Assmann 2014 PhD Thesis

Assmann N (2015) Impact of Fanconi-associated protein on the mitochonrial proteome. PhD Thesis 1-111.

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Assmann N (2015) PhD Thesis

Abstract: This work describes the analysis of a novel, isolated, autosomal dominant form of Fanconi´s syndrome, a disorder of the renal proximal tubule associated with decreased reapsorption of solutes from the primary urine. This yet unknown Fanconi´s syndrome is evoked by a mutation in the third codon of the peroxisomal protein enoyl-CoA hydratase / L-3-hydroxyacyl-CoA dehydrogenase (EHHADH), also called “Fanconi-associated protein”, which results in the substitution of a glutamic acid residue with lysine (p.E3K). By complementing proteomic and metabolomic analyses of wildtype- and mutant-EHHADH-expressing proximal tubular cell lines (LLC-PK1) with different biochemical and cell biological investigations, the underlying pathomechanism is elucidated. The E3K-mutation leads to the erroneous localization of peroxisomal EHHADH into mitochondria causing a mitochondriopathy. Upon mistargeting of EHHADHMUT into mitochondria, it replaces an alpha subunit of the mitochondrial trifunctional protein (MTP). The MTP normally builds a heterooctamer consisting of four alpha and four beta subunits and is involved in mitochondrial fatty acid β-oxidation. The incorporation into MTP impairs both mitochondrial β-oxidation and respiratory supercomplex assembly, leading to a decreased oxidative phosphorylation capacity. Impairment of the former is shown by the characteristic accumulation of hydroxyacyl-, enoyl- and acylcarnitines in the cell culture supernatant, thus resembling the situation in patients with MTP and/or LCHAD deficiency. The impaired mitochondrial β-oxidation consequently decreases cellular long-chain fatty acid uptake and the acetyl-CoA production in EHHADHMUT cell line. In addition, EHHADHMUT is also incorporated into respiratory supercomplexes, thereby disturbing their assembly, as shown by blue native PAGE. As a result of impaired mitochondrial β-oxidation and diminished supercomplex assembly the EHHADHMUT cell line shows a decreased oxidative phosphorylation capacity and reduced ATP generation. This mitochondriopathy results in the decreased tubular reabsorption of electrolytes and low-molecular-weight proteins, leading to the Fanconi´s syndrome.

• O2k-Network Lab: DE Regensburg Renner-Sattler K

Labels: MiParea: Respiration, Comparative MiP;environmental MiP  Pathology: Other 

Organism: Pig  Tissue;cell: Kidney, Other cell lines  Preparation: Intact cells, Permeabilized cells 

Coupling state: LEAK, ROUTINE, OXPHOS, ET  Pathway: F, N, S, CIV, NS, ROX  HRR: Oxygraph-2k