library_construction_protocol: Tissues were homogenized in TRIzol Reagent (ThermoFisher) using a Pellet Pestle Motor (Kimbal) and RNA was isolated using the miRNeasy Mini kit (Qiagen), according to manufacturers' protocols, including the optional DNase digest step. RNA concentration and quality were assessed using the Nanodrop 2000 spectrophotometer (Thermo Scientific) and the RNA 6000 Nano Assay (Agilent Technologies). All samples had RIN values above 9 Stranded libraries were constructed using the KAPA mRNA HyperPrep Kit (Roche Sequencing and Life Science), according to the manufacturer's protocol.  Briefly, the protocol entails isolation of polyA containing mRNA using oligo-dT magnetic beads, RNA fragmentation, first and second strand cDNA synthesis, ligation of Illumina-specific adapters containing a unique barcode sequence for each library, and PCR amplification. The quality and concentration of the libraries were assessed using the D5000 ScreenTape (Agilent Technologies) and KAPA Library Quantification Kit (Roche Sequencing and Life Science), respectively, according to the manufacturers' instructions. Libraries were sequenced 100 bp paired-end on an Illumina HiSeq 4000 using HiSeq 3000/4000 SBS Kit reagents.