Intrauterine growth restriction in humans is associated with abnormalities in placental insulin-like growth factor signaling.
Level 4 - case-series / case-control
Case-control study comparing human placental tissue from IUGR and normal pregnancies
PubMed 15564321 · doi:10.1210/en.2004-1332
What was done
Researchers measured the expression and phosphorylation of insulin-like growth factor (IGF) signaling pathway proteins in human placenta samples from pregnancies complicated by intrauterine growth restriction (IUGR) compared to normal control pregnancies.
What was found
In IUGR placentas compared to normal controls: - IGF-I receptor protein content was reduced by 33% (insulin receptor levels were unchanged). - Insulin receptor substrate-2 (IRS-2) protein was reduced with a parallel decrease in IRS-2-associated phosphatidylinositol 3-kinase (PI3K) activity (IRS-1 and Shc were unchanged). - Total Akt protein expression was reduced, but phosphorylation of Akt and glycogen synthase kinase-3 (GSK-3) was unchanged. - Phosphorylation of p38 and c-Jun N-terminal kinase (JNK) was reduced by 70%.
Why it matters
This work identifies specific molecular defects in placental IGF-I signaling, specifically the IRS-2/PI3K and p38/JNK pathways, that may contribute to impaired fetal growth in human IUGR.
Limits
The abstract does not disclose sample sizes, matching criteria, or maternal clinical details. As a cross-sectional tissue study at delivery, it cannot establish whether signaling alterations cause fetal growth restriction or reflect secondary placental pathology.
Cited by
- supports The insulin receptor is coupled to the mitogen-activated protein kinase (MAP kinase) pathway, which stimulates cell growth and division.