GLA-3 is the C. elegans homolog of the mammalian tristetraprolin (TTP) which encodes a protein that contains two CCCH-like zinc-finger domains that function either as transcription factors or RNA-binding proteins. This gene which encodes two splice variants GLA-3A and GLA3B and the protein is expressed in both germline and soma. Loss of gla-3
function present different alterations: protein degradation in muscle leading to a progressive loss of motility, increased germ cell death by apoptosis, severe defects in meiosis progression, reduced brood size and a low frequency of embryonic lethality. Stress granules (SG) are dynamic cytoplasmic membrane-less organelles that are formed under harsh conditions. SG are composed of mRNAs that are stalled in translation pre-initiation complexes and different types of mRNA binding proteins like TIA-1 and TTP. It has been probed by immunoprecipitation that GLA-3A-B associates with the MAP kinase protein MPK-1/ERK, which is required for pachytene progression during oogenesis, but this association is poorly understood. Additionally, in mammals was observed that TTP is phosphorilated by ERK and this modification affects SG formation, however this interaction has not been studied in C. elegans. Since TTP has been shown to be associated with SG, the aim of this work is to study the function of GLA-3 and to identify whether this protein forms SG under different adverse conditions and the role of MPK-1 / ERK in SG formation. We tested different stress conditions: heat shock (31oC for 3 hours), starvation (6 hours without bacteria) and oxidative stress (1 hour in Paraquat 0.2 mM) and evaluated SG formation using the strain tn1734
which had the protein GFP fused whit GLA-3A ([gfp::3xflag::gla-3a
]). It was proved that GLA-3 express in germ line from larval stage L2 to adulthood, and in adult gonads, GFP::GLA-3A form SG under heat shock, starvation and oxidative stress. We also observed that iRNA knock-down by feeding animals with dsRNA for mpk-1
prevent the formation of GLA-3 SG. We conclude that GLA-3 is a SG component and MPK-1 participate in SG assembly.