structure of hippocampal neurons, decreased Ca(2+) -ATPase activity and mitochondrial membrane potential, and increased [Ca(2+) ](i) . The expression levels for VDAC, ANT, and Cyp-D in all groups were significantly (P < 0.05) higher than those in the normal control group after Aß(25-35) injection. These results indicate that Aß(25-35) damages mitochondria in rat hippocampal neurons and effects mitochondrial dysfunction, as well as increasing the expression of genes associated with the MPTP. Mitochondrial dysfunction may result in increased MPTP gene expression, leading to neurodegenerative effects.

The adenine nucleotide translocator 1 acts as a type 2 transglutaminase substrate: implications for mitochondrial-dependent apoptosis.

In this study we provide in vitro and in vivo evidence showing that the protein disulphide isomerase (PDI) activity of type 2 transglutaminase (TG2) regulates the correct assembly and function of the mitochondrial ADP/ATP transporter adenine nucleotide translocator 1 (ANT1). We demonstrate, by means of biochemical and morphological analyses, that ANT1 and TG2 physically interact in the mitochondria. Under physiological conditions, TG2's PDI activity regulates the ADP/ATP transporter function by controlling the oligomerization of ANT1. In fact, mitochondria isolated from hearts of TG2(-/-) mice exhibit increased polymerization of ANT1, paralleled by an enhanced ADP/ATP carrier activity, as compared to mitochondria belonging to TG2(+/+) mice. Interestingly, upon cell-death induction, ANT1 becomes a substrate for TG2's cross-linking activity and the lack of TG2 results in a reduction of apoptosis as well as in a marked sensitivity to the ADP/ATP exchange inhibition by atractyloside. These findings suggest a complex TG2-dependent regulation of the ADP/ATP transporter and reveal new important avenues for its potential applications in the treatment of some mitochondrial-dependent diseases, including cardiovascular and neurodegenerative diseases.

Cardiac expression of adenine nucleotide translocase-1 in transgenic mice overexpressing bovine GH.

Heart hypertrophy is a common finding of acromegaly, a syndrome due to GH excess. Impairment of adenine nucleotide translocase-1 (ANT-1) gene, the main mitochondrial ADP/ATP exchanger, leads to cardiac hypertrophy. The aim of the study was to evaluate cardiac expression and the functional role of ANT-1 in 1- to 12-month-old transgenic mice overexpressing bovine GH (acromegalic mice, Acro) and littermate controls (wild-type mice, Wt). GH specificity of protein degree variation was assessed treating Acro with pegvisomant, a GH receptor competitor. Tissue levels of ANT-1, NF-kappaB, ATP, and lactic acid were evaluated by western blot, bioluminescence, and Fourier transform infrared spectroscopy respectively. The degree of ANT-1 expression was higher in 1-month-old Acro than in Wt (47+/-5% OD vs 33+/-4% OD, P<0 01). On the contrary, ANT-1 expression was lower in 3- to 12-month-old Acro than in Wt (P<0 03). Changes in ANT-1 expression were associated with consistent changes of cellular ATP content, increasing at 1 month (P<0 05) and reducing thereafter in Acro when compared with Wt (P<0 04). Treatment with pegvisomant abolished ANT-1 and ATP changes observed in 1- and 3-month-old Acro, thus supporting a GH-dependent mechanism. Reduced ATP generation in hypertrophied hearts of older Acro was associated with increased lactic acid levels suggesting that part of energy was due to glycolysis. Variations in ANT-1 expression were linked to GH through changes in NF-kappaB, the levels of which changed accordingly. In conclusion, 1-month-old acromegalic mice had increased ANT-1 expression and higher degree of ATP production. Long-standing disease was associated with a consistent reduction of ANT-1 and ATP tissue levels, which became GH-independent in older animals. This study demonstrated a direct effect of GH on key proteins involved in energy metabolism of acromegalic hearts.

Oxidatively damaged proteins of heart mitochondrial electron transport complexes.

Protein modifications, such as carbonylation, nitration and formation of lipid peroxidation adducts, e.g. 4-hydroxynonenal (HNE), are products of oxidative damage attributed to reactive oxygen species (ROS). The mitochondrial respiratory chain Complexes I and III have been shown to be a major source of ROS in vitro. Additionally, modifications of the respiratory chain Complexes (I-V) by nitration, carbonylation and HNE adduct decrease their enzymatic activity in vitro. However, modification of these respiratory chain complex proteins due to in vivo basal level ROS generation has not been investigated. In this study, we show a basal level of oxidative damage to specific proteins of adult bovine heart submitochondrial particle (SMP) complexes, and find that most of these proteins are localized in the mitochondrial matrix. We postulate that electron leakage from respiratory chain complexes and subsequent ROS formation may cause damage to specific complex subunits and contribute to long-term accumulation of mitochondrial dysfunction.