Distinct modes of stress granule assembly mediated by the KH‐type RNA‐binding protein Rnc1

Abstract

We have previously identified the KH-type RNA-binding protein Rnc1 as an important regulator of the posttranscriptional expression of the MAPK phosphatase Pmp1 in fission yeast. Rnc1 localization in response to stress has not been elucidated thus far. Here, we report the dual roles of Rnc1 in assembly of stress granules (SGs), nonmembranous cytoplasmic foci composed of messenger ribonucleoproteins. Rnc1 can localize to poly(A)-binding protein (Pabp)-positive SGs upon various stress stimuli, including heat shock (HS) and arsenite treatment. Furthermore, Rnc1 deletion results in decreased SGs, indicating that Rnc1 is a new component and a regulator of SGs. Notably, Rnc1 translocates to the dot-like structures faster than Pabp, and this stress-induced Rnc1 translocation does not require its RNA-binding ability, as the Rnc1 mutant protein with impaired RNA-binding activity forms dots rather more efficiently than the wild-type Rnc1 upon HS. Interestingly, in the absence of stress, Rnc1 overproduction induced massive aggregation of Pabp-positive SGs and eIF2α phosphorylation. In clear contrast, overproduction of the Rnc1 mutant failed to induce Pabp aggregation and eIF2α phosphorylation, indicating that Rnc1 overproduction-induced SG assembly requires Rnc1 RNA-binding activity. Collectively, Rnc1 regulates SG assembly, dependently or independently of its RNA-binding activity.

Unveiling the Role of SlRNC1 in Chloroplast Development and Global Gene Regulation in Tomato Plants

“…Furthermore, the structural analysis using AlphaFold 2 revealed the presence of two RNase III domains in SlRNC1, consistent with its role in RNA processing and splicing. However, it is well established that RNC1 in maize lacks catalytic activity [17,23]. Hence, there is a need for a meticulous examination of the precise function of the RNase III domains in RNC1 genes.…”

Yeast stress granules at a glance

“…factor (Nilsson & Sunnerhagen, 2011;Wang et al, 2012;Wen et al, 2010). On the other hand, an effect of other protein factors (i.e., Nrd1, Rnc1/PCBP, Puf2, and Ppb1/PPP3C), or the application of the chemical drug doxorubicin on fission SGs dynamics has been observed (Higa et al, 2015;Hsiao et al, 2020;Morita et al, 2012;Satoh et al, 2012Satoh et al, , 2018.…”

“…However, unlike mammalian SGs, fission yeast SGs are neither structurally dependent on these proteins nor assembled in response to the phosphorylation of eIF2α factor (Nilsson & Sunnerhagen, 2011; Wang et al, 2012; Wen et al, 2010). On the other hand, an effect of other protein factors (i.e., Nrd1, Rnc1/PCBP, Puf2, and Ppb1/PPP3C), or the application of the chemical drug doxorubicin on fission SGs dynamics has been observed (Higa et al, 2015; Hsiao et al, 2020; Morita et al, 2012; Satoh et al, 2012, 2018).…”