Cooperation between p27 and p107 during endochondral ossification suggests a genetic pathway controlled by p27 and p130.

Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
Molecular and Cellular Biology (Impact Factor: 5.04). 08/2007; 27(14):5161-71. DOI: 10.1128/MCB.02431-06
Source: PubMed

ABSTRACT Pocket proteins and cyclin-dependent kinase (CDK) inhibitors negatively regulate cell proliferation and can promote differentiation. However, which members of these gene families, which cell type they interact in, and what they do to promote differentiation in that cell type during mouse development are largely unknown. To identify the cell types in which p107 and p27 interact, we generated compound mutant mice. These mice were null for p107 and had a deletion in p27 that prevented its binding to cyclin-CDK complexes. Although a fraction of these animals survived into adulthood and looked similar to single p27 mutant mice, a larger number of animals died at birth or within a few weeks thereafter. These animals displayed defects in chondrocyte maturation and endochondral bone formation. Proliferation of chondrocytes was increased, and ectopic ossification was observed. Uncommitted mouse embryo fibroblasts could be induced into the chondrocytic lineage ex vivo, but these cells failed to mature normally. These results demonstrate that p27 carries out overlapping functions with p107 in controlling cell cycle exit during chondrocyte maturation. The phenotypic similarities between p107(-/-) p27(D51/D51) and p107(-/-) p130(-/-) mice and the cells derived from them suggest that p27 and p130 act in an analogous pathway during chondrocyte maturation.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Upconversion nanoparticles (UCNPs) have been proposed as a promising new class of biological luminescent labels because of their weak auto-fluorescence background, strong penetration ability under near-infrared (NIR) radiation, resistance to photobleaching, and low toxicity. Although UCNPs hold great promise in nanotechnology and nanomedicine, their applications in ECL fields still remain unexplored. Herein, a label-free, ultra-sensitive and selective electrochemiluminescence (ECL) assay is developed for detection of cyclin A2 by using highly efficient ECL graphene-upconversion hybrid. Being an important member of the cyclin family, cyclin A2 is involved in the initiation of DNA replication, transcription and cell cycle reg-ulation through the association of cyclin-dependent kinases (CDK). Cyclin A2 is a prognostic indicator in early-stage cancers and a target for treatment of different types of cancers. However, the expression level of cyclin A2 is quite low, direct detection of cyclin A2 in crude cancer cell extracts is challenging and important for both clinical diagnosis of cancer in the early stage and the treatment. By chemically grafting cyclin A2 detection specific probe, a PEGlyted hexapeptide, to graphene-upconversion hybrid, the constructed ECL biosensor displays a superior performance for cyclin A2 , which can not only detect cyclin A2 directly in cancer cell extracts, but also discriminate between normal cells and cancer cells. More importantly, the ECL biosensor has different responses between clinical used anticancer drug-treated and non-treated cancer cells, which demonstrates that the sensor can be potentially used for drug screening, and for evaluation of therapeutic treatments in early-stage cancers.
    Small 01/2014; 10(2). DOI:10.1002/smll.201301273 · 7.51 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent evidence suggests that tissue accumulation of senescent p16INK4a positive cells during lifespan would be deleterious for tissue functions and could be the consequence of the inherent age-associated disorders. Osteoarthritis (OA) is characterized by the accumulation of chondrocytes expressing p16INK4a and markers of the senescence-associated secretory phenotype (SASP) including the matrix remodelling metallo-proteases MMP1/MMP13 and pro-inflammatory cytokines IL-8, IL-6. Here we evaluated the role of p16INK4a in the OA-induced SASP and its regulation by microRNAs (miRs). We used IL-1beta-treated primary OA chondrocytes cultured in 3D or mesenchymal stem cells (MSC) differentiated into chondrocyte to follow p16INK4a expression. By transient transfection experiments and the use of knock out mice we validate p16INK4a function in chondrocytes and its regulation by one miR identified by means of a genome wide miR-arrays analysis. p16INK4a is induced upon IL-1beta treatment and also during in vitro chondrogenesis. In mouse model, Ink4a locus favors in vivo the proportion of terminally differentiated chondrocytes. When overexpressed in chondrocytes, p16INK4a is sufficient to induce the production of the two matrix remodelling enzymes, MMP1 and MMP13, thus linking senescence with OA pathogenesis and bone development. We identified miR-24, as a negative regulator of p16INK4a. Accordingly, p16INK4a expression increased while miR-24 level was repressed upon IL-1beta addition, in OA cartilage and during in vitro terminal chondrogenesis. We disclosed herein a new role of the senescence marker p16INK4a and its regulation by miR-24 during OA and terminal chondrogenesis.
    Arthritis research & therapy 02/2014; 16(1):R58. DOI:10.1186/ar4494 · 4.12 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The retinoblastoma protein family is intimately involved in the regulation of tissue specific gene expression during mesenchymal stem cell differentiation. The role of the following proteins, pRB, p107 and p130, is particularly significant in differentiation to the osteoblast lineage, as human germ-line mutations of RB1 greatly increase susceptibility to osteosarcoma. During differentiation, pRB directly targets certain osteogenic genes for activation, including the alkaline phosphatase-encoding gene Alpl. Chromatin immunoprecipitation (ChIP) assays indicate that Alpl is targeted by p107 in differentiating osteoblasts selectively during activation with the same dynamics as pRB, which suggests that p107 helps promote Alpl activation. Mouse models indicate overlapping roles for pRB and p107 in bone and cartilage formation, but very little is known about direct tissue-specific gene targets of p107, or the consequences of targeting by p107. Here, the roles of p107 and pRB were compared using shRNA-mediated knockdown genetics in an osteoblast progenitor model, MC3T3-E1 cells. The results show that p107 has a distinct role along with pRB in induction of Alpl. Deficiency of p107 does not impede recruitment of transcription factors recognized as pRB co-activation partners at the promoter; however, p107 is required for the efficient recruitment of an activating SWI/SNF chromatin-remodeling complex, an essential event in Alpl induction.
    Bone 08/2014; 69. DOI:10.1016/j.bone.2014.08.009 · 4.46 Impact Factor


Available from
Jun 4, 2014