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Triglyceride deposit cardiomyovasculopathy (TGCV), a rare cardiovascular disorder caused by genetic or acquired dysfunction of adipose triglyceride lipase (ATGL), is marked by defective intracellular lipolysis that results in excessive accumulation of triglycerides (TGs) in the myocardium and coronary arteries, leading to intractable heart failure (HF). We have developed a specific treatment for TGCV using tricaprin, a medium chain TG, as part of a governmental rare disease project in Japan. We recently reported that tricaprin diet improved cardiac TG metabolism and left ventricular function in an ATGL-knockout (KO) mouse, a mouse model for TGCV. Here, we report the effect of tricaprin on the myocardial proteome of KO mice to elucidate the mechanisms of action of tricaprin at protein expression levels. We compared proteomic changes in the hearts of KO mice fed control or tricaprin diet. Tandem mass tag-based shotgun proteomics identified 1832 proteins common to all sample groups. Whole proteomic distribution in the heart was largely up-regulated in KO mice fed control diet. When using cut-off values (>1.5 or <0.67, FDR-adjusted p value<0.01), in fact, 65 proteins were up-regulated whereas only 2 proteins were down-regulated in the hearts of KO mice fed control diet. The former included proteins assigned to "Cardiac Arrhythmia", and "Cardiac Damage" reflecting HF by a toxicity function analysis. One of the latter was Ces1d, which is known to regulate intracellular TG metabolism. These proteomic changes observed in KO mice were dramatically rescued by the tricaprin diet. These results indicated that tricaprin diet ameliorated HF in a TGCV mouse model at protein expression levels and also provided important clues to understand mechanisms for the beneficial effect of tricaprin.

Triglyceride deposit cardiomyovasculopathy (TGCV) is an intractable cardiovascular disease for which a specific treatment is urgently required. In TGCV, adipose triglyceride lipase (ATGL) deficiency results in the abnormal intracellular metabolism of long-chain fatty acid (LCFA) which leads to TG deposition. Medium-chain triglycerides have been used as an important functional food for various human diseases. To address the potential activities of tricaprin, a medium-chain triglyceride, on cardiac dysfunctions of TGCV, we examined the effects of tricaprin diet on Atgl knock out (KO) mice, an animal model for TGCV. Cardiac imaging tests showed that the tricaprin diet reduced TG accumulation, resulting from improvement of LCFA metabolism, and improved left ventricular function in Atgl KO mice compared to that in mice fed the control diet. In conclusion, tricaprin improved myocardial abnormality in the TGCV model, thus, it may be useful for the treatment of patients with TGCV.

Background: Triglyceride deposit cardiomyovasculopathy (TGCV) is a rare disease, characterized by the massive accumulation of triglyceride (TG) in multiple tissues, especially skeletal muscle, heart muscle and the coronary artery. TGCV is caused by mutation of adipose triglyceride lipase, which is an essential molecule for the hydrolysis of TG. TGCV is at high risk for skeletal myopathy and heart dysfunction, and therefore premature death. Development of therapeutic methods for TGCV is highly desirable. This study aims to discover specific molecules responsible for TGCV pathogenesis., Methods: To identify differentially expressed proteins in TGCV patient cells, the stable isotope labeling with amino acids in cell culture (SILAC) method coupled with LC-MS/MS was performed using skin fibroblast cells derived from two TGCV patients and three healthy volunteers. Altered protein expression in TGCV cells was confirmed using the selected reaction monitoring (SRM) method. Microarray-based transcriptome analysis was simultaneously performed to identify changes in gene expression in TGCV cells., Results: Using SILAC proteomics, 4033 proteins were quantified, 53 of which showed significantly altered expression in both TGCV patient cells. Twenty altered proteins were chosen and confirmed using SRM. SRM analysis successfully quantified 14 proteins, 13 of which showed the same trend as SILAC proteomics. The altered protein expression data set was used in Ingenuity Pathway Analysis (IPA), and significant networks were identified. Several of these proteins have been previously implicated in lipid metabolism, while others represent new therapeutic targets or markers for TGCV. Microarray analysis quantified 20743 transcripts, and 252 genes showed significantly altered expression in both TGCV patient cells. Ten altered genes were chosen, 9 of which were successfully confirmed using quantitative RT-PCR. Biological networks of altered genes were analyzed using an IPA search., Conclusions: We performed the SILAC- and SRM-based identification-through-confirmation study using skin fibroblast cells derived from TGCV patients, and first identified altered proteins specific for TGCV. Microarray analysis also identified changes in gene expression. The functional networks of the altered proteins and genes are discussed. Our findings will be exploited to elucidate the pathogenesis of TGCV and discover clinically relevant molecules for TGCV in the near future.

Background: Triglyceride deposit cardiomyovasculopathy (TGCV) is a rare disease, characterized by the massive accumulation of triglyceride (TG) in multiple tissues, especially skeletal muscle, heart muscle and the coronary artery. TGCV is caused by mutation of adipose triglyceride lipase, which is an essential molecule for the hydrolysis of TG. TGCV is at high risk for skeletal myopathy and heart dysfunction, and therefore premature death. Development of therapeutic methods for TGCV is highly desirable. This study aims to discover specific molecules responsible for TGCV pathogenesis.Methods: To identify differentially expressed proteins in TGCV patient cells, the stable isotope labeling with amino acids in cell culture (SILAC) method coupled with LC-MS/MS was performed using skin fibroblast cells derived from two TGCV patients and three healthy volunteers. Altered protein expression in TGCV cells was confirmed using the selected reaction monitoring (SRM) method. Microarray-based transcriptome analysis was simultaneously performed to identify changes in gene expression in TGCV cells.Results: Using SILAC proteomics, 4033 proteins were quantified, 53 of which showed significantly altered expression in both TGCV patient cells. Twenty altered proteins were chosen and confirmed using SRM. SRM analysis successfully quantified 14 proteins, 13 of which showed the same trend as SILAC proteomics. The altered protein expression data set was used in Ingenuity Pathway Analysis (IPA), and significant networks were identified. Several of these proteins have been previously implicated in lipid metabolism, while others represent new therapeutic targets or markers for TGCV. Microarray analysis quantified 20743 transcripts, and 252 genes showed significantly altered expression in both TGCV patient cells. Ten altered genes were chosen, 9 of which were successfully confirmed using quantitative RT-PCR. Biological networks of altered genes were analyzed using an IPA search.Conclusions: We performed the SILAC- and SRM-based identification-through-confirmation study using skin fibroblast cells derived from TGCV patients, and first identified altered proteins specific for TGCV. Microarray analysis also identified changes in gene expression. The functional networks of the altered proteins and genes are discussed. Our findings will be exploited to elucidate the pathogenesis of TGCV and discover clinically relevant molecules for TGCV in the near future. [ABSTRACT FROM AUTHOR]

Triglyceride deposit cardiomyovasculopathy (TGCV) is a rare and newly identified disease among patients requiring cardiac transplantation. TGCV is characterized by cardiomyocyte steatosis and triglyceride (TG)-deposit atherosclerosis, resulting from the abnormal intracellular metabolism of TG. TGCV is classified into primary and idiopathic types. Primary TGCV carries ultra-rare genetic mutations in the adipose triglyceride lipase (ATGL), a rate-liming enzyme that hydrolyzes intracellular TG in adipose and non-adipose tissues. Idiopathic TGCV, first identified among autopsied individuals with diabetes mellitus (DM) with severe heart diseases, shows no ATGL mutations and its causes and underlying mechanisms are still unknown. TGCV is difficult to diagnose in daily clinics, thereby demanding feasible diagnostic procedures. We aimed to develop an assay to measure ATGL activity using peripheral leucocytes. Human his6-ATGL was expressed in COS1 cells, purified to homogeneity, and used to raise a polyclonal antibody neutralizing TG-hydrolyzing activity of ATGL. We developed a selective immunoinactivation assay (SIIA) for the quantitation of ATGL activity in cell lysates of leucocytes by the antibody neutralizing ATGL activities. ATGL activity was measured in 13 idiopathic TGCV patients, with two patients with primary TGCV as the negative control. Healthy (non-DM) and DM controls without heart diseases were also subjected. The developed SIIA assay revealed significant reduction in ATGL activity in leucocytes from patients with idiopathic TGCV who did not carry ATGL mutations as compared with non-DM and DM controls. Thus, ATGL in leucocytes may be an important biomarker for the diagnosis of TGCV and our assay may provide insights into pathophysiology and elucidate the underlying mechanism of TGCV and related disorders. [ABSTRACT FROM AUTHOR]