title: miRNA profiling of naïve, effector and memory CD8 T cells.
abstract: microRNAs have recently emerged as master regulators of gene expression during development and cell differentiation. Although profound changes in gene expression also occur during antigen-induced T cell differentiation, the role of miRNAs in the process is not known. We compared the miRNA expression profiles between antigen-specific naïve, effector and memory CD8+ T cells using 3 different methods--small RNA cloning, miRNA microarray analysis and real-time PCR. Although many miRNAs were expressed in all the T cell subsets, the frequency of 7 miRNAs (miR-16, miR-21, miR-142-3p, miR-142-5p, miR-150, miR-15b and let-7f) alone accounted for approximately 60% of all miRNAs, and their expression was several fold higher than the other expressed miRNAs. Global downregulation of miRNAs (including 6/7 dominantly expressed miRNAs) was observed in effector T cells compared to naïve cells and the miRNA expression levels tended to come back up in memory T cells. However, a few miRNAs, notably miR-21 were higher in effector and memory T cells compared to naïve T cells. These results suggest that concomitant with profound changes in gene expression, miRNA profile also changes dynamically during T cell differentiation. Sequence analysis of the cloned mature miRNAs revealed an extensive degree of end polymorphism. While 3'end polymorphisms dominated, heterogeneity at both ends, resembling drosha/dicer processing shift was also seen in miR-142, suggesting a possible novel mechanism to generate new miRNA and/or to diversify miRNA target selection. Overall, our results suggest that dynamic changes in the expression of miRNAs may be important for the regulation of gene expression during antigen-induced T cell differentiation. Our study also suggests possible novel mechanisms for miRNA biogenesis and function.
authors.affiliation: The CBR Institute for Biomedical Research and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Haoquan
authors.initials: H
authors.lastname: Wu
authors.forename: Joel R
authors.initials: JR
authors.lastname: Neilson
authors.forename: Priti
authors.initials: P
authors.lastname: Kumar
authors.forename: Monika
authors.initials: M
authors.lastname: Manocha
authors.forename: Premlata
authors.initials: P
authors.lastname: Shankar
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Sharp
authors.forename: N
authors.initials: N
authors.lastname: Manjunath
mesh_terms: D000818:Animals; D000941:Antigens / Q000737:chemistry; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002454:Cell Differentiation; D003001:Cloning, Molecular; D017931:DNA Primers / Q000737:chemistry; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007156:Immunologic Memory; D051379:Mice; D035683:MicroRNAs; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D011110:Polymorphism, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000941:Antigens; D017931:DNA Primers; D035683:MicroRNAs