Project description:The CDK inhibitor p27Kip1 is a critical regulator of cell cycle progression, but the mechanisms by which p27Kip1 controls cell proliferation in vivo are still not fully elucidated. We recently demonstrated that the microtubule destabilizing protein stathmin is a relevant p27Kip1binding partner involved in the regulation of cell motility. To get more insights into the in vivo significance of this interaction, we generated p27Kip1 and stathmin double knock out (DKO) mice. Interestingly, thorough characterization of DKO mice demonstrated that most of the phenotypes of p27Kip1 null mice linked to the hyperproliferative behavior, such as the increased body and organ weights, the outgrowth of the retina basal layer and the development of pituitary adenomas, were reverted by co-ablation of stathmin. In vivo analyses showed a reduced proliferation rate in DKO compared to p27kip1 null mice, linked, at molecular level, to decreased kinase activity of CDK4/6, rather than of CDK1 and CDK2. Gene expression profile analyses of mouse thymuses confirmed the phenotypes observed in vivo, demonstrating that DKO clustered with WT and not with p27KO thymuses. Taken together, the results demonstrate that stathmin cooperates with p27Kip1 to control the early phase of G1 to S phase transition and strongly suggest that this function has particular relevance in the contest of tumor progression. Four-conditions experiment (four different mouse genotypes), 6 biological replicates of wild type mouse thymus, 6 biological replicates of p27 knock-out mouse thymus, 6 biological replicates of stathmin knock-out mouse thymus, 6 biological replicates of double knock-out (p27 and stathmin) mouse thymus. Reference design: pool of RNAs derived from mouse fibroblasts of all the genotypes.Reference design;
Project description:The CDK inhibitor p27Kip1 is a critical regulator of cell cycle progression, but the mechanisms by which p27Kip1 controls cell proliferation in vivo are still not fully elucidated. We recently demonstrated that the microtubule destabilizing protein stathmin is a relevant p27Kip1binding partner involved in the regulation of cell motility. To get more insights into the in vivo significance of this interaction, we generated p27Kip1 and stathmin double knock out (DKO) mice. Interestingly, thorough characterization of DKO mice demonstrated that most of the phenotypes of p27Kip1 null mice linked to the hyperproliferative behavior, such as the increased body and organ weights, the outgrowth of the retina basal layer and the development of pituitary adenomas, were reverted by co-ablation of stathmin. In vivo analyses showed a reduced proliferation rate in DKO compared to p27kip1 null mice, linked, at molecular level, to decreased kinase activity of CDK4/6, rather than of CDK1 and CDK2. Gene expression profile analyses of mouse thymuses confirmed the phenotypes observed in vivo, demonstrating that DKO clustered with WT and not with p27KO thymuses. Taken together, the results demonstrate that stathmin cooperates with p27Kip1 to control the early phase of G1 to S phase transition and strongly suggest that this function has particular relevance in the contest of tumor progression.
Project description:The integrated regulation of different intracellular signaling pathways is fundamental to ensure appropriate timing of cell division and, more in general, proper development of any living organism. Adopted mechanisms include the instauration of feedback regulations and/or to rely on a single molecule for the control of multiple processes. We now present evidences that in mammalian cells the CDK inhibitor p27kip1, by a CDK-independent and stathmin-dependent mechanism, is implicated in the control of the MAPK pathway, eventually influencing cell proliferation in vitro and mice growth in vivo. This p27kip1 activity regulates H-Ras driven transformation in mice and controls tumor progression in humans. Altogether, our work unveils a new mechanism that in mammalian cells contributes to proper regulation of cell proliferation and whose alteration may contribute to tumor onset and/or progression.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility.
Project description:To characterize the genetic basis of hybrid male sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven ‘hotspots,’ seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL - but not cis eQTL - were substantially lower when mapping was restricted to a ‘fertile’ subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility.