The Translational Regulators GCN-1 and ABCF-3 Act Together to Promote Apoptosis in C. elegans

The proper regulation of apoptosis requires precise spatial and temporal control of gene expression. While the transcriptional and translational activation of pro-apoptotic genes is known to be crucial to triggering apoptosis, how different mechanisms cooperate to drive apoptosis is largely unexplored. Here we report that pro-apoptotic transcriptional and translational regulators act in distinct pathways to promote programmed cell death. We show that the evolutionarily conserved C. elegans translational regulators GCN-1 and ABCF-3 contribute to promoting the deaths of most somatic cells during development. GCN-1 and ABCF-3 are not obviously involved in the physiological germ-cell deaths that occur during oocyte maturation. By striking contrast, these proteins play an essential role in the deaths of germ cells in response to ionizing irradiation. GCN-1 and ABCF-3 are similarly co-expressed in many somatic and germ cells and physically interact in vivo, suggesting that GCN-1 and ABCF-3 function as members of a protein complex. GCN-1 and ABCF-3 are required for the basal level of phosphorylation of eukaryotic initiation factor 2α (eIF2α), an evolutionarily conserved regulator of mRNA translation. The S. cerevisiae homologs of GCN-1 and ABCF-3, which are known to control eIF2α phosphorylation, can substitute for the worm proteins in promoting somatic cell deaths in C. elegans. We conclude that GCN-1 and ABCF-3 likely control translational initiation in C. elegans. GCN-1 and ABCF-3 act independently of the anti-apoptotic BCL-2 homolog CED-9 and of transcriptional regulators that upregulate the pro-apoptotic BH3-only gene egl-1. Our results suggest that GCN-1 and ABCF-3 function in a pathway distinct from the canonical CED-9-regulated cell-death execution pathway. We propose that the translational regulators GCN-1 and ABCF-3 maternally contribute to general apoptosis in C. elegans via a novel pathway and that the function of GCN-1 and ABCF-3 in apoptosis might be evolutionarily conserved.Howard Hughes Medical Institut

Combined use of repeated active shots and ambient noise to detect temporal changes in seismic velocity: application to Sakurajima volcano, Japan

Additional file 1. Comparison of the results of coda-wave interferometry and seismic interferometry on the almost identical wave paths. Gray dots in top two panels are daily dv/v values obtained from seismic interferometry. The dv/v values obtained from coda-wave interferometry are shown by red squares and are overwritten assuming that the results for the 2012 experiment are the same as those on the same day from seismic interferometry. Error bars show Âą one standard deviation. Spatial distribution of three seismometers (squares) and a shot point (star) used in top two panels is shown in the bottom panel with black letters and red letters, respectively

Distinct roles of the Src family kinases, SRC-1 and KIN-22, that are negatively regulated by CSK-1 in C. elegans

AbstractTo elucidate the primitive roles of the Src family kinases (SFKs), here we characterized Caenorhabditis elegans orthologues of SFKs (src-1 and kin-22) and their regulator kinase Csk (csk-1). SRC-1 and KIN-22 possess the C-terminal regulatory tyrosines characteristic of SFKs, and their activities are negatively regulated by CSK-1 in a yeast expression system. The src-1 and csk-1 genes are co-expressed in some head neurons, the anchor cell and the tail region, while kin-22 and csk-1 genes are co-expressed in pharyngeal muscles and tail region. Expression of KIN-22 induced morphological defects in the pharynx, whereas expression of SRC-1 did not show any overt phenotype in adult. RNA interference of src-1, but not that of kin-22, caused a developmental arrest in early development. These results suggest that SRC-1 and KIN-22 play distinct roles under the control of CSK-1

An Sp1 transcription factor coordinates caspase-dependent and -independent apoptotic pathways

During animal development, the proper regulation of apoptosis requires the precise spatial and temporal execution of cell-death programs, which can include both caspase-dependent and caspaseindependent pathways The C. elegans pharyngeal M4 motor neuron is generated during embryonic development, whereas the M4 sister cell dies by apoptosis soon after its generation . We constructed a P ceh-28 ::gfp reporter transgene that expresses green fluorescent protein (GFP) specifically in the M4 neuron of wild-type animals and in both the M4 neuron and the surviving M4 sister of ced-3 caspase mutants defective in apoptosis ( 8 , allowing us to identify efficiently mutants defective in M4 sister cell death from a large-scale genetic screen. Among our isolates were two non-allelic mutations-n4850 and n4780-which, on the basis of mapping and transformation-rescue studies, are alleles of the genes sptf-3 and pig-1, respectively sptf-3 encodes an Sp1 family transcription factor with a characteristic glutamine-rich domain and three C2H2-type zinc finger domains pig-1 encodes an AMP-activated protein kinase (AMPK)-related protein kinase most similar to mammalian maternal embryonic leucine zipper kinase (MELK); pig-1 is known to regulate the asymmetric cell divisions of several neuroblasts that divide to produce an apoptotic cell, including the M4 sister 4 Both sptf-3 and pig-1 are required for the deaths of multiple cells, including the sisters of the AQR neuron, the pharyngeal gland cells 1A (g1A) and the pharyngeal I2 interneuron

Midkine inhibitors: application of a simple assay procedure to screening of inhibitory compounds

<p>Abstract</p> <p>Background</p> <p>Midkine is a heparin-binding cytokine and is involved in etiology of various diseases. Thus, midkine inhibitors are expected to be helpful in treatment of many diseases.</p> <p>Methods</p> <p>We developed a simple assay for midkine activity based on midkine-dependent migration of osteblastic cells. Midkine inhibitors were searched as materials that inhibit this midkine activity. To develop peptides that inhibit midkine activity, we constructed models in which C-terminal half of midkine interacted with α₄β₁-integrin. Low molecular weight compounds which are expected to bind to midkine with high affinity were searched by <it>in silico </it>screening with the aid of Presto-X2 program.</p> <p>Results</p> <p>Among peptides in putative binding sites of midkine and the integrin, a peptide derived from β₁-integrin and that derived from the first β sheet of the C-terminal half of midkine significantly inhibited midkine activity. Two low molecular weight compounds found by <it>in silico </it>screening exhibited no toxicity to target cells, but inhibited midkine activity. They are trifluoro compounds: one (PubChem 4603792) is 2-(2,6-dimethylpiperidin-1-yl)-4-thiophen-2-yl-6-(trifluoromethy)pyrimidine, and the other has a related structure.</p> <p>Conclusions</p> <p>The assay procedure is helpful in screening midkine inhibitors. All reagents described here might become mother material to develop clinically effective midkine inhibitors.</p