DDX6 is an abundant DEAD-box helicase associated with various complexes involved in mRNA decay and repression. Its interactome in human cells was analyzed to identify its most prominent partners. Among them, three proteins were essential for P-body assembly in all tested conditions: DDX6, 4E-T, and LSM14A.

Leber hereditary optic neuropathy is due to mitochondrial DNA mutations; in ~70% of all cases, a point mutation in the mitochondrial NADH dehydrogenase subunit 4, ND4, gene leads to central vision loss. We optimized allotopic expression (nuclear transcription of a gene that is normally transcribed inside the mitochondria) aimed at designing a gene therapy for ND4; its coding sequence was associated with the cis-acting elements of the human COX10 mRNA to allow the efficient mitochondrial delivery of the protein. After ocular administration to adult rats of a recombinant adeno-associated viral vector containing the human ND4 gene, we demonstrated that: (i) the sustained expression of human ND4 did not lead to harmful effects, instead the human protein is efficiently imported inside the mitochondria and assembled in respiratory chain complex I; (ii) the presence of the human protein in the experimental model of Leber hereditary optic neuropathy significantly prevents retinal ganglion cell degeneration and preserves both complex I function in optic nerves and visual function. Hence, the use of optimized allotopic expression is relevant for treating mitochondrial disorders due to mutations in the organelle genome.

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Ageing is a common feature of living organisms, showing shared molecular features called hallmarks of ageing. Usually they are quantified in groups of individuals as a function of their chronological age (time passed since birth) and display continuous and progressive changes. Such approaches are based on the assumption that individuals taken at a given chronological age are biological replicates. However, even in genetically homogeneous and synchronised populations individuals do die at different chronological ages. This highlights the difference between chronological age and biological age, the latter being defined by the actual mortality risk of the organism, reflecting its physiology. The Smurf assay, previously described by Rera and colleagues, allows the identification of individuals at higher risk of death from natural causes amongst a population of a given chronological age. We found that the categorization of individuals as Smurf or non-Smurf, permits to distinguish transcriptional changes associated with either chronological or biological age. We show that transcriptional heterogeneity increases with chronological age, while four out of the six currently defined transcriptional hallmarks of ageing are associated with the biological age of individuals, i.e. their Smurf state. In conclusion, we demonstrate that studying properties of ageing by applying the Smurf classification allows us to differentiate the effect of time from the effect of a physiological response triggering an end-of-life switch (i.e. Smurf phase). More specifically, we show that the ability to isolate a pre-death phase of life in vivo enables us not only to study late life mechanisms preceding death, but also investigate early physiological changes triggering such phase. This allowed the identification of novel pro-longevity genetic interventions. We anticipate that the use of the evolutionary conserved Smurf phenotype in ageing studies will allow significant advances in our comprehension of the underlying mechanisms of ageing.

Multivesicular vesicles, i. e. vesicles containing internal, non‐concentrically arranged smaller vesicles, are artificial, polymolecular compartment systems, which can be prepared from naturally occurring or fully synthetic bilayer‐forming amphiphiles in aqueous solution through various guided assembly procedures. The general concepts for the preparation of such “vesicles‐inside‐vesicles” systems (also called “vesosomes”) are summarized, and the different methods used are compared. Selected applications of multivesicular vesicles in the field of drug delivery, cell‐mimicking model systems, and as versatile compartments for the investigation of confined reactions are discussed.

Multivesicular vesicles, i. e. vesicles containing internal, nonconcentrically arranged smaller vesicles, are artificial, polymolecular compartment systems, which can be prepared from naturally occurring or fully synthetic bilayer-forming amphiphiles in aqueous solution through various guided assembly procedures. The general concepts for the preparation of such "vesicles-inside-vesicles" systems (also called "vesosomes") are summarized, and the different methods used are compared. Selected applications of multivesicular vesicles in the field of drug delivery, cell-mimicking model systems, and as versatile compartments for the investigation of confined reactions are discussed.

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