Identifying the Molecular Phenotype of Renal Progenitor Cells

Abstract

Abstract. Although many of the molecular interactions in kidney development are now well understood, the molecules involved in the specification of the metanephric mesenchyme from surrounding intermediate mesoderm and, hence, the formation of the renal progenitor population are poorly characterized. In this study, cDNA microarrays were used to identify genes enriched in the murine embryonic day 10.5 (E10.5) uninduced metanephric mesenchyme, the renal progenitor population, in comparison with more rostral derivatives of the intermediate mesoderm. Microarray data were analyzed using R statistical software to determine accurately genes differentially expressed between these populations. Microarray outliers were biologically verified, and the spatial expression pattern of these genes at E10.5 and subsequent stages of early kidney development was determined by RNA in situ hybridization. This approach identified 21 genes preferentially expressed by the E10.5 metanephric mesenchyme, including Ewing sarcoma homolog, 14-3-3 , retinoic acid receptor-␣, stearoyl-CoA desaturase 2, CD24, and cadherin-11, that may be important in formation of renal progenitor cells. Cell surface proteins such as CD24 and cadherin-11 that were strongly and specifically expressed in the uninduced metanephric mesenchyme and mark the renal progenitor population may prove useful in the purification of renal progenitor cells by FACS. These findings may assist in the isolation and characterization of potential renal stem cells for use in cellular therapies for kidney disease.There is increasing evidence from a number of organ systems that cells with at least multipotentiality (1,2) and possibly pluripotentiality (3) exist in adult organs that previously were thought not to contain such populations. Although cell division is infrequent in the adult kidney, this organ possesses the capacity for regeneration as evidenced by the cellular proliferation observed during recovery from conditions such as acute tubular necrosis (4). Although cell lineage relationships during renal repair and regeneration are poorly defined, it is possible that these processes recapitulate some aspects of embryonic renal development. The permanent kidney (metanephros) arises via reciprocal interactions between two tissues, the ureteric bud (UB) and the metanephric mesenchyme (MM) (5). Each of these tissues is initially derived from the intermediate mesoderm (IM), although the UB develops as a caudal outgrowth from the nephric duct (ND), whereas the MM develops from the nephrogenic cord, the same block of tissue that gives rise to the pronephroi and the mesonephroi (5). After invasion by the UB, cells of the MM are induced to differentiate into specific renal lineages. The central dogma of kidney development suggests that the UB forms the ureter and collecting duct system of the mature kidney, whereas the MM gives rise to the remaining portions of the nephrons, from Bowman's capsule to distal tubule (6). Although many of the interactions between the UB and MM are now well chara...

Regrow or Repair

“…With the increasing amount of literature on the expression profile of the developing kidney across time and subcompartment, it may become possible to dissect better the compartments, such as the nephrogenic zone and the cap mesenchyme, and identify cell surface marker combinations with which to search for a persistent fetal renal progenitor. In an attempt to define the profile of a renal progenitor population, expression profiling of the 10.5 d postcoitus mouse MM versus adjacent IM was performed (44). This identified the specific expression of transmembrane proteins such as CD24a and cadherin11 that differentially marked the MM at that time point.…”

Kidney Side Population Reveals Multilineage Potential and Renal Functional Capacity but also Cellular Heterogeneity

“…Stem cell biology in general but particularly in solid tissues suffers from the lack of specific cell surface markers that unambiguously label all stem cells and/or only stem cells. Bioinformatics was applied to the gene lists of interest to identify genes that encode transmembrane proteins, as described previously (17). The subset of cell surface markers that were enriched in kidney SP cells compared with total kidney is shown in Table 1.…”

“…Membrane organization classes for representative sequences of Affymetrix probes were bioinformatically predicted as described previously (17). All primary microarray data and supplementary tables are available at http:// kidney.scgap.org/files (username: reviewer, password: 4321).…”

Definition and spatial annotation of the dynamic secretome during early kidney development

“…Microarray data was analysed as previously described (Challen et al, 2004). Briefly, microarray data was uploaded into BioArray Software Environment (BASE) 1.2.10 (Saal et al, 2002) and analysed with R statistical software using the LIMMA package (http://bioinf.wehi.edu.au/limma/) with scripts developed by Ola Spjuth of the Linnaeus Centre for Bioinformatics (http://www.lcb.uu.se/baseplugins.…”

“…To predict the membrane organisation of elements in the set examined, the RIKEN RTPS6.3 set was annotated with a prediction of secretory status and membrane organisation using a protocol modified from that described by Kanapin et al (2003), as described previously (Challen et al, 2004). In brief, proteins were classified as belonging to one of six types based on the presence or absence of endoplasmic reticulum signal peptides (SP) and alpha-helical transmembrane domains (TMD).…”