Baraldo 2017 MiPschool Obergurgl
Event: MiPschool Obergurgl 2017
Old age is associated with the emerging of many diseases, among which neurodegenerative diseases are probably the most deleterious. A strong correlation exists between mitochondrial dysfunction and neurological disease ; however, the underlying connection between these factors remains elusive. About ten years ago the Fumarylacetoacetate hydrolase domain-containing protein 1 (FAHD1) protein, a member of the FAH superfamily, has been discovered and attributed regulation of the citric acid cycle by decarboxylation of oxaloacetate into pyruvate . Findings in Caenorhabditis elegans (C. elegans) on the proteins orthologue, FAHD-1, show, that deficiency of the enzyme causes severe locomotion impairment and defects in egg laying in the nematode . Additionally fahd-1 (tm5005) deletion mutants (fahd-1) were found to be resistant to serotonin induced egg laying (personal communication). Since locomotion and egg laying are both dependent on neuronal and muscular activity, we asked whether the tissue specific expression of fahd-1 in neurons or muscles were sufficient to restore the locomotion and egg laying phenotype.
Two tissue specific rescue strains for muscle and neurons were generated by microinjection using myo-3 and rab-3 promoter respectively. The expression of FAHD-1 has been confirmed by Western Blot. Body bend assay was performed for both rescue strains. Furthermore, an egg laying assay was performed in M9 buffer using the N2 wild type, fahd-1 and rab-3 rescue strain. Further observations indicated that fahd-1 rescue strain was challenged when searching for food sources. To investigate the matter we performed a food searching assay on the three named strains by starving the nematodes in M9 buffer for 1h and subsequently placing them on a 10cm dish, opposite to a food source containing E. coli OP50. The amount of time that the nematodes needed to find the food was recorded.
We observed a partial increase of the locomotion of the fahd-1 deletion mutant when fahd-1 is re-introduced in the neurons and the muscles of the nematode, compared to fahd-1 mutant. However, the observed rescue is more prominent in rab-3::fahd-1 rescue stain (Figure 1). Further investigations on the rab-3::fahd-1 mutant suggest the involvement of FAHD-1 in the correct egg-laying in absence of food (Figure 2). Preliminary data indicate a similar rescue effect of the decreased egg laying phenotype when fahd-1(tm5005) mutants are exposed to dopamine. Furthermore, data of the food searching assay has confirmed that fahd-1(tm5005) mutants have a reduced ability to localize a food source in comparison to the N2 wild type. This deficiency, however, could not be rescued by FAHD-1 expression in the neurons.
The deletion of fahd-1 shows a deleterious phenotype in C. elegans including decreased locomotion, increased egg laying in absence of food and inability to find a distant food source. Neurological rescue of fahd-1 is sufficient to partially reestablish the phenotype of fahd-1 deletion strain. Our findings suggest that the protein FAHD-1 might constitutes a link between cellular metabolism and neurological function. An understanding of the function of fahd-1 and its connection to a correct neurological function might link cellular metabolism to neurological diseases.
Labels: Pathology: Aging;senescence, Neurodegenerative
Organism: Caenorhabditis elegans
Event: D2, Oral
- Inst Biomedical Aging Research, Dept Molecular Cell Biol, Univ Innsbruck, Austria. - [email protected]
Figure 1. The number of body bends was established for the wild type strain (N2), fahd-1(tm5005), the rab-3::fahd-1 rescue strain (rab-3) and the myo-3::fahd-1 rescue strain (myo-3). Therefore, each nematode was placed singularly on a NGM agar plate without E. coli OP50. [A, B] A difference in locomotion between N2 and fahd-1 (tm5005) deletion mutant was observed with the wild type performing significantly better. [A] This impaired locomotion of fahd-1(tm5005) was rescued when fahd-1 was reintegrated in the neurons of the nematodes using a rab-3 promoter, emphasizing the role of fahd-1 for a correct neuronal function. [B] A significant rescue of the phenotype was also achieved with the muscle specific rescue strain using the myo-3 promoter to express fahd-1. However, the rescue is not as prominent as with rab-3 promoter.
Figure 2. The nematodes were incubated in M9 buffer for four consecutive hours and the number of eggs laid were counted once per hour. The collected data shows a clear difference in egg laying in absence of food between Wild type N2 (n=60) and fahd-1 (n = 60). The fahd-1 deletion mutant lays up to 3 times more eggs than the wild type. However, this phenotype is fully rescued in rab-3::fahd-1 rescue strains (n = 48).
References and support
- Ghosh A, Tyson T, George S, Hildebrandt EN, Steiner JA, Madaj Z, Schulz E, Machiela E, McDonald WG, Escobar Galvis ML, Kordower JH, Van Raamsdonk JM, Colca JR, Brundin P (2016) Mitochondrial pyruvate carrier regulates autophagy, inflammation, and neurodegeneration in experimental models of Parkinson's disease. Sci Transl Med. 8:368ra174.
- Pircher H, von Grafenstein S, Diener T, Metzger C, Albertini E, Taferner A, Unterluggauer H, Kramer C, Liedl KR, Jansen-Dürr P (2015) Identification of FAH domain-containing protein 1 (FAHD1) as oxaloacetate decarboxylase. J Biol Chem 290:6755-62.
- Taferner A, Pircher H, Koziel R, von Grafenstein S, Baraldo G, Palikaras K, Liedl KR, Tavernarakis N, Jansen-Dürr P (2015) FAH domain containing protein 1 (FAHD-1) is required for mitochondrial function and locomotion activity in C. elegans. PLOS ONE 10:e0134161.
- Selected mentor: Prof. Dr. Tavernarakis Nektarios