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Stem cells integrate inputs from multiple sources. Stem cell niches provide signals that promote stem cell maintenance, while differentiated daughter cells are known to provide feedback signals to regulate stem cell replication and differentiation. Recently, stem cells have been shown to regulate themselves using an autocrine mechanism. The existence of a 'stem cell niche' was first postulated by Schofield in 1978 to define local environments necessary for the maintenance of haematopoietic stem cells. Since then, an increasing body of work has focused on defining stem cell niches. Yet little is known about how progenitor cell and differentiated cell numbers and proportions are maintained. In the airway epithelium, basal cells function as stem/progenitor cells that can both self-renew and produce differentiated secretory cells and ciliated cells. Secretory cells also act as transit-amplifying cells that eventually differentiate into post-mitotic ciliated cells . Here we describe a mode of cell regulation in which adult mammalian stem/progenitor cells relay a forward signal to their own progeny. Surprisingly, this forward signal is shown to be necessary for daughter cell maintenance. Using a combination of cell ablation, lineage tracing and signalling pathway modulation, we show that airway basal stem/progenitor cells continuously supply a Notch ligand to their daughter secretory cells. Without these forward signals, the secretory progenitor cell pool fails to be maintained and secretory cells execute a terminal differentiation program and convert into ciliated cells. Thus, a parent stem/progenitor cell can serve as a functional daughter cell niche. [ABSTRACT FROM AUTHOR]

Despite the relatively simplified organization of the olfactory epithelium (OE), our understanding of the factors that regulate its cellular diversity is limited. Genetic and localization studies suggest that Notch signaling may be important in this process. We characterize here a population of Notch1 + olfactory basal cells in embryonic mice that coordinately express both the Notch effector Hes5 and the glycosyltransferase Lfng. These cells are distinct from Mash1 + neuronal precursors, but give rise to sensory neurons, suggesting that Notch1 signals may in part function to maintain a neurogenic progenitor pool. Furthermore, Lfng + cells also generate a population of cells in the migratory mass that appear to be ensheathing glial precursors, indicating potential multipotency in these progenitors. The Notch ligand Dll4 is expressed by basal OE cells that are interspersed with Notch1 + progenitors during later OE neurogenesis. In contrast, mice deficient in Dll1 exhibit a smaller OE and a loss of Hes5 expression, indicating an earlier function in olfactory progenitor cell development. Taken together, these results further support a role for Notch signaling in the regulation of olfactory neurogenesis and cell diversity. [ABSTRACT FROM AUTHOR]

Presents research which showed that mice homozygous for a targeted mutation of the lunatic fringe (Lfng) gene have defects in somite formation and anterior-posterior patterning of the somites. Development of segmentation in vertebrates; Role of the Notch signaling pathway; Fringe gene in Drosophila; Irregularities of somites; Results of marker analysis; Importance of Lfng encoding.

The article discusses a study conducted by P. Bi and colleagues on the multiple roles played by Notch signalling in the regulation of adipose browning and energy homeostasis in mammals. It mentions the deletion of gene encoding the Notch 1 receptor or the gene encoding the Notch signaling pathway primary transcriptional effector by the authors to assess the direct relationship between Notch signaling levels and brown adipose tissue (BAT).

The article presents a discovery of the new role of Notch pathway in vascular biology. An over view of the papers published in the journal on vascular endothelial growth factor (VEGF) and Notch signaling pathways and role for Dll 4 Notch signaling during vascular development, is presented. The new findings are supposed to help a better understanding of cancer and in the treatment of it.

The authors focus on the laser surgery on mice which are subjected to genetic testing. In order to accelerate phenotype analysis, mutant mice from embryonic stem cells are being generated. The eight cell microinjection procedure in two approaches is being suggested for production of homozygotes. The authors conclude that the need for cost effectiveness for breeding, phenotyping and maintaining the mice will be met by laser surgery.

Offers background and analysis of a paper that provides important data linking the Notch signalling pathway to familial causes of stroke in humans. The familial syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL); The study by Tournier-Lasserve and colleagues found in the October 24, 1996 issue of `Nature'; The possible relationship to Alzheimer's disease.