Kidney Week

Abstract: TH-PO928

Regulation of Renal Fibroblast Migration, Contraction, and Myofibroblast Differentiation by LPA-LPA1 Signaling via Specific G Proteins

Session Information

• Molecular Mechanisms of CKD - I
  October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

• 1903 CKD (Non-Dialysis): Mechanisms

Authors

• Sakai, Norihiko, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Norihiko Sakai,

• Sato, Koichi, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Koichi Sato,

• Miyake, Taito, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Taito Miyake,

• Sagara, Akihiro, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Akihiro Sagara,

• Kitajima, Shinji, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Shinji Kitajima,

• Toyama, Tadashi, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Tadashi Toyama,

• Hara, Akinori, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Akinori Hara,

• Iwata, Yasunori, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Yasunori Iwata,

• Shimizu, Miho, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Miho Shimizu,

• Furuichi, Kengo, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Kengo Furuichi,

• Wada, Takashi, Kanazawa University, Kanazawa, ISHIKAWA, Japan

Takashi Wada,

Background

Renal fibrosis is a common pathway leading to end-stage renal disease regardless of etiologies. Pathologically, tissue fibrosis is characterized by the accumulation of fibroblasts/myofibroblasts and the excessive deposition and contraction of extracellular matrix. We have previously found the lipid mediator lysophosphatidic acid (LPA) and one of its receptors, LPA₁, contributes to the development of renal fibrosis. However, the precise mechanisms by which LPA-LPA₁ signaling activates renal fibroblasts (RFBs) remain to be determined.

Methods

In this study, we focused on the direct effects of LPA-LPA₁ signaling on RFBs biologies, especially migration, contraction and myofibroblast differentiation. Cultured RFBs were used to examine cell migration, cell contraction and the expression of alpha smooth muscle actin (aSMA), a marker for myofibroblast differentiation, in response to LPA. RFBs were transfected with either LPA₁ siRNA or control siRNA to determine the impact of LPA₁ on RFBs biologies. In addition, we also investigated the involvement of G proteins in the LPA-LPA₁ signaling-associated biologies of RFBs.

Results

RFBs treated with control siRNA were attracted by LPA in a dose-dependent manner, whereas LPA did not stimulate LPA₁ siRNA-treated RFBs migration. In addition to RFBs migration, we also found that LPA directly induced cell contraction and aSMA gene expression by RFBs dependent on LPA₁. To determine the involvement of G proteins in the LPA-LPA₁ signaling, RFBs were transfected with siRNAs targeting G proteins. The chemotactic activity of LPA was significantly inhibited by siRNA treatment against Ga_i class of G proteins. In addition to that, pertussis toxin (an inhibitor of Ga_i) also blocked LPA-induced migration of RFBs. We also found that LPA-LPA₁ signaling enhanced cell contraction and aSMA expression through Ga_12/13 class of G proteins.

Conclusion

Our results suggest that LPA-LPA₁ signaling directly modulates RFBs biologies dependent on specific G proteins in the pathogenesis of renal fibrosis.

Funding

• Other U.S. Government Support