Reducing betaglycan expression by RNA interference (RNAi) attenuates inhibin bioactivity in LβT2 gonadotropes

Ruth M. Escalona, Kaye L. Stenvers, Paul G. Farnworth, Jock K. Findlay, Guck T. Ooi

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13 Citations (Scopus)

Abstract

Betaglycan is an inhibin-binding protein co-receptor, the forced expression of which confers inhibin responsiveness on cells previously non-responsive to inhibin. The present study determines whether removal of betaglycan expression in otherwise inhibin-responsive cells will render the cells insensitive to inhibin. Small interfering RNAs (siRNAs) designed to the betaglycan gene were transfected into LβT2 gonadotrope cells to 'knock-down' betaglycan expression. To control for non-specific effects, siRNAs corresponding to an unrelated sequence (BF-1) were used. Two activin-responsive promoter constructs were used to assess inhibin bioactivity; an ovine FSHβ promoter (oFSHβ-lux), and a construct containing three copies of the activin-responsive sequence from the GnRHR promoter (3XpGRAS-PRL-lux). Activin stimulated the activity of both promoters 5-8-fold. Inhibin suppressed these activin-stimulated promoter activities by 52 ± 11% and 51 ± 7%, respectively. Similar inhibin suppression was also seen for cells co-transfected with the control BF-1 siRNAs. In contrast, inhibin's ability to suppress activin-stimulated activity was significantly reduced (33 ± 3%, p <0.005 and 24 ± 4%, p <0.045, respectively) in cells co-transfected with betaglycan siRNAs. These results demonstrated that endocrine effects of inhibin as a negative feedback controller of FSH production in gonadotropes are dependent on betaglycan expression.

Original languageEnglish
Pages (from-to)149-156
Number of pages8
JournalMolecular and Cellular Endocrinology
Volume307
Issue number1-2
DOIs
Publication statusPublished - 13 Aug 2009

Keywords

  • Betaglycan
  • FSH
  • Inhibin
  • LβT2
  • Pituitary cells
  • siRNA

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