Sonic Hedgehog Is a Novel Tubule-Derived Growth Factor for... : Journal of the American Society of Nephrology (original) (raw)

Basic Research

Sonic Hedgehog Is a Novel Tubule-Derived Growth Factor for Interstitial Fibroblasts after Kidney Injury

Zhou, Dong*; Li, Yingjian*; Zhou, Lili†; Tan, Roderick J.‡; Xiao, Liangxiang†; Liang, Min†; Hou, Fan Fan†; Liu, Youhua*,†

*Departments of Pathology, and

‡Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and

†State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University and Guangdong Provincial Institute of Nephrology, Guangzhou, China

Correspondence: Dr. Youhua Liu, Department of Pathology, University of Pittsburgh, S-405 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261. Email: [email protected]

Received August 26, 2013

Accepted January 16, 2014

Abstract

Tubular epithelium constitutes the majority of the renal parenchyma and is the primary target of various kidney injuries. However, how the injured tubules drive interstitial fibroblast activation and proliferation remains poorly understood. Here, we investigated the role of sonic hedgehog (Shh), a secreted extracellular signaling protein, in fibroblast proliferation. Shh was induced in renal tubular epithelia in animal models of CKD induced by ischemia/reperfusion injury (IRI), adriamycin, or renal mass ablation, and in renal tubules of kidney biopsy specimens from CKD patients with different etiologies. Using Gli1-CreERT2 reporter mice, we identified interstitial fibroblasts as the principal targets of renal Shh signaling in vivo. In vitro, incubation with Shh promoted normal rat kidney fibroblast proliferation, which was assessed by cell counting, MTT assay, and BrdU incorporation assay, and stimulated the induction of numerous proliferation-related genes. However, Shh had no effect on the proliferation of renal tubular epithelial cells. In vivo, overexpression of Shh promoted fibroblast expansion and aggravated kidney fibrotic lesions after IRI. Correspondingly, blockade of Shh signaling by cyclopamine, a small molecule inhibitor of Smoothened, inhibited fibroblast proliferation, reduced myofibroblast accumulation, and attenuated renal fibrosis. These studies identify Shh as a novel, specific, and potent tubule-derived growth factor that promotes interstitial fibroblast proliferation and activation. Our data also suggest that blockade of Shh signaling is a plausible strategy for therapeutic intervention of renal fibrosis.