Heat stress induces distinct responses in porcine cumulus cells and oocytes associated with disrupted gap junction and trans-zonal projection colocalization.
Cumulus cells (CCs), the granulosa cells surrounding the oocytes, play critical roles in oocytes maturation through intercellular communication by extending trans-zonal projections (TZPs) to contact oocytes via gap junctions (GJs). The adverse effect of heat stress (HS) on oocyte maturation has been well documented, whereas the HS responses of CCs and the oocytes in association with GJ/TZP colocalization remain unclear. In this study, porcine cumulus-oocyte complexes (COCs) were subjected to HS at 41.5°C for 24 hr during in vitro maturation. Cumulus expansion was impaired and oocyte quality was reduced with lower survival rate, polar body extrusion rate, and early embryo developmental potentials. CCs and oocytes isolated from COCs demonstrated distinct responses to HS. The messenger RNA abundance of heat shock protein-related genes and mitochondrial DNA-encoded genes, together with ATP content, were significantly increased in CCs, yet decreased in oocytes, despite activation of caspase 3 detected in both CCs and oocytes. Similar changes were observed when denuded oocytes and isolated CCs subjected to HS separately, except mitochondria reactive oxygen species (mROS). In heat-stressed COCs, mROS was significantly increased only in oocytes. However, when isolated CCs and denuded oocytes were heat-stressed separately, mROS was significantly increased only in CCs. Moreover, F-actin, a TZP marker, and its colocalization with a GJ protein connexin-45, were significantly reduced in heat-exposed COCs. These results indicate that HS induces distinct responses in porcine CCs and oocytes in association with disrupted GJ and TZP colocalization.
['Yin|Chao|C|', 'Liu|Jie|J|', 'He|Bin|B|0000-0001-8019-8480', 'Jia|Longfei|L|', 'Gong|Yabin|Y|', 'Guo|Huiduo|H|', 'Zhao|Ruqian|R|0000-0002-7337-8173']
D000199:Actins D000255:Adenosine Triphosphate D000818:Animals D002450:Cell Communication D017630:Connexins D054885:Cumulus Cells D004272:DNA, Mitochondrial D005260:Female D017629:Gap Junctions D006360:Heat-Shock Proteins D018869:Heat-Shock Response D006358:Hot Temperature D059471:In Vitro Oocyte Maturation Techniques D008928:Mitochondria D009865:Oocytes D017382:Reactive Oxygen Species D015398:Signal Transduction D034421:Sus scrofa
heat stress cumulus cell oocyte ATP heat shock protein mitochondrial reactive oxygen species sow