No abstract

Translation is an elementary cellular process that involves a large number of factors interacting in a concerted fashion with the ribosome. Numerous natural products have emerged that interfere with the ribosomal function, such as puromycin, which mimics an aminoacyl tRNA and causes premature chain termination. Here, we introduce a photoswitchable version of puromycin that, in effect, puts translation under optical control. Our compound, termed puroswitch, features a diazocine that allows for reversible and nearly quantitative isomerization and pharmacological modulation. Its synthesis involves a new photoswitchable amino acid building block. Puroswitch shows little activity in the dark and becomes substantially more active and cytotoxic, in a graded fashion, upon irradiation with various wavelengths of visible light. In vitro translation assays confirm that puroswitch inhibits translation with a mechanism similar to that of puromycin itself. Once incorporated into nascent proteins, puroswitch reacts with standard puromycin antibodies, which allows for tracking de novo protein synthesis using western blots and immunohistochemistry. As a cell-permeable small molecule, puroswitch can be used for nascent proteome profiling in a variety of cell types, including primary mouse neurons. We envision puroswitch as a useful biochemical tool for the optical control of translation and for monitoring newly synthesized proteins in defined locations and at precise time points.

Perception of our environment entirely depends on the close interaction between the central and peripheral nervous system. In order to communicate each other, both systems must develop in parallel and in coordination. During development, axonal projections from the CNS as well as the PNS must extend over large distances to reach their appropriate target cells. To do so, they read and follow a series of axon guidance molecules. Interestingly, while these molecules play critical roles in guiding developing axons, they have also been shown to be critical in other major neurodevelopmental processes, such as the migration of cortical progenitors. Currently, a major hurdle for brain repair after injury or neurodegeneration is the absence of axonal regeneration in the mammalian CNS. By contrasts, PNS axons can regenerate. Many hypotheses have been put forward to explain this paradox but recent studies suggest that hacking neurodevelopmental mechanisms may be the key to promote CNS regeneration. Here we provide a seminar report written by trainees attending the second Flagship school held in Alpbach, Austria in September 2018 organized by the International Society for Neurochemistry (ISN) together with the Journal of Neurochemistry (JCN). This advanced school has brought together leaders in the fields of neurodevelopment and regeneration in order to discuss major keystones and future challenges in these respective fields.

Alzheimer’s disease (AD) is an age-related neurodegenerative disorder associated with memory loss, but the AD-associated neuropathological changes begin years before memory impairments. Investigation of the early molecular abnormalities in AD might offer innovative opportunities to target memory impairment prior to onset. Decreased protein synthesis plays a fundamental role in AD, yet the consequences of this dysregulation for cellular function remain unknown. We hypothesize that alterations in the de novo proteome drive early metabolic alterations in the hippocampus that persist throughout AD progression. Using a combinatorial amino acid tagging approach to selectively label and enrich newly synthesized proteins, we found that the de novo proteome is disturbed in young APP/PS1 mice prior to symptom onset, affecting the synthesis of multiple components of the synaptic, lysosomal, and mitochondrial pathways. Furthermore, the synthesis of large clusters of ribosomal subunits were affected throughout development. Our data suggest that large-scale changes in protein synthesis could underlie cellular dysfunction in AD.