We have investigated the developmental expression pattern and knockdown phenotypes of a C.elegans RNA-binding protein (CeHRP-2) identified in the genome database (cosmid locus F58D5.1). The predicted polypeptide sequence has significant homology to mammalian heterogeneous nuclear RNA binding proteins, hnRNP R, hnRNP Q (equivalent to gry-rbp), and to an essential complementation factor for the RNA-editing activity of mammalian cytidine deaminase, apobec-1 (ACF). These all possess a similar molecular architecture, with three closely linked RNA-binding domains and a C-terminus that contains RG/RGG repeat motifs. Expression of HRP-2 as a gfp fusion under the control of 4.0kb of upstream sequence indicated that
hrp-2 is ubiquitously expressed both during embryogenesis and subsequent larval development. These results were confirmed by immunofluorescence using a specific antibody which also detected expression in the gonad. HRP-2 is predominantly located to nuclei, although additional preliminary evidence suggests it may move between nucleus and cytoplasm. The level of HRP-2 was reduced by feeding of double-stranded RNA. After two days of feeding, >98% of embryos arrested development. Feeding for a shorter time allowed some larvae to hatch and go through further development. These were characterised by lethargy, infertility and abnormal vulval development. As adult worms do not appear to be adversely affected by RNAi in terms of viability and egg production, we predict that CeHRP-2 may have a role in processing of specific pre-mRNAs during development.