Transgenic mice: beyond the knockout

Abstract

mice have had a tremendous impact on biomedical research. Most researchers are familiar with transgenic mice that carry Cre recombinase (Cre) and how they are used to create conditional knockouts. However, some researchers are less familiar with many of the other types of transgenic mice and their applications. For example, transgenic mice can be used to study biochemical and molecular pathways in primary cultures and cell suspensions derived from transgenic mice, cell-cell interactions using multiple fluorescent proteins in the same mouse, and the cell cycle in real time and in the whole animal, and they can be used to perform deep tissue imaging in the whole animal, follow cell lineage during development and disease, and isolate large quantities of a pure cell type directly from organs. These novel transgenic mice and their applications provide the means for studying of molecular and biochemical events in the whole animal that was previously limited to cell cultures. In conclusion, transgenic mice are not just for generating knockouts.Cre; enhanced green fluorescent protein; high-throughput; renal-specific; transgenics TRANSGENIC MICE HAVE REVOLUTIONIZED biomedical research. They permit the manipulation of genetic, molecular, biochemical, and physiological processes in the whole animal with nearly the same specificity seen in cell culture models. Most researchers are familiar with the Cre/loxP system and how it is used to create conditional knockouts. However, most are unfamiliar with the many other transgenic mice and their applications, novel and well-established alike. These novel mice go beyond the knockout and provide the means to study of cellular processes in the whole animal that was traditionally limited to culture models. This review highlights a few of these transgenic mice and their applications.

Modeling human neurodegenerative diseases in transgenic systems

“…To circumvent these problems, conditional recombination systems, such as the Cre-loxP (Nagy 2000;Miller 2011;Wang 2009) and Flp-FRT systems described above, allow for the location and timing of gene inactivation to be closely regulated. An ever-expanding number of mouse Cre deleter lines have been created (http://nagy.mshri.on.ca/cre_new/).…”

A primary culture of distal convoluted tubules expressing functional thiazide-sensitive NaCl transport

“…Few cell models exist, but not one displays true distal convoluted tubule (DCT) characteristics. Heterologous expression systems, such as NCC-transfected HEK293 cells and Xenopus laevis oocytes have been used for 22 Na ϩ uptake experiments (24,26), while isolated mDCT cells [which contain cells from the thick ascending limb (TAL) and are therefore not pure cultures] and mpkDCT cells have been used to study phosphorylated signaling pathways involved in NCC regulation (8,16). In these cells, the different regulators of NCC, angiotensin II, and hypotonic low-chloride medium, have been shown to phosphorylate and activate NCC (25,27,28,30,32).…”

Bio-applications Derived from Site-Directed Genome Modification Technologies

“…By limiting the expression of Cre or Flp recombinases to a speci fi c tissue or cell type, and/or for a given time, based on the use of an inducible expression system, it has been possible to control the inactivation of a gene (Miller 2011 ;Wang 2009 ;Bockamp et al 2008 ) . The common strategy for conditional knockout of alleles is to fl ank with loxP or FRT sites at a proximal exon within the target gene, leading to frameshift and null allele mutations following Cre-mediated recombination.…”