• 2015-2024close
• Publications close
• Research data close
• Other research products close
• HU close
• Hungarian close

In the last few decades genetic analysis has been playing an increasing role in tracing the origin and relation of human populations. DNA sequences isolated from ancient human remains can be used, to unravel ancestor-descendant relationships between populations and reconstruct population history. In our research we successfully optimized ancient DNA extraction methods and adapted the latest haplotyping methods. We complemented the traditional PCR based HVR sequencing method with the SNaPshot assay, which is used to determine 22 haplotype defining SNP-s in the mtDNA coding region. In the case of bone samples with best DNA preservation the same method could also be used to determine the paternal (Y chromosome) haplogroup. In the last few years the next generation sequencing method (NGS) has revolutionized the aDNA field, by providing reliable high quality sequence reads, and enabling to sequence even whole ancient genomes. Recently we have adapted the NGS method in our lab (Archoegenetic Laboratory, University of Szeged) and sequenced whole mtDNA genomes from a large number of Hungarian conqueror samples. Some 40% of the conquerors had East-Central Asian origin, other 60% of the samples had best matches with modern people from Europe.

Autophagy is an evolutionarily conserved intracellular degradation process of cellular self-eating and the major pathway for degradation of cytoplasmatic material by the lysosomal machinery. Selective autophagy receptors can recognize ubiquitinated aggregates, and bind to Atg8/LC3 proteins to ensure the capture of cargo into autophagosomes. In Drosophila, p62/Ref(2)P is the first autophagy receptor. P62 possesses a C-terminal ubiquitin-binding domain, an N-terminal PB1 domain to mediate aggregate formation, and a LIR (LC3-interacting region) motif in an unstructured region, which is responsible for LC3/Atg8a binding on autophagic membranes. The topic of my PhD work is to investigate the role of p62/Ref(2)P. We replaced two previously characterized key amino acids within the LIR motif: a Tryptophan and an Isoleucine were changed to Alanines by editing the endogenous gene using CRISPR. We generated Drosophila lines carrying this p62 LIR mutation, which disrupted the autophagic degradation of p62 and ubiquitinated cargo. To summarize, we generated a Ref(2)PLIR mutant stock. These flies accumulated copious amounts of Ref(2)P and poly-ubiquitin. We find that these polyUb aggregates contain ubiquitinated Keap1, a negative regulator of the Nrf2-dependent oxidative stress response. Keap1 autophagic degradation in flies is facilitated by Ref(2)P through its LIR-mediated interaction with the Atg8a-Keap1 complex, which promotes engulfment of the resulting aggregates. Thus, free Keap1 levels and by extension, Nrf2 activity is regulated by Ref(2)P similar to mammals. An important consequence of the Ref(2)P-Keap1 co-sequestration in the LIR mutant is persistently elevated Nrf2 activity as its proteasomal degradation is prevented, ultimately leading to increased PQ tolerance. We find that persistent Nrf2 activation in our Ref(2)PLIR mutants can have physiological benefits even compared to wild-type animals. In our model that is gleaned from the experimental results, sequestration of ubiquitinated cargoes firstly increases their proteotoxicity. However, subsequent Nrf2-mediated increased detoxification likely reduces the burden of ubiquitinated proteins, which may also reduce the levels of soluble, presumably more toxic species. Our selective ubiquitinated protein autophagy defective flies develop just as many poly-Ub aggregates as Atg mutants do, but they do not show any major physiological defects.