GCL: Sheep IgG was detected in mice given disease-inducing antibody, which costained with podocyte proteins (yellow). number decreases after disease-induced injury, podocytes cannot replace themselves because they are terminally differentiated cells and cannot proliferate. 11C17 This inadequate regeneration of podocytes directly underlies the development of progressive glomerulosclerosis and reduced kidney function.2,4,6,7,10,18C20 Recent studies have challenged this conventional paradigm, showing that podocyte number can be restored under certain circumstances.21C23 Importantly, this occurs in the absence of podocyte proliferation,22 suggesting that there may be one or more podocyte progenitors. Several seminal studies have shown that this neighboring glomerular PECs might serve this role.24C28 After podocyte loss, PECs activate expression of proteins considered to be restricted to podocytes.24,29,30 Such cells may be in transition, because they express both PEC and podocyte proteins, and have therefore been called glomerular epithelial transition cells.24,29,30 The number of glomerular epithelial transition cells detected lining Bowman’s capsule and within the glomerular tuft increases in membranous nephropathy,30 classical FSGS,30 and aging nephropathy.29 Based on these various studies, F1063-0967 a new paradigm has emerged, that in proteinuric glomerular diseases characterized by reduced F1063-0967 podocyte number subpopulations of PECs express podocyte markers and migrate to the glomerular basement membrane.31C33 Progenitor cells are oligopotent cells that frequently lie dormant in the tissue in which they reside; however, after local injury or death of mature, functioning cells, they replace the lost cell or cells by transdifferentiating into a new type of cell, acquiring its ultrastructure, activating transcriptional programs unique to those cells, and performing the biological functions of those cells. Although recent studies indicating that PECs may become podocytes are convincing, it remains to be shown that PECs become fully functional podocytes. Previous studies have recognized the juxtaglomerular compartment (JGC) as a reservoir of kidney progenitors.34,35 In adults, juxtaglomerular granular cells are modified easy muscle cells (also called myoepithelioid-like cells) present in the vascular component of the juxtaglomerular apparatus, at the distal end of afferent arterioles and, to a lesser extent, of the efferent arterioles.36 These cells are the major Mouse monoclonal antibody to PEG10. This is a paternally expressed imprinted gene that encodes transcripts containing twooverlapping open reading frames (ORFs), RF1 and RF1/RF2, as well as retroviral-like slippageand pseudoknot elements, which can induce a -1 nucleotide frame-shift. ORF1 encodes ashorter isoform with a CCHC-type zinc finger motif containing a sequence characteristic of gagproteins of most retroviruses and some retrotransposons. The longer isoform is the result of -1translational frame-shifting leading to translation of a gag/pol-like protein combining RF1 andRF2. It contains the active-site consensus sequence of the protease domain of pol proteins.Additional isoforms resulting from alternatively spliced transcript variants, as well as from use ofupstream non-AUG (CUG) start codon, have been reported for this gene. Increased expressionof this gene is associated with hepatocellular carcinomas. [provided by RefSeq, May 2010] source of total renin production and circulating active renin37,38 and therefore play critical roles in the regulation of vascular tone and the reninCangiotensinCaldosterone system.39 An elegant study showed that cells of renin lineage can also serve a progenitor function for easy muscle, epithelial, mesangial, and extrarenal cells and can be detected in low numbers in normal glomeruli.34 Moreover, we have F1063-0967 previously shown that nonCrenin-expressing cells of the extraglomerular mesangium,36 residing in the JGC, repopulate the glomerular tuft and restore mesangial cell number after mesangiolysis in a model of mesangioproliferative glomerulonephritis.35 The purpose of these studies was to apply genetic cell fate-mapping strategies in four transgenic geneCtargeted mice that report for cells of renin lineage to test the hypothesis that these cells serve as progenitor cells for podocytes and PECs during experimental glomerular disease characterized by a decrease in podocyte number. Three newly generated renin-reporter mouse strains and one existing reporter mouse strain were used. Materials and Methods Reporter Mice Four different reporter mouse strains were used to genetically fate-map cells of renin lineage, three of which were newly generated. gene with tomato reddish protein only after the administration of tamoxifen (Sigma-Aldrich, St. Louis, MO). Because renin expression might be switched on later in life, thus confounding the data from your constitutive reporter mice, we launched a Cre recombinase fused to the human estrogen receptor (ER) ligand-binding domain name40 into exon 1 of F1063-0967 the gene residing within a 240-kb bacterial artificial chromosome (BAC), here represented as gene with ZsGreen. To tag cells of renin lineage indefinitely, even after renin is usually no longer being transcribed, a Cre-recombinase cassette40 was cloned into the BAC using homologous recombination, as explained previously42,43 (Supplemental Physique?S1). The renin regulatory region can then control Cre recombinase, which recognizes and excises loxP sites in DNA. When the gene with GFP, as previously reported.34 The power of this knock-in mouse is that all cells of renin lineage and their descendants permanently express GFP, even if renin expression is subsequently decreased or absent.44 Mice with Cre recombinase under control of the renin locus34 were crossed with Z/EG reporter mice.44 Z/EG reporter mice constitutively express lacZ under the control of the CMV enhancer/chicken actin promoter. When crossed with a Cre recombinase-expressing strain, lacZ expression is replaced with enhanced GFP expression in tissues expressing Cre. gene residing within a 240-kb BAC to generate a construct that has GFP expression controlled from within the entire natural genomic sequence context for renin (Supplemental Physique?S1). The insertion.