Differentiation of trophoblast giant cells and their metabolic functions are dependent on peroxisome proliferator-activated receptor beta/delta.
Mutation of the nuclear receptor peroxisome proliferator-activated receptor beta/delta (PPARbeta/delta) severely affects placenta development, leading to embryonic death at embryonic day 9.5 (E9.5) to E10.5 of most, but not all, PPARbeta/delta-null mutant embryos. While very little is known at present about the pathway governed by PPARbeta/delta in the developing placenta, this paper demonstrates that the main alteration of the placenta of PPARbeta/delta-null embryos is found in the giant cell layer. PPARbeta/delta activity is in fact essential for the differentiation of the Rcho-1 cells in giant cells, as shown by the severe inhibition of differentiation once PPARbeta/delta is silenced. Conversely, exposure of Rcho-1 cells to a PPARbeta/delta agonist triggers a massive differentiation via increased expression of 3-phosphoinositide-dependent kinase 1 and integrin-linked kinase and subsequent phosphorylation of Akt. The links between PPARbeta/delta activity in giant cells and its role on Akt activity are further strengthened by the remarkable pattern of phospho-Akt expression in vivo at E9.5, specifically in the nucleus of the giant cells. In addition to this phosphatidylinositol 3-kinase/Akt main pathway, PPARbeta/delta also induced giant cell differentiation via increased expression of I-mfa, an inhibitor of Mash-2 activity. Finally, giant cell differentiation at E9.5 is accompanied by a PPARbeta/delta-dependent accumulation of lipid droplets and an increased expression of the adipose differentiation-related protein (also called adipophilin), which may participate to lipid metabolism and/or steroidogenesis. Altogether, this important role of PPARbeta/delta in placenta development and giant cell differentiation should be considered when contemplating the potency of PPARbeta/delta agonist as therapeutic agents of broad application.
Nadra
Karim
K
Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland.
Anghel
Silvia I
SI
Joye
Elisabeth
E
Tan
Nguan Soon
NS
Basu-Modak
Sharmila
S
Trono
Didier
D
Wahli
Walter
W
Desvergne
Béatrice
B
D000818:Animals; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D005260:Female; D005822:Genetic Vectors; D015726:Giant Cells / Q000378:metabolism* / Q000502:physiology; D008055:Lipids / Q000096:biosynthesis; D008565:Membrane Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008954:Models, Biological; D047494:PPAR delta / Q000235:genetics / Q000378:metabolism*; D048068:PPAR-beta / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D000070780:Perilipin-2; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011247:Pregnancy; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D014170:Transformation, Genetic; D014327:Trophoblasts / Q000378:metabolism* / Q000502:physiology
D008055:Lipids; D008565:Membrane Proteins; D047494:PPAR delta; D048068:PPAR-beta; D010455:Peptides; D000070780:Perilipin-2; C000602983:Plin2 protein, mouse; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt