First name
Francesco
Last name
Ghini
Year of Study
Research Center
Thesis Title
The plasticity of miRNA pool: a novel approach to reveal mechanisms behind miRNA turnover
Thesis Abstract
MicroRNAs (miRNAs) are a small (18-25nt long), evolutionary conserved, class of noncoding
RNAs that appears as a major regulatory component of gene expression, implicated in
virtually all known physiological and pathological processes. They act at post-transcriptional
level by silencing the expression of a multitude of target mRNAs through various
mechanisms, including target degradation and protein synthesis inhibition. As a result, the
regulation of the miRNA pool is one of the critical events in the definition of cell identity and
behavior both in physiology and disease. To date, the dynamics of miRNA degradation and
the mechanisms involved in remain largely obscure, in particular, in higher organisms. We
developed a pulse-chase approach based on metabolic RNA labeling to calculate miRNA
decay rates at genome-wide scale in mammalian cells. Our analysis revealed heterogeneous
miRNA half-lives, with many species behaving as stable molecules (T1/2 > 24 h), while
others, including passenger miRNAs and a number (25/129) of guide miRNAs, are quickly
turned over (T1/2 = 4–14 h). Decay rates were coupled with other features, including genomic
organization, tran- scription rates, structural heterogeneity (isomiRs), and target abundance,
measured through quantitative experimental approaches. This comprehensive analysis
highlighted functional mechanisms that mediate miRNA degradation, as well as the
importance of decay dynamics in the regulation of the miRNA pool under both steady-state
conditions and during cell transitions.
RNAs that appears as a major regulatory component of gene expression, implicated in
virtually all known physiological and pathological processes. They act at post-transcriptional
level by silencing the expression of a multitude of target mRNAs through various
mechanisms, including target degradation and protein synthesis inhibition. As a result, the
regulation of the miRNA pool is one of the critical events in the definition of cell identity and
behavior both in physiology and disease. To date, the dynamics of miRNA degradation and
the mechanisms involved in remain largely obscure, in particular, in higher organisms. We
developed a pulse-chase approach based on metabolic RNA labeling to calculate miRNA
decay rates at genome-wide scale in mammalian cells. Our analysis revealed heterogeneous
miRNA half-lives, with many species behaving as stable molecules (T1/2 > 24 h), while
others, including passenger miRNAs and a number (25/129) of guide miRNAs, are quickly
turned over (T1/2 = 4–14 h). Decay rates were coupled with other features, including genomic
organization, tran- scription rates, structural heterogeneity (isomiRs), and target abundance,
measured through quantitative experimental approaches. This comprehensive analysis
highlighted functional mechanisms that mediate miRNA degradation, as well as the
importance of decay dynamics in the regulation of the miRNA pool under both steady-state
conditions and during cell transitions.
Email
francesco.ghini@iit.it
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