The C2H2 zinc-finger protein SYD-9 is a putative posttranscriptional regulator for synaptic transmission

Communication between neurons is largely achieved through chemical synapses, where neurotransmitters are released from synaptic vesicles at presynaptic terminals to activate postsynaptic cells. Exo- and endocytosis are coordinated to replenish the synaptic vesicle pool for sustained neuronal activity. We identified syd-9 (syd, synapse defective), a gene that encodes multiple C2H2 zinc-finger domain-containing proteins specifically required for synaptic function in Caenorhabditis elegans. syd-9 loss-of-function mutants exhibit locomotory defects, a diffuse distribution of synaptic proteins, and decreased synaptic transmission with unaffected neurodevelopment. syd-9 mutants share phenotypic and ultrastructural characteristics with mutants that lack synaptic proteins that are required for endocytosis. syd-9 mutants also display genetic interactions with these endocytotic mutants, suggesting that SYD-9 regulates endocytosis. SYD-9 proteins are enriched in the nuclei of both neuron and muscle cells, but their neuronal expression plays a major role in locomotion. SYD-9 isoforms display a speckle-like expression pattern that is typical of RNA-binding proteins that regulate premRNA splicing. Furthermore, syd-9 functions in parallel with unc-75 (unc, uncoordinated), the C. elegans homologue of the CELF/BrunoL family protein that regulates mRNA alternative splicing and processing, and is also required specifically for synaptic transmission. We propose that neuronal SYD-9 proteins are previously uncharacterized and specific posttranscriptional regulators of synaptic vesicle endocytosis

Discovery and Characterization of a Highly Potent and Selective Aminopyrazoline-Based in Vivo Probe (BAY-598) for the Protein Lysine Methyltransferase SMYD2

Protein lysine methyltransferases have recently emerged as a new target class for the development of inhibitors that modulate gene transcription or signaling pathways. SET and MYND domain containing protein 2 (SMYD2) is a catalytic SET domain containing methyltransferase reported to monomethylate lysine residues on histone and nonhistone proteins. Although several studies have uncovered an important role of SMYD2 in promoting cancer by protein methylation, the biology of SMYD2 is far from being fully understood. Utilization of highly potent and selective chemical probes for target validation has emerged as a concept which circumvents possible limitations of knockdown experiments and, in particular, could result in an improved exploration of drug targets with a complex underlying biology. Here, we report the development of a potent, selective, and cell-active, substrate-competitive inhibitor of SMYD2, which is the first reported inhibitor suitable for in vivo target validation studies in rodents