Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Regulation of endoplasmic reticulum turnover by selective autophagy

Abstract

The endoplasmic reticulum (ER) is the largest intracellular endomembrane system, enabling protein and lipid synthesis, ion homeostasis, quality control of newly synthesized proteins and organelle communication1. Constant ER turnover and modulation is needed to meet different cellular requirements and autophagy has an important role in this process2,3,4,5,6,7,8. However, its underlying regulatory mechanisms remain unexplained. Here we show that members of the FAM134 reticulon protein family are ER-resident receptors that bind to autophagy modifiers LC3 and GABARAP, and facilitate ER degradation by autophagy (‘ER-phagy’). Downregulation of FAM134B protein in human cells causes an expansion of the ER, while FAM134B overexpression results in ER fragmentation and lysosomal degradation. Mutant FAM134B proteins that cause sensory neuropathy in humans9 are unable to act as ER-phagy receptors. Consistently, disruption of Fam134b in mice causes expansion of the ER, inhibits ER turnover, sensitizes cells to stress-induced apoptotic cell death and leads to degeneration of sensory neurons. Therefore, selective ER-phagy via FAM134 proteins is indispensable for mammalian cell homeostasis and controls ER morphology and turnover in mice and humans.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: FAM134B binds LC3-like modifiers and co-localizes with ER marker proteins.
Figure 2: FAM134B targets ER into autophagosomes.
Figure 3: FAM134B and autophagy regulate ER volume and structure.
Figure 4: Impaired selective ER turnover and sensory neuropathy in Fam134b–/– mice.

Similar content being viewed by others

Accession codes

Primary accessions

Protein Data Bank

Data deposits

Atomic coordinates of the crystal structure of FAM134B-LIR–LC3A have been deposited in the Protein Data Bank under accession number 4ZDV.

References

  1. Borgese, N., Francolini, M. & Snapp, E. Endoplasmic reticulum architecture: structures in flux. Curr. Opin. Cell Biol. 18, 358–364 (2006)

    Article  CAS  Google Scholar 

  2. Walter, P. & Ron, D. The unfolded protein response: from stress pathway to homeostatic regulation. Science 334, 1081–1086 (2011)

    Article  CAS  ADS  Google Scholar 

  3. Schuck, S., Prinz, W. A., Thorn, K. S., Voss, C. & Walter, P. Membrane expansion alleviates endoplasmic reticulum stress independently of the unfolded protein response. J. Cell Biol. 187, 525–536 (2009)

    Article  CAS  Google Scholar 

  4. Maiuolo, J., Bulotta, S., Verderio, C., Benfante, R. & Borgese, N. Selective activation of the transcription factor ATF6 mediates endoplasmic reticulum proliferation triggered by a membrane protein. Proc. Natl Acad. Sci. USA 108, 7832–7837 (2011)

    Article  CAS  ADS  Google Scholar 

  5. Hamasaki, M., Noda, T., Baba, M. & Ohsumi, Y. Starvation triggers the delivery of the endoplasmic reticulum to the vacuole via autophagy in yeast. Traffic 6, 56–65 (2005)

    Article  CAS  Google Scholar 

  6. Bernales, S., McDonald, K. L. & Walter, P. Autophagy counterbalances endoplasmic reticulum expansion during the unfolded protein response. PLoS Biol. 4, e423 (2006)

    Article  Google Scholar 

  7. Tasdemir, E. et al. Cell cycle-dependent induction of autophagy, mitophagy and reticulophagy. Cell Cycle 6, 2263–2267 (2007)

    Article  CAS  Google Scholar 

  8. Yorimitsu, T. & Klionsky, D. J. Eating the endoplasmic reticulum: quality control by autophagy. Trends Cell Biol. 17, 279–285 (2007)

    Article  CAS  Google Scholar 

  9. Kurth, I. et al. Mutations in FAM134B, encoding a newly identified Golgi protein, cause severe sensory and autonomic neuropathy. Nature Genet. 41, 1179–1181 (2009)

    Article  CAS  Google Scholar 

  10. Stolz, A., Ernst, A. & Dikic, I. Cargo recognition and trafficking in selective autophagy. Nature Cell Biol. 16, 495–501 (2014)

    Article  CAS  Google Scholar 

  11. Weidberg, H., Shvets, E. & Elazar, Z. Biogenesis and cargo selectivity of autophagosomes. Annu. Rev. Biochem. 80, 125–156 (2011)

    Article  CAS  Google Scholar 

  12. Rogov, V., Dotsch, V., Johansen, T. & Kirkin, V. Interactions between autophagy receptors and ubiquitin-like proteins form the molecular basis for selective autophagy. Mol. Cell 53, 167–178 (2014)

    Article  CAS  Google Scholar 

  13. Kirkin, V. et al. A role for NBR1 in autophagosomal degradation of ubiquitinated substrates. Mol. Cell 33, 505–516 (2009)

    Article  CAS  Google Scholar 

  14. Wild, P. et al. Phosphorylation of the autophagy receptor optineurin restricts Salmonella growth. Science 333, 228–233 (2011)

    Article  CAS  ADS  Google Scholar 

  15. Rogov, V. V. et al. Structural basis for phosphorylation-triggered autophagic clearance of Salmonella. Biochem. J. 454, 459–466 (2013)

    Article  CAS  Google Scholar 

  16. Voeltz, G. K., Prinz, W. A., Shibata, Y., Rist, J. M. & Rapoport, T. A. A class of membrane proteins shaping the tubular endoplasmic reticulum. Cell 124, 573–586 (2006)

    Article  CAS  Google Scholar 

  17. Shibata, Y. et al. Mechanisms determining the morphology of the peripheral ER. Cell 143, 774–788 (2010)

    Article  CAS  Google Scholar 

  18. Schuck, S., Gallagher, C. M. & Walter, P. ER-phagy mediates selective degradation of endoplasmic reticulum independently of the core autophagy machinery. J. Cell Sci. 127, 4078–4088 (2014)

    Article  CAS  Google Scholar 

  19. Cebollero, E., Reggiori, F. & Kraft, C. Reticulophagy and ribophagy: regulated degradation of protein production factories. Int. J. Cell Biol. 2012, 182834 (2012)

    Article  Google Scholar 

  20. Beetz, C. et al. A spastic paraplegia mouse model reveals REEP1-dependent ER shaping. J. Clin. Invest. 123, 4273–4282 (2013)

    Article  CAS  Google Scholar 

  21. Hübner, C. A. & Kurth, I. Membrane-shaping disorders: a common pathway in axon degeneration. Brain 137, 3109–3121 (2014)

    Article  Google Scholar 

  22. Renvoisé, B. & Blackstone, C. Emerging themes of ER organization in the development and maintenance of axons. Curr. Opin. Neurobiol. 20, 531–537 (2010)

    Article  Google Scholar 

  23. Spoerri, P. E., Dresp, W. & Heyder, E. A simple embedding technique for monolayer neuronal cultures grown in plastic flasks. Acta Anat. 107, 221–223 (1980)

    Article  CAS  Google Scholar 

  24. Mao, K., Wang, K., Liu, X. & Klionsky, D. J. The scaffold protein Atg11 recruits fission machinery to drive selective mitochondria degradation by autophagy. Dev. Cell 26, 9–18 (2013)

    Article  CAS  Google Scholar 

  25. Mochida, K. et al. Receptor-mediated selective autophagy degrades the endoplasmic reticulum and the nucleus. Naturehttp://dx.doi.org/10.1038/nature14506 (2015)

  26. Behrends, C., Sowa, M. E., Gygi, S. P. & Harper, J. W. Network organization of the human autophagy system. Nature 466, 68–76 (2010)

    Article  CAS  ADS  Google Scholar 

  27. Altan-Bonnet, N. et al. Golgi inheritance in mammalian cells is mediated through endoplasmic reticulum export activities. Mol. Biol. Cell 17, 990–1005 (2006)

    Article  CAS  Google Scholar 

  28. GrandPré, T., Nakamura, F., Vartanian, T. & Strittmatter, S. M. Identification of the Nogo inhibitor of axon regeneration as a Reticulon protein. Nature 403, 439–444 (2000)

    Article  ADS  Google Scholar 

  29. Klopfenstein, D. R. et al. Subdomain-specific localization of CLIMP-63 (p63) in the endoplasmic reticulum is mediated by its luminal alpha-helical segment. J. Cell Biol. 153, 1287–1300 (2001)

    Article  CAS  Google Scholar 

  30. Stewart, S. A. et al. Lentivirus-delivered stable gene silencing by RNAi in primary cells. RNA 9, 493–501 (2003)

    Article  CAS  Google Scholar 

  31. Popovic, D. et al. Rab GTPase-activating proteins in autophagy: regulation of endocytic and autophagy pathways by direct binding to human ATG8 modifiers. Mol. Cell. Biol. 32, 1733–1744 (2012)

    Article  CAS  Google Scholar 

  32. Kuma, A. et al. The role of autophagy during the early neonatal starvation period. Nature 432, 1032–1036 (2004)

    Article  CAS  ADS  Google Scholar 

  33. Yang, M., Ellenberg, J., Bonifacino, J. S. & Weissman, A. M. The transmembrane domain of a carboxyl-terminal anchored protein determines localization to the endoplasmic reticulum. J. Biol. Chem. 272, 1970–1975 (1997)

    Article  CAS  Google Scholar 

  34. Chan, E. Y., Kir, S. & Tooze, S. A. siRNA screening of the kinome identifies ULK1 as a multidomain modulator of autophagy. J. Biol. Chem. 282, 25464–25474 (2007)

    Article  CAS  Google Scholar 

  35. Verheije, M. H. et al. Mouse hepatitis coronavirus RNA replication depends on GBF1-mediated ARF1 activation. PLoS Pathog. 4, e1000088 (2008)

    Article  Google Scholar 

  36. Slot, J. W. & Geuze, H. J. Cryosectioning and immunolabeling. Nature Protocols 2, 2480–2491 (2007)

    Article  CAS  Google Scholar 

  37. Khundadze, M. et al. A hereditary spastic paraplegia mouse model supports a role of ZFYVE26/SPASTIZIN for the endolysosomal system. PLoS Genet. 9, e1003988 (2013)

    Article  Google Scholar 

  38. Le Bars, D., Gozariu, M. & Cadden, S. W. Animal models of nociception. Pharmacol. Rev. 53, 597–652 (2001)

    CAS  PubMed  Google Scholar 

Download references

Acknowledgements

We would like to thank S. Horwitz, K. Rajalingam, C. Behrends and J. Lippincott-Schwartz for cell lines and vectors, N. Mizushima for Atg5–/– and control immortalized MEFs, H.-P. Hauri and H. Farhan for vectors, and S. Gießelmann and K. Schorr for excellent technical assistance. We acknowledge D. McEwan, D. Hoeller, D. Popovic and K. Koch for critical reading of the manuscript and valuable insights. We also thank M. M. Kessels for support. This work was supported by grants from the Deutsche Forschungsgemeinschaft to I.D. (DI 931/3-1), I.K. (KU 1587/2-1, KU 1587/3-1, KU 1587/4-1), C.A.H. (HU 800/5-1, RTG 1715, HU 800/6-1, HU 800/7-1), B.Q. (QU116/6-2, RTG1715), J.W. (WE1406/13-1), the Cluster of Excellence ‘Macromolecular Complexes’ of the Goethe University Frankfurt (EXC115), LOEWE grant Ub-Net and LOEWE Centrum for Gene and Cell therapy Frankfurt and the European Research Council/ERC grant agreement number (250241-LineUb) to I.D. F.R. is supported by ECHO (700.59.003), ALW Open Program (821.02.017 and 822.02.014), DFG-NWO cooperation (DN82-303) and ZonMW VICI (016.130.606) grants. P.G. is supported by the 7.FP, COFUND, Goethe International Postdoc Programme GO-IN, No. 291776.

Author information

Authors and Affiliations

Authors

Contributions

A.K. performed biochemical analyses, immunofluorescence and cellular localization, functional analysis and contributed to interpretation of data and manuscript writing and preparation. T.H. characterized Fam134b–/– mice, carried out FAM134B topology analysis and contributed to manuscript preparation. M.Mar. performed transmission electron microscopy of cells and neurons in culture. P.G. performed apoptosis and autophagy analysis, and contributed to manuscript preparation and writing. A.K.H. generated the Fam134b–/– mouse model and was involved in mouse phenotyping. M.A. performed crystal structure assay. L.L. performed the electrophysiological analysis of Fam134b–/– mice. S.N., I. Ka. and J.W. performed transmission electron microscopy on murine tissues. A.S. performed fractionation and autophagy flux experiments. M.Mau. carried out the assay for the turnover of long-lived proteins. N.K. performed liposome assays, B.Q. supervised liposome assays. F.R., I.Ku., C.A.H. and I.D. designed the study, analysed data and wrote the manuscript. I.Ku., C.A.H. and I.D. contributed equally to the study. All the authors discussed the results and the manuscript.

Corresponding authors

Correspondence to Ingo Kurth, Christian A. Hübner or Ivan Dikic.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 FAM134 proteins bind to GST-LC3-like modifiers.

a, A549 cell lysates were added to beads with various immobilized GST fusion proteins (GST, GST–LC3A, GST–LC3B, GST–GABARAP, GST–GABARAP–L1), followed by western blotting using an antibody against FAM134B. b, Co-immunoprecipitation between Fam134b and Lc3b in wild-type (WT) mouse embryonic fibroblasts (MEFs). MEFs isolated from Fam134b-knockout (KO) mice served as control. c, Interaction of FAM134A and FAM134C with LC3-like modifiers. d, FAM134B proteins lacking the reticulon domain (Δret), disease-associated truncating FAM134B variants Q145X and S309X, and FAM134B with a mutated LIR-motif (mutLIR) fail to bind GST–LC3-like modifiers (LC3B) in contrast to wild-type FAM134B and FAM134B lacking the coiled-coil domain (ΔCC). e, Crystal structure of a FAM134B-LIR peptide interacting with LC3A. Ribbon and surface representation model of the FAM134B-LIR–LC3A interaction and crystallographic symmetry related molecule. (LIR, magenta; LC3A, yellow). 2FoFc electron density (blue mesh) of FAM134B-LIR (amino acids 453–459), contoured at 1σ and with ball-and-stick model.

Extended Data Figure 2 Subcellular localization and topology of endogenous FAM134B.

a, The post-nuclear fraction of wild-type MEF lysate was loaded on a linear Iodixanol gradient (0–20%). Fractions (top to bottom) were subjected to western blot and analysed with antibodies directed against endogenous proteins as indicated. Images are from two different gels, while the exposure time is the same. Asterik indicates non-specific band. b, A549 cells and MEFs were transfected with a KDEL–RFP expression plasmid for 24 h. After fixation, endogenous FAM134B was detected. FAM134B co-localizes with KDEL–RFP. Representatives of five images are shown. Scale bar, 10 μm. c, HeLa and U2OS cells were fixed and stained for endogenous FAM134B and CLIMP-63. FAM134B co-localizes with CLIMP-63. Representatives of five images are shown. Scale bar, 10 μm. d, FAM134B topology analysis. COS-7 cells transiently overexpressing C-terminal tagged FAM134B (FAM134B–eGFP) or N-terminal tagged FAM134B (eGFP–FAM134B) were subjected to fluorescence protein protection (FPP) assay. COS-7 cells transfected with plasmids encoding the luminal ER peptide RFP–KDEL and C-terminal RFP-tagged CD3 (CD3–RFP) served as controls. RFP–KDEL, which localized to the ER lumen, shows fluorescence protein protection upon trypsin administration following digitonin treatment. By contrast, according to the known topology of CD3–RFP the RFP-tag faces the cytosol and as a consequence trypsin treatment abolishes protein fluorescence. Scale bar, 10 μm. e, C-terminal RFP-tagged CD3 (CD3–RFP) served as control (RFP-tag faces the cytosol). A N-terminal tagged FAM134B variant was also subjected to the FPP assay. A strong decrease in fluorescence was observed for CD3–RFP, FAM134B–eGFP and eGFP–FAM134B after sequenced digitonin and trypsin treatment, but not for RFP–KDEL (n = number of cells, error bars indicate s.e.m.).

Extended Data Figure 3 FAM134B is a membrane-shaping protein that remodels lipid bilayers.

a, Liposome co-floatation assays. Proteins were detected using anti-GST antibodies in immunoblots of sucrose gradient fractions 1 (top) to 6 (bottom). GST–FAM134B, but not GST (Ctrl), floated with liposomes in fraction 2. Disease-related truncating mutations S309X and Q145X only partially floated with the liposome fraction. b, Representative transmission electron microscopy (TEM) images of freeze-fractured incubations of liposomes with recombinant GST-fusion proteins (GST–FAM134B; GST–FAM134B(Q145X); Ctrl, GST). Scale bar, 200 nm. c, Distribution of liposome diameters observed by TEM of freeze-fractured liposome incubations. Incubation with FAM134B and S309X leads to a pronounced increase in the relative numbers of smaller structures in comparison to control (GST) and Q145X. Inset, box plots of data presented in c; y axis is logarithmic. n.s., not significant; ***P < 0.001 one-way ANOVA, error bars indicate s.e.m. (n = 2,682 for Ctrl, n = 2,683 for FAM134B, n = 1,685 for Q145X, n = 1,612 for S309X, n = number of liposomes). Boxes contain 50% of the values; minimal, maximal, and median values are marked by vertical lines.

Extended Data Figure 4 Fam134b determines ER degradation through autophagy.

a, U2OS cells transiently co-transfected with 0.25 µg of GFP–SEC61 plasmid expressing full length or mutLIR FAM134B–HA at the indicated quantities (µg). Cell lysates were immunoblotted with antibodies against HA, GFP and vinculin. Black arrow-head indicates protein-degradation products. b, Wild-type (WT) and Atg5-knockout (KO) MEFs transiently expressing mCherry–eGFP–FAM134B were fixed and processed for immunofluorescence analysis. Cells with mCherry-positive and simultaneously GFP-negative punctae were counted in three independent experiments (biological replicates). Representative of 50 images is shown. Scale bar, 10 μm. c, d, Atg5-knockout and control MEFs were co-transfected with plasmids expressing full-length LIR (c) or mutLIR (d) FAM134B–HA and KDEL–RFP for 24 h, fixed and processed for immunofluorescence using antibodies against the HA tag and Lc3b. Overexpression of FAM134B–HA in wild-type but not in Atg5-knockout MEFs leads to the formation of punctae positive for both KDEL–RFP and Lc3b. Representatives of five images are shown. Scale bar, 10 μm. e, Quantification of cells displaying KDEL–RFP- and Lc3b-positive punctae shown in c and d. At least 50 cells per experiment from three independent experiments (biological replicates) were quantified (error bars indicate s.d.). f, Fam134b is stabilized in starved Atg5-knockout MEFs. Wild-type and Atg5-knockout MEFs were starved in EBSS for the indicated periods of time. Cell lysates were processed by SDS–PAGE and western blot using antibodies against Fam134b and vinculin.

Extended Data Figure 5 FAM134B knockdown causes ER expansions.

a, Ultrastructural analysis of FAM134B-depleted cells. Constructs expressing control shRNA or α-FAM134B shRNA were lentivirally delivered into U2OS cells. Cells were chemically fixed and embedded with Epon resin. Longitudinal and transversal sections and a part of the nuclear membrane is shown. FAM134B-depleted cells display ER expansions, particularly in the cell periphery. The membrane of the nucleus of FAM134B-knockdown cells also undergoes expansion. M, mitochondria; N, nucleus; PM, plasma membrane. Scale bars, 2 μm (left images) and 500 nm (middle and right images) (n = 150 cells). b, c, ER sheets are expanded in FAM134B-deficient cells. Constructs expressing control shRNA or α-FAM134B shRNA were lentivirally delivered in U2OS cells. After selection, cells were fixed, stained for CLIMP-63 and RTN4A and RTN4B and analysed by fluorescence microscopy. Representatives of five images are shown. Scale bar, 10 μm. d, CLIMP-63 and TRAPα levels in autophagy-deficient and FAM134B-depleted cells.

Extended Data Figure 6 FAM134B is not required for bulk autophagy and aggrephagy.

a, Fam134b+/+ and Fam134b–/– MEFs were starved in EBSS for 2 h, fixed and stained for Lc3b (using two different anti-Lc3b antibodies to enhance the signal). Representatives of five images are shown. Scale bar, 10 μm. b, Lc3b-positive punctae in 50 cells per experiment from three independent experiments were counted. *P < 0.0001, one-way ANOVA. c, Long-living proteins degradation assay. For autophagy induction, cells were starved with EBSS. Protein degradation was assessed in three independent experiments in triplicate. Error bars represent s.e.m. of three independent counts (three technical replicates, n = 20 cells per each replicate, P value is calculated using t-test, *P < 0.05). d, Transmission electron microscopy of Fam134b+/+ and Fam134b–/– cells. Autophagosomal/degradative compartments (that is, autophagosomes, autolysosomes and lysosomes) were counted. Quantification was performed by counting 20 cells in three different grids (three biological replicates). Error bars represent s.d., P value is calculated using t-test. e, Lc3b lipidation and p62 degradation was analysed in Fam134b+/+ and Fam134b–/– MEFs treated with 200 nM bafilomycin A1 for the indicated time. f, g, For autophagy induction, cells were starved with EBSS (f) or treated with the chemical Ku-0063794 (10 µM) (g) for the indicated periods of time. Bafilomycin A1 was added 1 h before the beginning of the treatment. h, Control and FAM134B-knockdown (shRNA-mediated) U2OS cells were starved in EBSS for 2 h, fixed and stained for LC3B (using two different anti-LC3B antibodies to enhance the signal). Representatives of five images are shown. Scale bar, 10 μm. i, LC3B-positive punctae in 150 cells per experiment from three independent experiments were counted. *P < 0.0001, Mann–Whitney U-test. j, LC3B lipidation and p62 degradation were analysed in control and FAM134B shRNA cells treated with 200 nM bafilomycin A1 for the indicated time. k, l, For autophagy induction, cells were starved with EBSS (k) or treated with the chemical Ku-0063794 (10 µM) (l) for the indicated periods of time. Bafilomycin A1 was added 1 h before the beginning of the treatment. m, Fam134b+/+ and Fam134b–/– MEFs were either treated with 5 µg ml−1 puromycin for 2 h or treated and subsequently washed and incubated in puromycin-free medium for 3 h, fixed and stained for ubiquitin (Ub) and p62. Representatives of five images are shown. Scale bar, 10 μm. n, The number of cells with Ub/p62 punctae before and after puromycin release per 100 cells per experiment was determined from three independent experiments (biological replicates). Error bars indicate s.d.

Extended Data Figure 7 FAM134B deficiency sensitizes cells to apoptosis.

a, b, Fam134b+/+ and Fam134b–/– MEFs were treated with 25 µM CCCP (carbonyl cyanide 3-chlorophenylhydrazone) (a) or starved in EBSS(b) for the time indicated. Cell lysates were processed by SDS–PAGE and western blot using antibodies against vinculin, Parp and Fam134b. c, Fam134b+/+ and Fam134b–/– MEFs were treated with 2 μg ml−1 tunicamycin (Tm) or 1 μM thapsigargin (Tg) for 12 h or left untreated. Cell lysates were processed by SDS–PAGE and western blot using antibodies against vinculin and Parp. d, FACS analysis for annexin V and propidium iodide (PI) in Fam134b+/+ and Fam134b–/– MEFs. Quantifications of annexin V/propidium iodide-positive cells after the indicated experimental settings (EBSS starvation for 8 h, treatment with 1 μM thapsigargin, 2 μg ml−1 tunicamycin, 25 μM CCCP for 12 h and 200 nM staurosporin (STS) for 6 h). Data are shown as mean ± s.d. of two independent biological replicates; for each biological replicate two experiments were performed and for each experiment 10,000 cells were analysed. **P < 0.01, one-way ANOVA. e, A549 cells stably expressing control and anti-FAM134B no. 1 and no. 2 shRNAs were either starved in EBSS or treated with 10 μM Ku-0063794, 200 ng ml−1 bafilomycin A1 (BafA), 1 μM thapsigargin or 2 μg ml−1 tunicamycin for 12 h or left untreated. Cell lysates were processed by SDS–PAGE and western blot using antibodies against vinculin and PARP. f, g, FAM134B knockdown induces apoptosis involving the mitochondrial pathway. A549 cells stably expressing control and anti-FAM134B no. 2 shRNAs were starved in EBSS for the time indicated. Cell lysates were processed by SDS–PAGE and western blot using antibodies against vinculin, PARP and caspase 8 (f) or caspase 9 (g). ac, eg, Filled arrowheads indicate processed PARP and caspase 8/9; empty arrowheads indicate unprocessed PARP and caspase 8/9.

Extended Data Figure 8 Fam134b deficiency does not affect spinal cord motor neurons.

a, Western blot analysis of mouse embryonic tissue lysates with a Fam134b antibody. b, Transmission electron microscopy analysis of Fam134b+/+ and Fam134b–/– MEFs. Cells lacking Fam134b display an expanded ER. M, mitochondria. Scale bar, 1 μm; n = 150 cells. c, Compound muscle action potential (CMAP). CMAP latencies were recorded from tail nerves of wild-type (+/+) and knockout (−/−) mice at the ages indicated. No significant differences were observed between Fam134b+/+ and Fam134b−/− mice. One-way ANOVA, error bars indicate s.e.m.; n = 6 for +/+ and −/− at 6 months; n = 10 for +/+ and n = 13 for −/− at 12 months. n.s., not significant. d, Motor neurons in Nissl-stained thoracic spinal cord sections (10-µm thick) of Fam134b+/+ and Fam134b−/− mice. Scale bar, 20 µm. Representatives of seven images per genotype are shown. e, Quantification of motor neuron cell bodies in the ventral horn. Motor neuron number was unchanged in Fam134b+/+ and Fam134b−/− mice at an age of 12 and 20 months (n = 7 for +/+ and n = 7 for −/−). n.s., not significant, Student’s t-test, error bars indicate s.e.m. f, Normal ultrastructure of motor neurons in spinal cord sections of 12-month-old mice. Arrows in the middle and right panels highlight that there were no observed alterations in ER and Golgi architecture, respectively. Scale bar, 1 µm. Representatives of three images per genotype are shown.

Extended Data Figure 9 Ultrastructural analysis of dorsal root ganglia neurons in Fam134b−/− mice.

ae, Ex vivo analysis of dorsal root ganglia (DRG) neurons. DRG neurons from 3-month-old Fam134b+/+ and Fam134b−/− littermates were cultured for 2 days before transmission electron microscopy using the flat embedding approach. a, b, The ultrastructural architecture of the peripheral ER as found in the DRG neuron cell body above or below the nucleus (a) and ER (b) adjacent to the nucleus of DRG neurons is shown. Scale bars: a, 500 nm; b, 200 nm. c, Representative examples of Golgi compartments. Scale bar, 200 nm. (n = 25 cells for ac). d, e, Lateral cross-sections of the axons recognizable by their heavy myelination around the plasma membrane and their emptiness in organelles. Panel d shows a bundle of axons whereas panel e presents a single axon. e, lower panels, longitudinal cross-sections of neurites, which are typically packed with microtubules and ER. ER appears as thin black stripes in these images. ax, axon; ER, endoplasmic reticulum; G, Golgi; M, mitochondrium; mt, microtubule; my, myelin; N, nucleus, LD, lipid droplet. Scale bars: d, 1 µm; e, upper panels, 1 μm; lower panels, 500 nm. Representatives of 25 images per genotype are shown.

Extended Data Figure 10 Model of FAM134B function.

To drive ER-phagy, FAM134B clusters at the edges of cisternal ER. Local enrichment of FAM134B LIR leads to the recruitment of autophagosomal membranes and subsequent budding of ER-derived vesicles. Mature autophagosomes fuse with lysosomes leading to the degradation of enclosed ER fragments.

Supplementary information

Supplementary Information

This file contains the Western blot scans for figures 1, 3, 4 in the main paper and extended data figures 1, 2, 4, 5, 6, 7, 8. It also contains Supplementary Tables 1 and 2. (PDF 4662 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Khaminets, A., Heinrich, T., Mari, M. et al. Regulation of endoplasmic reticulum turnover by selective autophagy. Nature 522, 354–358 (2015). https://doi.org/10.1038/nature14498

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature14498

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing