Search results for "Asymmetric cell division"
showing 6 items of 6 documents
Increasing Neural Stem Cell Division Asymmetry and Quiescence Are Predicted to Contribute to the Age-Related Decline in Neurogenesis.
2018
Summary: Adult murine neural stem cells (NSCs) generate neurons in drastically declining numbers with age. How cellular dynamics sustain neurogenesis and how alterations with age may result in this decline are unresolved issues. We therefore clonally traced NSC lineages using confetti reporters in young and middle-aged adult mice. To understand the underlying mechanisms, we derived mathematical models that explain observed clonal cell type abundances. The best models consistently show self-renewal of transit-amplifying progenitors and rapid neuroblast cell cycle exit. In middle-aged mice, we identified an increased probability of asymmetric stem cell divisions at the expense of symmetric di…
Asymmetric cell division requires specific mechanisms for adjusting global transcription
2017
Most cells divide symmetrically into two approximately identical cells. There are many examples, however, of asymmetric cell division that can generate sibling cell size differences. Whereas physical asymmetric division mechanisms and cell fate consequences have been investigated, the specific problem caused by asymmetric division at the transcription level has not yet been addressed. In symmetrically dividing cells the nascent transcription rate increases in parallel to cell volume to compensate it by keeping the actualmRNA synthesis rate constant. This cannot apply to the yeast Saccharomyces cerevisiae, where this mechanism would provoke a neverending increasing mRNA synthesis rate in sma…
The p21-activated kinase Mbt is a component of the apical protein complex in central brain neuroblasts and controls cell proliferation
2013
The final size of the central nervous system is determined by precisely controlled generation, proliferation and death of neural stem cells. We show here that the Drosophila PAK protein Mushroom bodies tiny (Mbt) is expressed in central brain progenitor cells (neuroblasts) and becomes enriched to the apical cortex of neuroblasts in a cell cycle- and Cdc42-dependent manner. Using mushroom body neuroblasts as a model system, we demonstrate that in the absence of Mbt function, neuroblasts and their progeny are correctly specified and are able to generate different neuron subclasses as in the wild type, but are impaired in their proliferation activity throughout development. In general, loss of…
The Fate Choice Between Effector and Memory T Cell Lineages: Asymmetry, Signal Integration, and Feedback to Create Bistability
2018
Abstract CD8+ T cells clear primary infections with intracellular pathogens and provide long-term immunity against reinfection. Two different types of CD8+ T cells are responsible for these functions: short-lived effector T cells and memory T cells. The cellular relationship between these two types of CD8+ T cells has been subject to much investigation. Both cell types can derive from a single naive CD8+ T cell precursor. Their generation requires a fate choice early during a T cell response. As a result, two populations of T cells emerge. One of these consists of terminally differentiated short-lived effector T cells. The other contains cells able to develop into long-lived memory T cells.…
On the roles of Notch, Delta, kuzbanian, and inscuteable during the development of Drosophila embryonic neuroblast lineages
2009
AbstractThe generation of cellular diversity in the nervous system involves the mechanism of asymmetric cell division. Besides an array of molecules, including the Par protein cassette, a heterotrimeric G protein signalling complex, Inscuteable plays a major role in controlling asymmetric cell division, which ultimately leads to differential activation of the Notch signalling pathway and correct specification of the two daughter cells. In this context, Notch is required to be active in one sibling and inactive in the other. Here, we investigated the requirement of genes previously known to play key roles in sibling cell fate specification such as members of the Notch signalling pathway, e.g…
Cell cycle independent role of Cyclin E during neural cell fate specification in Drosophila is mediated by its regulation of Prospero function
2009
AbstractDuring development, neural progenitor cells or neuroblasts generate a great intra- and inter-segmental diversity of neuronal and glial cell types in the nervous system. In thoracic segments of the embryonic central nervous system of Drosophila, the neuroblast NB6-4t undergoes an asymmetric first division to generate a neuronal and a glial sublineage, while abdominal NB6-4a divides once symmetrically to generate only 2 glial cells. We had earlier reported a critical function for the G1 cyclin, CyclinE (CycE) in regulating asymmetric cell division in NB6-4t. Here we show that (i) this function of CycE is independent of its role in cell cycle regulation and (ii) the two functions are m…