Naslov
Differential metabolic consequences of fumarate hydratase and respiratory chain defects

Autori
Raimundo, N. ; Ahtinen, J. ; Fumić, Ksenija ; Barić, Ivo ; Remes, A.M. ; Renkonen, R. ; Lapatto, R. ; Suomalainen, A.

Izvornik
Biochimica et biophysica acta-molecular basis of disease (0925-4439) 1782 (2008), 5; 287-294

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
mitochondria; fumarate hydratase; redox state; respiratory chain defect

Sažetak
Defects of the oxidative ATP production pathway lead to an amazing variety of disease phenotypes, ranging from childhood encephalomyopathies to hereditary tumor formation. A key enzyme of tricarboxylic cycle, fumarate hydratase (FH), is involved in encephalopathies, but also in leiomyoma formation, and occasionally also in various types of cancer. MELAS (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes) and NARP (neuropathy ataxia retinitis pigmentosa) are progressive neurological disorders, caused by mitochondrial DNA mutations and respiratory chain (RC) deficiency. These diseases lead to disability and premature death, but not to tumorigenesis. We studied the cellular consequences of FH and RC deficiencies, aiming to identify general responses to energy metabolism defect and those specific for FH-deficiency, suggestively connected to tumorigenesis. Unlike in RC deficiency, the FH-deficient diploid human fibroblasts showed no signs of oxidative stress, but had a reduced redox state with high glutathione levels. The cytoplasmic FH isoform, previously described, but with an unknown function, was completely lacking in all FH-deficient lines. Fumarate was increased in two of our FH-lines, but accumulation of HIF-1alpha was not detected. Glycolysis was induced in both MELAS and in FH-deficiency. Accumulation of fumarate in primary fibroblasts did not activate a hypoxia response, suggesting that hypoxia activation due to fumarate accumulation may be a tissue-specific response. The lack of cytoplasmic form of FH and the reduced redox environment were typical for all FH-mutant lines, and their role in FH-related tumorigenesis requires further attention.

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

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