Development of a new macrophage-specific TRAP mouse (MacTRAP) and the definition of the renal macrophage translational signature

We generated a new macrophage-specific mouse line for the application of Translating Ribosome Affinity Purification (MacTRAP). MacTRAP mice express an eGFP-tagged ribosomal protein (L10a) under the control of the macrophage-specific c-fms promoter (driver of Csf1r). The TRAP line was characterized and expression of the transgene confirmed in kidney and other tissues. Validation included testing the responsiveness of the transgene under pro-inflammatory challenge in the kidney. Using TRAP, we successfully extracted macrophage-specific polysomal RNA from MacTRAP kidneys and conducted RNA-Seq following bioinformatic analyses to establish a comprehensive in vivo gene expression and pathway signature of resident renal macrophages, which may be of use to investigators studying the gene expression profile of these cells. Overall, this new in vivo tool may be of great value for the study of macrophage biology in different organs and various models of injury and disease. Overall design: Unbound and bound (immunopreciptated) fractions of three nine week old male MacTRAP mice were analyzed.