RESUMO
The hypoxic microenvironment that occurs in fast-growing tissue such as the corpus luteum (CL) is a major contributor to its ability to survive via the induction of an intricate vascular network. Cellular responses to hypoxia are mediated by hypoxia-inducible factor-1 (HIF-1), an oxygen-regulated transcriptional activator. HIF-1, a heterodimer consisting of a constitutively-expressed ß subunit and an oxygen-regulated α subunit, binds to the hypoxia responsive element (HRE) present in the promoter regions of responsive genes. This review summarises evidence for the involvement of hypoxia and HIF-1α in CL development and function. Special emphasis is given to hypoxia-induced, luteal cell-specific expression of multiple genes (vascular endothelial growth factor A (VEGFA), fibroblast growth factor 2 (FGF-2), prokineticin receptor 2 (PK-R2), stanniocalcin 1 (STC-1) and endothelin 2 (EDN-2) that participate in the angiogenic process during CL formation.
Assuntos
Hipóxia Celular/fisiologia , Corpo Lúteo/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Fator 1 Induzível por Hipóxia/metabolismo , Neovascularização Fisiológica/fisiologia , Ovário/irrigação sanguínea , Ovário/embriologia , Corpo Lúteo/embriologia , Endotelina-2/metabolismo , Feminino , Fator 2 de Crescimento de Fibroblastos/metabolismo , Hormônios Gastrointestinais/metabolismo , Glicoproteínas/metabolismo , Humanos , Modelos Biológicos , Neovascularização Fisiológica/genética , Neuropeptídeos/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
We recently compared prostaglandin F2alpha (PG)-induced global gene expression profiles in PG-refractory, bovine corpus luteum (CL) collected on Day 4 of the estrous cycle, versus PG-responsive, Day 11 CL. Transcriptome analyses led us to study the regulation of angiogenesis-related genes by PG and their functions in luteal endothelial cells (ECs). We found that PG regulated angiogenesis-modulating factors in a luteal stage-dependent way. A robust increase in FGF2 expression (mRNA and protein) occurred in the PG-refractory Day 4 CL promoting CL survival and function. Inhibitors of FGF2 action, thrombospondin 1 and 2, their receptor (CD36), and PTX3 were upregulated by PG specifically in Day 11 CL undergoing luteolysis. VEGF mRNA decreased 4 h post-PG in both Day 4 and Day 11 CL. The resulting destabilization of blood vessels in Day 11 CL is expected to weaken the gland and reduce its hormonal output. These genes were expressed in dispersed luteal ECs and steroidogenic cells; however, thrombospondin 1 and FGF2 were more abundant in luteal ECs. Expression of such genes and their ability to modulate FGF2 actions were investigated. Similar to its in vivo effect, PG, in vitro, stimulated the expression of thrombospondins and PTX3 genes in several luteal cell models. Importantly, these factors influenced the angiogenic properties of luteal ECs. FGF2 dose-dependently enhanced cell migration and proliferation, whereas thrombospondin 1 and PTX3 inhibited FGF2 actions in luteal ECs. Collectively, the data presented here suggest that, by tilting the balance between pro- and antiangiogenic factors, PG can potentially control the ability of the CL to resist or advance toward luteolysis.
Assuntos
Bovinos/fisiologia , Corpo Lúteo/fisiologia , Dinoprosta/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Luteólise/fisiologia , Neovascularização Fisiológica/fisiologia , Animais , Proteína C-Reativa/genética , Proteína C-Reativa/fisiologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Feminino , Fator 2 de Crescimento de Fibroblastos/genética , Fator 2 de Crescimento de Fibroblastos/fisiologia , Regulação da Expressão Gênica/fisiologia , Fase Luteal/fisiologia , Modelos Animais , Componente Amiloide P Sérico/genética , Componente Amiloide P Sérico/fisiologia , Trombospondina 1/genética , Trombospondina 1/fisiologia , Trombospondinas/genética , Trombospondinas/fisiologiaRESUMO
The objective of this study was to identify prostaglandin F(2α) (PG)-induced changes in the transcriptome of bovine corpora lutea (CL) that are specific to mature, PG-responsive (day 11) CL vs. developing (day 4) CL, which do not undergo luteolysis in response to PG administration. CL were collected at 0, 4, and 24 h after PG injection on days 4 and 11 of the estrous cycle (n = 5 per day and time point), and microarray analysis was performed with GeneChip Bovine Genome Arrays. Data normalization was performed with affy package and significance testing with maanova from Bioconductor. Significance (relative to 0 h time point) was declared at fold change >2.0 or <0.5 and false discovery rate of <5%. At 4 and 24 h after PG, 221 (day 4) and 661 (day 11) and 248 (day 4) and 1,421 (day 11) regulated genes, respectively, were identified. The accentuated gene expression response in day 11 CL was accompanied by specific enrichment of PG-regulated genes in distinctive gene ontology categories (immune related and other), particularly at 24 h after injection. Specificity in putative transcription factor binding sites was observed among PG-regulated genes on day 11 vs. day 4, including a potential association of ETS transcription factors with acute PG-induced gene expression specific to day 11 CL. Temporal and PG-induced regulation of abundance of mRNA for ETS transcription factor family members linked to the stage-specific response to PG was not observed. Increased abundance of protein and/or mRNA for six PG-regulated putative ETS-responsive genes was noted in day 11 but not day 4 CL. Results reveal insight into stage-specific gene expression in bovine CL in response to PG and potential transcriptional mediators of luteolysis.