Plant Science, General Biochemistry, Genetics and Molecular Biology, Cell Biology, Physiology
15
Scopus Publications
Scopus Publications
Fully Tunable Phosphorylation of RPS6A Ensures the Successful Development of Arabidopsis Seedlings Yueh Cho, Guan‐Hong Chen, Shu‐Hsing Wu Plant Cell and Environment, 2026 Light enhances protein translation, enabling young seedlings to rapidly and timely acquire photosynthetic capacities. Sequential phosphorylation of ribosomal protein S6 (RPS6) was implicated in the light‐enhanced translation; however, the exact phosphorylation sites and the biological relevance of RPS6 multi‐phosphorylation in seedling development remain elusive. Here, we report the identification and quantification of RPS6A residues that exhibit dynamic, differential phosphorylation in seedlings grown in darkness or during the initial exposure to light. Among six C‐terminal sites, four serine residues, serine‐229 (S229), S231, S237 and S240, serve as seed sites for light‐regulated sequential phosphorylation. Combinatorial mutations of the C‐terminal serines/threonine (S/T) to aspartic acids (phospho‐mimic) or alanines (phospho‐null) partially rescued the reduced hypocotyl elongation in etiolated rps6a seedlings. De‐etiolating rps6a seedlings expressing phospho‐mimic or phospho‐null RPS6A showed decreased photosynthetic protein accumulation and reduced translation capacity. These findings indicate that fully tunable phosphorylation of RPS6A is essential for its complete function in hypocotyl elongation, translation efficiency, and photosynthetic capacities in both etiolated and de‐etiolating seedlings. Our results demonstrate that the structural integrity of the C‐terminal S/T residues is vital for establishing precise phosphorylation codes of RPS6A in light or dark conditions. Even a single substitution at these conserved residues can disrupt the light‐regulated phosphorylation‐dephosphorylation dynamics of RPS6A, thereby impairing its functions. This also explains the evolutionary conservation and importance of these C‐terminal S/T residues to warrant young seedlings' capacities to adapt effectively to changing light environments in their natural habitats.
Arabidopsis Heterotrimeric G Beta Variants Shape Plant Development and Modulate Responses to Endoplasmic Reticulum Stress and Salt Stress Yueh Cho Plant Cell and Environment, 2025 Heterotrimeric G‐protein signaling underpins plant growth and stress adaptation, yet the full functional scope of the sole Arabidopsis Gβ subunit, AGB1, has remained unclear. We show that alternative splicing generates four isoforms with nonredundant roles. Full‐length AGB1.1 resides at the plasma membrane and endoplasmic reticulum (ER), forms high‐affinity dimers with all three Gγ subunits (AGG1‐3) and completely rescues the developmental and abiotic‐stress defects of agb1 null plants. AGB1.4, lacking part of the N‐terminal coiled‐coil, retains strong Gγ binding and affords partial rescue. By contrast, AGB1.2 and AGB1.3 show weak or transient Gγ interactions, reflecting missing coiled‐coil/WD40 elements, and do not restore chronic‐stress phenotypes. Nevertheless, each truncated variant confers niche advantages: AGB1.2 is rapidly induced by tunicamycin, accumulates in nuclei and mitigates early ER damage, whereas AGB1.3 associates with chloroplast margins and improves survival under moderate or delayed salinity stress. Collectively, the four isoforms expand potential Gβγ combinations from three to twelve, thereby diversifying plant G‐protein outputs without gene family expansion. These findings provide a mechanistic framework whereby alternative splicing, rather than gene duplication, endows plants with flexible G‐protein signaling modules to balance development and environmental resilience.
Arabidopsis AGB1 participates in salinity response through bZIP17-mediated unfolded protein response Yueh Cho BMC Plant Biology, 2024 Background Plant heterotrimeric G proteins respond to various environmental stresses, including high salinity. It is known that Gβ subunit AGB1 functions in maintaining local and systemic Na+/K+ homeostasis to accommodate ionic toxicity under salt stress. However, whether AGB1 contributes to regulating gene expression for seedling’s survival under high salinity remains unclear. Results We showed that AGB1-Venus localized to nuclei when facing excessive salt, and the induction of a set of bZIP17-dependent salt stress-responsive genes was reduced in the agb1 mutant. We confirmed both genetic and physical interactions of AGB1 and bZIP17 in plant salinity response by comparing salt responses in the single and double mutants of agb1 and bzip17 and by BiFC assay, respectively. In addition, we show that AGB1 depletion decreases nuclei-localization of transgenic mRFP-bZIP17 under salt stress, as shown in s1p s2p double mutant in the Agrobacteria-mediated transient mRFP-bZIP17 expression in young seedlings. Conclusions Our results indicate that AGB1 functions in S1P and/or S2P-mediated proteolytic processing of bZIP17 under salt stress to regulate the induction of salinity-responsive gene expression.
A lipid viewpoint on the plant endoplasmic reticulum stress response Kazue Kanehara, Yueh Cho, Chao-Yuan Yu Journal of Experimental Botany, 2022 Organisms, including humans, seem to be constantly exposed to various changes, which often have undesirable effects, referred to as stress. To keep up with these changes, eukaryotic cells may have evolved a number of relevant cellular processes, such as the endoplasmic reticulum (ER) stress response. Owing to presumably intimate links between human diseases and the ER function, the ER stress response has been extensively investigated in various organisms for a few decades. Based on these studies, we now have a picture of the molecular mechanisms of the ER stress response, one of which, the unfolded protein response (UPR), is highly conserved among yeasts, mammals, higher plants, and green algae. In this review, we attempt to highlight the plant UPR from the perspective of lipids, especially membrane phospholipids. Phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) are the most abundant membrane phospholipids in eukaryotic cells. The ratio of PtdCho to PtdEtn and the unsaturation of fatty acyl tails in both phospholipids may be critical factors for the UPR, but the pathways responsible for PtdCho and PtdEtn biosynthesis are distinct in animals and plants. We discuss the plant UPR in comparison with the system in yeasts and animals in the context of membrane phospholipids.
What's unique? the unfolded protein response in plants Chao-Yuan Yu, Yueh Cho, Oshin Sharma, Kazue Kanehara Journal of Experimental Botany, 2022 The investigation of a phenomenon called the unfolded protein response (UPR) started approximately three decades ago, and we now know that the UPR is involved in a number of cellular events among metazoans, higher plants, and algae. The relevance of the UPR in human diseases featuring protein folding defects, such as Alzheimer’s and Huntington’s diseases, has drawn much attention to the response in medical research to date. While metazoans and plants share similar molecular mechanisms of the UPR, recent studies shed light on the uniqueness of the plant UPR, with plant-specific protein families appearing to play pivotal roles. Given the considerable emphasis on the original discoveries of key factors in metazoans, this review highlights the uniqueness of the plant UPR based on current knowledge.
A targeted RNAi screen reveals Drosophila female-sterile genes that control the size of germline stem cell niche during development Yueh Cho, Chun-Ming Lai, Kun-Yang Lin, Hwei-Jan Hsu G3 Genes Genomes Genetics, 2018 Adult stem cells maintain tissue homeostasis. This unique capability largely depends on the stem cell niche, a specialized microenvironment, which preserves stem cell identity through physical contacts and secreted factors. In many cancers, latent tumor cell niches are thought to house stem cells and aid tumor initiation. However, in developing tissue and cancer it is unclear how the niche is established. The well-characterized germline stem cells (GSCs) and niches in the Drosophila melanogaster ovary provide an excellent model to address this fundamental issue. As such, we conducted a small-scale RNAi screen of 560 individually expressed UAS-RNAi lines with targets implicated in female fertility. RNAi was expressed in the soma of larval gonads, and screening for reduced egg production and abnormal ovarian morphology was performed in adults. Twenty candidates that affect ovarian development were identified and subsequently knocked down in the soma only during niche formation. Feminization factors (Transformer, Sex lethal, and Virilizer), a histone methyltransferase (Enhancer of Zeste), a transcriptional machinery component (Enhancer of yellow 1), a chromatin remodeling complex member (Enhancer of yellow 3) and a chromosome passenger complex constituent (Incenp) were identified as potentially functioning in the control of niche size. The identification of these molecules highlights specific molecular events that are critical for niche formation and will provide a basis for future studies to fully understand the mechanisms of GSC recruitment and maintenance.
Peeking at a plant through the holes in the wall – exploring the roles of plasmodesmata Kuan-Ju Lu, Florence R. Danila, Yueh Cho, Christine Faulkner New Phytologist, 2018 Plasmodesmata (PD) are membrane-lined pores that connect neighbouring plant cells and allow molecular exchange via the symplast. Past studies have revealed the basic structure of PD, some of the transport mechanisms for molecules through PD, and a variety of physiological processes in which they function. Recently, with the help of newly developed technologies, several exciting new features of PD have been revealed. New PD structures were observed during early formation of PD and between phloem sieve elements and phloem pole pericycle cells in roots. Both observations challenge our current understanding of PD structure and function. Research into novel physiological responses, which are regulated by PD, indicates that we have not yet fully explored the potential contribution of PD to overall plant function. In this Viewpoint article, we summarize some of the recent advances in understanding the structure and function of PD and propose the challenges ahead for the community.
Arabidopsis dolichol kinase AtDOK1 is involved in flowering time control Yueh Cho, Chao-Yuan Yu, Yuki Nakamura, Kazue Kanehara Journal of Experimental Botany, 2017 The early flowering phenotype of dok1 mutants and localization of DOK1 at meristems suggests the potential importance of dolichol kinase function in flowering time control.
Endoplasmic reticulum stress response in Arabidopsis roots Yueh Cho, Kazue Kanehara Frontiers in Plant Science, 2017 Roots are the frontier of plant body to perceive underground environmental change. Endoplasmic reticulum (ER) stress response represents circumvention of cellular stress caused by various environmental changes; however, a limited number of studies are available on the ER stress responses in roots. Here, we report the tunicamycin (TM) -induced ER stress response in Arabidopsis roots by monitoring expression patterns of immunoglobulin-binding protein 3 (BiP3), a representative marker for the response. Roots promptly responded to the TM-induced ER stress through the induction of similar sets of ER stress-responsive genes. However, not all cells responded uniformly to the TM-induced ER stress in roots, as BiP3 was highly expressed in root tips, an outer layer in elongation zone, and an inner layer in mature zone of roots. We suggest that ER stress response in roots has tissue specificity.
