Glucose or Altered Ceramide Biosynthesis Mediate Oxygen Deprivation Sensitivity Through Novel Pathways Revealed by Transcriptome Analysis inCaenorhabditis elegans

Abstract

Individuals with type 2 diabetes display metabolic abnormalities, such as hyperglycemia, increased free fatty acids, insulin resistance, and altered ceramide levels, that contribute to vascular dysfunctions and compromised oxygen delivery. Caenorhabditis elegans fed a glucose-supplemented diet or with altered ceramide metabolism, due to a hyl-2 mutation, are sensitive to oxygen deprivation (anoxia). Our experiments showed that the combination of these factors further decreased the anoxia survival. RNA-sequencing analysis was performed to assess how a glucose-supplemented diet and/or a hyl-2 mutation altered the transcriptome. Comparison analysis of transcripts associated with anoxia-sensitive animals [hyl-2(tm2031) mutation or a glucose diet] revealed 199 common transcripts encoded by genes with known or predicted functions involving innate immunity, cuticle function (collagens), or xenobiotic and endobiotic phase I and II detoxification system. Use of RNA interference (RNAi) to target gene products of the xenobiotic and endobiotic phase I and II detoxification system (UDP-glycosyltransferase and Cytochrome p450 genes; ugt-15, ugt-18, ugt-19, ugt-41, ugt-63, cyp-13A12, cyp-25A1, and cyp-33C8) increased anoxia survival in wild-type animals fed a standard diet. Anoxia sensitivity of the hyl-2(tm2031) animals was suppressed by RNAi of cyp-25A1 or cyp-33C8 genes. A glucose diet fed to the P0 hermaphrodite decreased the anoxia survival of its F1 embryos; however, the RNAi of ugt-63 and cyp-33C8 suppressed anoxia sensitivity. These studies provide evidence that the detoxification system impacts oxygen deprivation responses and that C. elegans can be used to model the conserved detoxification system.

NHR-14 loss of function couples intestinal iron uptake with innate immunity in C. elegans through PQM-1 signaling

“…Comparison of upregulated nhr-14 genes with C. elegans mutant datasets using WormExp v1.0 showed significant overlap with genes upregulated in nhr-8(hd117) mutants and hyl-2 mutants (Figure 6—source data 4). nhr-8 encodes a nuclear receptor that regulates cholesterol and bile acid homeostasis (Magner et al, 2013) and hyl-2 encodes ceramide synthase that is involved in oxygen deprivation and regulation of innate immune genes (Ladage et al, 2016). Downregulated nhr-14 genes showed significant overlap with genes downregulated in elo-5(gk208) mutants (Kniazeva et al, 2015).…”

High-glucose diets induce mitochondrial dysfunction in Caenorhabditis elegans

“…A mutation in hyl-1 increases oxygen deprivation survival, while a mutation in hyl-2 results in oxygen deprivation sensitivity [15,32]. The sensitivity to oxygen deprivation of a hyl-2 mutant is worsened if the worms are fed a glucose diet, showing an altered expression of genes involved in innate immunity, cuticle function and phase I and II detoxification system [68]. We observed that both hyl-1 and hyl-2 mRNAs were downregulated in glucose-treated worms.…”

The cisd gene family regulates physiological germline apoptosis through ced-13 and the canonical cell death pathway in Caenorhabditis elegans

“…One-day old adult hermaphrodites were collected for mRNA isolation and RT-PCR as previously described [56, 57]. Briefly, mRNA was isolated using TRIzol Reagent (Life Technology, 15596026), NucleoSpin RNA Clean-up (Machenerey-Nagel, 740948-50) and TURBO DNA-free TM kit (Life Technology, AM1907) reagents.…”

“…The number of progeny produced by cisd-1(tm4993) and cisd-1(pnIs27) mutants, relative to N2 control, was determined as previously described [57]. At least four synchronized animals were collected at the L4-to-adult molt, placed as individuals onto a NGM plate and allowed to lay eggs over a 24-h period.…”