Neural stem/progenitor cell (NSPC) multipotency is highly regulated so that specific neural networks form during development. NSPCs cannot respond to gliogenic signals without acquiring gliogenic competence and decreasing their neurogenic competence as development proceeds. Coup-tfI and Coup-tfII are triggers of these temporal NSPC competence changes. However, the downstream effectors of Coup-tfs that mediate the neurogenic-togliogenic competence transition remain unknown. Here, we identified the microRNA-17/106 (miR-17/106)-p38 axis as a critical regulator of this transition. Overexpression of miR-17 inhibited the acquisition of gliogenic competence and forced stage-progressed NSPCs to regain neurogenic competence without altering the methylation status of a glial gene promoter. We also identified Mapk14 (also known as p38) as a target of miR-17/106 and found that Mapk14 inhibition restored neurogenic competence after the neurogenic phase. These results demonstrate that the miR-17/106-p38 axis is a key regulator of the neurogenic-to-gliogenic NSPC competence transition and that manipulation of this axis permits bidirectional control of NSPC multipotency.reatments of central nervous system (CNS) injury and diseases have become more promising with advances in modern medicine. Recent progress in stem cell biology has drawn attention to stem cells as innovative resources for transplantation therapies and individualized drug screenings (1, 2). Multipotent neural stem/progenitor cells (NSPCs) that give rise to all types of neural cells can now be readily obtained from induced pluripotent stem cells. However, specific and efficient induction of homogeneous target cell populations from NSPCs remains difficult because of the complex mechanisms that regulate NSPC development and differentiation. Therefore, further elucidation of how specific cell types can be generated from NSPCs is required to facilitate therapeutic applications.We recently used a newly developed embryonic stem cell (ESC)-derived neurosphere culture system to investigate the molecular mechanisms that govern NSPC differentiation (3). Although NSPCs are multipotent, and are thus able to differentiate into neurons and glial cells, neurogenesis largely precedes gliogenesis during CNS development in vertebrates. The neurogenesis-to-gliogenesis switch requires temporal identity transitions of NSPCs (4). Importantly, our neurosphere culture system recapitulates neural development in vivo. Using this system, we found that Coup-tfI and Coup-tfII (also known as Nr2f1 and Nr2f2, respectively) are critical molecular switches in the temporal identity transition of NSPCs (3). Remarkably, Coup-tfs do not repress neurogenesis or promote gliogenesis but, instead, change the competence of NSPCs. Although Coup-tfs permit alterations by changing the responsiveness of NSPCs to extrinsic gliogenic signals, the critical regulators and/or drivers of this process remain largely unknown. The aim of this study was to determine the molecular machinery underlying the neurogenicto-g...

If M is a (separable) von Neumann algebra and A is a Cartan subalgebra of M, then M is determined by an equivalence relation and a 2-cocycle. By constructing an equivalence subrelation, we show that for any intermediate von Neumann subalgebra N between M and A, there exists a faithful normal conditional expectation from M onto N.

It is shown that for the inclusion of factors (B ⊆ A) := (W * (S, ω) ⊆ W * (R, ω)) corresponding to an inclusion of ergodic discrete measured equivalence relations S ⊆ R, S is normal in R in the sense of Feldman-Sutherland-Zimmer [J. Feldman, C.E. Sutherland, R.J. Zimmer, Subrelations of ergodic equivalence relations, Ergodic Theory Dynam. Systems 9 (1989) 239-269] if and only if A is generated by the normalizing groupoid of B. Moreover, we show that there exists the largest intermediate equivalence subrelation N R (S) which contains S as a normal subrelation. We further give a definition of "commensurability groupoid" as a generalization of normality. We show that the commensurability groupoid of B in A generates A if and only if the inclusion B ⊆ A is discrete in the sense of Izumi-Longo-Popa [M. Izumi, R. Longo, S. Popa, A Galois correspondence for compact groups of automorphisms of von Neumann algebras with a generalization to Kac algebras, J. Funct. Anal. 155 (1998) 25-63]. We also show that there exists the largest equivalence subrelation Comm R (S) such that the inclusion B ⊆ W * (Comm R (S), ω) is discrete. It turns out that the intermediate equivalence subrelations N R (S) and Comm R (S) ⊆ R thus defined can be viewed as groupoid-theoretic counterparts of a normalizer subgroup and a commensurability subgroup in group theory.

Abstract. It is shown that, for the von Neumann algebra A obtained from a principal measured groupoid R with the diagonal subalgebra D of A, there exists a natural 'bijective' correspondence between coactions on A that fix D pointwise and Borel 1-cocycles on R.As an application of this result, we classify a certain type of coactions on approximately finite-dimensional type II factors up to cocycle conjugacy. By using our characterization of coactions mentioned above, we are also able to generalize to some extent those results of Zimmer concerning 1-cocycles on ergodic equivalence relations into compact groups. IntroductionFor each action α of a locally compact quantum group G = (M, ) on a von Neumann algebra A, we obtain an inclusion of A and the fixed-point algebra A α . The Galois theory for α means the natural correspondence between the intermediate subalgebras of (A α ⊆ A) and the left coideals of G. It is known that there exists a bijective Galois correspondence when G is a compact Kac algebra and the action α on a factor A is minimal, i.e. the relative commutant (A α ) ∩ A is trivial [17]. In particular, if α is a minimal action of an ordinary compact group K, then there exists a bijective correspondence between the set of intermediate subalgebras of (A α ⊆ A) and the set of closed subgroups of K (we note that the minimality of α implies that all the intermediate subalgebras of (A α ⊆ A) are factors). Motivated by this work, many results concerning minimal actions have been obtained [6,29,36]. However, there seems to be little hope that the arguments made in those results go beyond the case of minimal actions.

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