Mitochondrial DNA levels in Huntington disease leukocytes and dermal fibroblasts

Abstract

Huntington disease (HD) is an inherited neurodegenerative disorder caused by mutations in the huntingtin gene. Involvement of mitochondrial dysfunctions in, and especially influence of the level of mitochondrial DNA (mtDNA) on, development of this disease is unclear. Here, samples of blood from 84 HD patients and 79 controls, and dermal fibroblasts from 10 HD patients and 9 controls were analysed for mtDNA levels. Although the type of mitochondrial haplogroup had no influence on the mtDNA level, and there was no correlation between mtDNA level in leukocytes in HD patients and various parameters of HD severity, some considerable differences between HD patients and controls were identified. The average mtDNA/nDNA relative copy number was significantly higher in leukocytes, but lower in fibroblasts, of symptomatic HD patients relative to the control group. Moreover, HD women displayed higher mtDNA levels in leukocytes than HD men. Because this is the largest population analysed to date, these results might contribute to explanation of discrepancies between previously published studies concerning levels of mtDNA in cells of HD patients. We suggest that the size of the investigated population and type of cells from which DNA is isolated could significantly affect results of mtDNA copy number estimation in HD. Hence, these parameters should be taken into consideration in studies on mtDNA in HD, and perhaps also in other diseases where mitochondrial dysfunction occurs.Electronic supplementary materialThe online version of this article (doi:10.1007/s11011-017-0026-0) contains supplementary material, which is available to authorized users.

Mitochondria and redox balance in coeliac disease: A case‐control study

“…This phenomenon has already been demonstrated in ageing human skeletal muscle or, more recently, in patients with diabetic retinopathy . Furthermore, the disease‐related oxidative stress characterizing various pathologies has been shown to affect the mtDNA level of patients’ blood cells suggesting such mtDNA content as a valuable indicator of mitochondrial dysfunction . The mitochondrial compensatory response also includes the patients’ increased activity of the mitochondrial MnSOD.…”

Mitochondria and Reactive Oxygen Species in Aging and Age-Related Diseases

“…The problem of mtDNA depletion is more complicated, as different groups reported either decreased (Liu et al, 2008;Petersen et al, 2014) or increased (Chen et al, 2007a) levels of mtDNA in HD patients relative to controls. Recent studies, based on testing biological material from a relatively large population, indicated higher levels of mtDNA in leukocytes, but depletion of mtDNA in fibroblasts of HD patients relative to healthy controls (Jędrak et al, 2017). Therefore, it was suggested that both size of the study group, and particularly the kind of investigated tissue, as well as some methodological and technical details important for adequate measurement of mtDNA levels, might be responsible for differences in results published by various groups (Jedrak et al, 2017).…”

Characterization of conditions and determination of practical tips for mtDNA level estimation in various human cells

“…After these periods, the blood sample was divided into 2 samples, from one of which leukocytes were separated by LIZ-MIX, as reported previously (Jedrak et al, 2017). Total DNA was extracted from 200 µl of whole blood or leukocyte pellet suspended in the PBS buffer (Sigma-Aldrich Co.…”

“…Proper determination of mtDNA copy number in the cell is important for understanding many cellular processes, and changes in mtDNA level can correlate with a wide range of human diseases like autism, heart failure, cancer, diabetes and neurodegenerative diseases (Chinnery & Samuels, 1999;Wallace, 2010;Greaves et al, 2012;Chen et al, 2015;Huang et al, 2016;Pyle et al, 2016;Jedrak et al, 2017). For mtDNA level estimation, real-time quantitative PCR (qPCR) is used to determine the ratio of mitochondrial genome to the nuclear DNA (Kalinowski et al, 1992;Zhang et al, 1994;Meissner et al, 2000;Chabi et al, 2003).…”

“…Despite using the same method, many data that are available cannot be compared between research centers due to the use of different laboratory protocols, which may affect the mtDNA estimate. This causes discrepancies in the determination of mtDNA content in various diseases, like the Huntington disease (HD) (Chen et al, 2007;Liu et al, 2008;Petersen et al, 2014;Jedrak et al, 2017), or diabetes (Lee et al, 1998;Malik et al, 2009;Weng et al, 2009;Wong et al, 2009), and leads to an inability to clearly assess the mtDNA level in these disorders.…”