Modulated expression of human peripheral blood micro RNAs from infancy to adulthood and its role in aging.

Accumulating evidence suggests a role for micro RNAs (mi RNAs) in regulating various processes of mammalian postnatal development and aging. To investigate the changes in blood-based mi RNA expression from preterm infants to adulthood, we compared 365 mi RNA expression profiles in a screening set of preterm infants and adults. Approximately one-third of the mi RNAs were constantly expressed from postnatal development to adulthood, another one-third were differentially expressed between preterm infants and adults, and the remaining one-third were not detectable in these two groups. Based on their expression in infants and adults, the mi RNAs were categorized into five classes, and six of the seven mi RNAs chosen from each class except one with age-constant expression were confirmed in a validation set containing infants, children, and adults. Comparing the chromosomal locations of the different mi RNA classes revealed two hot spots: the mi RNA cluster on 14q32.31 exhibited age-constant expression, and the one on 9q22.21 exhibited up-regulation in adults. Furthermore, six mi RNAs detectable in adults were down-regulated in older adults, and four chosen for individual quantification were verified in the validation set. Analysis of the network functions revealed that differentially regulated mi RNAs between infants and adults and mi RNAs that decreased during aging shared two network functions: inflammatory disease and inflammatory response. Four expression patterns existed in the 11 mi RNAs from infancy to adulthood, with a significant transition in ages 9-20 years. Our results provide an overview on the regulation pattern of blood mi RNAs throughout life and the possible biological functions performed by different classes of mi RNAs. [ABSTRACT FROM AUTHOR]