Insulin receptor substrate‐1 is expressed at high levels in all cells of the peri‐implantation mouse embryo

Abstract

Insulin and insulinlike growth factors are important for embryonic growth and metabolism. Intracellular transduction for these factors has not been studied in the preimplantation mouse embryo. Peri-implantation mouse embryos synthesize insulinlike growth factor (IGF)-II ligand, insulin receptor, IGF-I receptor, and IGF-II receptor and respond to IGF-II, IGF-I, and insulin metabolically and mitogenically. Maternal tissues in the oviduct and uterus are also sources of IGF-I and insulin. Signaling of IGFs occurs through insulin receptor substrate (IRS)-1 and IRS-2. This paper shows that IRS-1 mRNA and protein are highly expressed in preimplantation mouse embryos, in embryonic cell lines, and in cultured blastocyst outgrowths. IRS-1 mRNA and protein are detected in embryo-derived cell lines cultured to produce the three cell lineages (stem cells, endoderm, and trophoblast cells). IRS-1 mRNA is detected by reverse transcription-polymerase chain reaction (RT-PCR) in the E3.5 blastocyst before implantation and in F9 teratocarcinoma stem cells and parietal endoderm cells. IRS-1 mRNA is detected by Northern blot hybridization at high levels in stem cells and in differentiated progeny of F9 cells and C3H/NE trophectoderm cells. IRS-1 protein was detected in these cell lines and in an overexpressing CHO-IRS-1 fibroblast cell line by immunocytochemistry. Cultured blastocyst outgrowths are a model for implantation events of the trophoblast/placenta lineage and endoderm/yolk sac lineage. In the blastocyst outgrowth, IRS-1 protein is detected in inner cell mass cells (ICM cells), primitive endoderm, parietal endoderm, and trophectoderm cells. These data suggest that IRS-1 is expressed in all cell lineages of the peri-implantation mouse embryo and mediates some effects of insulin and IGFs at this stage.

GLUT8 is a glucose transporter responsible for insulin-stimulated glucose uptake in the blastocyst

“…This uptake would facilitate vectorial transport of glucose from the blastocoel to the ICM. It has also been noted recently that expression of insulin receptor substrate-1 at both the mRNA and protein levels increases significantly at the blastocyst stage of mouse development (23). Although this expression has not been localized to a particular cell type, this finding suggests that activity of this IGF-1͞insulin-IGF-1 receptor-insulin receptor substrate-1-GLUT8 pathway may be functional within the trophectoderm and endoderm.…”

GLUT8 is a glucose transporter responsible for insulin-stimulated glucose uptake in the blastocyst

“…This uptake would facilitate vectorial transport of glucose from the blastocoel to the ICM. It has also been noted recently that expression of insulin receptor substrate-1 at both the mRNA and protein levels increases significantly at the blastocyst stage of mouse development (23). Although this expression has not been localized to a particular cell type, this finding suggests that activity of this IGF-1͞insulin-IGF-1 receptor-insulin receptor substrate-1-GLUT8 pathway may be functional within the trophectoderm and endoderm.…”

Glucose Transporter 8 Expression and Translocation Are Critical for Murine Blastocyst Survival1

“…Downstream activation of Akt/protein kinase B is then believed to trigger translocation of GLUT4 from specialized intracellular compartments known as GLUT4 storage vesicles (GSVs) to the plasma membrane. In the mouse preimplantation embryo, expression of IRS-1 has recently been reported at both the mRNA and protein levels, and these levels increase significantly at the blastocyst stage of development [32]. Although this expression has not been localized to a particular cell type, this finding suggests that activity of this IGF-1/ insulin-IGF-1R-IRS-1-GLUT8 pathway may be functional within the blastocyst, possibly within the trophectoderm and inner cell mass.…”

The phosphoinositide 3-kinase/Akt pathway is essential for the retinoic acid-induced differentiation of F9 cells

“…The action of insulin is mediated through a specific transmembrane RTK and the subsequent activation of PI3K and Akt activities (Brazil et al, 2004). F9 cells express insulin receptors as well as the adaptor protein IRS-1 (Puscheck et al, 1998), and within minutes, insulin enhances Akt phosphorylation at S473 (Figure 3a, lanes 3 and 7). This effect was further enhanced when F9 WT cells were pretreated with RA for 24 h ( Figure 3a, lane 4), suggesting that the early RA-induced activation of Akt reflects an activation of PI3K.…”

GLUT8 is a glucose transporter responsible for insulin-stimulated glucose uptake in the blastocyst

“…This uptake would facilitate vectorial transport of glucose from the blastocoel to the ICM. It has also been noted recently that expression of insulin receptor substrate-1 at both the mRNA and protein levels increases significantly at the blastocyst stage of mouse development (23). Although this expression has not been localized to a particular cell type, this finding suggests that activity of this IGF-1͞insulin-IGF-1 receptor-insulin receptor substrate-1-GLUT8 pathway may be functional within the trophectoderm and endoderm.…”

Glucose Transporter 8 Expression and Translocation Are Critical for Murine Blastocyst Survival1

“…Downstream activation of Akt/protein kinase B is then believed to trigger translocation of GLUT4 from specialized intracellular compartments known as GLUT4 storage vesicles (GSVs) to the plasma membrane. In the mouse preimplantation embryo, expression of IRS-1 has recently been reported at both the mRNA and protein levels, and these levels increase significantly at the blastocyst stage of development [32]. Although this expression has not been localized to a particular cell type, this finding suggests that activity of this IGF-1/ insulin-IGF-1R-IRS-1-GLUT8 pathway may be functional within the blastocyst, possibly within the trophectoderm and inner cell mass.…”

The phosphoinositide 3-kinase/Akt pathway is essential for the retinoic acid-induced differentiation of F9 cells

“…The action of insulin is mediated through a specific transmembrane RTK and the subsequent activation of PI3K and Akt activities (Brazil et al, 2004). F9 cells express insulin receptors as well as the adaptor protein IRS-1 (Puscheck et al, 1998), and within minutes, insulin enhances Akt phosphorylation at S473 (Figure 3a, lanes 3 and 7). This effect was further enhanced when F9 WT cells were pretreated with RA for 24 h ( Figure 3a, lane 4), suggesting that the early RA-induced activation of Akt reflects an activation of PI3K.…”

GLUT8 is a glucose transporter responsible for insulin-stimulated glucose uptake in the blastocyst

“…This uptake would facilitate vectorial transport of glucose from the blastocoel to the ICM. It has also been noted recently that expression of insulin receptor substrate-1 at both the mRNA and protein levels increases significantly at the blastocyst stage of mouse development (23). Although this expression has not been localized to a particular cell type, this finding suggests that activity of this IGF-1͞insulin-IGF-1 receptor-insulin receptor substrate-1-GLUT8 pathway may be functional within the trophectoderm and endoderm.…”

Glucose Transporter 8 Expression and Translocation Are Critical for Murine Blastocyst Survival1

“…Downstream activation of Akt/protein kinase B is then believed to trigger translocation of GLUT4 from specialized intracellular compartments known as GLUT4 storage vesicles (GSVs) to the plasma membrane. In the mouse preimplantation embryo, expression of IRS-1 has recently been reported at both the mRNA and protein levels, and these levels increase significantly at the blastocyst stage of development [32]. Although this expression has not been localized to a particular cell type, this finding suggests that activity of this IGF-1/ insulin-IGF-1R-IRS-1-GLUT8 pathway may be functional within the blastocyst, possibly within the trophectoderm and inner cell mass.…”

The phosphoinositide 3-kinase/Akt pathway is essential for the retinoic acid-induced differentiation of F9 cells

“…The action of insulin is mediated through a specific transmembrane RTK and the subsequent activation of PI3K and Akt activities (Brazil et al, 2004). F9 cells express insulin receptors as well as the adaptor protein IRS-1 (Puscheck et al, 1998), and within minutes, insulin enhances Akt phosphorylation at S473 (Figure 3a, lanes 3 and 7). This effect was further enhanced when F9 WT cells were pretreated with RA for 24 h ( Figure 3a, lane 4), suggesting that the early RA-induced activation of Akt reflects an activation of PI3K.…”