Home  About us  Contact
 

Progenitor Pool (progenitor + pool)

Distribution by Scientific Domains
Life Sciences100%

Selected Abstracts

The Allantoic Core Domain: New insights into development of the murine allantois and its relation to the primitive streak

DEVELOPMENTAL DYNAMICS, Issue 3 2009
Karen M. Downs
Abstract The whereabouts and properties of the posterior end of the primitive streak have not been identified in any species. In the mouse, the streak's posterior terminus is assumed to be confined to the embryonic compartment, and to give rise to the allantois, which links the embryo to its mother during pregnancy. In this study, we have refined our understanding of the biology of the murine posterior primitive streak and its relation to the allantois. Through a combination of immunostaining and morphology, we demonstrate that the primitive streak spans the posterior extraembryonic and embryonic regions at the onset of the neural plate stage (,7.0 days postcoitum, dpc). Several hours later, the allantoic bud emerges from the extraembryonic component of the primitive streak (XPS). Then, possibly in collaboration with overlying allantois-associated extraembryonic visceral endoderm, the XPS establishes a germinal center within the allantois, named here the Allantoic Core Domain (ACD). Microsurgical removal of the ACD beyond headfold (HF) stages resulted in the formation of allantoic regenerates that lacked the ACD and failed to elongate; nevertheless, vasculogenesis and vascular patterning proceeded. In situ and transplantation fate mapping demonstrated that, from HF stages onward, the ACD's progenitor pool contributed to the allantois exclusive of the proximal flanks. By contrast, the posterior intraembryonic primitive streak (IPS) provided the flanks. Grafting the ACD into TC/TC hosts, whose allantoises are significantly foreshortened, restored allantoic elongation. These results revealed that the ACD is essential for allantoic elongation, but the cues required for vascularization lie outside of it. On the basis of these and previous findings, we conclude that the posterior primitive streak of the mouse conceptus is far more complex than was previously believed. Our results provide new directives for addressing the origin and development of the umbilical cord, and establish a novel paradigm for investigating the fetal/placental relationship. Developmental Dynamics 238:532,553, 2009. © 2009 Wiley-Liss, Inc. [source]

Effect of canonical Wnt inhibition in the neurogenic cortex, hippocampus, and premigratory dentate gyrus progenitor pool

DEVELOPMENTAL DYNAMICS, Issue 7 2008
Nina Solberg
Abstract Canonical Wnt signaling is crucial for the correct development of both cortical and hippocampal structures in the dorsal telencephalon. In this study, we examined the role of the canonical Wnt signaling in the dorsal telencephalon of mouse embryos at defined time periods by inhibition of the pathway with ectopic expression of Dkk1. Transgenic mice with the D6-driven Dkk1 gene exhibited reduced canonical Wnt signaling in the cortex and hippocampus. As a result, all hippocampal fields were reduced in size. Neurogenesis in the dentate gyrus was severely reduced both in the premigratory and migratory progenitor pool. The lower number of progenitors in the dentate gyrus was not rescued after migration to the subgranular zone and thus the dentate gyrus lacked the entire internal blade and a part of the external blade from postnatal to adult stages. Developmental Dynamics 237:1799,1811, 2008. © 2008 Wiley-Liss, Inc. [source]

Thiazolidinedione treatment and constitutive-PPAR, activation induces ectopic adipogenesis and promotes age-related thymic involution

AGING CELL, Issue 4 2010
Yun-Hee Youm
Summary Age-related thymic involution is characterized by reduction in T cell production together with ectopic adipocyte development within the hematopoietic and thymic niches. Peroxisome proliferator-activated receptor gamma (PPAR,) is required for adipocyte development, glucose homeostasis and is a target for several insulin-sensitizing drugs. Our prior studies showed that age-related elevation of PPAR, expression in thymic stromal cells is associated with thymic involution. Here, using clinically relevant pharmacological and genetic manipulations in mouse models, we provide evidence that activation of PPAR, leads to reduction in thymopoiesis. Treatment of aged mice with antihyperglycemic PPAR,-ligand class of thiazolidinedione drug, rosiglitazone caused robust thymic expression of classical pro-adipogenic transcripts. Rosiglitazone reduced thymic cellularity, lowered the naïve T cell number and T cell receptor excision circles (TRECs) indicative of compromised thymopoiesis. To directly investigate whether PPAR, activation induces thymic involution, we created transgenic mice with constitutive-active PPAR, (CA-PPARg) fusion protein in cells of adipogenic lineage. Importantly, CA-PPAR, transgene was expressed in thymus and in fibroblast-specific protein-1/S100A4 (FSP1+) cells, a marker of secondary mesenchymal cells. The CAPPAR, fusion protein mimicked the liganded PPAR, receptor and the transgenic mice displayed increased ectopic thymic adipogenesis and reduced thymopoiesis. Furthermore, the reduction in thymopoiesis in CA-PPAR, mice was associated with higher bone marrow adiposity and lower hematopoietic stem cell progenitor pool. Consistent with lower thymic output, CAPPAR, transgenic mice had restricted T cell receptor repertoire diversity. Collectively, our data suggest that activation of PPAR, accelerates thymic aging and thymus-specific PPAR, antagonist may forestall age-related decline in T cell diversity. [source]

Ethanol exposure during embryogenesis decreases the radial glial progenitorpool and affects the generation of neurons and astrocytes

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2006
Gemma Rubert
Abstract Prenatal ethanol exposure induces functional abnormalities during brain development affecting neurogenesis and gliogenesis. We have previously reported that alcohol exposure during embryogenesis disrupts radial glia (RG) and gliogenesis. Taking into account the new role of RG as neural progenitors, we have investigated whether ethanol affects RG as a neural stem cell. We found that in utero ethanol exposure impairs cell proliferation and decreases neurons and astrocytes generated in cultured RG and in embryonic cerebral cortex. Telencephalic cultures obtained at E12 from ethanol-treated rats displayed a reduction in the proportion of actively dividing RG progenitors, as demonstrated by 5-bromo-2,-deoxyuridine incorporation, and in the percentage of brain lipid binding protein-positive RG. Consistently, neurosphere formation assay from E12 telencephalon showed a reduced number of multipotent progenitor cells in cultures isolated from ethanol-treated rats in comparison with pair-fed control group. Moreover, levels of activated Notch1 and fibroblast growth factor receptor 2, which regulate the maintenance of the progenitor state of RG, are decreased by prenatal ethanol exposure. These findings demonstrate that ethanol reduces the telencephalic RG progenitor pool and its transformation into neurons and astrocytes, which may contribute to an explanation of the defects in brain function often observed in fetal alcohol syndrome. © 2006 Wiley-Liss, Inc. [source]

Notch signaling promotes astrogliogenesis via direct CSL-mediated glial gene activation

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2002
Weihong Ge
Abstract In the developing central nervous system (CNS), Notch signaling preserves progenitor pools and inhibits neurogenesis and oligodendroglial differentiation. It has recently been postulated that Notch instructively drives astrocyte differentiation. Whether the role of Notch signaling in promoting astroglial differentiation is permissive or instructive has been debated. We report here that the astrogliogenic role of Notch is in part mediated by direct binding of the Notch intracellular domain to the CSL DNA binding protein, forming a transcriptional activation complex onto the astrocyte marker gene, glial fibrillary acidic protein (GFAP). In addition, we found that, in CSL,/, neural stem cell cultures, astrocyte differentiation was delayed but continued at a normal rate once initiated, suggesting that CSL is involved in regulating the onset of astrogliogenesis. Importantly, although the classical CSL-dependent Notch signaling pathway is intact and able to activate the Notch canonical target promoter during the neurogenic phase, it is unable to activate the GFAP promoter during neurogenesis. Therefore, the effect of Notch signaling on target genes is influenced by cellular context in regulation of neurogenesis and gliogenesis. © 2002 Wiley-Liss, Inc. [source]

Patterned assembly and neurogenesis in the chick dorsal root ganglion

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2010
Lynn George
The birth of small-diameter TrkA+ neurons that mediate pain and thermoreception begins ,24 hours after the cessation of neural crest cell migration from progenitors residing in the nascent dorsal root ganglion. Although multiple geographically distinct progenitor pools have been proposed, this study is the first to comprehensively characterize the derivation of small-diameter neurons. In the developing chick embryo we identify novel patterns in neural crest cell migration and colonization that sculpt the incipient ganglion into a postmitotic neuronal core encapsulated by a layer of proliferative progenitor cells. Furthermore, we show that this outer progenitor layer is composed of three spatially, temporally, and molecularly distinct progenitor zones, two of which give rise to distinct populations of TrkA+ neurons. J. Comp. Neurol. 518:405,422, 2010. © 2009 Wiley-Liss, Inc. [source]

Patterned assembly and neurogenesis in the chick dorsal root ganglion

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2010
Lynn George
Abstract The birth of small-diameter TrkA+ neurons that mediate pain and thermoreception begins ,24 hours after the cessation of neural crest cell migration from progenitors residing in the nascent dorsal root ganglion. Although multiple geographically distinct progenitor pools have been proposed, this study is the first to comprehensively characterize the derivation of small-diameter neurons. In the developing chick embryo we identify novel patterns in neural crest cell migration and colonization that sculpt the incipient ganglion into a postmitotic neuronal core encapsulated by a layer of proliferative progenitor cells. Furthermore, we show that this outer progenitor layer is composed of three spatially, temporally, and molecularly distinct progenitor zones, two of which give rise to distinct populations of TrkA+ neurons. J. Comp. Neurol. 518:405,422, 2010. © 2009 Wiley-Liss, Inc. [source]