Protein Translation Rates Are Negatively Correlated With Lifespan in Inbred Drosophila Strains
Year: 2024
Type: article
Abstract: Protein translation (PT) is an essential cellular process that plays a critical role in growth and development. PT occurs at high levels in early adulthood but declines with age across multiple species. For example, PT in rat liver tissue shows a peak at 6 months with a progressive decline until at least 22 months (1). Human skeletal muscle shows a decline from 24±1-year to 54±1-year (2). This has been replicated in a number of different animal models and tissues (3–7). In Drosophila, we demonstrate a peak in PT on Day 2 and then a subsequent decline back to baseline by Day 15 (Figure 1A). Our prior studies show this phenotype in males and females and after Day 15 for PT to remain low for the remainder of the flies’ life (8). Our previous research demonstrated that the transient elevation in PT during early adulthood can have long-lasting negative impacts on aging trajectories and proteostasis in Drosophila (8). We found that blocking the early-life PT elevation significantly improved lifespan via treatment with a low dose of the PT inhibitor cycloheximide (Figure 1B); a mechanistic exploration of this process and demonstration of healthspan improvements are described in our previous paper (8). Blocking the transient protein translation (PT) elevation during early adulthood improves lifespan and healthspan. (A) PT across ages, determined by puromycin incorporation normalized to Ponceau staining (n = 3). Analyses compared PT relative to Day 0. (B) Early adulthood (Days 0–10) 1 μM cycloheximide (CHX) treatment prolongs lifespan in W1118 Drosophila females/males. n = 250/group. (C–F) PT in varied Drosophila Genetic Reference Panel (DGRP) lines at Day 0 and Day 2, determined by puromycin incorporation normalized to Ponceau staining; C and D shows ♀ and E and F shows ♂. Lifespan values based on prior published work (8). Linear regression/Pearson’s correlation (r) comparing the PT increase from Day 0 to 2 with mean lifespan. n = 9. Solid line: the regression line; dotted line: 95% confidence interval. (G) Linear regression/Pearson’s correlation (r) comparing the PT increase from Day 0 to 2 with Week 1 and lifetime fecundity. n = 9. (H, I). Lifespan assay comparing 2 short-lived and 2 long-lived DGRP lines in the absence and presence of 1 μM CHX incorporated into food from Day 0 to Day 10. Drosophila females (males were not examined) n = 250/group. Linear regression/Pearson’s correlation (r) comparing the median lifespan with lifespan extension from CHX n = 4 DGRP lines. In this study, we investigated whether PT in early life could predict natural variations in lifespan across Drosophila strains. We employed the Drosophila Genetic Reference Panel (DGRP), a community resource consisting of ~200 fully sequenced inbred Drosophila lines derived from a natural population (9). We hypothesized that the level of PT in early life would negatively correlate with lifespan across different DGRP lines, and that repressing PT would produce a larger extension in lifespan in lines with high early-life PT compared to lines with low early-life PT. We measured PT dynamics in several DGRP lines with substantial differences in lifespan. Using puromycin incorporation, we quantified PT levels at Day 0 (baseline) and Day 2 (PT peak). In both male and female flies, we observed a strong negative correlation between the extent of the early-life elevation in PT and mean lifespan, based on prior published DGRP lifespan data (10) (Figure 1C and F; ♀: r = −0.8995, p = .0010, ♂: r = −0.9180, p = .0005). This finding suggests that the greater the level of PT during early adulthood, the shorter the flies lived. These data support our hypothesis that the level of PT in early life is a powerful predictor of future lifespan and indicate that our previous findings can be generalized to other fly strains. Fecundity was also evaluated; we saw a negative trend between early-life PT rates and fecundity in the first week of adulthood and whole-life fecundity, however, these trends did not reach statistical significance (Figure 1G; Week 1: r = −0.3699, p = .3271, lifetime: r = −0.5058, p = .1648). To further validate these findings, we examined the impact of repressing PT in short-lived DGRP lines with high PT in early life compared to long-lived DGRP lines with low PT in early life. Animals were grouped based on prior published DGRP lifespan data (10). Female flies were treated with cycloheximide (CHX) during early adulthood (Days 0–10) to repress PT. We found a negative correlation between the median lifespan and the percent increase in lifespan under PT repression (Figure 1H and I; r = −0.7278, p = .029). This suggests that long-lived flies, which have low PT in early life, receive less benefit from PT repression. In contrast, short-lived flies with high early-life PT showed greater lifespan extension upon PT repression, highlighting the differential impact of PT dynamics on longevity. In our previous work, we reported that high PT in early life disrupts protein homeostasis (proteostasis) late in life, triggering age-related protein aggregation, and driving functional declines. This occurs via the engagement of the insulin-receptor/PI3K/S6K axis through the juvenile hormone. We show this to modulate lipid transfer protein expression and germline signaling leading to proteostatic dysfunction by overwhelming cellular protein-folding capacity and silencing stress responses, thereby facilitating age-related functional decline (8). In this study, we showed that Drosophila lifespan among genetically diverse strains is correlated with PT levels in early adulthood. We showed that PT repression in early adulthood can robustly extend lifespan but produces more robust effects in short-lived lines with high early-life PT compared to long-lived lines with low early-life PT. Drosophila lines from the DGRP were maintained under standard laboratory conditions in a humidified incubator at 25°C with a 12-hour light/dark cycle. Flies were reared on agar–cornmeal–dextrose–yeast medium and transferred to 10% sugar/yeast (SY10) medium after eclosion. For lifespan assays, flies were separated by sex and maintained in groups of 25 per vial, with 10 vials per group for each sex. Flies were transferred to fresh food every 2–3 days and survival was recorded. PT levels were quantified using puromycin incorporation flies were fed SY10 medium supplemented with 600 µM puromycin for 24 hours. Whole-body lysates were prepared, and puromycin incorporation was detected by Western blotting. PT levels were normalized to total protein content. To repress PT, flies were treated with 1 µM CHX during early adulthood (Days 0–10). CHX was dissolved in SY10 medium, and flies were maintained on CHX-containing food for the duration of the treatment period. Control flies were fed SY10 medium without CHX. This research was supported by NIA/NIH R56AG061051 and R01AG065301, American Federation for Aging Research (AFAR) and T32-GM008361. None.
Language: English
Subfield: Aging
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W4405367604