Neural stem cells in the adult olfactory bulb core generate mature neurons in vivo.

17 páginas, 7 figuras.

Telomere shortening and chromosomal instability abrogates proliferation of adult but not embryonic neural stem cells.

Chromosome integrity is essential for cell viability and, therefore, highly proliferative cell types require active telomere elongation mechanisms to grow indefinitely. Consistently, deletion of telomerase activity in a genetically modified mouse strain results in growth impairments in all highly proliferative cell populations analyzed so far. We show that telomere attrition dramatically impairs the in vitro proliferation of adult neural stem cells (NSCs) isolated from the subventricular zone (SVZ) of telomerase-deficient adult mice. Reduced proliferation of postnatal neurogenic progenitors was also observed in vivo, in the absence of exogenous mitogenic stimulation. Strikingly, severe telo…

Identification of a Functional Homolog of the Yeast Copper Homeostasis Gene ATX1 from Arabidopsis1

Abstract A cDNA clone encoding a homolog of the yeast (Saccharomyces cerevisiae) gene Anti-oxidant 1(ATX1) has been identified from Arabidopsis. This gene, referred to as CopperCHaperone(CCH), encodes a protein that is 36% identical to the amino acid sequence of ATX1 and has a 48-amino acid extension at the C-terminal end, which is absent from ATX1 homologs identified in animals. ATX1-deficient yeast (atx1) displayed a loss of high-affinity iron uptake. Expression of CCH in the atx1 strain restored high-affinity iron uptake, demonstrating thatCCH is a functional homolog of ATX1. When overexpressed in yeast lacking the superoxide dismutase geneSOD1, both ATX1 and CCHprotected the cell from t…

Signaling through BMPR-IA regulates quiescence and long-term activity of neural stem cells in the adult hippocampus.

SummaryNeural stem cells (NSCs) in the adult hippocampus divide infrequently, and the molecules that modulate their quiescence are largely unknown. Here, we show that bone morphogenetic protein (BMP) signaling is active in hippocampal NSCs, downstream of BMPR-IA. BMPs reversibly diminish proliferation of cultured NSCs while maintaining their undifferentiated state. In vivo, acute blockade of BMP signaling in the hippocampus by intracerebral infusion of Noggin first recruits quiescent NSCs into the cycle and increases neurogenesis; subsequently, it leads to decreased stem cell division and depletion of precursors and newborn neurons. Consistently, selective ablation of Bmpr1a in hippocampal …

Symmetric expansion of neural stem cells from the adult olfactory bulb is driven by astrocytes via WNT7A.

Adult neural stem cells (NSCs) located in the subventricular zone (SVZ) persistently produce new neurons destined to the olfactory bulb (OB). Recent research suggests that the OB is also a source of NSCs that remains largely unexplored. Using single/dual-labeling procedures, we address the existence of NSCs in the innermost layers of the OB. In vivo, these cells are more quiescent that their SVZ counterparts, but after in vitro expansion, they behave similarly. Self-renewal and proliferation assays in co-culture with niche astrocytes indicate that OB-glia restricts NSC activity whereas SVZ-glia has the opposite effect. Gene expression profiling identifies WNT7A as a key SVZ-glial factor lac…

Evidence for the plant-specific intercellular transport of the Arabidopsis copper chaperone CCH

Summary Arabidopsis copper chaperone (CCH) belongs to a family of eukaryotic proteins that participates in intracellular copper homeostasis by delivering this metal to the secretory pathway. In this work we show that the CCH protein is mainly located along the vascular bundles of senescing leaves and petioles, as shown by tissue prints and immunohistochemical detection. CCH protein also accumulates in stem sieve elements and is collected in phloem exudates. Accordingly, Arabidopsis CCH is the only member of the metallochaperone family described to function intercellularly to date. Moreover, the CCH protein remains stable when plants are subjected to excess copper that causes a rapid and spe…

Higher plants possess two different types of ATX1-like copper chaperones.

Abstract Copper (Cu) chaperones constitute a family of small Cu+-binding proteins required for Cu homeostasis in eukaryotes. The ATX1 family of Cu chaperones specifically delivers Cu to heavy metal P-type ATPases. The plant Arabidopsis thaliana expresses the ATX1-like Cu chaperone CCH, which exhibits a plant-specific carboxy-terminal domain (CTD) with unique structural properties. We show that CCH homologues from other higher plants contain CTDs with structural properties similar to Arabidopsis CCH. Furthermore, we identify a new ATX1-like Cu chaperone in Arabidopsis, AtATX1, which functionally complements yeast atx1Δ and sod1Δ associated phenotypes, and localizes to the cytosol of Arabidop…

Pigment epithelium-derived factor is a niche signal for neural stem cell renewal.

Adult stem cells are characterized by self-renewal and multilineage differentiation, and these properties seem to be regulated by signals from adjacent differentiated cell types and by extracellular matrix molecules, which collectively define the stem cell "niche." Self-renewal is essential for the lifelong persistence of stem cells, but its regulation is poorly understood. In the mammalian brain, neurogenesis persists in two germinal areas, the subventricular zone (SVZ) and the hippocampus, where continuous postnatal neuronal production seems to be supported by neural stem cells (NSCs). Here we show that pigment epithelium-derived factor (PEDF) is secreted by components of the murine SVZ a…

Ionic self-complementarity induces amyloid-like fibril formation in an isolated domain of a plant copper metallochaperone protein

This article is available from: http://www.biomedcentral.com/1472-6807/4/7

Expression of a vegetative-storage-protein gene from Arabidopsis is regulated by copper, senescence and ozone

Emerging data suggest that the mechanisms regulating plant copper homeostasis could be implicated in stress and senescence signal transduction pathways. To gain insight into copper-modulated patterns of gene expression, copper-treated Arabidopsis thaliana (L.) Heynh. plants were analysed by mRNA differential display. The experimental conditions were selected using aggregation of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) as a molecular sensor to monitor copper-induced oxidative stress. Two copper-induced messengers encoding a vegetative storage protein (VSP2) were isolated by this technique. Both clones differed in the length of their 3'-untranslated region according to the p…

Telomere Shortening in Neural Stem Cells Disrupts Neuronal Differentiation and Neuritogenesis

Proliferation in the subependymal zone (SEZ) and neurogenesis in the olfactory bulb decline in the forebrain of telomerase-deficient mice. The present work reveals additional effects of telomere shortening on neuronal differentiation, as adult multipotent progenitors with critically short telomeres yield reduced numbers of neurons that, furthermore, exhibit underdeveloped neuritic arbors. Genetic data indicate that the tumor suppressor protein p53 not only mediates the adverse effects of telomere attrition on proliferation and self-renewal but it is also involved in preventing normal neuronal differentiation of adult progenitors with dysfunctional telomeres. Interestingly, progenitor cells …

Background Arabidopsis thaliana copper metallochaperone CCH is a functional homologue of yeast antioxidant ATX1, involved in cytosolic copper transport. In higher plants, CCH has to be transported to specialised cells through plasmodesmata, being the only metallochaperone reported to date that leaves the cell where it is synthesised. CCH has two different domains, the N-terminal domain conserved among other copper-metallochaperones and a C-terminal domain absent in all the identified non-plant metallochaperones. The aim of the present study was the biochemical and biophysical characterisation of the C-terminal domain of the copper metallochaperone CCH.

A combined ex/in vivo assay to detect effects of exogenously added factors in neural stem cells.

We describe a protocol developed/modified by our group for the ex vivo and in vivo assessment of the response to a soluble factor of murine neural stem cells from the adult sub-ventricular zone (SVZ). The procedure includes several experimental options that can be used either independently or in combination. Potential factor effects on self-renewal, survival and proliferation are assayed by means of neurosphere cultures, with the factor administered directly in vitro to the culture plates (Step 1) or infused in vivo immediately before tissue dissociation (Step 3). We also use bromodeoxiuridine (BrdU) retention to label slowly dividing cells in vivo and subsequently perform two different typ…