In Nature this week, a team of German researchers report on the discovery that microRNA-34a is induced in the aging heart, and that in vivo silencing or genetic deletion of the small, non-coding RNA reduces age-related cardiomyocyte cell death. Additionally, inhibition of the miRNA reduces cell death and fibrosis following heart attack and improves recovery. The team also reports on a novel direct target of the miRNA, which reduces telomere shortening, DNA damage responses, and cardiomyocyte apoptosis, as well as improves functional recovery after acute myocardial infarction.
In Nature Biotechnology, a multi-institute team of Korean researchers publishes a genome-scale collection of transcription activator-like effector nucleases, or TALENs, which can be engineered to bind specific genomic loci and enable the introduction of precise genetic modifications in human cells. The scientists selected target sites that did not have highly similar sequences elsewhere in the genome to avoid off-target mutations and assembled TALEN plasmids for 18,740 protein-coding genes. They used the library to generate single- and double-gene-knockout cells in which NF-kappa B signaling pathways were disrupted, and found that these cells "showed unambiguous suppression of signal transduction" compared with ones treated with short interfering RNAs.
Meanwhile, in Nature Cell Biology, a team led by Max Planck Institute investigators report on the development of a genomic toolkit enabling the examination of kinesin and myosin motor functions in cells. They generated of a library of 243 amino- and carboxy-terminally tagged mouse and human bacterial artificial chromosome transgenes to establish 227 stably transfected HeLa cell lines, 15 mouse embryonic stem cell lines, and 1 transgenic mouse line. "The cells were characterized by expression and localization analyses and further investigated by affinity-purification mass spectrometry, identifying 191 candidate protein-protein interactions." The result is a set of validated resources and candidate molecular pathways for investigating motor protein function across cell lineages.