title: Incidence of apoptosis and transcript abundance in bovine follicular cells is associated with the quality of the enclosed oocyte.
abstract: The close contact and interaction between the oocyte and the follicular environment influence the establishment of oocyte developmental competence. Moreover, it is assumed that apoptosis in the follicular cells has a beneficial influence on the developmental competence of oocytes. The aim of this study was to investigate whether bovine oocytes with varied developmental competence show differences in the degree of apoptosis and gene expression pattern in their surrounding follicular cells (cumulus and granulosa cells). Oocytes and follicular cells from follicles of 3 to 5 mm in diameter were grouped as brilliant cresyl blue (BCB)+ and BCB- based on glucose-6-phosphate dehydrogenase (G6PDH) activity in the ooplasm by BCB staining. In the follicular cells initial, early and late apoptotic events were assessed by analyzing caspase-3 activity, annexin-V and TUNEL, respectively. Global gene expression was investigated in immature oocytes and corresponding follicular cells. BCB+ oocytes resulted in a higher blastocyst rate (19.3%) compared to the BCB- group (7.4%, P < 0.05). Moreover, the analysis of apoptosis showed a higher caspase-3 activity in the follicular cells and an increased degree of late apoptotic events in granulosa cells in the BCB+ compared with the BCB- group. Additionally, the global gene expression profile revealed a total of 34 and 37 differentially expressed genes between BCB+ and BCB- cumulus cells and granulosa cells, respectively, whereas 207 genes showed an altered transcript abundance between BCB+ and BCB- oocytes. Among these, EIF3F, RARRES2, RNF34, ACTA1, GSTA1, EIF3A, VIM and CS gene transcripts were most highly enriched in the BCB+ oocytes, whereas OLFM1, LINGO1, ALDH1A3, PTHLH, BTN3A3, MRPS2 and PPM1K were most significantly reduced in these cells. Therefore, the follicular cells enclosing developmentally competent oocytes show a higher level of apoptosis and a different pattern of gene expression compared to follicular cells enclosing non-competent bovine oocytes.
authors.affiliation: Leibniz Institute for Farm Animal Biology, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany. janowski@fbn-dummerstorf.de
authors.forename: D
authors.initials: D
authors.lastname: Janowski
authors.forename: D
authors.initials: D
authors.lastname: Salilew-Wondim
authors.forename: H
authors.initials: H
authors.lastname: Torner
authors.forename: D
authors.initials: D
authors.lastname: Tesfaye
authors.forename: N
authors.initials: N
authors.lastname: Ghanem
authors.forename: W
authors.initials: W
authors.lastname: Tomek
authors.forename: A
authors.initials: A
authors.lastname: El-Sayed
authors.forename: K
authors.initials: K
authors.lastname: Schellander
authors.forename: M
authors.initials: M
authors.lastname: Hölker
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000032:analysis; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002417:Cattle; D002469:Cell Separation; D004396:Coloring Agents; D054885:Cumulus Cells / Q000737:chemistry / Q000201:enzymology / Q000502:physiology*; D005260:Female; D020869:Gene Expression Profiling / Q000662:veterinary*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D006107:Granulosa Cells / Q000737:chemistry / Q000201:enzymology / Q000502:physiology*; D020287:In Situ Nick-End Labeling; D009865:Oocytes / Q000737:chemistry / Q000201:enzymology / Q000502:physiology*; D010078:Oxazines; D012333:RNA, Messenger / Q000032:analysis; D013194:Staining and Labeling
chemical_list: D017304:Annexin A5; D004396:Coloring Agents; D010078:Oxazines; D012333:RNA, Messenger; C006797:Brilliant Cresyl Blue; D005954:Glucosephosphate Dehydrogenase; D053148:Caspase 3