Sar1 assembly regulates membrane constriction and ER export

Long, Kimberly R.; Yamamoto, Yasunori; Baker, Adam; Watkins, Simon C.; Coyne, Carolyn B.; Conway, James F.; Aridor, Meir

doi:10.1083/jcb.201004132

Cited by 77 publications

(90 citation statements)

References 46 publications

(112 reference statements)

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“…Furthermore, depletion of SEC24D or SEC13-SEC31 blocks secretion of the extracellular matrix or procollagen (8 -10) and TANGO1, which plays a critical role in ER export of procollagen interacts with SEC24C (43,44). Thus, the data established by us and others (7)(8)(9)(10) clearly show that all COPII proteins (SAR1, SEC23-SEC24, and SEC13-SEC31) are required for procollagen export from the ER.…”

Section: Discussionsupporting

confidence: 52%

SEC23-SEC31 the Interface Plays Critical Role for Export of Procollagen from the Endoplasmic Reticulum

Kim

Pahuja

Ravazzola

et al. 2012

Journal of Biological Chemistry

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Background: SEC23 plays a critical role in generating transport vesicles from the endoplasmic reticulum (ER). Results: SEC23A M702V mutation at the SEC23-SEC31 interface causes a selective retention of procollagen in the ER. We correlate this defect with an enhanced SAR1 GTPase activity by M702V SEC23A through SEC13-SEC31. Conclusion: The SEC23-SEC31 interface plays a critical role in capturing various cargo molecules. Significance: SAR1 GTP hydrolysis is critical for cargo selection.

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Section: Discussionsupporting

confidence: 52%

SEC23-SEC31 the Interface Plays Critical Role for Export of Procollagen from the Endoplasmic Reticulum

Kim

Pahuja

Ravazzola

et al. 2012

Journal of Biological Chemistry

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“…Whether this occurs via a receptor-mediated mechanism as has been proposed for TANGO1-mediated export of collagen (Saito et al, 2009;Wilson et al, 2011), or simply due to a geometric requirement for ordered Sec13-Sec31 assembly around larger export containers (Stagg et al, 2008), or even a combination of the two, is a question for future research. In further support of the notion of encapsulation of collagen within a COPII-coated carrier, Aridor and colleagues showed recently that a mutant form of Sar1 (with key substitutions in a conserved C-terminal loop) did not affect recruitment of other COPII proteins, nor Sar1 activation, but did inhibit oligomerization of Sar1 and type I procollagen export from the ER (Long et al, 2010). The authors propose that deregulation of membrane constriction is responsible, such that the mutant form of Sar1 indirectly prevents entry of procollagen into Sar1-coated tubules.…”

Section: Discussionmentioning

confidence: 94%

Epithelial organization and cyst lumen expansion require efficient Sec13–Sec31-driven secretion

Townley

Schmidt

Hodgson

et al. 2012

Journal of Cell Science

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SummaryEpithelial morphogenesis is directed by interactions with the underlying extracellular matrix. Secretion of collagen and other matrix components requires efficient coat complex II (COPII) vesicle formation at the endoplasmic reticulum. Here, we show that suppression of the outer layer COPII component, Sec13, in zebrafish embryos results in a disorganized gut epithelium. In human intestinal epithelial cells (Caco-2), Sec13 depletion causes defective epithelial polarity and organization on permeable supports. Defects are seen in the ability of cells to adhere to the substrate, form a monolayer and form intercellular junctions. When embedded in a three-dimensional matrix, Sec13-depleted Caco-2 cells form cysts but, unlike controls, are defective in lumen expansion. Incorporation of primary fibroblasts within the three-dimensional culture substantially restores normal morphogenesis. We conclude that efficient COPIIdependent secretion, notably assembly of Sec13-Sec31, is required to drive epithelial morphogenesis in both two-and three-dimensional cultures in vitro, as well as in vivo. Our results provide insight into the role of COPII in epithelial morphogenesis and have implications for the interpretation of epithelial polarity and organization assays in cell culture.

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“…First, FLI-06 has no direct effect in a COPII in vitro budding assay (Krämer et al, 2013) and did not inhibit exit of preaccumulated VSVG-EYFP from ERES. Sar1 controls not only assembly but also fission of COPII vesicles (Long et al, 2010); therefore, if Sar1 is the target, FLI-06 would inhibit export of preaccumulated cargo. Second, in contrast to FLI-06 treatment, overexpressing Sar1 and two inactive Sar1 mutants caused a reduction in number of ERES, but not a conversion in morphology from ER tubules to sheets, again suggesting FLI-06 does not act through Sar1.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of cargo export at ER exit sites and the trans-Golgi network by the secretion inhibitor FLI-06

Yonemura

Müller

et al. 2016

Journal of Cell Science

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Export out of the endoplasmic reticulum (ER) involves the Sar1 and COPII machinery acting at ER exit sites (ERES). Whether and how cargo proteins are recruited upstream of Sar1 and COPII is unclear. Two models are conceivable, a recruitment model where cargo is actively transported through a transport factor and handed over to the Sar1 and COPII machinery in ERES, and a capture model, where cargo freely diffuses into ERES where it is captured by the Sar1 and COPII machinery. Using the novel secretion inhibitor FLI-06, we show that recruitment of the cargo VSVG to ERES is an active process upstream of Sar1 and COPII. Applying FLI-06 before concentration of VSVG in ERES completely abolishes its recruitment. In contrast, applying FLI-06 after VSVG concentration in ERES does not lead to dispersal of the concentrated VSVG, arguing that it inhibits recruitment to ERES as opposed to capture in ERES. FLI-06 also inhibits export out of the trans-Golgi network (TGN), suggesting that similar mechanisms might orchestrate cargo selection and concentration at the ER and TGN. FLI-06 does not inhibit autophagosome biogenesis and the ER-peroxisomal transport route, suggesting that these rely on different mechanisms.

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Sar1 assembly regulates membrane constriction and ER export

Abstract: While dynamin pinches vesicles from the plasma membrane, the Sar1 GTPase specializes in cinching ER membrane tubules.

Cited by 77 publications

References 46 publications

SEC23-SEC31 the Interface Plays Critical Role for Export of Procollagen from the Endoplasmic Reticulum

SEC23-SEC31 the Interface Plays Critical Role for Export of Procollagen from the Endoplasmic Reticulum

Epithelial organization and cyst lumen expansion require efficient Sec13–Sec31-driven secretion

Inhibition of cargo export at ER exit sites and the trans-Golgi network by the secretion inhibitor FLI-06

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