Abstract 280: Cardiac Disease Status Dictates Functional mRNA Targeting Profiles of Individual microRNAs
Background: Gain- and loss-of-function experiments have demonstrated that microRNAs are key players in cardiac stress responses, but the mRNAs whose abundance and/or translational potential are primarily affected by changes in cardiac microRNAs are not well characterized. Stimulus-induced, large-scale alterations in the cardiac transcriptome, together with consideration of the law of mass action, further suggest that the mRNAs most substantively targeted by individual microRNAs vary between unstressed and stressed conditions. To test the hypothesis that microRNA target profiles differ in health and disease, we traced the fate of miR-133a and miR-378 targets in mouse hearts undergoing pressure-overload hypertrophy.
Methods and Results: Ago2 immunoprecipitation with RNA-sequencing (RISC-sequencing) was used for unbiased definition of microRNA-dependent and -independent alterations occurring amongst ~13,000 mRNAs in response to transverse aortic constriction (TAC), in response to the microRNA overexpression needed to define miR-133a and miR-378 targets and to track their fate, and in response to the combined stimuli. Of 51 direct targets of miR-133a defined in unstressed hearts (fold-change ≥25%, FDR<0.02), only 8 (16%) continued to be targeted by miR-133a during TAC, while for miR-378 direct targets, 17 of 28 (61%) targets were maintained during TAC. Similarly, only 9% (for miR-133a) and 58% (for miR-378) of hundreds of indirectly affected mRNAs underwent comparable regulation, demonstrating that the significant effect of TAC on microRNA direct target selection resulted in wider alterations of signaling function. Numerous microRNA-mediated regulatory events occurring exclusively during pressure overload revealed signaling networks likely responsive to the endogenous decreases in miR-133a and miR-378 during TAC.
Conclusions: Pressure overload-mediated changes in overall cardiac RNA content alter microRNA targeting profiles, reinforcing the need to define microRNA targets in tissue-, cell- and status-specific contexts. Such considerations need to be taken into account for tailoring of therapeutic manipulation of microRNAs toward the most appropriate microRNAs active under defined stimuli.
Author Disclosures: S.J. Matkovich: 2. Research Grant; Significant; AHA Grant-in-Aid. G.W. Dorn: 2. Research Grant; Significant; NIH R01. T.C. Grossenheider: None. P.J. Hecker: None.
This research has received full or partial funding support from the American Heart Association, Midwest Affiliate (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, South Dakota & Wisconsin).
- © 2015 by American Heart Association, Inc.