Small RNAs Altered in Human Calorie Restriction
Researchers have been publishing more data of late from the CALERIE trial of human calorie restriction that took place over the course of a few years. The participants aimed at a 25% reduction in calorie intake, and ended up achieving something more like 12-15%. The trial started nearly 20 years ago at this point. It is often the case that tissue samples and data remain intact and potentially useful long after the study is complete, awaiting greater funding and interest, as well as the existence of more advanced analysis technologies.
Small non-coding RNAs (smRNAs), approximately 20-35 nucleotides in length, represent a diverse class of regulatory molecules that include microRNAs (miRs) and piwi-interacting RNAs (piRs). These nanoscale molecules are key regulators of gene expression, orchestrating complex networks to maintain genome stability and contribute to post-transcriptional gene regulation and cellular homeostasis.
Caloric restriction (CR) extends lifespan and enhances healthspan across species. In humans, the CALERIE Phase 2 trial demonstrated that CR improves inflammation, cardiometabolic health, and molecular aging. To explore underlying mechanisms, we examined CR-induced changes vs. ad libitum (AL) in smRNAs across plasma, muscle, and adipose tissue. Using smRNA sequencing, we analyzed miRs and piRs over 12 and 24 months, comparing CR levels (%CR) and group assignments (CR vs. AL).
We identified 16 smRNAs associated with %CR and 41 with CR vs. AL. Although tissue-specific expression varied, shared pathways emerged, including insulin signaling, circadian rhythm, cell cycle regulation, and stress response. Cross-species analysis revealed 17 miRs altered by CR in both humans and rhesus monkeys. These findings suggest smRNAs are key molecular mediators of CR's effects on aging and longevity, offering insight into biological mechanisms of CR and potential targets for age-related interventions.