A novel sphingolipid-TORC1 pathway critically promotes postembryonic development in Caenorhabditis elegans
- Howard Hughes Medical Institute, University of Colorado, Boulder, United States
- University of Colorado, Boulder, United States
- Fudan University, China
Figures
Figure 1
Iso-branched d17iso-sphinganine rescues elo-5(-) L1 arrest.
(A) Sphingolipid biogenesis pathway in C. elegans, including the catalytic enzymes (blue) and corresponding genes (red) used in this study. Molecular structures in green and in light blue indicate …
Figure 2 with 2 supplements
ku540 mutant suppresses L1 arrest of mmBCFA and sphingolipid biosynthetic mutants without restoring the levels of mmBCFAs.
(A) Screening strategy to isolate elo-5(−) suppressors. Green-colored C. elegans carry the extrachromosomal array containing copies of the elo-5(+), sur-5-gfp, and rol-6(dn) genes. (B) Percentages …
Figure 2—figure supplement 1
Quantification of GC and mass spectrometry analyses of elo-5(−) ku540 animals.
(A) Tables show relative intensities of the five strongest signals by mass spectrometry precursor scan (m/z = −241.2) in wild-type animals (second right column) and their normalized relative …
Figure 2—figure supplement 2
Suppression of fath-1(−) by nprl-3(ku540).
Microscopic images showing that nprl-3(ku540) suppresses the L1 arrest phenotype of fath-1 (injection RNAi) with or without C17ISO supplementation.
Figure 3 with 1 supplement
ku540 is a loss-of-function missense mutation of nprl-3.
(A) Predicted structure and position of the ku540 mutation in the nprl-3 gene (F35H10.7). (B) Abbreviated alignment of C. elegans NPRL-3 with its orthologs in other organisms. (C) C. elegans images …
Figure 3—figure supplement 1
Mapping and expression of nprl-3.
(A) A simplified diagram of the mapping process. ku540 is genetically linked to the E03H12 SNP marker on chromosome IV (upper section). Further three-point mapping narrowed the ku540 locus to near un…
Figure 4 with 5 supplements
TORC1 activation is sufficient for mmBCFAs-mediated growth regulation.
(A) Representative florescent images showing that elo-5(−) animals with each of four RFP-marked transgenes, which constitutively activated TORC1, bypass L1 arrest to reach beyond L3 stage …
Figure 4—figure supplement 1
Microscopic images of C. elegans with raga-1(RNAi) treatment.
Animals without C17ISO supplement were developmentally arrested at L1 stage (arrows). Animals with C17ISO supplement reached adulthood (arrowhead), suggesting that the arrest depends on mmBCFA …
Figure 4—figure supplement 2
Leucine could not promote postembryonic development independent of the mmBCFA/d17isoGlcCer/TORC1 pathway.
Normalized percentages of elo-5(−) animals that reached adulthood on various supplements. While 1 mM C17ISO could suppress the L1 arrest of elo-5(−), 10 mM leucine could not. Error bar: SD.
Figure 4—figure supplement 3
mmBCFA/GlcCer/TORC1 pathway is independent of the DAF-7/TGF-β pathway.
(A) Cartoon illustration of a simplified DAF-7/TGF-β pathway in C. elegans. Mutations in daf-3, daf-5, or bra-1 have been shown to cause constitutive activity of the TGF-β pathway and suppress dauer …
Figure 4—figure supplement 4
Lysosome integrity is not disrupted in mmBCFA-deficient animals.
(A)–(H) DIC and GFP images illustrating LMP-1::GFP (A–D) and GLO-1::GFP (E–H) expression patterns are similar throughout the intestine of young wild-type or elo-5(RNAi) larvae. Both LMP-1::GFP (A–D) …
Figure 4—figure supplement 5
Neutral red staining of let-363 -and elo-5-deficient animals.
(A)–(H) DIC and Rhodamine channel fluorescence images of larvae stained with Neutral red. (A–D) let-363 homozygous L3 animals have increased size and intensity of Neutral red stained lysosomes (D) …
Tables
Table 1
Intact TORC1 function is necessary for mmBCFA-mediated growth regulation
| Genotype | RNAi | Dietary C17ISO | Normalized % of F1 reached adulthood | N | p |
| elo-5(−) | Vector | − | 0 | 208 | |
| elo-5(−) | Vector | + | 86.9 | 205 | 0 |
| elo-5(−) nprl-3(−) | Vector | − | 71.5 | 69 | |
| elo-5(−) nprl-3(−) | Vector | + | 111.5 | 103 | 0.24 |
| elo-5(−) nprl-3(−) | raga-1 (a) | − | 35.5 | 56 | |
| elo-5(−) nprl-3(−) | raga-1 (a) | + | 102.5 | 83 | 0.031 |
| elo-5(−) nprl-3(−) | raga-1 (b) | − | 25.5 | 214 | |
| elo-5(−) nprl-3(−) | raga-1 (b) | + | 88.0 | 279 | 0.00001 |
| elo-5(−) nprl-3(−) | rheb-1 (a) | − | 14.2 | 351 | |
| elo-5(−) nprl-3(−) | rheb-1 (a) | + | 64.6 | 526 | 0.0000001 |
| elo-5(−) nprl-3(−) | rheb-1 (b) | − | 32.5 | 201 | |
| elo-5(−) nprl-3(−) | rheb-1 (b) | + | 86.0 | 116 | 0.0037 |
| elo-5(−) nprl-3(−) | rsks-1 (a) | − | 15.0 | 68 | |
| elo-5(−) nprl-3(−) | rsks-1 (a) | + | 72.5 | 83 | 0.022 |
| elo-5(−) nprl-3(−) | rsks-1 (b) | − | 19.0 | 183 | |
| elo-5(−) nprl-3(−) | rsks-1 (b) | + | 61.0 | 180 | 0.0034 |
| elo-5(−) nprl-3(−) | ife-2 (a) | − | 10.5 | 144 | |
| elo-5(−) nprl-3(−) | ife-2 (a) | + | 71.5 | 49 | 0.003 |
| elo-5(−) nprl-3(−) | ife-2 (b) | − | 0 | 103 | |
| elo-5(−) nprl-3(−) | ife-2 (b) | + | 103.5 | 150 | 0 |
| elo-5(−) nprl-3(−) | let-363 | − | 0 | >100 | |
| elo-5(−) nprl-3(−) | let-363 | + | 0 | >100 | NA |
-
Percentages of elo-5(−);nprl-3(ku540) homozygotes with the indicated RNAi treatments that reached adulthood, where (a) and (b) indicate two different RNAi constructs targeting different parts of the same gene. The presented percentage of elo-5(−) nprl-3(ku540) animals that reached adulthood was calculated by normalizing against the percentage of elo-5(−/+) nprl-3(ku540)/+ heterozygotes (see ‘Materials and methods’ for detail). Without C17ISO supplementation, RNAi knockdown of multiple TORC1 components reverted elo-5(−);nprl-3(ku540) animals to larval arrest.
Additional files
-
Supplementary file 1
Detailed description of phenotypes listed in Figure 1B.
- https://doi.org/10.7554/eLife.00429.016
