Lall S et al. (2005) Mol Biol Cell "Caenorhabditis elegans decapping proteins: localization and functional analysis of Dcp1, Dcp2, and DcpS during embryogenesis."

Lall S, Piano F, Davis RE

[Mol Biol Cell, 2005]

Monitoring Editor: Marvin P. Wickens Though posttranscriptional regulation is important for early embryogenesis, little is understood regarding control of mRNA decay during development. Previous work defined two major pathways by which normal transcripts are degraded in eukaryotes. However it is not known which pathways are key in mRNA decay during early patterning, or whether developmental transcripts are turned over via specific pathways. Here we show that C. elegans Dcp2 is localized to distinct foci during embryogenesis, reminiscent of P-bodies, the sites of mRNA degradation in yeast and mammals. However the decapping enzyme of the 3'' to 5'' transcript decay system (DcpS) localizes throughout the cytoplasm, suggesting this degradation pathway is not highly organized. In addition we find that Dcp2 is localized to P-granules, showing that Dcp2 is stored and/or active in these structures. However RNAi of these decapping enzymes has no obvious effect on embryogenesis. In contrast we find that nuclear cap binding proteins (CBP-20 and 80), eIF4G, and PAB-1 are absolutely required for development. Together our data provides further evidence that pathways of general mRNA metabolism can be remarkably organized during development, with two different decapping enzymes localized in distinct cytoplasmic domains.

Sundaram P et al. (2006) Mol Biol Cell "ATP-binding cassette transporters are required for efficient RNA interference in Caenorhabditis elegans."

Sundaram P, Han W, Echalier B, Hull D, Timmons L

[Mol Biol Cell, 2006]

Monitoring Editor: Marvin P. Wickens RNA interference (RNAi) is a conserved gene-silencing phenomenon that can be triggered by delivery of double-stranded RNA (dsRNA) to cells and is a widely exploited technology in analyses of gene function. While a number of proteins that facilitate RNAi have been identified, current descriptions of RNAi and interrelated mechanisms are far from complete. Here we report that the Caenorhabditis elegans gene haf-6 is required for efficient RNAi. HAF-6 is a member of the ATP binding Cassette (ABC) transporter gene superfamily. ABC transporters utilize ATP to translocate small molecule substrates across the membranes in which they reside, often against a steep concentration gradient. Collectively, ABC transporters are involved in a variety of activities, including protective or barrier mechanisms that export drugs or toxins from cells (Broeks et al., 1996; Bauer et al., 1999; Begley, 2004; Fromm, 2004), in organellar biogenesis (Aubourg, 1994), and in mechanisms that protect against viral infection (Trowsdale et al., 1990; Abele and Tampe, 2004). HAF-6 is expressed predominantly in the intestine and germline and is localized to intracellular reticular organelles. We further demonstrate that nine additional ABC genes from diverse subfamilies are each required for efficient RNAi in C. elegans. Thus, the ability to mount a robust RNAi response to dsRNA depends upon the deployment of two ancient systems that respond to environmental assaults: RNAi mechanisms and membrane transport systems that utilize ABC proteins.