Unexplained intrauterine growth restriction of the
fetus (IUGR) results from impaired placental development,
frequently associated with maternal malperfusion.
Some cases are complicated further by preeclampsia
(PEIUGR). Here, we provide the first
evidence that placental protein synthesis inhibition
and endoplasmic reticulum (ER) stress play key roles
in IUGR pathophysiology. Increased phosphorylation
of eukaryotic initiation factor 2 suggests suppression
of translation initiation in IUGR placentas, with
a further increase in PEIUGR cases. Consequently,
AKT levels were reduced at the protein, but not
mRNA, level. Additionally, levels of other proteins in
the AKT-mammalian target of rapamycin pathway
were decreased, and there was associated dephosphorylation
of 4E-binding protein 1 and activation of
glycogen synthase kinase 3. Cyclin D1 and the eukaryotic
initiation factor 2B epsilon subunit were also
down-regulated, providing additional evidence for
this placental phenotype. The central role of AKT
signaling in placental growth regulation was confirmed
in Akt1 null mice, which display IUGR. In
addition, we demonstrated ultrastructural and molecular
evidence of ER stress in human IUGR and
PEIUGR placentas, providing a potential mechanism
for eukaryotic initiation factor 2 phosphorylation.
In confirmation, induction of low-grade ER
stress in trophoblast-like cell lines reduced cellular
proliferation. PEIUGR placentas showed elevated ER
stress with the additional expression of the pro-apoptotic
protein C/EBP-homologous protein/growth arrest
and DNA damage 153. These findings may account
for the increased microparticulate placental
debris in the maternal circulation of these cases, leading
to endothelial cell activation and impairing placental
development.
Unexplained intrauterine growth restriction of thefetus (IUGR) results from impaired placental development,frequently associated with maternal malperfusion.Some cases are complicated further by preeclampsia(PEIUGR). Here, we provide the firstevidence that placental protein synthesis inhibitionand endoplasmic reticulum (ER) stress play key rolesin IUGR pathophysiology. Increased phosphorylationof eukaryotic initiation factor 2 suggests suppressionof translation initiation in IUGR placentas, witha further increase in PEIUGR cases. Consequently,AKT levels were reduced at the protein, but notmRNA, level. Additionally, levels of other proteins inthe AKT-mammalian target of rapamycin pathwaywere decreased, and there was associated dephosphorylationof 4E-binding protein 1 and activation ofglycogen synthase kinase 3. Cyclin D1 and the eukaryoticinitiation factor 2B epsilon subunit were alsodown-regulated, providing additional evidence forthis placental phenotype. The central role of AKTsignaling in placental growth regulation was confirmedin Akt1 null mice, which display IUGR. Inaddition, we demonstrated ultrastructural and molecularevidence of ER stress in human IUGR andPEIUGR placentas, providing a potential mechanismfor eukaryotic initiation factor 2 phosphorylation.In confirmation, induction of low-grade ERstress in trophoblast-like cell lines reduced cellularproliferation. PEIUGR placentas showed elevated ERความเครียด มีค่าเพิ่มเติมของ pro apoptoticโปรตีน C/EBP-homologous จับโปรตีน/เติบโตและความเสียหายของดีเอ็นเอ 153 ผลการวิจัยเหล่านี้อาจบัญชีสำหรับ microparticulate เพิ่มขึ้นรกลอกเศษในการหมุนเวียนของกรณีเหล่านี้ นำแม่การเปิดใช้งานของเซลล์บุผนังหลอดเลือดและ impairing รกลอกการพัฒนา
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