Yongzhi Yang’s research while affiliated with Sanford Burnham Prebys Medical Discovery Institute and other places

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Publications (3)


Neuronal expression of SID-1, an RNA channel protein, leads to RNAi-competent neurons
(a) Mean GFP fluorescence intensity in head region of rgef-1p::gfp animals on day 1 to day 12 of adulthood, relative to day 1. Error bars are s.d. of n = 3 experiments, with n = 29, 34, 32, 24, 28, 19 animals over 3 independent experiments. ns P = 0.78, P = 0.05, P = 0.116, ****P < 0.0001, **P = 0.005, by one-way ANOVA with Dunnett’s multiple comparisons test. (b-f) Wild-type animals (N2, WT), sid-1; rgef-1p::sid-1 + rgef-1p::gfp, and sid-1 mutants after whole-life RNAi against the indicated gene with tissue-specific functions, compared to control (CTRL). (b) Representative animals are shown with WT animals displaying paralysis (Prz) on unc-112 RNAi, larval arrest (Lva) on rpl-2 RNAi, blister formation (Bli) and larval arrest (Lva) on bli-1 RNAi, and clear (Clr) and larval arrest on elt-2 RNAi. Mean percent phenotypic penetrance after knockdown of genes with functions in (c) body-wall muscle; unc-22 – twitching and uncoordinated movement (Unc) (n = 8 experiments, ****P < 0.0001) and unc-112 – paralysis (n = 7 experiments, ****P < 0.0001), (d) a ubiquitous manner; rpl-2 – larval arrest (n = 8 experiments, ****P < 0.0001), (e) hypodermis; tsp-15 – blisters (n = 8 experiments, ****P < 0.0001) and bli-1 – blisters and larval arrest; (f) intestine; elt-2 – clear and larval arrest. Error bars are s.d. (g) Mean GFP fluorescence intensity in head region of day 1 sid-1; rgef-1p::sid-1 + rgef-1p::gfp rgef-1p::gfp animals after whole-life gfp RNAi compared to control (CTRL). Error bars are s.d. with n = 30 over 3 independent experiments. ****P < 0.0001, **P = 0.005, by two-tailed Student’s t-test. Scale bar: 100 µm. (h) Mean GFP fluorescence intensity in head region of day 1 sid-1; rgef-1p::sid-1 + rgef-1p::gfp rgef-1p::gfp animals after whole-life lgg-1 RNAi (n = 32) compared to control (CTRL) (n = 35). Error bars are s.d. over 3 independent experiments. ****P < 0.0001 by two-tailed Student’s t-test. Scale bar: 100 µm. (i) Mean percent of shrinker phenotype in day 2 WT, rde-1; unc-47p::rde-1::SL2::sid-1 (capable of GABA neuron-specific RNAi), sid-1; rgef-1p::sid-1 + rgef-1p::gfp, or sid-1 animals after two generations of whole-life snb-1 or unc-13 RNAi compared to control (CTRL). Error bars are s.d. with ****P < 0.0001 and ns P > 0.99 by one-way ANOVA with Dunnett’s multiple comparisons test.
Source data
Healthspan and neuronal phenotypes of animals after neuronal inhibition of atg-7 and lgg-1/ATG8
(a) Mean body bends per 20 s of sid-1; rgef-1p::sid-1 + rgef-1p::gfp animals after whole-life atg-7, or lgg-1/ATG8 RNAi compared to control (CTRL). Error bars are s.e.m. of one representative experiment, each with n = 16 animals. Experiment was performed three times with similar results. Linear regression comparison versus CTRL: atg-7 RNAi: Pslope = 0.5; Py-intercept = 0.02; lgg-1/ATG8 RNAi: Pslope = 0.3; Py-intercept = 0.01. (b) Mean number of contractions in the terminal pharyngeal bulb per 30 s of sid-1; rgef-1p::sid-1 + rgef-1p::gfp animals after whole-life atg-7, or lgg-1/ATG8 RNAi compared to control (CTRL). Error bars are s.d. of n = 30 animals over 3 independent experiments. Linear regression comparison versus CTRL: atg-7 RNAi: Pslope = 0.4; Py-intercept = 0.4; lgg-1 RNAi: Pslope = 0.3; Py-intercept = 0.5. (c) Mean number of progeny produced per day in sid-1; rgef-1p::sid-1 + rgef-1p::gfp animals after atg-7 (n = 19 animals), or lgg-1/ATG8 RNAi (n = 18 animals) compared to control (CTRL) (n = 22 animals) over 2 independent experiments. Error bars are s.d. CTRL versus atg-7 RNAi: ns P = 0.72, 0.89, 0.91, 0.82, >0.99; CTRL versus lgg-1/ATG8 RNAi: ns P = 0.95, 0.96,0.60, 0.70, >0.99, by two-way ANOVA with Dunnett’s multiple comparisons test. (d) Analysis of integrity of sensory neurons in day 5 sid-1; rgef-1p::sid-1 + rgef-1p::gfp animals after atg-7, or lgg-1/ATG8 RNAi compared to control (CTRL). Sensory mutants daf-10(e1387) and osm-6(p811) are negative controls. Shown are representative images of n = 10 animals. Experiment was performed three times with similar results. Scale bar, 20 μm. (e) Representative image of neuronal branch (arrowhead) from ALM neuron in day 15 sid-1; rgef-1p::sid-1+ rgef-1p::gfp animals. Scale bar: 20 µm. Mean percent of animals with branches after whole-life atg-7, or lgg-1/ATG8 dsRNA compared to control (CTRL) of n = 4 experiments. Error bars are s.d. ***P = 0.0002, ****P < 0.0001 by Cochran-Mantel-Haenszel test. (f) Mean chemotaxis index of day 5 sid-1; rgef-1p::sid-1 + rgef-1p::gfp animals after whole-life atg-7, or lgg-1/ATG8 RNAi using the chemoattractant butanone. Error bars are 95% C.I. of n = 4 experiments. *P = 0.048, **P = 0.0094, by one-way ANOVA with Dunnett’s multiple comparisons test.
Source data
Autophagy status is unchanged in animals expressing sid-1 and in non-neuronal tissues after neuronal knockdown of early-acting autophagy genes
(a) Mean neuronal GFP::LGG-1 and GFP::LGG-1(G116A) punctae in day 1 wild-type (sid-1 + /+) (n = 28, 29) and sid-1(qt9) (sid-1-/-) animals (n = 27, 27) with or without rgef-1p::sid-1 transgene (rgef-1p::sid-1 (+)) (n = 26, 29). Error bars are s.d. over 3 independent experiments. Comparison between strains: LGG-1: ns P = 0.75, P = 0.97, G116A: ns P = 0.98, P > 0.99. Comparison of lipidated and unlipidated structures: ****P < 0.0001, by two-way ANOVA with Tukey’s multiple comparisons test. (b) Mean sqst-1p::sqst-1::gfp fluorescence intensity in head region of day 1 wild-type (sid-1 + /+), and sid-1(qt9) (sid-1(-/-)) animals with or without rgef-1p::sid-1 transgene (rgef-1p::sid-1 (+)) on day 1 of adulthood. Error bars are s.d. of n = 31 animals over 3 independent experiments. ns P = 0.18 and P = 0.59 by one-way ANOVA with Dunnett’s multiple comparisons test. (c) GFP::LGG-1 punctae in intestinal cells of day 1 wild-type (sid-1 + /+) (n = 59) and sid-1(qt9) (sid-1-/-) animals (n = 62) with or without rgef-1p::sid-1 transgene (rgef-1p::sid-1 (+)) (n = 62). Violin plots with solid line indicating median and dashed lines indicating quartiles. ns P = 0.79, P = 0.99 by one-way ANOVA with Dunnett’s multiple comparisons test. (d) GFP::LGG-1 punctae in body-wall muscle areas of day 1 wild-type (sid-1 + /+) (n = 48) and sid-1(qt9) (sid-1-/-) animals (n = 45) with or without rgef-1p::sid-1 transgene (rgef-1p::sid-1 (+)) (n = 52). Violin plots with solid line indicating median and dashed lines indicating quartiles. ns P = 0.64, P = 0.70 by one-way ANOVA with Dunnett’s multiple comparisons test. (e) GFP::LGG-1 punctae in intestinal cells of day 1 sid-1; rgef-1p::sid-1 + rgef-1p::gfp; lgg-1p::gfp::lgg-1 animals after whole-life atg-7 (n = 65), or lgg-1/ATG8 (n = 48) RNAi compared to control (CTRL) (n = 81). Violin plots with solid line indicating median and dashed lines indicating quartiles. ns P = 0.98, P = 0.71 by one-way ANOVA with Dunnett’s multiple comparisons test. (f) GFP::LGG-1 punctae in body-wall muscle areas of day 1 sid-1; rgef-1p::sid-1 + rgef-1p::gfp; lgg-1p::gfp::lgg-1 animals after whole-life atg-7 (n = 54), or lgg-1/ATG8 (n = 53) RNAi compared to control (CTRL) (n = 49). Violin plots with solid line indicating median and dashed lines indicating quartiles. ns P = 0.34, P = 0.96 by one-way ANOVA with Dunnett’s multiple comparisons test.
Source data
Neuronal PolyQ aggregation, exopher formation and lifespan extension are correlated
(a) Number of neuronal PolyQ aggregates in day 7 rgef-1::Q40::yfp wild-type (sid-1 + /+) (n = 41) and sid-1(qt9) (sid-1-/-) animals (n = 48 with or without rgef-1p::sid-1 transgene (rgef-1p::sid-1 (+)) (n = 42). Violin plots with solid line indicating median and dashed lines indicating quartiles. ns P = 0.79, P = 0.82 by one-way ANOVA with Dunnett’s multiple comparisons test. (b) Mean percent of ALMR neurons with exophers of day 2 mec-4p::mCherry wild-type (sid-1 + /+) (n = 228 animals) and sid-1(qt9) (sid-1-/-) (n = 262 animals) with or without rgef-1p::sid-1 transgene (rgef-1p::sid-1 (+)) (n = 295 animals). Error bars are s.d. of n = 7 experiments, ns P = 0.62, P = 0.54 by two-sided Cochran-Mantel-Haenszel test. (c) Mean percent of ALMR neurons with exophers of day 2 sid-1; rgef-1p::sid-1 + rgef-1p::gfp; mec-4p::mCherry animals (n = 247 animals) after adult-only atg-7 (n = 271 animals), or lgg-1/ATG8 (n = 285 animals) RNAi compared to control (CTRL). Error bars are s.d. of n = 6 experiments, *P = 0.028, P = 0.00006 by two-sided Cochran-Mantel-Haenszel test. (d) Mean percent of ALMR neurons with exophers of day 2 mec-4p::mCherry animals (n = 151 animals) after whole-life atg-7 (n = 157 animals), or lgg-1/ATG8 (n = 180 animals) RNAi compared to control (CTRL). Error bars are s.d. of n = 5 experiments, ns P = 0.39, P = 0.53 by two-sided Cochran-Mantel-Haenszel test. (e-g) Percent mean lifespan (LS) change (Fig. 1b), number of neuronal PolyQ aggregates (Fig. 3b), and mean percent of AMLR neurons with exophers (Fig. 4b) plotted against each other with simple linear regression (solid line with 95% C.I. as dashed lines). Numbers refer to specific RNAi treatment; ¹unc-51/ATG1, ²atg-13, ³bec-1/BECN1, ⁴atg-9, ⁵atg-16.2, ⁶atg-7, ⁷atg-4.1, ⁸lgg-1/ATG8, ⁹cup-5, ¹⁰epg-5, ¹¹vha-13, ¹²vha-15, ¹³vha-16. P values determined by two-sided Spearman correlation test.
Source data
Atg-16.2 and atg-4.1 mutants display similar RNAi phenotypes
(a-d) Phenotypes of day 2 WT, atg-16.2(ok3224), atg-4.1(bp501), and sid-1(qt9) animals after whole-life RNAi against a specific gene expressed in different tissues. Mean percent phenotypic penetrance after knockdown of genes with functions in (a) body-wall muscle; unc-22 – twitching and uncoordinated movement (Unc) and unc-112 – paralysis, (b) a ubiquitous manner; rpl-2 – larval arrest, (c) hypodermis; tsp-15 – blisters and bli-1 – blisters and larval arrest; (d) intestine; elt-2 – clear and larval arrest. Error bars are s.d. of n = 4 experiments. (a) unc-22 RNAi: ns P = 0.59, P = 0.87, ****P < 0.0001. unc-112 RNAi: ns P = 0.92, P = 0.96, ****P < 0.0001. (b) rpl-2 RNAi: ns P = 0.82, P = 0.96, ****P < 0.0001. (c) tsp-15 RNAi: ns P = 0.99, P = 0.64, ****P < 0.0001. bli-1 RNAi: ns P = 0.24, P = 0.99, ****P < 0.0001. (d) elt-2 RNAi: ns P = 0.76, P = 0.18, ****P < 0.0001 by one-way one-way ANOVA with Dunnett’s multiple comparisons test.
Source data

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Autophagy protein ATG-16.2 and its WD40 domain mediate the beneficial effects of inhibiting early-acting autophagy genes in C. elegans neurons
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January 2024

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228 Reads

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16 Citations

Nature Aging

Yongzhi Yang

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Caitlin M. Lange

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Malene Hansen

While autophagy genes are required for lifespan of long-lived animals, their tissue-specific roles in aging remain unclear. Here, we inhibited autophagy genes in Caenorhabditis elegans neurons, and found that knockdown of early-acting autophagy genes, except atg-16.2, increased lifespan, and decreased neuronal PolyQ aggregates, independently of autophagosomal degradation. Neurons can secrete protein aggregates via vesicles called exophers. Inhibiting neuronal early-acting autophagy genes, except atg-16.2, increased exopher formation and exopher events extended lifespan, suggesting exophers promote organismal fitness. Lifespan extension, reduction in PolyQ aggregates and increase in exophers were absent in atg-16.2 null mutants, and restored by full-length ATG-16.2 expression in neurons, but not by ATG-16.2 lacking its WD40 domain, which mediates noncanonical functions in mammalian systems. We discovered a neuronal role for C. elegans ATG-16.2 and its WD40 domain in lifespan, proteostasis and exopher biogenesis. Our findings suggest noncanonical functions for select autophagy genes in both exopher formation and in aging.

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Inhibition of early-acting autophagy genes in C. elegans neurons improves protein homeostasis, promotes exopher production, and extends lifespan via the ATG-16.2 WD40 domain

December 2022

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43 Reads

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3 Citations

While autophagy is key to maintain cellular homeostasis, tissue-specific roles of individual autophagy genes are less understood. To study neuronal autophagy in vivo, we inhibited autophagy genes specifically in C. elegans neurons, and unexpectedly found that knockdown of early-acting autophagy genes, i.e., involved in formation of the autophagosome, except for atg-16.2, decreased PolyQ aggregates and increased lifespan, albeit independently of the degradation of autophagosomal cargo. Neuronal aggregates can be secreted from neurons via vesicles called exophers, and we found that neuronal inhibition of early-acting autophagy genes atg-7 and lgg-1/Atg8, but not atg-16.2 increased exopher formation. Moreover, atg-16.2 mutants were unable to form exophers, and atg-16.2 was required for the effects of early autophagy gene reduction on neuronal PolyQ aggregation, exopher formation, and lifespan. Notably, neuronal expression of full-length ATG-16.2 but not ATG-16.2 without a functional WD40 domain, important for non-canonical functions of ATG16L1 in mammalian cells, restored these phenotypes. Collectively, we discovered a specific role for C. elegans ATG-16.2 and its WD40 domain in exopher biogenesis, neuronal proteostasis, and lifespan determination, highlighting a possible role for non-canonical autophagy functions in both exopher formation and in aging.


sqst-1 is required for autophagy induction after hormetic heat shock (HS). a–d Autophagy flux was measured at 20 °C in WT and sqst-1(ok2892) (sqst-1) animals on day 1 of adulthood expressing rgef-1p::gfp::lgg-1 (a) or lgg-1p::gfp::lgg-1 (b–d). WT and sqst-1 animals were injected with vehicle (DMSO) or bafilomycin A1 (BafA) to block autophagy at the lysosomal acidification step. GFP::LGG-1/Atg8-positive punctae were quantified from three independent experiments in a nerve-ring neurons (WT-DMSO, N = 25; WT-BafA, N = 28; sqst-1-DMSO, N = 25, sqst-1-BafA, N = 24 animals), b proximal intestinal cells (WT-DMSO, N = 49; WT-BafA, N = 50; sqst-1-DMSO, N = 55, sqst-1-BafA, N = 46 cells), c body-wall muscle (WT-DMSO, N = 71; WT-BafA, N = 44; sqst-1-DMSO, N = 48, sqst-1-BafA, N = 53 animals), and d and the terminal pharyngeal bulb (WT-DMSO, N = 28; WT-BafA, N = 29; sqst-1-DMSO, N = 28, sqst-1-BafA, N = 27 animals), Error bars indicate 95% CI. ns: P > 0.05, **P < 0.01, ****P < 0.0001, by two-way ANOVA with Tukey’s multiple comparisons test. e–h GFP::LGG-1/Atg8-positive punctae were counted in WT and sqst-1(ok2892) (sqst-1) animals on day 1 of adulthood expressing rgef-1p::gfp::lgg-1 (e) or lgg-1p::gfp::lgg-1 (f–h). Animals were maintained under control conditions 15 °C (CTRL) or subjected to HS for 1 h at 36 °C (HS). Animals were imaged at time of highest induction in autophagy as previously characterized². GFP::LGG-1/Atg8 punctae were quantified from three independent experiments in e nerve-ring neurons (WT-CTRL, N = 24; WT-HS, N = 23; sqst-1-CTRL, N = 23, sqst-1-HS, N = 24 animals) with 2 h of recovery after HS, f proximal intestinal cells (WT-CTRL, N = 67; WT-HS, N = 70; sqst-1-CTRL, N = 66, sqst-1-HS, N = 71 cells) with 4 h of recovery after HS, g body-wall muscle (WT-CTRL, N = 60; WT-HS, N = 48; sqst-1-CTRL, N = 50, sqst-1-HS, N = 60 animals) (no recovery), and h terminal pharyngeal bulb (WT-CTRL, N = 26; WT-HS, N = 32; sqst-1-CTRL, N = 26, sqst-1-HS, N = 25 animals) with 4 h of recovery after HS. Error bars indicate 95% CI. ns: P > 0.05, **P < 0.01, ****P < 0.0001, by two-way ANOVA with Tukey’s multiple comparisons test. Scale bar: 10 μm. Source data are provided in the Source Data file.
sqst-1 is required for the organismal benefits of a hormetic heat shock (HS). a Survival of WT (N2) and sqst-1(ok2892) (sqst-1) animals subjected to HS on day 1 of adulthood, and then incubated for 7 h at 36 °C on day 3 of adulthood (n = 4 plates). Error bars indicate SD, ns: P > 0.8, ***P < 0.001 by two-way ANOVA with Tukey’s multiple comparisons test. See Supplementary Table 1 for experimental details and additional repeats. b Lifespan analysis of WT and sqst-1(ok2892) (sqst-1) animals at 20 °C subjected to 1h HS at 36 °C on day 1 of adulthood. WT-CTRL animals (N = 126) compared with WT-HS animals (N = 110): P < 0.0001; sqst-1-CTRL animals (N = 128) (P = 0.3 to WT) compared with sqst-1-HS animals (N = 115): P = 0.004, by log-rank test. See Supplementary Table 2 for experimental details and additional repeats. c Neuronal PolyQ (rgef-1p::Q40::yfp) aggregates detected on day 4 of adulthood in WT and sqst-1(ok2892) (sqst-1) animals maintained under control conditions (20 °C, CTRL) or subjected to HS (1 h at 36 °C) on day 1 of adulthood (HS). Scale bar 20 μm. The number of neuronal PolyQ aggregates were quantified from three independent experiments in WT-CTRL, N = 43; WT-HS, N = 50; sqst-1-CTRL, N = 48, sqst-1-HS, N = 45 animals. Error bars indicate 95% CI. ns: P > 0.6, **P < 0.01, ****P < 0.0001, by two-way ANOVA with Tukey’s multiple comparisons test. Scale bar 20 and 10 μm for close-up. d, e FRAP measurements of neuronal PolyQ (rgef-1p::Q40::yfp) aggregates on day 8 of adulthood in WT (e) and sqst-1(ok2892) (sqst-1) (f) animals maintained under control conditions (20 °C, CTRL) or subjected to HS (1 h at 36 °C) on day 1 of adulthood (HS). The fluorescence signal was bleached after 20 s and fluorescence recovery was measured for 2 min. The average % of fluorescence intensity was quantified from three independent experiments in WT-CTRL, N = 32; WT-HS, N = 30; sqst-1-CTRL, N = 32, sqst-1-HS, N = 31 animals. Error bars indicate 95% CI. **P < 0.05, **P < 0.01, ***P < 0.001, by two-way ANOVA with Sidak’s multiple comparisons test. P > 0.05 for all timepoints when comparing WT-CTRL and sqst-1-CTRL by two-way ANOVA with Sidak’s multiple comparisons test. Source data are provided in the Source Data file.
SQST-1 overexpression extends C. elegans lifespan and improves proteostasis. a Lifespan analysis of WT (N2) (N = 58 animals) and SQST-1 OE (sqst-1p::sqst-1::gfp (1)) (N = 88 animals) animals at 20 °C: P-value by log-rank test. b Lifespan analysis of WT (N2) (N = 92 animals), sqst-1(syb764) (N = 88 animals), and sqst-1(syb764) animals expressing either sqst-1p::sqst-1 + rol-6 (sqst-1; SQST-1) (N = 124 animals) or sqst-1p::sqst-1ΔUBA + rol-6 (sqst-1; SQST-1ΔUBA) (N = 107 animals) at 20 °C. P-values by log-rank test. c Lifespan analysis of WT (N2) (N = 85 animals) and neuronal SQST-1 OE (rgef-1p::sqst-1::gfp (1)) (N = 85 animals) animals at 20 °C. P-value by log-rank test. d Lifespan analysis of WT (N2) and SQST-1 OE (sqst-1p::sqst-1::gfp (1)) animals subjected to hormetic HS on day 1 of adulthood. WT-CTRL, N = 126; WT-HS, N = 111; SQST-1 OE-CTRL, N = 116, SQST-1 OE-HS, N = 106 animals at 20 °C. P-values by log-rank test. e Lifespan analysis of WT (N2) and neuronal SQST-1 OE (rgef-1p::sqst-1::gfp (1)) animals subjected to hormetic HS on day 1 of adulthood. WT-CTRL, N = 126; WT-HS, N = 111; Neuronal SQST-1 OE-CTRL, N = 123, SQST-1 OE-HS, N = 120 animals at 20 °C. P-values by log-rank test. a–e See Supplementary Data 2 and Table 3 for experimental repeats. f Quantification of neuronal PolyQ aggregates (rgef-1p::Q40::yfp) on day 5 of adulthood from three independent experiments in WT (N = 31 animals) and SQST-1 OE animals (sqst-1p::sqst-1 + rol-6) (N = 30 animals). Error bars indicate 95% CI. ns: P > 0.05 by t-test. g Fluorescence images and FRAP measurements of the aggregated (white dashed circles) and diffuse (yellow dashed circles) portion of neuronal PolyQ (rgef-1p::Q40::yfp) on day 8 of adulthood in WT and SQST-1-overexpressing animals sqst-1p::sqst-1 + rol-6 (SQST-1 OE) at 20 °C. Fluorescence signal bleached after 10 s (timepoint 2) and fluorescence recovery was measured for 2 min. The average % of fluorescence intensity was quantified from three independent experiments in WT, N = 32; SQST-1 OE, N = 31. Image numbers correspond to the indicated timepoints. Error bars indicate 95% CI. All measurements are P > 0.05 by two-way ANOVA with Sidak’s multiple comparisons test unless indicated otherwise *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Outline of pharyngeal bulbs in image of head region. Scale bar: 20 and 10 μm for close-up. h Lifespan analysis of Neuronal Q40-expressing animals (rgef-1p::Q40::yfp) (N = 39 animals) and Neuronal Q40; SQST-1 OE (rgef-1p::Q40::yfp; sqst-1p::sqst-1 + rol-6) (N = 79 animals) at 20 °C. P-value by log-rank test. See Supplementary Table 4 for experimental repeats. Source data are provided in the Source Data file.
SQST-1 overexpression induces neuronal autophagy. a, b Lifespan analysis of WT and sqst-1p::sqst-1::gfp (SQST-1 OE) animals at 20 °C subjected to bacteria expressing empty vector (CTRL) or dsRNA targeting autophagy genes (a) lgg-1/ATG8 and (b) cup-5 from day 1 of adulthood. WT-CTRL, N = 121; WT-lgg-1/ATG8 RNAi, N = 121; WT-cup-5 RNAi, N = 124; SQST-1 OE-CTRL, N = 108, SQST-1 OE-lgg-1/ATG8 RNAi, N = 116; SQST-1 OE-cup-5 RNAi, N = 129 animals. P-values by log-rank test. See Supplementary Data 3 for experimental repeats. c Colocalization of SQST-1 and LGG-1/Atg8 in the head region of animals expressing sqst-1p::sqst-1::gfp and lgg-1p::tdtomato::lgg-1. First panel is overlay of DIC (differential interference contrast) image and GFP (SQST-1) and tdTOMATO (LGG-1/Atg8) fluorescence. Second panel is overlay of GFP (SQST-1) and tdTOMATO (LGG-1/Atg8) fluorescence, followed by single fluorescent channels. Scale bar: 10 and 2.5 μm in close-up. Intensity correlation quotient (ICQ) values between 0 and 0.5 indicate colocalization and values between 0 and −0.5 indicate segregated fluorescence. ICQ score were quantified in entire head region from two independent experiments (N = 17 animals). Error bars indicate 95% CI. d GFP::LGG-1/Atg8-positive punctae in nerve-ring neurons of WT and SQST-1 OE (sqst-1p::sqst-1) animals on day 1 of adulthood expressing neuronal GFP::LGG-1 (rgef-1p::gfp::lgg-1). Scale bar: 10 μm. e Histogram of GFP::LGG-1/Atg8 structures binned by their diameter in nerve-ring neurons of WT (N = 519 GFP::LGG-1/Atg8 structures) and SQST-1 OE (N = 1196 GFP::LGG-1/Atg8 structures) animals with indicated median diameter. P < 0.0001 by Wilcoxon signed rank test. See Supplementary Table 5. f GFP::LGG-1/Atg8-positive punctae in nerve-ring neurons of WT and SQST-1 OE (sqst-1p::sqst-1) animals on day 1 of adulthood expressing GFP::LGG-1 under its endogenous promoter (lgg-1p::gfp::lgg-1). Scale bar: 10 μm. g Autophagy-flux measurements were performed at 20 °C in WT and SQST-1 OE animals on day 1 of adulthood expressing rgef-1p::gfp::lgg-1. WT and SQST-1 OE animals were injected with vehicle (DMSO) or bafilomycin A1 (BafA) to block autophagy at the lysosomal acidification step. GFP::LGG-1/Atg8-positive punctae were quantified from three independent experiments (WT-DMSO, N = 30; WT-BafA, N = 32; SQST-1 OE-DMSO, N = 31, SQST-1 OE-BafA, N = 32 animals). Error bars indicate 95% CI. **P < 0.01, ****P < 0.0001, by two-way ANOVA with Tukey’s multiple comparisons test. Source data for (a), (b), (c), (e), and (g) are provided in the Source Data file.
The autophagy receptor p62/SQST-1 promotes proteostasis and longevity in C. elegans by inducing autophagy

December 2019

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108 Citations

Autophagy can degrade cargos with the help of selective autophagy receptors such as p62/SQSTM1, which facilitates the degradation of ubiquitinated cargo. While the process of autophagy has been linked to aging, the impact of selective autophagy in lifespan regulation remains unclear. We have recently shown in Caenorhabditis elegans that transcript levels of sqst-1/p62 increase upon a hormetic heat shock, suggesting a role of SQST-1/p62 in stress response and aging. Here, we find that sqst-1/p62 is required for hormetic benefits of heat shock, including longevity, improved neuronal proteostasis, and autophagy induction. Furthermore, overexpression of SQST-1/p62 is sufficient to induce autophagy in distinct tissues, extend lifespan, and improve the fitness of mutants with defects in proteostasis in an autophagy-dependent manner. Collectively, these findings illustrate that increased expression of a selective autophagy receptor is sufficient to induce autophagy, enhance proteostasis and extend longevity, and demonstrate an important role for sqst-1/p62 in proteotoxic stress responses. While the cellular recycling process autophagy has been linked to aging, the impact of selective autophagy on lifespan remains unclear. Here Kumsta et al. show that the autophagy receptor p62/SQSTM1 is required for hormetic benefits and p62/SQSTM1 overexpression is sufficient to extend C. elegans lifespan and improve proteostasis.

Citations (3)


... In addition, the previously described so-called 'nodal vesicular parcels' (Tanaka et al., 2005) might be special examples of amphiectosomes. Finally, in Caenorhabditis elegans, the release autophagy and stress-related large EVs (lEVs) (exophers) has been documented (Melentijevic et al., 2017;Cooper et al., 2021;Yang et al., 2024). They contain damaged organelles and do not have an MV-lEV-like ultrastructure. ...

Reference:

A ‘torn bag mechanism’ of small extracellular vesicle release via limiting membrane rupture of en bloc released amphisomes (amphiectosomes)
Autophagy protein ATG-16.2 and its WD40 domain mediate the beneficial effects of inhibiting early-acting autophagy genes in C. elegans neurons

Nature Aging

... We speculate that young adult physiology might be temporally tweaked such that some tissues have optimized capacity to manage/degrade large aggregates and organelles at an early adult developmental 'clean up' time, possibly analogous to how a town service for bulky oversized garbage pick-up might be limited to particular days during the year. As exopher production appears generally beneficial for neuronal function and survival (Melentijevic et al., 2017;Yang et al., 2022), the early life extrusion phase appears a positive feature of reproductive life. More broadly, proteome 'clean up' phases may be programmed as key steps at specific transitions during development and homeostasis, for example, as occurs in the temporal lysosome activation that clears aggregate debris in C. elegans maturing oocytes (Bohnert and Kenyon, 2017) or in the maturation of mouse adult neuronal stem cells via vimentin-dependent proteasome activity during quiescence exit (Morrow et al., 2020). ...

Inhibition of early-acting autophagy genes in C. elegans neurons improves protein homeostasis, promotes exopher production, and extends lifespan via the ATG-16.2 WD40 domain
  • Citing Preprint
  • December 2022

... Study conducted in C. elegans, mild hormetic heat shock at 20ºC upregulates selective autophagy receptor SQST-1/p62 transcripts level. Enhanced SQST-1/p62 transcripts elevate autophagy and extend longevity (Kumsta et al. 2019). According to the in vitro research conducted on senescent human skin fibroblast, using immunofluorescence, five-fold increases in basal LC3 was found, and no difference in thick skin biopsies and photo-exposed and photoprotected region was observed (Demirovic et al. 2015). ...

The autophagy receptor p62/SQST-1 promotes proteostasis and longevity in C. elegans by inducing autophagy