Culture medium, gas atmosphere and MAPK inhibition affect regulation of RNA-binding protein targets during mouse preimplantation development.

During oogenesis, mammalian oocytes accumulate maternal mRNAs that support the embryo until embryonic genome activation. RNA-binding proteins (RBP) may regulate the stability and turnover of maternal and embryonic mRNAs. We hypothesised that varying embryo culture conditions, such as culture medium, oxygen tension and MAPK inhibition, affects regulation of RBPs and their targets during preimplantation development.

Mitogen-activated protein kinase (MAPK) pathways mediate embryonic responses to culture medium osmolarity by regulating Aquaporin 3 and 9 expression and localization, as well as embryonic apoptosis.

Background: In order to advance the development of culture conditions and increase the potential for supporting normal preimplantation embryo development in vitro, it is critical to define the mechanisms that early embryos utilize to survive in culture. We investigated the mechanisms that embryos employ in response to culture medium osmolarity. We hypothesized that mitogen-activated protein kinase (MAPK) pathways mediate responses to hyperosmotic stress by regulating Aquaporin (AQP) 3 and 9 expression as well as embryonic apoptosis.

Nuclear trafficking of the G-protein-coupled parathyroid hormone receptor.

G-protein-coupled receptors are a family of receptors that signal primarily through heterotrimeric G proteins. However, new evidence has emerged to show that the signaling capabilities of the receptors are beyond those of traditional signaling cascades. One such example is that the parathyroid hormone (PTH) type 1 receptor is found not only at the plasma membrane but also in the nucleus of cells in cell lines and tissues.

Expression of PTH1R constructs in LLC-PK1 cells: protein nuclear targeting is mediated by the PTH1R NLS.

This study demonstrates that the PTH1R NLS can target a fusion protein to the nucleus, and that this is blocked by sequences downstream of the NLS. GFP fused to the NLS showed a significant increase in nuclear targeting compared to GFP alone or GFP fused to a peptide of the same length. In previous studies, we demonstrated that the type I PTH/PTHrP receptor (PTH1R) localizes to the nucleus of cells within rat liver, kidney, uterus, ovary and gut.

Type 1 parathyroid hormone receptor (PTH1R) nuclear trafficking: regulation of PTH1R nuclear-cytoplasmic shuttling by importin-alpha/beta and chromosomal region maintenance 1/exportin 1.

The type 1 PTH/PTH-related peptide receptor (PTH1R) is a class B G protein-coupled receptor that demonstrates immunoreactivity in the nucleus as well as cytoplasm of target cells. Our previous studies on the PTH1R have shown that it associates with the importin family of transport regulatory proteins. To investigate the role of the importins in PTH1R nuclear import, we used small interfering (si)RNA technology to knock down the expression of importin-beta in the mouse osteoblast-like cell line, MC3T3-E1.

PP2Cdelta (Ppm1d, WIP1), an endogenous inhibitor of p38 MAPK, is regulated along with Trp53 and Cdkn2a following p38 MAPK inhibition during mouse preimplantation development.

Preimplantation embryos utilize mitogen-activated protein kinase signaling (MAPK) pathways to relay signals from the external environment to prepare appropriate responses and adaptations to a changing milieu. It is therefore important to investigate how MAPK pathways are regulated during preimplantation development. This study was conducted to investigate whether PP2Cdelta (Ppm1d, WIP1) is expressed during mouse preimplantation development and to determine the influences of p38 MAPK inhibition on expression of Trp53 (p53), Ppm1d, (WIP1), and Cdkn2a (p16) during mouse preimplantation development.

Mouse preimplantation embryo responses to culture medium osmolarity include increased expression of CCM2 and p38 MAPK activation.

Background: Mechanisms that confer an ability to respond positively to environmental osmolarity are fundamental to ensuring embryo survival during the preimplantation period. Activation of p38 mitogen-activated protein kinase (MAPK) occurs following exposure to hyperosmotic treatment. Recently, a novel scaffolding protein called Osmosensing Scaffold for MEKK3 (OSM) was linked to p38 MAPK activation in response to sorbitol-induced hypertonicity.

Type 1 parathyroid hormone receptor (PTH1R) nuclear trafficking: association of PTH1R with importin alpha1 and beta.

Previous studies have shown that the type 1 PTH receptor (PTH1R), a class B G protein-coupled receptor, appears in the nucleus of target cells. Through immunofluorescence and deconvolution microscopy, we demonstrate that PTH1R, importin alpha(1), and importin beta are present within the nucleus and cytoplasm of osteoblast-like cell lines with the nuclear PTH1R being restricted to the nucleoplasm. Immunofluorescence studies showed that nuclear accumulation of PTH1R was associated with specific stages of the cell cycle.