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Pyruvate therapy is a promising approach for the treatment of mitochondrial diseases. To identify novel biomarkers for diagnosis and to evaluate therapeutic efficacy, we performed microarray analysis of 2SD cybrid cells harboring a MELAS-causing mutation and control cells treated with either lactate or pyruvate. We found that expression and secretion of growth differentiation factor 15 (GDF15) were increased in 2SD cells treated with lactate and that serum GDF15 levels were significantly higher in patients with mitochondrial diseases than in those with other diseases, suggesting that GDF15 could be a useful marker for diagnosis and evaluating the therapeutic efficacy of pyruvate. [ABSTRACT FROM AUTHOR]

Background: There has been no clinically useful diagnostic or prognostic biomarker for renal cell carcinoma (RCC). Serum γ-glutamyltransferase (GGT) activity has been reported to be a prognostic marker for several types of cancer including RCC. Exosomes or small extracellular vesicles present in body fluids have potential as a biomarker. We have recently demonstrated that GGT activity on exosomes isolated from serum is useful for the differential diagnosis of prostate cancer and benign prostate hyperplasia. In this study, we aimed to examine if serum exosomal GGT activity could be a marker for RCC. Methods: We examined GGT1 expression and GGT activity in cell lysates and exosomes from culture medium of HK-2 proximal tubule epithelial and RCC cell lines. GGT activity was measured using a fluorescent probe for GGT, γ-glutamyl hydroxymethyl rhodamine green. Serum and serum exosomal GGT activities were measured in patients with RCC. GGT1 expression in RCC tissues was evaluated by immunohistochemical staining. Results: GGT1 levels in exosomes from KMRC-1, OS-RC-2 and 786-O cells were elevated compared with those from HK-2 cells. In exosomes, GGT1 expression correlated with GGT activity determined using a fluorescent probe for GGT. In RCC patients, serum exosomal GGT activity was elevated in those with advanced stages (III/IV vs. I/II, p = 0.037) and those with microvascular invasion (with vs. without, p = 0.034). Immunohistochemical analysis showed that membranous GGT1 expression was increased in RCC with microvascular invasion. Notably, preoperative serum exosomal GGT activity could predict the likelihood of having microvascular invasion diagnosed by pathological examination of surgically resected specimens. Conclusions: Our results suggest that serum exosomal GGT activity could be a clinically useful marker for advanced clinicopathological features of RCC patients, and its combined use with conventional diagnostic modalities may improve the diagnosis and treatment of patients. [ABSTRACT FROM AUTHOR]

Aims: Sarcopenia is a serious problem because of its poor prognosis. Growth differentiation factor 15 (GDF15) is associated with mitochondrial dysfunction, inflammation, insulin resistance and oxidative stress, which may play crucial roles for the development of sarcopenia. We aimed to examine whether serum GDF15 level is associated with muscle mass, strength and lower extremity function in older patients with cardiometabolic disease. Methods: Serum GDF15 levels were measured in 257 patients with cardiometabolic diseases (including 133 patients with diabetes) who had visited the frailty clinic, using a latex turbidimetric immunoassay. Appendicular skeletal muscle index, handgrip strength, timed‐up‐and‐go test and gait speed were evaluated. Power, speed, balance and total scores based on the sit‐to‐stand test were calculated to assess lower extremity function. Results: The highest tertile of serum GDF15 was independently associated with low handgrip strength, low gait speed, long timed‐up‐and‐go time and scores of lower extremity function but not an appendicular skeletal muscle index in multiple logistic regression analyses after adjustment for covariates. Patients in the highest tertile of GDF15 were at the risk of having three to nine times lower grip strength, three times lower gait speed, five to six times lower mobility and five to 11 times reduction in lower extremity function as compared with those in the lowest GDF15 tertile dependent on the models. Conclusions: Elevated serum GDF15 level was independently associated with low muscle strength and lower extremity function in older patients with cardiometabolic disease. Serum GDF15 could be one of the biomarkers for muscle weakness and low physical performance. Geriatr Gerontol Int 2020; 20: 980–987. [ABSTRACT FROM AUTHOR]

We and other have recently shown that growth differentiation factor 15 ( GDF15) is a useful diagnostic marker for mitochondrial diseases, which are inherited disorders caused by mitochondrial or nuclear genomic mutations that lead to impaired energy production. As the primary cause of mitochondrial diseases is mitochondrial dysfunction, the blood level of GDF15 might reflect mitochondrial function in patients, and thus could be a marker for mitochondrial dysfunction. GDF15 has been implicated in aging and various age-related disorders, such as cardiovascular diseases and diabetes, the blood level of which is reportedly elevated in older adults as well as in patients. Although GDF15 might be induced as a result of various cellular stresses and dysfunctions, it would also be possible that the blood GDF15 level reflects at least in part mitochondrial dysfunction in aging and age-related disorders. In the present review, we summarized the current literature regarding GDF15 in aging and age-related disorders from the perspective of biomarkers, with a particular focus on mitochondrial dysfunction. Geriatr Gerontol Int 2016; 16 (Suppl. 1): 17-29. [ABSTRACT FROM AUTHOR]

Abstract: Background: We sought to elucidate the effect of an ascorbic acid (AA) deficiency on gene expression, because the water soluble antioxidant AA is an important bioactive substance in vivo. Methods: We performed microarray analyses of the transcriptome in the liver from senescence marker protein-30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice, which are unable to synthesize AA in vivo. Results: Our microarray analysis revealed that the AA deficiency increased gene expression related to the oxidation–reduction process, i.e., the nuclear factor, erythroid derived 2, like 2 (Nrf2) gene, which is a reactive oxygen species-sensitive transcriptional factor. Moreover, this AA deficiency increased the expression of genes for lipid metabolism including the cytochrome P450, family 7, subfamily a, polypeptide 1 (Cyp7a1), which is a late-limiting enzyme of the primary bile acid biosynthesis pathway. Although an AA deficiency increased the Cyp7a1 protein level, bile acid levels in the liver and gallbladder decreased. Since Cyp7a1 has a heme iron at the active site, AA must function as a reductant of the iron required for the continuous activation of Cyp7a1. Conclusions: This experimental evidence strongly supports a role for AA in the physiologic oxidation–reduction process and lipid metabolism including bile acid biosynthesis. General significance: Although many effects of AA supplementation have been reported, no microarray analysis of AA deficiency in vivo is available. Results from using this unique model of AA deficiency, the SMP30/GNL-KO mouse, now provide new information about formerly unknown AA functions that will implement further study of AA in vivo. [Copyright &y& Elsevier]