Mediterranean Institute for Life Sciences

Split, Croatia

Mediterranean Institute for Life Sciences

Split, Croatia
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Relkovic D.,Mediterranean Institute for Life Sciences | Isles A.R.,University of Cardiff
Brain Research Bulletin | Year: 2013

Prader-Willi syndrome (PWS) is a neurodevelopmental disorder with aspects of psychiatric illness caused by genetic mutations at chromosome 15q11-q13. In addition to causing PWS, this interval is also thought to be of importance more generally in the development of autism and psychotic illness. The PWS genetic interval is conserved in mammals, and consequently mice carrying genetic manipulations affecting one or all of the genes in the region of conserved synteny have been generated and used in neurobehavioural studies. Here we give an overview of these models and describe the behavioural and neurobiological analyses that have been performed, many of which have provide new insights into the molecular and neural processes influenced by genes within the PWS interval. © 2011 Elsevier Inc.

Usenovic M.,Harvard University | Usenovic M.,MassGeneral Institute for Neurodegenerative Disease | Usenovic M.,Mediterranean Institute for Life Sciences | Tresse E.,St Jude Childrens Research Hospital | And 3 more authors.
Journal of Neuroscience | Year: 2012

The autophagy-lysosomal pathway plays an important role in the clearance of long-lived proteins and dysfunctional organelles. Lysosomal dysfunction has been implicated in several neurodegenerative disorders including Parkinson's disease and related synucleinopa-thies that are characterized by accumulations of a-synuclein in Lewy bodies. Recent identification of mutations in genes linked to lysosomal function and neurodegeneration has offered a unique opportunity to directly examine the role of lysosomes in disease pathogenesis. Mutations in lysosomal membrane protein ATP13A2 (PARK9) cause familial Kufor-Rakeb syndrome characterized by early-onset parkinsonism, pyramidal degeneration and dementia. While previous data suggested a role of ATP13A2 in α-synuclein misfolding and toxicity, the mechanistic link has not been established. Here we report that loss of ATP13A2 in human fibroblasts from patients with Kufor-Rakeb syndrome or in mouse primary neurons leads to impaired lysosomal degradation capacity. This lysosomal dysfunction results in accumulation of α-synuclein and toxicity in primary cortical neurons. Importantly, silencing of endogenous α-synuclein attenuated the toxicity in ATP13A2-depleted neurons, suggesting that loss of ATP13A2 mediates neurotoxicity at least in part via the accumulation of α-synuclein. Our findings implicate lysosomal dysfunction in the pathogenesis of Kufor-Rakeb syndrome and suggest that upregulation of lysosomal function and downregulation of α-synuclein represent important therapeutic strategies for this disorder. © 2012 the authors.

Slade D.,University of Paris Descartes | Radman M.,University of Paris Descartes | Radman M.,Mediterranean Institute for Life Sciences
Microbiology and Molecular Biology Reviews | Year: 2011

Deinococcus radiodurans is a robust bacterium best known for its capacity to repair massive DNA damage efficiently and accurately. It is extremely resistant to many DNA-damaging agents, including ionizing radiation and UV radiation (100 to 295 nm), desiccation, and mitomycin C, which induce oxidative damage not only to DNA but also to all cellular macromolecules via the production of reactive oxygen species. The extreme resilience of D. radiodurans to oxidative stress is imparted synergistically by an efficient protection of proteins against oxidative stress and an efficient DNA repair mechanism, enhanced by functional redundancies in both systems. D. radiodurans assets for the prevention of and recovery from oxidative stress are extensively reviewed here. Radiation- and desiccation-resistant bacteria such as D. radiodurans have substantially lower protein oxidation levels than do sensitive bacteria but have similar yields of DNA double-strand breaks. These findings challenge the concept of DNA as the primary target of radiation toxicity while advancing protein damage, and the protection of proteins against oxidative damage, as a new paradigm of radiation toxicity and survival. The protection of DNA repair and other proteins against oxidative damage is imparted by enzymatic and nonenzymatic antioxidant defense systems dominated by divalent manganese complexes. Given that oxidative stress caused by the accumulation of reactive oxygen species is associated with aging and cancer, a comprehensive outlook on D. radiodurans strategies of combating oxidative stress may open new avenues for antiaging and anticancer treatments. The study of the antioxidation protection in D. radiodurans is therefore of considerable potential interest for medicine and public health. Copyright © 2011, American Society for Microbiology. All Rights Reserved.

The proteome of the radiation- and desiccation-resistant bacterium D. radiodurans features a group of proteins that contain significant intrinsically disordered regions that are not present in non-extremophile homologues. Interestingly, this group includes a number of housekeeping and repair proteins such as DNA polymerase III, nudix hydrolase and rotamase. Here, we focus on a member of the nudix hydrolase family from D. radiodurans possessing low-complexity N- and C-terminal tails, which exhibit sequence signatures of intrinsic disorder and have unknown function. The enzyme catalyzes the hydrolysis of oxidatively damaged and mutagenic nucleotides, and it is thought to play an important role in D. radiodurans during the recovery phase after exposure to ionizing radiation or desiccation. We use molecular dynamics simulations to study the dynamics of the protein, and study its hydration free energy using the GB/SA formalism. We show that the presence of disordered tails significantly decreases the hydration free energy of the whole protein. We hypothesize that the tails increase the chances of the protein to be located in the remaining water patches in the desiccated cell, where it is protected from the desiccation effects and can function normally. We extrapolate this to other intrinsically disordered regions in proteins, and propose a novel function for them: intrinsically disordered regions increase the "surface-properties" of the folded domains they are attached to, making them on the whole more hydrophilic and potentially influencing, in this way, their localization and cellular activity.

Kuzmanic A.,Mediterranean Institute for Life Sciences | Zagrovic B.,University of Split
Biophysical Journal | Year: 2010

Root mean-square deviation (RMSD) after roto-translational least-squares fitting is a measure of global structural similarity of macromolecules used commonly. On the other hand, experimental x-ray B-factors are used frequently to study local structural heterogeneity and dynamics in macromolecules by providing direct information about root mean-square fluctuations (RMSF) that can also be calculated from molecular dynamics simulations. We provide a mathematical derivation showing that, given a set of conservative assumptions, a root mean-square ensemble-average of an all-against-all distribution of pairwise RMSD for a single molecular species, 〈RMSD2〉 1/2, is directly related to average B-factors (〈B〉) and 〈RMSF2〉1/2. We show this relationship and explore its limits of validity on a heterogeneous ensemble of structures taken from molecular dynamics simulations of villin headpiece generated using distributed-computing techniques and the Folding@Home cluster. Our results provide a basis for quantifying global structural diversity of macromolecules in crystals directly from x-ray experiments, and we show this on a large set of structures taken from the Protein Data Bank. In particular, we show that the ensemble-average pairwise backbone RMSD for a microscopic ensemble underlying a typical protein x-ray structure is ∼1.1 Å , under the assumption that the principal contribution to experimental B-factors is conformational variability. © 2010 by the Biophysical Society.

Krisko A.,Mediterranean Institute for Life Sciences | Radman M.,Mediterranean Institute for Life Sciences | Radman M.,French Institute of Health and Medical Research
Cold Spring Harbor Perspectives in Biology | Year: 2013

The bacterium Deinococcus radiodurans is a champion of extreme radiation resistance that is accounted for by a highly efficient protection against proteome, but not genome, damage. A well-protected functional proteome ensures cell recovery from extensive radiation damage to other cellular constituents by molecular repair and turnover processes, including an efficient repair of disintegrated DNA. Therefore, cell death correlates with radiationinduced protein damage, rather than DNA damage, in both robust and standard species. From the reviewed biology of resistance to radiation and other sources of oxidative damage, we conclude that the impact of protein damage on the maintenance of life has been largely underestimated in biology and medicine. © 2013 Cold Spring Harbor Laboratory Press; all rights reserved.

Krisko A.,Mediterranean Institute for Life Sciences | Radman M.,Mediterranean Institute for Life Sciences | Radman M.,French Institute of Health and Medical Research
PLoS Genetics | Year: 2013

Although the genome contains all the information necessary for maintenance and perpetuation of life, it is the proteome that repairs, duplicates and expresses the genome and actually performs most cellular functions. Here we reveal strong phenotypes of physiological oxidative proteome damage at the functional and genomic levels. Genome-wide mutations rates and biosynthetic capacity were monitored in real time, in single Escherichia coli cells with identical levels of reactive oxygen species and oxidative DNA damage, but with different levels of irreversible oxidative proteome damage (carbonylation). Increased protein carbonylation correlates with a mutator phenotype, whereas reducing it below wild type level produces an anti-mutator phenotype identifying proteome damage as the leading cause of spontaneous mutations. Proteome oxidation elevates also UV-light induced mutagenesis and impairs cellular biosynthesis. In conclusion, protein damage reduces the efficacy and precision of vital cellular processes resulting in high mutation rates and functional degeneracy akin to cellular aging. © 2013 Krisko, Radman.

Elez M.,University of Paris Descartes | Radman M.,University of Paris Descartes | Radman M.,Mediterranean Institute for Life Sciences | Matic I.,University of Paris Descartes
Nucleic Acids Research | Year: 2012

Mismatch repair (MMR) is an evolutionarily conserved DNA repair system, which corrects mismatched bases arising during DNA replication. MutS recognizes and binds base pair mismatches, while the MutL protein interacts with MutS-mismatch complex and triggers MutH endonuclease activity at a distal-strand discrimination site on the DNA. The mechanism of communication between these two distal sites on the DNA is not known. We used functional fluorescent MMR proteins, MutS and MutL, in order to investigate the formation of the fluorescent MMR protein complexes on mismatches in real-time in growing Escherichia coli cells. We found that MutS and MutL proteins co-localize on unrepaired mismatches to form fluorescent foci. MutL foci were, on average, 2.7 times more intense than the MutS foci co-localized on individual mismatches. A steric block on the DNA provided by the MutHE56A mutant protein, which binds to but does not cut the DNA at the strand discrimination site, decreased MutL foci fluorescence 3-fold. This indicates that MutL accumulates from the mismatch site toward strand discrimination site along the DNA. Our results corroborate the hypothesis postulating that MutL accumulation assures the coordination of the MMR activities between the mismatch and the strand discrimination site. © 2012 The Author(s).

Mediterranean Institute for Life Sciences | Date: 2013-12-18

Vaccines and therapeutic proteins, including polyclonal and monoclonal antibodies, must be maximally pure and stable in their most active native form. This is a requirement for their maximal efficacy, specificity and stability as well as for precluding immune responses against erroneous or damaged moieties. Similar considerations hold for proteins used in diagnostics, industry and research. The most frequent source of damage to proteins produced in living cells is the diverse product of oxidative damage. Two main sources of protein oxidation are the level of reactive oxygen species (ROS) and even more importantly the intrinsic susceptibility of proteins to oxidative damage. Methods for avoiding oxidative protein damage are disclosed, including providing for (i) a decrease in intracellular ROS levels and (ii) an increase in the intrinsic resilience of proteins to oxidative damage. Metabolites synthesized by the most robust species provide exceptionally high levels of protection against oxidative damage from ROS. High fidelity ribosomal mutations and over-expression of diverse chaperones increase the accuracy of protein biosynthesis and of protein post-synthetic folding, both greatly contributing to increased intrinsic resistance of proteins to oxidative damage.

Mediterranean Institute for Life Sciences | Date: 2014-02-15

The process of aging and the development of age-related diseases are related to the emerging phenotypes of increasingly damaged and progressively malfunctioning proteomes. The present invention provides methods of preventing aging and age-related diseases in mammals by assessment of protein-specific oxidative damage. Methods of providing treatments that reduce intracellular reactive oxygen and/or nitrogen species, or protein-specific damage caused by reactive oxygen and/or nitrogen species, are disclosed. Furthermore, methods of screening for compounds that reduce intracellular reactive oxidative species, and/or molecules that prevent protein-specific damage by protecting the susceptible protein from such damage and therefore prevent or treat degenerative or age-related diseases, are also disclosed.

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