The adult liver progenitor cells appear in response to several types of pathological liver injury, especially when hepatocyte replication is blocked. These cells are histologically identified as cells that express cholangiocyte markers and proliferate in the portal area of the hepatic lobule. Although these cells play an important role in liver regeneration, the precise characterization that determines these cells as self-renewing bipotent primitive hepatic cells remains to be shown. Here we attempted to isolate cells that express a cholangiocyte marker from the adult mouse liver and perform single cell-based analysis to examine precisely bilineage differentiation potential and self-renewing capability of these cells. Based on the results of microarray analysis and immunohistochemistry, we used an antibody against CD133 and isolate CD133 ؉ cells via flow cytometry. We then cultured and propagated isolated cells in a single cell culture condition and examined their potential for proliferation and differentiation in vitro and in vivo. Isolated cells that could form large colonies (LCs) in culture gave rise to both hepatocytes and cholangiocytes as descendants, while maintaining undifferentiated cells by self-renewing cell divisions. The clonogenic progeny of an LCforming cell is capable of reconstituting hepatic tissues in vivo by differentiating into fully functional hepatocytes. Moreover, the deletion of p53 in isolated LC-forming cells resulted in the formation of tumors with some characteristics of hepatocellular carcinoma and cholangiocarcinoma upon subcutaneous injection into immunodeficient mutant mice. These data provide evidence for the stem cell-like capacity of isolated and clonally cultured CD133 ؉ LC-forming cells. Conclusion: Our method for prospectively isolating hepatic progenitor cells from the adult mouse liver will facilitate study of their roles in liver regeneration and carcinogenesis. (HEPATOLOGY 2008;48

Axonal maturation and myelination are essential processes for establishing an efficient neuronal signaling network. We found that nardilysin (N-arginine dibasic convertase, also known as Nrd1 and NRDc), a metalloendopeptidase enhancer of protein ectodomain shedding, is a critical regulator of these processes. Nrd1-/- mice had smaller brains and a thin cerebral cortex, in which there were less myelinated fibers with thinner myelin sheaths and smaller axon diameters. We also found hypomyelination in the peripheral nervous system (PNS) of Nrd1-/- mice. Neuron-specific overexpression of NRDc induced hypermyelination, indicating that the level of neuronal NRDc regulates myelin thickness. Consistent with these findings, Nrd1-/- mice had impaired motor activities and cognitive deficits. Furthermore, NRDc enhanced ectodomain shedding of neuregulin1 (NRG1), which is a master regulator of myelination in the PNS. On the basis of these data, we propose that NRDc regulates axonal maturation and myelination in the CNS and PNS, in part, through the modulation of NRG1 shedding.

The kidney develops through reciprocal interactions between two precursor tissues: the metanephric mesenchyme and the ureteric bud. We previously demonstrated that the zinc finger protein Sall1 is essential for ureteric bud attraction toward the mesenchyme. Here, we show that Kif26b, a kinesin family gene, is a downstream target of Sall1 and that disruption of this gene causes kidney agenesis because of impaired ureteric bud attraction. In the Kif26b-null metanephros, compact adhesion between mesenchymal cells adjacent to the ureteric buds and the polarized distribution of integrin α8 were impaired, resulting in failed maintenance of Gdnf, a critical ureteric bud attractant. Overexpression of Kif26b in vitro caused increased cell adhesion through interactions with nonmuscle myosin. Thus, Kif26b is essential for kidney development because it regulates the adhesion of mesenchymal cells in contact with ureteric buds.kinesin | Gdnf | kidney development | metanephric mesenchyme | Sall1

a b s t r a c tGlis3 is a member of the Gli-similar subfamily. GLIS3 mutations in humans lead to neonatal diabetes, hypothyroidism, and cystic kidney disease. We generated Glis3-deficient mice by gene-targeting. The Glis3 À/À mice had significant increases in the basal blood sugar level during the first few days after birth. The high levels of blood sugar are attributed to a decrease in the Insulin mRNA level in the pancreas that is caused by impaired islet development and the subsequent impairment of Insulinproducing cell formation. The pancreatic phenotypes indicate that the Glis3-deficient mice are a model for GLIS3 mutation and diabetes mellitus in humans.

BackgroundDevelopmental angiogenesis proceeds through multiple morphogenetic events including sprouting, intussusception, and pruning. Mice lacking the membrane-anchored metalloproteinase regulator Reck die in utero around embryonic day 10.5 with halted vascular development; however, the mechanisms by which this phenotype arises remain unclear.ResultsWe found that Reck is abundantly expressed in the cells associated with blood vessels undergoing angiogenesis or remodelling in the uteri of pregnant female mice. Some of the Reck-positive vessels show morphological features consistent with non-sprouting angiogenesis. Treatment with a vector expressing a small hairpin RNA against Reck severely disrupts the formation of blood vessels with a compact, round lumen. Similar defects were found in the vasculature of Reck-deficient or Reck conditional knockout embryos.ConclusionsOur findings implicate Reck in vascular remodeling, possibly through non-sprouting angiogenesis, in both maternal and embyornic tissues.