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Reduced Mitochondrial Function in Human Huntington Disease Lymphoblasts is Not Due to Alterations in Cardiolipin Metabolism or Mitochondrial Supercomplex Assembly
Author(s) -
Mejia Edgard M.,
Chau Sarah,
Sparagna Genevieve C.,
Sipione Simonetta,
Hatch Grant M.
Publication year - 2016
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-015-4110-0
Subject(s) - cardiolipin , biology , mitochondrion , lymphoblast , mitochondrial disease , trinucleotide repeat expansion , huntington's disease , mitochondrial encephalomyopathies , mitochondrial myopathy , medicine , endocrinology , biochemistry , mitochondrial dna , genetics , cell culture , disease , gene , phospholipid , membrane , allele
Abstract Huntington's Disease (HD) is an autosomal dominant disease that occurs as a result of expansion of the trinucleotide repeat CAG (glutamine) on the HTT gene. HD patients exhibit various forms of mitochondrial dysfunction within neurons and peripheral tissues. Cardiolipin (Ptd 2 Gro) is a polyglycerophospholipid found exclusively in mitochondria and is important for maintaining mitochondrial function. We examined if altered Ptd 2 Gro metabolism was involved in the mitochondrial dysfunction associated with HD. Mitochondrial basal respiration, spare respiratory capacity, ATP coupling efficiency and rate of glycolysis were markedly diminished in Epstein‐Barr virus transformed HD lymphoblasts compared to controls (CTRL). Mitochondrial supercomplex formation and Complex I activity within these supercomplexes did not vary between HD patients with different length of CAG repeats and appeared unaltered compared to CTRL. In contrast, in vitro Complex I enzyme activity in mitochondrial enriched samples was reduced in HD lymphoblasts compared to CTRL. The total cellular pool size of Ptd 2 Gro and its synthesis/remodeling from [ 3 H]acetate/[ 14 C]oleate were unaltered in HD lymphoblasts compared to CTRL. In addition, the molecular species of Ptd 2 Gro were essentially unaltered in HD lymphoblasts compared to CTRL. We conclude that compared to CTRL lymphoblasts, HD lymphoblasts display impaired mitochondrial basal respiration, spare respiratory capacity, ATP coupling efficiency and rate of glycolysis with any pathological CAG repeat length, but this is not due to alterations in Ptd 2 Gro metabolism. We suggest that HD patient lymphoblasts may be a useful model to study defective energy metabolism that does not involve alterations in Ptd 2 Gro metabolism.