title: Endoplasmic reticulum (ER) stress in cumulus-oocyte complexes impairs pentraxin-3 secretion, mitochondrial membrane potential (DeltaPsi m), and embryo development.
abstract: Fatty acids such as palmitic acid at high levels are known to induce endoplasmic reticulum (ER) stress and lipotoxicity in numerous cell types and thereby contribute to cellular dysfunctions in obesity. To understand the impact of high fatty acids on oocytes, ER stress and lipotoxicity were induced in mouse cumulus-oocyte complexes during in vitro maturation using the ER Ca(2+) channel blocker thapsigargin or high physiological levels of palmitic acid; both of which significantly induced ER stress marker genes (Atf4, Atf6, Xbp1s, and Hspa5) and inositol-requiring protein-1α phosphorylation, demonstrating an ER stress response that was reversible with the ER stress inhibitor salubrinal. Assessment of pentraxin-3, an extracellular matrix protein essential for fertilization, by immunocytochemistry and Western blotting showed dramatically impaired secretion concurrent with ER stress. Mitochondrial activity in oocytes was assessed by 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide staining of inner mitochondrial membrane potential, and oocytes matured in thapsigargin or high-dose palmitic acid had significantly reduced mitochondrial activity, reduced in vitro fertilization rates, and were slower to develop to blastocysts. The deficiencies in protein secretion, mitochondrial activity, and oocyte developmental competence were each normalized by salubrinal, demonstrating that ER stress is a key mechanism mediating fatty acid-induced defects in oocyte developmental potential.
authors.affiliation: The Robinson Institute, School of Paediatrics and Reproductive Health, Research Centre for Reproductive Health, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Linda L
authors.initials: LL
authors.lastname: Wu
authors.forename: Darryl L
authors.initials: DL
authors.lastname: Russell
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Norman
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Robker
mesh_terms: D000818:Animals; D002097:C-Reactive Protein / Q000378:metabolism*; D002478:Cells, Cultured; D002934:Cinnamates / Q000494:pharmacology; D054885:Cumulus Cells / Q000166:cytology / Q000378:metabolism*; D046149:Embryo Culture Techniques; D047108:Embryonic Development; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D005260:Female; D005307:Fertilization in Vitro / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D019308:Palmitic Acid / Q000494:pharmacology; D000683:Serum Amyloid P-Component / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology; D000099153:Pentraxins
chemical_list: D002097:C-Reactive Protein; D002934:Cinnamates; D000091342:Endoplasmic Reticulum Chaperone BiP; D019308:Palmitic Acid; D000683:Serum Amyloid P-Component; D019284:Thapsigargin; D013890:Thiourea; D000099153:Pentraxins; C000717248:Hspa5 protein, mouse; C496827:salubrinal