title: Characterization of the constitutive pig ovary heat shock chaperone machinery and its response to acute thermal stress or to seasonal variations.
abstract: Reduced oocyte competence causes the lower fertility reported in domestic sows during the warm months of the year. Somatic cells express heat shock proteins (HSPs) to protect themselves from damage caused by thermal stress. HSPs are classified as molecular chaperones and control the correct folding of newly synthesized or damaged proteins. The present work performed a comprehensive survey of the different components of the heat shock chaperone machinery in the pig ovary, which included the HSP40, HSP70, HSP90, and HSP110 families, as well as heat shock factors (HSF) 1 and 2. Pig ovarian follicles constitutively expressed different members of these families; therefore, we examined their ability to respond to heat stress. In order to take into account the role of the complex follicular architecture, whole pig ovaries were exposed to 41.5°C for 1 h. This exposure significantly disrupted oocyte maturation and determined the upregulation of the HSP70, HSP40, HSPH1, HSPA4, HSPA4L, HSF1, and HFS2 genes, whereas expression levels of HSP90A and HSP90B, as well as those of genes unrelated to heat stress were not altered. Unexpectedly HSP and HSF expression levels changed only in oocytes but not in cumulus cells. Cumulus-oocyte complexes isolated from ovaries collected in summer showed the same pattern as those collected in winter. We conclude that the HSP chaperone machinery is constitutively fully operational in the pig ovary. However, following thermal stimuli or seasonal variations, cumulus cell HS-related gene expression remains unchanged, and only oocytes activate a response, suggesting why this mechanism is insufficient to preserve their competence both in vitro and in vivo.
authors.affiliation: Laboratory of Biomedical Embryology, Department of Health, Animal Science and Food Safety, Università degli Studi di Milano, Milan, Italy.
authors.forename: Georgia
authors.initials: G
authors.lastname: Pennarossa
authors.forename: Sara
authors.initials: S
authors.lastname: Maffei
authors.forename: Mahbubur M
authors.initials: MM
authors.lastname: Rahman
authors.forename: Giovanna
authors.initials: G
authors.lastname: Berruti
authors.forename: Tiziana A L
authors.initials: TA
authors.lastname: Brevini
authors.forename: Fulvio
authors.initials: F
authors.lastname: Gandolfi
mesh_terms: D000818:Animals; D005260:Female; D005786:Gene Expression Regulation; D050957:HSP110 Heat-Shock Proteins / Q000032:analysis / Q000235:genetics; D050956:HSP40 Heat-Shock Proteins / Q000032:analysis / Q000235:genetics; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis / Q000235:genetics; D018841:HSP90 Heat-Shock Proteins / Q000032:analysis / Q000235:genetics; D006360:Heat-Shock Proteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D006358:Hot Temperature; D018832:Molecular Chaperones; D010053:Ovary / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D012621:Seasons; D034421:Sus scrofa; D014157:Transcription Factors / Q000235:genetics; D015854:Up-Regulation
chemical_list: D050957:HSP110 Heat-Shock Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D012333:RNA, Messenger; D014157:Transcription Factors