The vacuolar ATPase enzyme (v-ATPase) is found in many organisms and is responsible for pumping protons across membranes, contributing to the overall pH of cellular compartments. v-ATPases therefore have a very important role in cells and have been found to be involved in many processes including sperm maturation, bone regeneration and tumour metastasis in mammals and cell fusion in yeast.
vha-19 is a C. elegans gene that encodes a protein similar to the mammalian protein Ac45, and it has been predicted to associate with v-ATPase. Despite these predictions, the association between VHA-19 and v-ATPase has yet to be proved directly, and the exact functions of VHA-19 are so far unknown. We have found that RNA interference mediated (RNAi) knockdown of
vha-19 starting from the first larval stage has a severe effect on development in C. elegans. This effect was observed using both a commercially obtained RNAi construct of
vha-19 and a shorter, more specific construct designed and made by our group, although arrest was observed at a later stage in development when the specific construct was used. Starting from the fourth C. elegans larval stage, silencing
vha-19 using the commercial
vha-19 construct produced adults that were grossly normal in appearance, but these worms produced very few viable embryos, and those progeny that did hatch all arrested in development by the third larval stage. The expression pattern of
vha-19 (determined using transgenic C. elegans containing the putative
vha-19 promoter fused to a GFP reporter gene) suggested that
vha-19 is expressed in similar tissues to other C. elegans v-ATPase genes, as well as in a region around the vulva hypothesised to be epidermis. Also, C. elegans in which
vha-19 had been knocked down by RNAi stained less intensely with the fluorescent dye acridine orange than controls. This suggests that knockdown of
vha-19 may affect pH in cell compartments, consistent with the predicted association between
vha-19 and v-ATPase. This is the first reported study of the role of
vha-19 in C. elegans. .