Fig. 4: Ttyh1 mediates lipid droplet degradation.

a Ttyh1 mediates lipid droplet (LD) breakdown in astrocytes. Triglycerides (TAG) levels in astrocytes were measured at 0 and 120 min after nutrient deprivation. Bafilomycin A1 (BafA1) inhibits lysosome degradation. Relative absorbance values were reported by the colorimetric TAG assay, and are normalized to the mean of Ttyh1 WT values at 0 min. Data were presented as mean ± SEM. Number of independent lipid extracts (n) is shown at the bottom of each bar. Unpaired two-tailed t-test (t = 105.2, df = 4). b, c Drosophila TTYH1 ortholog mediates LD breakdown in glia. Representative confocal images of primary glial cells isolated from wildtype (WT) and tty^−/− Drosophila brains in (b) show glial nuclei (nucRFP; magenta) and BODIPY493/503 (BODIPY; green) stained LDs. Quantifications of BODIPY signals in c reveal LD contents in the glial cells. Each datapoint represents one glial cell. Data are presented as mean ± SEM. Number of glial cells (n) from ≥3 primary cell culture is shown in bracket underneath each bar. Mann–Whitney test. d Lipidomic profiles show increased amounts of TAG and DAG species in tty^−/− Drosophila heads. Relative fold-changes are shown. Box plots show the median, the bounds of the box (25th and 75th percentiles) and whiskers representing minimum and maximum values. Data were from seven sample cohorts for each genotype; each cohort contained lipid extracts from ≥40 fly heads. Mann–Whitney test. e Astrocyte-specific knockout of Ttyh1 leads to TAG accumulation in mouse cortices. Two-month-old Aldh1l1-cre/ERT2; Ttyh1^fl/fl mice were injected with either vehicle or tamoxifen (TAM) for 5 consecutive days. Protein and TAG contents in the dissected cortices were measured. TAG contents were quantitated by enzyme-coupled assay. TAG contents in the cortical tissues of female (n = 3) and male (n = 6) mice were shown separately. [TAG] quantity in each cortical tissue sample was normalized to the respective protein quantity. Box plots show the median, the bounds of the box (25th and 75th percentiles) and whiskers representing minimum and maximum values. Unpaired two-tailed t-test (Female: t = 41.04, df = 4; male: t = 33.33, df = 10). Source data are provided as a Source Data file.