In situ hybridization in the study of the kidney and renal diseases

In situ hybridization (ISH), combined with immunohistochemistry, has become a powerful tool in the investigation of temporal and spatial relationships between specific cellular sources of mRNA and ultimate localization of translated protein. This review provides a discussion on basic ISH methods and a comprehensive examination of the literature on applications of ISH to the study of nephrogenesis, normal kidney, and renal disease. The review covers literature examining expression of mRNA encoding growth factors, proteins involved in signal transduction and transcription, proteolysis, extracellular matrix and a variety of other products involved in regulating cell remodeling during nephrogenesis. Expression of mRNA encoding many of these products diminishes in normal adult renal tissue, only to be reactivated during renal disease. Such a recapitulation of the expression of mRNAs involved in nephrogenesis might indicate that similar cellular events are required for remodeling during renal disease. In addition, ISH has allowed for the investigation of interactions between cells intrinsic to the kidney and inflammatory cells (and their biologically active products) recruited from exogenous sources. Although diagnostic use of ISH is currently limited, the implications for the use of this methodology in future clinical applications is promising.