Showing papers by "Keisuke Okita published in 2018"

Low Cell-Matrix Adhesion Reveals Two Subtypes of Human Pluripotent Stem Cells

Abstract: We show that a human pluripotent stem cell (hPSC) population cultured on a low-adhesion substrate developed two hPSC subtypes with different colony morphologies: flat and domed. Notably, the dome-like cells showed higher active proliferation capacity and increased several pluripotent genes' expression compared with the flat monolayer cells. We further demonstrated that cell-matrix adhesion mediates the interaction between cell morphology and expression of KLF4 and KLF5 through a serum response factor (SRF)-based regulatory double loop. Our results provide a mechanistic view on the coupling among adhesion, stem cell morphology, and pluripotency, shedding light on the critical role of cell-matrix adhesion in the induction and maintenance of hPSC.

Srf destabilizes cellular identity by suppressing cell-type-specific gene expression programs

Abstract: Multicellular organisms consist of multiple cell types. The identity of these cells is primarily maintained by cell-type-specific gene expression programs; however, mechanisms that suppress these programs are poorly defined. Here we show that serum response factor (Srf), a transcription factor that is activated by various extracellular stimuli, can repress cell-type-specific genes and promote cellular reprogramming to pluripotency. Manipulations that decrease β-actin monomer quantity result in the nuclear accumulation of Mkl1 and the activation of Srf, which downregulate cell-type-specific genes and alter the epigenetics of regulatory regions and chromatin organization. Mice overexpressing Srf exhibit various pathologies including an ulcerative colitis-like symptom and a metaplasia-like phenotype in the pancreas. Our results demonstrate an unexpected function of Srf via a mechanism by which extracellular stimuli actively destabilize cell identity and suggest Srf involvement in a wide range of diseases.

Evaluation method and selection method for induced pluripotent stem cells, and production method for induced pluripotent stem cells

Abstract: The present invention provides: an evaluation method for induced pluripotent stem cells, the evaluation method including a step for supplying cultured induced pluripotent stem cells, a step for measuring the natural frequency of occurrence in the supplied induced pluripotent stem cells of organelles that have abnormal nucleic acid structures, and a step for identifying the induced pluripotent stem cells for which the natural frequency of occurrence is at or below a reference value and the induced pluripotent stem cells for which the natural frequency of occurrence is above the reference value; and a selection method for induced pluripotent stem cells, the selection method including a step for selecting the induced pluripotent stem cells for which the natural frequency of occurrence is at or below the reference value. The present invention also provides a production method for induced pluripotent stem cells, the production method including a step for supplying created and cultured induced pluripotent stem cells, a step for measuring the natural frequency of occurrence in the supplied induced pluripotent stem cells of organelles that have abnormal nucleic acid structures, a step for identifying the induced pluripotent stem cells for which the natural frequency of occurrence is at or below a reference value and the induced pluripotent stem cells for which the natural frequency of occurrence is above the reference value, and a step for selecting the induced pluripotent stem cells for which the natural frequency of occurrence is at or below the reference value.