Search results for "Embryon"
showing 10 items of 988 documents
Germ Cell Differentiation from Pluripotent Cells
2013
Infertility is a medical condition with an increasing impact in Western societies with causes linked to toxins, genetics, and aging (primarily delay of motherhood). Within the different pathologies that can lead to infertility, poor quality or reduced quantity of gametes plays an important role. Gamete donation and therefore demand on donated sperm and eggs in fertility clinics is increasing. It is hoped that a better understanding of the conditions related to poor gamete quality may allow scientists to design rational treatments. However, to date, relatively little is known about human germ cell development in large part due to the inaccessibility of human development to molecular genetic …
Postnatal Deletion of Numb/Numblike Reveals Repair and Remodeling Capacity in the Subventricular Neurogenic Niche
2006
Neural stem cells are retained in the postnatal subventricular zone (SVZ), a specialized neurogenic niche with unique cytoarchitecture and cell-cell contacts. Although the SVZ stem cells continuously regenerate, how they and the niche respond to local changes is unclear. Here we generated nestin-creERtm transgenic mice with inducible Cre recombinase in the SVZ, and removed Numb/Numblike, key regulators of embryonic neurogenesis from postnatal SVZ progenitors and ependymal cells. This resulted in severe damage to brain lateral ventricle integrity, and identified previously unknown roles for Numb/Numblike in regulating ependymal wall integrity and SVZ neuroblast survival. Surprisingly, the ve…
Follistatin as potential therapeutic target in prostate cancer
2012
Follistatin is a single-chain glycosylated protein whose primary function consists in binding and neutralizing some members of the transforming growth factor-β superfamily such as activin and bone morphogenic proteins. Emerging evidence indicates that this molecule may also play a role in the malignant progression of several human tumors including prostate cancer. In particular, recent findings suggest that, in this tumor, follistatin may also contribute to the formation of bone metastasis through multiple mechanisms, some of which are not related to its specific activin or bone morphogenic proteins' inhibitory activity. This review provides insight into the most recent advances in understa…
Expression ofDNMT3A transcripts and nucleolar localization of DNMT3A protein in human testicular and fibroblast cells suggest a role for de novo DNA …
2006
Transcriptional silencing during differentiation of human male germ cells and serum starvation of human fibroblasts is controlled by epigenetic mechanisms that involve de novo DNA methylation. It is associated with high expression of different transcripts of the DNA methyltransferase 3A (DNMT3A) gene that encode two isoforms with de novo methyltransferase activity and one without catalytic activity. Western blots revealed that DNMT3A protein (with catalytic domain) is present at low levels in several tissues and at increased levels in testicular cells and growth-arrested fibroblasts. Immunofluorescence experiments localized DNMT3A to discrete nucleolar foci in B spermatogonia and resting fi…
In Vitro-Differentiated Embryonic Stem Cells Give Rise to Male Gametes that Can Generate Offspring Mice
2006
SummaryMale gametes originate from a small population of spermatogonial stem cells (SSCs). These cells are believed to divide infinitely and to support spermatogenesis throughout life in the male. Here, we developed a strategy for the establishment of SSC lines from embryonic stem (ES) cells. These cells are able to undergo meiosis, are able to generate haploid male gametes in vitro, and are functional, as shown by fertilization after intracytoplasmic injection into mouse oocytes. Resulting two-cell embryos were transferred into oviducts, and live mice were born. Six of seven animals developed to adult mice. This is a clear indication that male gametes derived in vitro from ES cells by this…
Atrial natriuretic factor-like immunoreactivity in spinal cord and in primary sensory neurons of spinal and trigeminal ganglia of guinea-pig: correla…
1989
Atrial natriuretic factor (ANF) is a cardiac hormone with various functions in body homeostasis. It is also processed in the brain and in the peripheral nervous system where it appears to play a role as a neuromodulator. Little is known about the presence of ANF throughout the spinal cord of the guinea-pig. We therefore examined the distribution of ANF and its possible interrelation with primary sensory afferents in this species. Using enzyme- and fluorescence-immunohistochemistry on deparaffinized sections, ANF-like immunoreactivity was found to be present in nerve fibers in laminae I/II of the spinal cord and in neurons of spinal and trigeminal ganglia. Tachykinins and ANF coexisted in ve…
Loss of desmoglein 2 suggests essential functions for early embryonic development and proliferation of embryonal stem cells.
2002
Summary Desmoglein 2 (Dsg2) is a Ca 2+ -dependent adhesion molecule of desmosomes and is synthesized in all desmosome-bearing tissues from their earliest appearance onward. To examine the function of Dsg2, its gene was inactivated by homologous recombination in embryonal stem (ES) cells for the generation of knockout mice. DSG2 −/− mice and a considerable number of DSG2 +/− mice died at or shortly after implantation. On the other hand, DSG2 −/− blastocysts developed an apparently normal trophectoderm layer, the first tissue known to produce desmosomes, and hatched properly. Immunofluorescence analyses of these blastocysts showed, however, that the distribution of the desmosomal plaque prote…
Derivation and characterization of three new Spanish human embryonic stem cell lines (VAL −3 −4 −5) on human feeder and in serum-free conditions
2006
A total of 184 human embryos, frozen for >5 years, were donated; informed consent was obtained according to Spanish law 45/2003. Survival rate was 40% and three out of 24 blastocysts (12.5%) developed into putative hESC lines, named VAL-3, VAL-4, and VAL-5. The derivation process was performed on microbiologically tested and irradiated human foreskin fibroblasts and designed to minimize contact with xeno-components in knockout DMEM supplemented with knockout serum replacement, and basic fibroblast growth factor. Fingerprinting and HLA typing of the cell lines allowed their identification and traceability. Karyotype was normal for VAL-3 (46XY), VAL-4 (46XX) and VAL-5 (46XX). All three hESC l…
Global and gene-specific histone modification profiles of mouse multipotent adult germline stem cells
2010
We previously reported the generation of multipotent adult germline stem cells (maGSCs) from spermatogonial stem cells (SSCs) isolated from adult mouse testis. In a later study, we substantiated the pluripotency of maGSCs by demonstrating their close similarity to pluripotent male embryonic stem cells (ESCs) at the epigenetic level of global and gene-specific DNA methylation. Here, we extended the comparative epigenetic analysis of maGSCs and male ESCs by investigating the second main epigenetic modification in mammals, i.e. global and gene-specific modifications of histones (H3K4 trimethylation, H3K9 acetylation, H3K9 trimethylation and H3K27 trimethylation). Using immunofluorescence stain…
FM19G11, a New Hypoxia-inducible Factor (HIF) Modulator, Affects Stem Cell Differentiation Status
2009
The biology of the alpha subunits of hypoxia-inducible factors (HIF alpha) has expanded from their role in angiogenesis to their current position in the self-renewal and differentiation of stem cells. The results reported in this article show the discovery of FM19G11, a novel chemical entity that inhibits HIF alpha proteins that repress target genes of the two alpha subunits, in various tumor cell lines as well as in adult and embryonic stem cell models from rodents and humans, respectively. FM19G11 inhibits at nanomolar range the transcriptional and protein expression of Oct4, Sox2, Nanog, and Tgf-alpha undifferentiating factors, in adult rat and human embryonic stem cells, FM19G11 activit…