Sec22 Regulates Endoplasmic Reticulum Morphology but Not Autophagy and Is Required for Eye Development in Drosophila

Zhao, Xiaocui; Yang, Huan; Liu, Wei; Duan, Xiuying; Shang, Wenjing; Xia, Dajing; Tong, Chao

doi:10.1074/jbc.m115.640920

Cited by 31 publications

(42 citation statements)

References 47 publications

(52 reference statements)

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“…Consistent with the previous report, the majority of Syx5 EP2313 mutant photoreceptors displayed larger numbers of ER membranes compared to that in the wild-type (Zhao et al, 2015). However, we found more notable abnormalities in Golgi units than ER.…”

Section: Resultssupporting

confidence: 92%

“…In a previous study, ectopic expression of ER-resident KDEL receptor in Syx5-deficient fat body cells displayed abnormal localization, suggesting ER membrane malformation (Zhao et al, 2015). Thus, we next determined the localization, and the level of resident proteins in ER and Golgi.…”

Section: Resultsmentioning

confidence: 96%

“…SNAREs seem to mediate membrane fusion in all the trafficking steps of the secretory pathway, except the fusion events in mitochondria and peroxisomes. Recent studies have identified two SNARE proteins, Sec22 and Gos28, which play essential roles in transporting Rh1 to the rhabdomeres (Rosenbaum et al, 2014; Zhao et al, 2015). An extensive Rh1 transport assay revealed that Gos28 is involved in intra-Golgi transport downstream of alpha-mannosidase-II in medial - Golgi (Rosenbaum et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…In Sec22-deficient photoreceptors, the Rh1 transport is also defective; however, the step at which the Rh1 transport is inhibited, or its effect on other rhabdomeric, stalk or basolateral membrane proteins, has not been described yet. The similarity of morphological defects on ER between Syx5 and Sec22 mutations, and biochemical data indicating Syx5 binding property to Sec22, suggested that Syx5 also functions on Rh1 transport (Zhao et al, 2015). …”

Section: Introductionmentioning

confidence: 99%

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The roles of Syx5 in Golgi morphology and Rhodopsin transport inDrosophilaphotoreceptors

Satoh

Nakamura

2016

Biology Open

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SNAREs (SNAP receptors) are the key components of protein complexes that drive membrane fusion. Here, we report the function of a SNARE, Syntaxin 5 (Syx5), in the development of photoreceptors in Drosophila. In wild-type photoreceptors, Syx5 localizes to cis-Golgi, along with cis-Golgi markers: Rab1 and GM130. We observed that Syx5-deficient photoreceptors show notable accumulation of these cis-Golgi markers accompanying drastic accumulation of vesicles between endoplasmic reticulum (ER) and Golgi cisternae. Extensive analysis of Rh1 (rhodopsin 1) trafficking revealed that in Syx5-deficient photoreceptors, Rh1 is exported from the ER with normal kinetics, retained in the cis-Golgi region along with GM130 for a prolonged period, and then subsequently degraded presumably by endoplasmic reticulum-associated protein degradation (ERAD) after retrieval to the ER. Unlike our previous report of Rab6-deficient photoreceptors – where two apical transport pathways are specifically inhibited – vesicle transport pathways to all plasma membrane domains are inhibited in Syx5-deficient photoreceptors, implying that Rab6 and Syx5 are acting in different steps of intra-Golgi transport. These results indicate that Syx5 is crucial for membrane protein transport, presumably during ER-derived vesicle fusion to form cis-Golgi cisternae.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The roles of Syx5 in Golgi morphology and Rhodopsin transport inDrosophilaphotoreceptors

Satoh

Nakamura

2016

Biology Open

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“…S3). In a recent study, enlarged late endosomes were observed in D. melanogaster Sec22 mutants and were suggested to result from defective ER-Golgi transport (Zhao et al 2015). Although more experiments are required to fully rule out a similar explanation for our observations, the mCherry:: SEC-22 colocalization with late endosomes indicates that, at least in C. elegans, SEC-22 affects late endosome size in a more direct manner.…”

Section: Loss Of Sec-22 Results In Enlarged Late Endosomesmentioning

confidence: 45%

The conserved SNARE SEC-22 localizes to late endosomes and negatively regulates RNA interference in Caenorhabditis elegans

Zhao

Holmgren

Hinas

2016

RNA

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Small RNA pathways, including RNA interference (RNAi), play crucial roles in regulation of gene expression. Initially considered to be cytoplasmic, these processes have later been demonstrated to associate with membranes. For example, maturation of late endosomes/multivesicular bodies (MVBs) is required for efficient RNAi, whereas fusion of MVBs to lysosomes appears to reduce silencing efficiency. SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) mediate membrane fusion and are thus at the core of membrane trafficking. In spite of this, no SNARE has previously been reported to affect RNAi. Here, we demonstrate that in Caenorhabditis elegans, loss of the conserved SNARE SEC-22 results in enhanced RNAi upon ingestion of double-stranded RNA. Furthermore, SEC-22 overexpression inhibits RNAi in wild-type animals. We find that overexpression of SEC-22 in the target tissue (body wall muscle) strongly suppresses the sec-22(−) enhanced RNAi phenotype, supporting a primary role for SEC-22 in import of RNAi silencing signals or cell autonomous RNAi. A functional mCherry::SEC-22 protein localizes primarily to late endosomes/MVBs and these compartments are enlarged in animals lacking sec-22. SEC-22 interacts with late endosome-associated RNA transport protein SID-5 in a yeast two-hybrid assay and functions in a sid-5-dependent manner. Taken together, our data indicate that SEC-22 reduces RNAi efficiency by affecting late endosome/MVB function, for example, by promoting fusion between late endosomes/MVBs and lysosomes. To our knowledge, this is the first report of a SNARE with a function in small RNA-mediated gene silencing.

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ER/Golgi trafficking is facilitated by unbranched actin filaments containing Tpm4.2

et al. 2017

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We have identified novel actin filaments defined by tropomyosin Tpm4.2 at the ER. EM analysis of mouse embryo fibroblasts (MEFs) isolated from mice expressing a mutant Tpm4.2 (Tpm4 ), incapable of incorporating into actin filaments, revealed swollen ER structures compared with wild-type (WT) MEFs (Tpm4 ). ER-to-Golgi, but not Golgi-to-ER trafficking was altered in the Tpm4 MEFs following the transfection of the temperature sensitive ER-associated ts045-VSVg construct. Exogenous Tpm4.2 was able to rescue the ER-to-Golgi trafficking defect in the Tpm4 cells. The treatment of WT MEFs with the myosin II inhibitor, blebbistatin, blocked the Tpm4.2-dependent ER-to-Golgi trafficking. The lack of an effect on ER-to-Golgi trafficking following treatment of MEFs with CK666 indicates that branched Arp2/3-containing actin filaments are not involved in anterograde vesicle trafficking. We propose that unbranched, Tpm4.2-containing filaments have an important role in maintaining ER/Golgi structure and that these structures, in conjunction with myosin II motors, mediate ER-to-Golgi trafficking.

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Sec22 Regulates Endoplasmic Reticulum Morphology but Not Autophagy and Is Required for Eye Development in Drosophila

Cited by 31 publications

References 47 publications

The roles of Syx5 in Golgi morphology and Rhodopsin transport inDrosophilaphotoreceptors

The roles of Syx5 in Golgi morphology and Rhodopsin transport inDrosophilaphotoreceptors

The conserved SNARE SEC-22 localizes to late endosomes and negatively regulates RNA interference in Caenorhabditis elegans

ER/Golgi trafficking is facilitated by unbranched actin filaments containing Tpm4.2

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