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This Article Full Text (PDF) All Versions of this Article: jas.2008-1222v1 87/6/1921    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Grado-Ahuir, J. A. Articles by Spicer, L. J. Search for Related Content PubMed PubMed Citation Articles by Grado-Ahuir, J. A. Articles by Spicer, L. J.

Microarray analysis of insulin-like growth factor-I-induced changes in mRNA expression in cultured porcine granulosa cells: Possible role of IGF-I in angiogenesis

Juan A. Grado-Ahuir^*, Pauline Y. Aad^*, Giovanni Ranzenigo, Francesca Caloni, Fausto Cremonesi and Leon J. Spicer^*

^* Department of Animal Science, Oklahoma State University, Stillwater, OK 74078 , Department of Veterinary Clinical Science Department of Veterinary Sciences and Technologies for Food Safety, University of Milan, via Celoria, 10 20133 Milan, Italy

leon.spicer{at}okstate.edu

Abstract

IGF-I in conjunction with gonadotropins are important stimulators of mitosis and ovarian steroid production by granulosa and thecal cells, which are required for normal oocyte development and hormonal feedback signaling to the hypothalamus and pituitary. However, a comprehensive evaluation of the changes in gene expression induced by IGF-I has not been conducted. Our objective was to characterize granulosa cell gene expression in response to IGF-I treatment. Porcine granulosa cells were pooled in 4 biological replicates and treated with FSH (baseline) or FSH+IGF-I for 24 h in vitro. The RNA was collected and hybridized to 8 Affymetrix Porcine GeneChips (Affymetrix, Santa Clara, CA) in a paired design. Differentially regulated gene sequence element sets (P < 0.01) were used as queries in the UniGene database searching for annotated genes. Abundance of mRNA for genes differentially expressed in the microarray analysis was determined through multiplex assays of one-step real-time RT-PCR and further analyzed under a statistical model including the fixed effect of treatment. A total of 388 gene sequence element sets were differentially expressed and 42 matched annotated genes in the UniGene database. Of the 3 upregulated target genes selected for further quantitative RT-PCR analysis, only FGF receptor 2 III c (FGFR2IIIc) mRNA abundance was significantly increased by IGF-I. Of the 3 down-regulated target genes selected for further analysis, only thrombospondin-1 (THBS1) mRNA abundance was significantly decreased by IGF-I. Further study revealed that neither FSH nor estradiol affected the IGF-I-induced suppression of THBS1 mRNA abundance. These results provide the first comprehensive assessment of IGF-I-induced gene expression in granulosa cells and will contribute to a better understanding of the molecular mechanisms of IGF-I regulation of follicular development. Involvement of FGFR2IIIc and THBS1 in mediating IGF-I-induced granulosa cell steroidogenesis and proliferation during follicular development is novel, but their specific roles will require further elucidation.

Key Words: gene expression • granulosa cells • IGF-I • pigs • Thrombospondin-1