Interferon-γ biphasically regulates angiotensinogen expression via a JAK-STAT pathway and suppressor of cytokine signaling 1 (SOCS1) in renal proximal tubular cells.

Abstract

Renal inflammation modulates angiotensinogen (AGT) production in renal proximal tubular cells (RPTCs) via inflammatory cytokines, including interleukin-6, tumor necrosis factor α, and interferon-γ (IFN-γ). Among these, the effects of IFN-γ on AGT regulation in RPTCs are incompletely delineated. This study aimed to elucidate mechanisms by which IFN-γ regulates AGT expression in RPTCs. RPTCs were incubated with or without IFN-γ up to 48 h. AGT expression, STAT1 and STAT3 activities, and SOCS1 expression were evaluated. RNA interference studies against STAT1, SOCS1, and STAT3 were performed to elucidate a signaling cascade. IFN-γ decreased AGT expression at 6 h (0.61±0.05, ratio to control) and 12 h (0.47±0.03). In contrast, longer exposure for 24 and 48 h increased AGT expression (1.76±0.18, EC(50)=3.4 ng/ml, and 1.45±0.08, respectively). IFN-γ treatment for 6 h strongly induced STAT1 phosphorylation and SOCS1 augmentation, and decreased STAT3 activity. However, STAT1 phosphorylation and SOCS1 augmentation waned at 24 h, while STAT3 activity increased. RNA interference studies revealed that activation of STAT1-SOCS1 axis decreased STAT3 activity. Thus, IFN-γ biphasically regulates AGT expression in RPTCs via STAT3 activity modulated by STAT1-SOCS1 axis, suggesting the STAT1-SOCS1 axis is important in IFN-γ-induced activation of the intrarenal renin-angiotensin system.

• Authors: Ryousuke Satou, Kayoko Miyata, Romer A Gonzalez-Villalobos, Julie R Ingelfinger, L Gabriel Navar, Hiroyuki Kobori
• Journal: FASEB journal : official publication of the Federation of American Societies for Experimental Biology (FASEB J) Vol. 26 Issue 5 Pg. 1821-30 (May 2012) ISSN: 1530-6860 [Electronic] United States
• PMID: 22302831 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• RNA, Small Interfering
• STAT1 Transcription Factor
• STAT3 Transcription Factor
• Socs1 protein, rat
• Stat1 protein, rat
• Stat3 protein, rat
• Suppressor of Cytokine Signaling 1 Protein
• Suppressor of Cytokine Signaling Proteins
• Angiotensinogen
• Interferon-gamma
• Janus Kinases

Topics

• Angiotensinogen (genetics)
• Animals
• Base Sequence
• Cell Line, Transformed
• Electrophoretic Mobility Shift Assay
• Enzyme-Linked Immunosorbent Assay
• Interferon-gamma (physiology)
• Janus Kinases (metabolism)
• Kidney Tubules, Proximal (cytology, metabolism)
• Phosphorylation
• RNA Interference
• RNA, Small Interfering
• Rats
• Real-Time Polymerase Chain Reaction
• STAT1 Transcription Factor (metabolism)
• STAT3 Transcription Factor (metabolism)
• Suppressor of Cytokine Signaling 1 Protein
• Suppressor of Cytokine Signaling Proteins (physiology)