We provide evidence that miRNA miR-71 is not required for the animals’ entry into L1 diapause, but plays a critical role in long-term survival by repressing the expression of insulin receptor/PI3K pathway genes and genes acting downstream or in parallel to the pathway. Full device encrypted backups to iTunes will back up both the account listings and private key pairs, but can only be restored on the SAME phone that created the backup. If you enabled third-party account backup, you can recover your accounts on your iOS or Android device. If your organization hasn’t enabled self-service device management, contact your IT Help Desk or Duo service administrator for assistance reactivating the account. If you can’t open Duo Mobile on your old device, for example, if your phone was lost or damaged, contact your Duo administrator to discuss your account recovery options. You must have access to Duo Mobile on your old Android device in order to use Instant Restore to restore your Duo-protected account backup to your new device.
Furthermore, a recent study suggests that the expression of certain miRNAs is differentially regulated by starvation-induced dauer diapause (15). Consistent with these ideas, several recent lines of evidence suggest that miRNA let-7 and the heterochronic genes lin-42 and hbl-1 are required to regulate the starvation-induced dauer diapause (10–12) and that a number of miRNAs including lin-4 and mir-71 are involved in regulating life span (13, 14). Furthermore, worms that are long-lived due to dietary restriction or decreased mitochondrial respiratory rates are short-lived during L1 diapause, suggesting that the mechanisms controlling L1 starvation survival are different at least in some aspects from those controlling aging (3).
- To investigate the roles of miRNAs in animal survival during starvation-induced L1 diapause, we impaired the overall miRISC function with loss-of-function (lf) mutants of ain-1 (ku322, ku425, and tm3681) and ain-2(tm2432) and examined their L1 starvation survival rate (Materials and Methods).
- MT12993 mir-71(n4115) worms were outcrossed with N2 for four generations before any test except the initial screen.
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- We further examined the functional relationship between miR-71 and DAF-16, a FOXO transcription factor acting critically and negatively downstream of AGE-1/PI3K in the InsR pathway.
MT12993 mir-71(n4115) worms were outcrossed with N2 for four generations before any test except the initial screen. A recent study showed that the expression of miR-71 was significantly increased relative to other miRNAs in starved L1 worms (15). However, miR-71 does not appear to regulate all postembryonic development during L1 diapause recovery. Unlike classical heterochronic miRNAs such as lin-4 and let-7, the role of miR-71 in vulval cell division is essential in animals recovering from starvation-induced L1 diapause, but not in animals hatched on plates with food. As pointed out above, multiple miRNAs in addition to miR-71 and the let-7 family miRNAs have roles in L1 diapause, and they may regulate the expression of many diverse targets that may include, but are not limited to, factors involved in UNC-31–InsR-signaling activities.
MiR-71 regulates vulval cell division during recovery of starved L1 worms. These results indicate that miR-71 is not essential for arresting seam cell or M-cell divisions during L1 diapause, suggesting that miR-71 function is distinct from DAF-16 function. DAF-16 (the FOXO homolog in C. elegans) has been shown to play an important role in cell cycle arrest and developmental progression partly by promoting cki-1 expression in some somatic cells during L1 arrest (2).
RRF Regulation
L1 starvation assay was adapted from a previously described protocol (3). Worms strains were grown and maintained at 20 °C as described (29). This result is consistent with the observation that miR-71 is specifically required for the starvation-induced stress response (Fig. S5). For example, we observed a robust retarded mutant phenotype in the vulval lineage but did not see obvious defects in seam cell differentiation or alae formation. It seems plausible that miRNAs that control developmental timing are also involved in regulating the metabolic rate through repressing the InsR pathway activity.
- Worms strains were grown and maintained at 20 °C as described (29).
- We recommend that incorporating trait-based recovery dynamics is essential for predicting ecosystem stability under compound climate extremes.
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- The effect observed in ain-1(lf) mutants is likely the consequence of the combined effects of attenuating functions of these individual miRNAs.
The roles of InsRs have also been implicated in arresting the cell cycle in germ cells and a portion of somatic cells during L1 diapause (2, 4). Contributed new reagents/analytic tools; X.Z., R.Z., and M.H. We recommend that incorporating trait-based recovery dynamics is essential for predicting ecosystem stability under compound climate extremes.
Previous studies showed that the release of postdocking calcium-regulated dense-core vesicles, the insulin receptor (InsR) pathway, the AMPK pathway, and protein chaperones are required for the long-term survival of starved L1 worms (2–4). Unlike dauer diapause, L1 diapause is not accompanied by life cycle changes and has not been shown to require certain signaling pathways that control the formation of dauer diapause such as TGF-β signaling (daf-1, daf-7) and nuclear hormone receptor (daf-12) (2, 3). The coordinated entrance into developmental arrest, long-term survival, and the reinitiation of development upon food availability are important biological processes to investigate. Different organisms have developed versatile growth arrest strategies to overcome starvation-induced metabolic and developmental problems.
