On the enigmatic disappearance of Rauber's layer
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Authors: van Leeuwen, Jessica; Rawson, Pisana; Berg, Debra K.; Wells, David N.; Pfeffer, Peter L.
Abstract
The polar trophoblast overlays the epiblast in eutherian mammals and, depending on the species, has one of two different fates. It either remains a single-layered, thinning epithelium called "Raub-er's layer," which soon disintegrates, or, alternatively, it keeps proliferating, contributing heavily to the population of differenti-ating, invasive trophoblast cells and, at least in mice, to the in-duction of gastrulation. While loss of the persistent polar trophoblast in mice leads to reduced induction of gastrulation, we show here that prevention of the loss of the polar trophoblast in cattle results in ectopic domains of the gastrulation marker, BRACHYURY. This phenotype, and increased epiblast proliferation, arose when Rauber's layer was maintained for a day longer by countering apoptosis through BCL2 overexpression. This suggests that the disappearance of Rauber's layer is a necessity, presumably to avoid excessive signaling interactions between this layer and the subjacent epiblast. We note that, in all species in which the polar trophoblast persists, including humans and mice, ectopic po-lar trophoblast signaling is prevented via epiblast cavitation which leads to the (pro)amniotic cavity, whose function is to distance the central epiblast from such signaling interactions.
Investigating The Alterations of Oxidative Stress Status, Antioxidant Defense Mechanisms, MAP Kinase and Mitochondrial Apoptotic Pathway in Adipose-Derived Mesenchymal Stem Cells from STZ Diabetic Rats
CELL JOURNAL
Authors: Aminzadeh, Azadeh; Maroof, Neda Tekiyeh; Mehrabani, Mehrnaz; Juybari, Kobra Bahrampour; Sharifi, Ali Mohammad
Abstract
Objective: This study aimed to investigate the reliability of diabetic adipose-derived stem cells (ADSCs) for autologous cell-based therapies by exploring the functionality of signalling pathways involved in regulating oxidative stress and apoptosis. Materials and Methods: In this experimental study, ADSCs were isolated from streptozotocin (STZ)-induced diabetic rats (dADSCs) and normal rats (nADSCs). The colonies derived from dADSCs and nADSCs were compared by colony-forming unit (CFU) assay. Reactive oxygen species (ROS) formation and total antioxidant power (TAP) were also measured. Furthermore, the expression of antioxidant enzymes, including catalase (Cat), superoxide dismutase (Sod)-1 and -3, glutathione peroxidase (Gpx)-1, -3 and -4 was measured at mRNA level by semi-quantitative reverse transcriptase polymerase chain reaction assay. The expression of Bax, Bcl2, caspase-3, total and phosphorylated c-Jun N-terminal kinase (JNK) and P38 Mitogen-Activated Protein Kinase (MAPK) at protein level was analyzed by western blotting. Results: The results of this study indicated that viability and plating efficiency of dADSCs were significantly lower than those of nADSCs. ROS generation and TAP level were respectively higher and lower in dADSCs. The gene expression of antioxidant enzymes, including Cat, Sod-1, Gpx-3 and Gpx-4 in dADSCs was significantly greater than that in nADSCs. However, Sod-3 and Gpx-1 mRNA levels were decreased in dADSCs. Moreover, Bax/Bcl-2 protein ratio, caspase-3 protein expression and phosphorylation of JNK and P38 proteins were increased in dADSCs compared to nADSCs. Conclusion: Taken together, diabetes might impair the cellular functions of dADSCs as candidates for autologous cell-based therapies. This impairment seems to be mediated by JNK, P38 MAPKs, and mitochondria pathway of apoptosis and partly by disruption of antioxidant capacity.