Foxp and Skor family proteins control differentiation of Purkinje cells from Ptf1a- and Neurog1-expressing progenitors in zebrafish.

Cerebellar neurons, such as GABAergic Purkinje cells (PCs), interneurons (INs) and glutamatergic granule cells (GCs) are differentiated from neural progenitors expressing proneural genes, including ptf1a, neurog1 and atoh1a/b/c. Studies in mammals previously suggested that these genes determine cerebellar neuron cell fate. However, our studies on ptf1a;neurog1 zebrafish mutants and lineage tracing of ptf1a-expressing progenitors have revealed that the ptf1a/neurog1-expressing progenitors can generate diverse cerebellar neurons, including PCs, INs and a subset of GCs in zebrafish. The precise mechanisms of how each cerebellar neuron type is specified remains elusive. We found that genes encoding the transcriptional regulators Foxp1b, Foxp4, Skor1b and Skor2, which are reportedly expressed in PCs, were absent in ptf1a;neurog1 mutants. foxp1b;foxp4 mutants showed a strong reduction in PCs, whereas skor1b;skor2 mutants completely lacked PCs, and displayed an increase in immature GCs. Misexpression of skor2 in GC progenitors expressing atoh1c suppressed GC fate. These data indicate that Foxp1b/4 and Skor1b/2 function as key transcriptional regulators in the initial step of PC differentiation from ptf1a/neurog1-expressing neural progenitors, and that Skor1b and Skor2 control PC differentiation by suppressing their differentiation into GCs.

Cut-off values of preoperative knee extensor strength and hip abductor strength for predicting good walking ability after total knee arthroplasty.

INTRODUCTION: Total knee arthroplasty (TKA) reduces pain and improves physical function; however, not all patients have successful outcomes after surgery. To identify these patients would be critical information for improving rehabilitation programs. The purpose of this study was to clarify the cut-off values of lower extremity muscle strength for predicting postoperative good walking ability. MATERIALS AND METHODS: Timed Up and Go test of 105 patients was measured at 6 months postoperatively, and participants were divided into good (< 9.1 s) and poor (≥ 9.1 s) walking ability. Both sides of knee extensor strength (KES) and hip abductor strength (HAS) were measured using hand-held dynamometer preoperatively. Receiver operating characteristic (ROC) curve analysis was used to identify cut-off values for classifying the participants into the two groups. RESULTS: Of the 105 patients, 54 were allocated in the poor walking ability group, whereas 51 were allocated in the good walking ability group. KES and HAS were significantly greater in the good walking ability group than in the poor walking ability group. ROC curve analysis revealed that the cut-off value for KES was 0.79 Nm/kg (area under the curve (AUC) 0.68; sensitivity 64.7%; specificity 68.5%) on the involved side and 0.86 Nm/kg (AUC 0.73; sensitivity 84.6%; specificity 55.6%) on the uninvolved side, and for HAS was 0.57 Nm/kg (AUC 0.71; sensitivity 60.8%; specificity 71.7%) on the involved side and 0.61 Nm/kg (AUC 0.76; sensitivity 66.7%; specificity 77.4%) on the uninvolved side. CONCLUSION: The cut-off values of preoperative KES and HAS for predicting good walking ability after TKA are 0.79 Nm/kg on the involved side and 0.86 Nm/kg on the uninvolved side, and 0.57 Nm/kg on the involved side and 0.61 Nm/kg on the uninvolved side, respectively. We should provide enhanced pre- and post-operative rehabilitation programs for patients with muscle strength lower than these values.

Cfdp1 controls the cell cycle and neural differentiation in the zebrafish cerebellum and retina.

BACKGROUND: Although the cell cycle and cell differentiation should be coordinately regulated to generate a variety of neurons in the brain, the molecules that are involved in this coordination still remain largely unknown. In this study, we analyzed the roles of a nuclear protein Cfdp1, which is thought to be involved in chromatin remodeling, in zebrafish neurogenesis. RESULTS: Zebrafish cfdp1 mutants maintained the progenitors of granule cells (GCs) in the cerebellum, but showed defects in their differentiation to GCs. cfdp1 mutants showed an increase in phospho-histone 3 (pH 3)-positive cells and apoptotic cells, as well as a delayed cell cycle transition from the G2 to the M phase in the cerebellum. The inhibition of tp53 prevented apoptosis but not GC differentiation in the cfdp1 mutant cerebellum. A similar increase in apoptotic cells and pH 3-positive cells, and defective cell differentiation, were observed in the cfdp1 mutant retina. Although mitotic spindles formed, mitosis was blocked before anaphase in both the cerebellum and retina of cfdp1 mutant larvae. Furthermore, expression of the G2/mitotic-specific cyclin B1 gene increased in the cfdp1 mutant cerebellum. CONCLUSIONS: Our findings suggest that Cfdp1 regulates the cell cycle of neural progenitors, thereby promoting neural differentiation in the brain.

Gsx2 is required for specification of neurons in the inferior olivary nuclei from Ptf1a-expressing neural progenitors in zebrafish.

Neurons in the inferior olivary nuclei (IO neurons) send climbing fibers to Purkinje cells to elicit functions of the cerebellum. IO neurons and Purkinje cells are derived from neural progenitors expressing the proneural gene ptf1a In this study, we found that the homeobox gene gsx2 was co-expressed with ptf1a in IO progenitors in zebrafish. Both gsx2 and ptf1a zebrafish mutants showed a strong reduction or loss of IO neurons. The expression of ptf1a was not affected in gsx2 mutants, and vice versa. In IO progenitors, the ptf1a mutation increased apoptosis whereas the gsx2 mutation did not, suggesting that ptf1a and gsx2 are regulated independently of each other and have distinct roles. The fibroblast growth factors (Fgf) 3 and 8a, and retinoic acid signals negatively and positively, respectively, regulated gsx2 expression and thereby the development of IO neurons. mafba and Hox genes are at least partly involved in the Fgf- and retinoic acid-dependent regulation of IO neuronal development. Our results indicate that gsx2 mediates the rostro-caudal positional signals to specify the identity of IO neurons from ptf1a-expressing neural progenitors.

Role of Reelin in cell positioning in the cerebellum and the cerebellum-like structure in zebrafish.

The cerebellum and the cerebellum-like structure in the mesencephalic tectum in zebrafish contain multiple cell types, including principal cells (i.e., Purkinje cells and type I neurons) and granule cells, that form neural circuits in which the principal cells receive and integrate inputs from granule cells and other neurons. It is largely unknown how these cells are positioned and how neural circuits form. While Reelin signaling is known to play an important role in cell positioning in the mammalian brain, its role in the formation of other vertebrate brains remains elusive. Here we found that zebrafish with mutations in Reelin or in the Reelin-signaling molecules Vldlr or Dab1a exhibited ectopic Purkinje cells, eurydendroid cells (projection neurons), and Bergmann glial cells in the cerebellum, and ectopic type I neurons in the tectum. The ectopic Purkinje cells and type I neurons received aberrant afferent fibers in these mutants. In wild-type zebrafish, reelin transcripts were detected in the internal granule cell layer, while Reelin protein was localized to the superficial layer of the cerebellum and the tectum. Laser ablation of the granule cell axons perturbed the localization of Reelin, and the mutation of both kif5aa and kif5ba, which encode major kinesin I components in the granule cells, disrupted the elongation of granule cell axons and the Reelin distribution. Our findings suggest that in zebrafish, (1) Reelin is transported from the granule cell soma to the superficial layer by axonal transport; (2) Reelin controls the migration of neurons and glial cells from the ventricular zone; and (3) Purkinje cells and type I neurons attract afferent axons during the formation of the cerebellum and the cerebellum-like structure.

Kinetically controlled Ferrier rearrangement of 3-O-mesyl-D-glycal derivatives.

The Ferrier rearrangement, which is widely used in carbohydrate chemistry, is generally performed under acidic conditions to give an alpha anomer with high stereoselectivity. We have found that 3-O-mesyl-D-glycals 2-4 were smoothly reacted with alcohols in the presence of triethylamine. The present reaction was shown to proceed under kinetic control to give approximately 1.3:1.0 mixture of alpha and beta anomers, indicating that a kinetic anomeric effect does not operate.