Archives

  • 2018-07
  • 2018-10
  • 2018-11
  • 2019-04
  • 2019-05
  • 2019-06
  • 2019-07
  • 2019-08
  • 2019-09
  • 2019-10
  • 2019-11
  • 2019-12
  • 2020-01
  • 2020-02
  • 2020-03
  • 2020-04
  • 2020-05
  • 2020-06
  • 2020-07
  • 2020-08
  • 2020-09
  • 2020-10
  • 2020-11
  • 2020-12
  • 2021-01
  • 2021-02
  • 2021-03
  • 2021-04
  • 2021-05
  • 2021-06
  • 2021-07
  • 2021-08
  • 2021-09
  • 2021-10
  • 2021-11
  • 2021-12
  • 2022-01
  • 2022-02
  • 2022-03
  • 2022-04
  • 2022-05
  • 2022-06
  • 2022-07
  • 2022-08
  • 2022-09
  • 2022-10
  • 2022-11
  • 2022-12
  • 2023-01
  • 2023-02
  • 2023-03
  • 2023-04
  • 2023-05
  • 2023-06
  • 2023-07
  • 2023-08
  • 2023-09
  • 2023-10
  • 2023-11
  • 2023-12
  • 2024-01
  • 2024-02
  • 2024-03
  • 2024-04

    • In summary our findings indicated

    2018-11-02

    In summary, our findings indicated that miR-375 promoted the osteogenic differentiation of hASCs both in vitro and in vivo, and miR-375 targeted DEPTOR to inhibit the activity of AKT signaling during this process. Furthermore, YAP1 together with miR-375 established a negative feedback loop to regulate osteogenesis. These findings suggest that miR-375 can be targeted to enhance bone formation and the feasibility of miRNA-targeted therapeutic approaches in bone tissue engineering.
    Experimental Procedures
    Author Contributions
    Acknowledgments This study was financially supported by grants from the National Natural Science Foundation of China (81371118, 81402235), the Culturing Program for Leading Talents in Beijing Science and Technology Innovation (Lj201725), the Ph.D. Programs Foundation of Ministry of Education of China (20130001110101), and the foundation of the Peking University School and Hospital of Stomatology (PKUSS20140104).
    Introduction Forced expression of OCT4, SOX2, KLF4, and c-MYC or other combinations of reprogramming factors reprogram somatic nadph oxidase inhibitor into induced pluripotent stem cells (iPSCs), which attract much attention for their potential applications in regenerative medicine and drug development, as well as for understanding how cells specify their fate during reprogramming and normal development (Stadtfeld and Hochedlinger, 2010; Takahashi and Yamanaka, 2016). Cells that undergo reprogramming progress through distinct stages, which can be distinguished by the expression of THY1, alkaline phosphatase (AP), and SSEA1 (Polo et al., 2012), initially losing somatic cell characteristics before acquiring full pluripotency. Reprogramming factors, in general, are transcription factors that alter gene expression and epigenetic status, which ultimately specify the cell fate (Theunissen and Jaenisch, 2014). Therefore, genome-wide analyses of gene expression and epigenetic status provide comprehensive views on the mechanism of reprogramming. In addition to alterations in gene expression and epigenetic status, cells undergo metabolic changes during reprogramming (Folmes et al., 2011; Samavarchi-Tehrani et al., 2010). Embryonic stem cells (ESCs), which originally comprise the inner cell mass, reside in the low-oxygen environment (Fischer and Bavister, 1993) and have few small mitochondria (Cho et al., 2006; St John et al., 2005), utilizing glycolysis as a main source of ATP production (Xu et al., 2013). By contrast, differentiated somatic cells largely depend on oxidative phosphorylation in mitochondria for efficient ATP production (DeBerardinis et al., 2008). Thus, somatic cell reprogramming by necessity entails a metabolic shift from oxidative phosphorylation to glycolysis, which has been corroborated by recent studies (Folmes et al., 2011; Prigione et al., 2010). Indeed, deliberate acceleration of glycolysis or inhibition of oxidative phosphorylation increases the reprogramming efficiency (Prigione et al., 2014). Furthermore, enhanced glycolysis produces higher amounts of metabolic intermediates that are used as cofactors by chromatin-modifying enzymes (Moussaieff et al., 2015). Thus, the metabolic shift and epigenetic regulation, both initiated by the reprogramming factors, are likely to concur during the reprogramming process. However, the molecular mechanisms by which the reprogramming factors initiate and execute the metabolic shift remains less well known. We developed a unique gene transfer system termed SeVdp (Sendai virus defective and persistent) vector, which stably expresses multiple genes from a single vector with a relatively constant stoichiometry without integrating into the host cell genome (Nishimura et al., 2011). An SeVdp-based vector, SeVdp(KOSM), which harbors the four Yamanaka factors, generates iPSCs efficiently from various sources of somatic cells (Kyttala et al., 2016; Matsumoto et al., 2016). Modifying SeVdp(KOSM), we devised SeVdp(fK-OSM) that expresses KLF4 tagged with a destabilizing domain (DD) (Banaszynski et al., 2006), the expression level of which can be manipulated by a small molecule, Shield1. In the SeVdp(fK-OSM)-infected cells, the KLF4 level, reduced to ∼30% by the DD, is readily restored to its original level by the addition of 100 nM Shield1. Reprogramming with SeVdp(fK-OSM) at a defined KLF4 level generates partially reprogrammed iPSCs, termed paused iPSCs, which have stalled at a specific intermediate stage but nonetheless resume reprogramming toward full pluripotency once the KLF4 level is restored by increased Shield1 (Nishimura et al., 2014). Because the SeVdp(fK-OSM)-based system, named the SeVdp-based stage-specific reprogramming system (3S reprogramming system), allows reprogramming to progress strictly in a KLF4-dependent manner, the system enables us to analyze the role for KLF4 in a gene regulatory network, which may occur only transiently during the complex process of reprogramming.