BackgroundWe previously reported the in vitro spontaneous transformation of human mesenchymal stem cells (MSC) generating a population with tumorigenic potential, that we termed transformed mesenchymal cells (TMC).Methodology/Principal FindingsHere we have characterized the molecular changes associated with TMC generation. Using microarrays techniques we identified a set of altered pathways and a greater number of downregulated than upregulated genes during MSC transformation, in part due to the expression of many untranslated RNAs in MSC. Microarray results were validated by qRT-PCR and protein detection.Conclusions/SignificanceIn our model, the transformation process takes place through two sequential steps; first MSC bypass senescence by upregulating c-myc and repressing p16 levels. The cells then bypass cell crisis with acquisition of telomerase activity, Ink4a/Arf locus deletion and Rb hyperphosphorylation. Other transformation-associated changes include modulation of mitochondrial metabolism, DNA damage-repair proteins and cell cycle regulators. In this work we have characterized the molecular mechanisms implicated in TMC generation and we propose a two-stage model by which a human MSC becomes a tumor cell.

Global gene expression profiles are a highly sensitive method to measure the toxicity degree of a gene delivery vehicle. The strong repression of IL17F, IL23R and IL23A, all of which are involved in autoimmune disease, by this particular dendrimer suggests a potential pharmacological application.

We identified a new member of the phosducin-like (PhLP) protein family that is predominantly, if not exclusively, expressed in male and female germ cells. In situ analysis on testis sections and analysis of purified spermatogenic cell fractions evidenced a stage-specific expression with high levels of RNA and protein in pachytene spermatocytes and round spermatids. Three mRNA species were detected, which correspond to different polyadenylation sites and vary in abundance during germ cell maturation. Only low levels of RNA were detected in whole ovary extracts, but expression of the protein became detectable within hours after hormonal induction of superovulation. The gene (Mgcphlp) is located on mouse chromosome 5 in the immediate vicinity of the Clock locus. The predicted amino acid sequence shows extensive similarities not only with the known mammalian PhLP proteins but also with the yeast phosducin-like protein Plp2, required for the production and growth of haploid cells. Expression of the murine protein was found to complement the defect of a yeast plp2⌬ mutant. We propose that MgcPhLP/Plp2 proteins exert a function in germ cell maturation that is conserved from yeast to mammals.Phosducin, a protein highly expressed in the retina and pineal gland, has been considered as playing a role in retinal phototransduction by interacting with the ␤␥ subunits of G proteins and thereby modulating their signaling functions (1). A partially similar, widely expressed phosducin-like protein (PhLP) 1 has been identified, which also inhibits G␤␥ function (2, 3). Two related genes identified in the yeast Saccharomyces cerevisiae were designated PLP1 and PLP2 (4). The Plp1 protein was shown to bind efficiently the G␤␥ subunits. Binding of Plp2 was also evidenced but with a lesser affinity. On the other hand, genetic analysis evidenced the role of Plp2 in the generation of viable haploid cells.The mammalian phosducin and phosducin-like proteins are expressed ubiquitously (5). Whether tissue-specific homologues exist remains an open question. In the course of screening a mouse testis cDNA library, we have identified a novel germ cell-specific phosducin-like protein, designated MgcPhLP (for "mouse germ cell-specific phosducin-like protein"), which exhibits significant similarities to both the mouse phosducin and phosducin-like proteins. Expression is strictly restricted to the male and female germ cells in a regulated manner depending on the stage of germ cell maturation. The murine gene complemented the defect of a yeast plp2⌬ mutant, suggesting an evolutionarily conserved function in meiotic and/or post-meiotic cells. EXPERIMENTAL PROCEDURESMice-Mice used in all experiments were C57BL/6 ϫ DBA/2 F1. Eggs were collected from either naturally ovulated females or after hormonal induction of superovulation according to standard procedures (6).Cell Cultures and Preparation of Germ Cells-Cultures of the 15P-1-established Sertoli cell line and primary Sertoli cell cultures, preparation of total germ cells, and fractionation by elutriat...

Genome-wide association studies have successfully identified 20 colorectal cancer susceptibility loci. Amongst these, four of the signals are defined by tagging single nucleotide polymorphisms (SNPs) on regions 14q22.2 (rs4444235 and rs1957636) and 20p12.3 (rs961253 and rs4813802). These markers are located close to two of the genes involved in bone morphogenetic protein (BMP) signaling (BMP4 and BMP2, respectively). By investigating these four SNPs in an initial cohort of Spanish origin, we found substantial evidence that minor allele frequencies (MAFs) may be different in northern and southern European populations. Therefore, we genotyped three additional southern European cohorts comprising a total of 2028 cases and 4273 controls. The meta-analysis results show that only one of the association signals (rs961253) is effectively replicated in the southern European populations, despite adequate power to detect all four. The other three SNPs (rs4444235, rs1957636 and rs4813802) presented discordant results in MAFs and linkage disequilibrium patterns between northern and southern European cohorts. We hypothesize that this lack of replication could be the result of differential tagging of the functional variant in both sets of populations. Were this true, it would have complex consequences in both our ability to understand the nature of the real causative variants, as well as for further study designs.

In mouse Sertoli cells, transcription of the