LUNAPARK Is an E3 Ligase That Mediates Degradation of ROOT HAIR DEFECTIVE3 to Maintain a Tubular ER Network in Arabidopsis

Sun, Jiaqi; Movahed, Nooshin; Zheng, Huanquan

doi:10.1105/tpc.18.00937

Cited by 31 publications

(14 citation statements)

References 42 publications

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“…As indicated, Cub-RHD3(ΔAIM1) did not interact with NubG-ATG8e ( Figure 5A , the fourth row). Moreover, in our 3-in-1-based BiFC analysis ( Sun et al, 2020a ), RHD3, but not RHD3(ΔAIM1), was found to interact with ATG8e on the ER membrane marked by mCherry-HDEL ( Figure 5C , the first and fourth panels, respectively). Neither RHD3 nor ATG8e interacted with p24, an ER membrane protein ( Chen et al, 2012 ; Figure 5C , negative controls, the second, and third panels).…”

Section: Resultsmentioning

confidence: 75%

“…The SUS-based Y2H was performed as previously described (Sun et al, 2020a). The AP4 cells expressing Cub-tagged proteins as indicated and the AP5 cells expressing NubG-tagged proteins as indicated were inoculated in Synthetic Complete (SC) selection liquid medium (-Leu for AP4 and -Trp for AP5) overnight at 30 • C. Then, AP4 and AP5 cells were mixed and plated on YPD plates for mating.…”

Section: Protein Interaction Assaysmentioning

confidence: 99%

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ROOT HAIR DEFECTIVE3 Is a Receptor for Selective Autophagy of the Endoplasmic Reticulum in Arabidopsis

2022

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ROOT HAIR DEFECTIVE3 (RHD3) is a plant member of atlastin GTPases, which belong to an evolutionally conserved family of proteins that mediate the homotypic fusion of the endoplasmic reticulum (ER). An atlastin in mammalian cells has recently been shown to act as an ER-phagy receptor for selective autophagy of the ER (ER-phagy) during nutrient starvation. Although RHD3 has been indicated to play a role in ER stress response, it is not very clear how RHD3 is involved in the process. In this study, we showed that the rhd3 mutant is hyposensitive to ER as well as salt stress. We employed an YFP-tagged ER membrane marker YFP-TMC to monitor the efficiency of ER-phagy microscopically and biochemically. We found that rhd3 is defective in ER-phagy under ER stress. Furthermore, there is an increased association of YFP-RHD3 with ATG8e-marked autophagosomes. YFP-RHD3 is also visible with ATG8e in the vacuole, and there is a breakdown of YFP-RHD3 under ER stress. RHD3 has two putative ATG8 interaction motifs (AIM1-2). We revealed that RHD3 but not RHD3(ΔAIM1) physically interacts with ATG8, a core autophagosomal component that interacts with various receptor proteins to recruit cargos for degradation by selective autophagy. Furthermore, their interaction is enhanced under ER stress. We thus propose that RHD3 acts as an ER-phagy receptor under ER stress to promote ER-phagy in Arabidopsis.

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Section: Resultsmentioning

confidence: 75%

Section: Protein Interaction Assaysmentioning

confidence: 99%

ROOT HAIR DEFECTIVE3 Is a Receptor for Selective Autophagy of the Endoplasmic Reticulum in Arabidopsis

2022

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“…8a, lane 1). We then used a 3-in-1 BiFC system where mCherry-HDEL is co-expressed 40 with the two testing genes to confirm the interaction. RHD3 interacted with full-length ARK1 at either three-way junctions, or two-way junctions, or at tips of ER tubules (Fig.…”

Section: Resultsmentioning

confidence: 99%

Armadillo-repeat kinesin1 interacts with Arabidopsis atlastin RHD3 to move ER with plus-end of microtubules

Sun

et al. 2020

Nat Commun

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In living cells, dynamics of the endoplasmic reticulum (ER) are driven by the cytoskeleton motor machinery as well as the action of ER-shaping proteins such as atlastin GTPases including RHD3 in Arabidopsis. It is not known if the two systems interplay, and, if so, how they do. Here we report the identification of ARK1 (Armadillo-Repeat Kinesin1) via a genetic screen for enhancers of the rhd3 mutant phenotype. In addition to defects in microtubule dynamics, ER organization is also defective in mutants lacking a functional ARK1. In growing root hair cells, ARK1 comets predominantly localize on the growing-end of microtubules and partially overlap with RHD3 in the cortex of the subapical region. ARK1 co-moves with RHD3 during tip growth of root hair cells. We show that there is a functional interdependence between ARK1 and RHD3. ARK1 physically interacts with RHD3 via its armadillo domain (ARM). In leaf epidermal cells where a polygonal ER network can be resolved, ARK1, but not ARK1ΔARM, moves together with RHD3 to pull an ER tubule toward another and stays with the newly formed 3-way junction of the ER for a while. We conclude that ARK1 acts together with RHD3 to move the ER on microtubules to generate a fine ER network.

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“…This network consists of sheets and tubules interconnected by three-way junctions. The conserved membrane protein LNP localizes at the ER junctions and stabilizes them [ 17 ], as depletions of the protein have resulted in a densely sheet-like ER [ 16 , 23 , 38 ]. The ER phenotype can be rescued by overexpression of LNP at a certain level [ 23 ].…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, these observations indicate the divergence of flaviviruses in employing the orchestra of ER-shaping proteins: LNP, RTN, and ATL for Ve generation. Interestingly, LNP has been demonstrated to act in synergy with RTN but antagonism to ATL to remodel the ER [ 16 , 38 ], which suggests enhanced anti-flavivirus conditions for future investigations.…”

Section: Discussionmentioning

confidence: 99%

Roles of the Endogenous Lunapark Protein during Flavivirus Replication

Tran

Asghar

Johansson

et al. 2021

Viruses

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The endoplasmic reticulum (ER) of eukaryotic cells is a dynamic organelle, which undergoes continuous remodeling. At the three-way tubular junctions of the ER, the lunapark (LNP) protein acts as a membrane remodeling factor to stabilize these highly curved membrane junctions. In addition, during flavivirus infection, the ER membrane is invaginated to form vesicles (Ve) for virus replication. Thus, LNP may have roles in the generation or maintenance of the Ve during flavivirus infection. In this study, our aim was to characterize the functions of LNP during flavivirus infection and investigate the underlying mechanisms of these functions. To specifically study virus replication, we generated cell lines expressing replicons of West Nile virus (Kunjin strain) or Langat virus. By using these replicon platforms and electron microscopy, we showed that depletion of LNP resulted in reduced virus replication, which is due to its role in the generation of the Ve. By using biochemical assays and high-resolution microscopy, we found that LNP is recruited to the Ve and the protein interacts with the nonstructural protein (NS) 4B. Therefore, these data shed new light on the interactions between flavivirus and host factors during viral replication.

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LUNAPARK Is an E3 Ligase That Mediates Degradation of ROOT HAIR DEFECTIVE3 to Maintain a Tubular ER Network in Arabidopsis

Cited by 31 publications

References 42 publications

ROOT HAIR DEFECTIVE3 Is a Receptor for Selective Autophagy of the Endoplasmic Reticulum in Arabidopsis

ROOT HAIR DEFECTIVE3 Is a Receptor for Selective Autophagy of the Endoplasmic Reticulum in Arabidopsis

Armadillo-repeat kinesin1 interacts with Arabidopsis atlastin RHD3 to move ER with plus-end of microtubules

Roles of the Endogenous Lunapark Protein during Flavivirus Replication

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