The Arabidopsis Tandem Zinc Finger Protein AtTZF1 Traffics between the Nucleus and Cytoplasmic Foci and Binds Both DNA and RNA        

Abstract

Processing bodies (PBs) are specialized cytoplasmic foci where mRNA turnover and translational repression can take place. Stress granules are related cytoplasmic foci. The CCCH tandem zinc finger proteins (TZFs) play pivotal roles in gene expression, cell fate specification, and various developmental processes. Human TZF binds AU-rich elements at the 3# untranslated region and recruits decapping, deadenylation, and exonucleolytic enzymes to PBs for RNA turnover. Recent genetic studies indicate that plant TZFs are involved in gene regulation and hormone-mediated environmental responses. It is unknown if plant TZFs can bind RNA and be localized to PBs or stress granules. The Arabidopsis (Arabidopsis thaliana) AtTZF1/AtCTH/AtC3H23 was identified as a sugar-sensitive gene in a previous microarray study. It is characterized by a TZF motif that is distinct from the human TZF. Higher plants such as Arabidopsis and rice (Oryza sativa) each have a gene family containing this unique TZF motif. Here, we show that AtTZF1 can traffic between the nucleus and cytoplasmic foci. AtTZF1 colocalizes with markers of PBs, and the morphology of these cytoplasmic foci resembles that of mammalian PBs and stress granules. AtTZF1-associated cytoplasmic foci are dynamic and tissue specific. They can be induced by dark and wound stresses and are preferentially present in actively growing tissues and stomatal precursor cells. Since AtTZF1 can bind both DNA and RNA in vitro, it raises the possibility that AtTZF1 might be involved in DNA and/or RNA regulation.

Vascular plant one-zinc-finger protein 2 is localized both to the nucleus and stress granules under heat stress in Arabidopsis

“…One of RR-TZF proteins, AtTZF1, can bind to both DNA and RNA in vitro and colocalizes with P-bodies and SGs under certain stress conditions. 14 In this study, we demonstrated that VOZ2 colocalized with both SGs and P-bodies under heat stress conditions (Fig. 3).…”

“…18 We speculated that the VOZ2 foci formed under the heat stress conditions were associated with SGs or P-bodies. To confirm that VOZ2 colocalizes with PABP8 and DCP1, 14 marker proteins of SGs and P-bodies, respectively, we generated transgenic Arabidopsis plants expressing both tagRFP-PABP8 or tagRFP-DCP1 and GFP-VOZ2 under the control of the CaMV35S promoter. Under normal temperature conditions, both tagRFP-PABP8 and GFP-VOZ2 were dispersed throughout the cytosol, whereas after the incubation at 42 C, the cytoplasmic granular structures of tagRFP-PABP8 and GFP-VOZ2 were formed after 20 min under the hightemperature condition, and the 2 types of granular structures merged completely (Fig.…”

“…12 In plants, environmental stressors such as heat, oxidative stress, UV irradiation, and translation inhibition lead to the formation of SGs and P-bodies. 13,14 We previously identified transcription factors called vascular plant one-zinc-finger protein (VOZ) 1 and VOZ2, which have been strongly conserved in land plant evolution. The VOZ2 protein has been demonstrated to bind to GCGTNx7ACGC in vitro in the V-PPase (AVP1) promoter.…”

The role of decapping proteins in the miRNA accumulation inArabidopsis thaliana

“…30,34,35 The involvement of DCP1, DCP2 and VCS in miRNA-mediated gene silencing has also been suspected in plants: AGO1 and DCP1 co-localize in protoplasts. 36 Moreover, VCS is involved in miRNA-mediated translational repression. 37 However, the role of decapping in the miRNA pathway remains unclear in plants.…”

“…Co-localization of DCP1 and AGO1 in P-bodies supports this hypothesis. 36 To find the common feature for class I miRNAs, we looked for the differences in structures between class I and class II miRNAs in terms of pri-miRNA framework, miRNA length, terminal base or 5' mRNA fragment after targeted by miRNA. However we could not find any common features for class I miRNAs.…”