Investigating the molecular mechanisms underlying Kombucha-induced lipid utilization in C. elegans (2024)

Undergraduate: Lillian Baker

Faculty Advisor: Rachel DuMez-Kornegay
Department: Cell Biology and Physiology

---

It has become increasingly evident that the colonization of the human gastrointestinal tract by diverse microbes can confer health benefits that extend beyond the breakdown of macromolecules. Previous work in our lab has shown that the probiotic microbes in Kombucha Tea, or Kombucha Tea-associated microbes (KTM), remodel host transcriptional programs to produce a fasting-like, catabolic state even in the presence of sufficient nutrients. In response to KTM consumption, the fat-5/SCD gene, which encodes a palmitoyl-CoA desaturase that catalyzes the synthesis of palmitoleic acid (16:1) from palmitic acid (16:0), is reproducibly down-regulated. In order to identify regulators of the KTM induced fat-5 down-regulation, we performed an EMS forward genetic screen using a fat-5 reporter on animals fed KTM. A candidate mutation was identified by whole genome sequencing in the acs-5/ACSL5 locus, which encodes a lipid coA ligase. This allele suppressed the KTM-induced fat-5 down-regulation phenotype. Interestingly, we observed that acs-5 is not a KTM-specific regulator of fat-5 expression. This suggests that ACS-5 may act as a singling molecule in the regulation of lipid metabolism, a function beyond its canonical role in modulating fatty acids. Therefore, to investigate acs-5 induced transcriptional regulators of fat-5, I performed a RNAi reverse genetic screen targeting transcription factors known to regulate the expression of fat-5. I identified DAF-16/FOXO as a fat-5 activator and HLH-11/TFAP4 and HLH-30/TFEB as fat-5 repressors. Using translational reporters, I observed reduced nuclear accumulation of HLH-11 and HLH-30 on acs-5 RNAi. Therefore, I hypothesize that ACS-5 may repress fat-5 expression by controlling the nuclear localization of the HLH-11 and HLH-30 transcription factors.