Intronic locus determines SHROOM3 expression and potentiates renal allograft fibrosis
Madhav C. Menon, … , John Cijiang He, Barbara Murphy
Madhav C. Menon, … , John Cijiang He, Barbara Murphy
Published December 1, 2014
Citation Information: J Clin Invest. 2015;125(1):208-221. https://doi.org/10.1172/JCI76902.
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Research Article Nephrology

Intronic locus determines SHROOM3 expression and potentiates renal allograft fibrosis

Abstract

Fibrosis underlies the loss of renal function in patients with chronic kidney disease (CKD) and in kidney transplant recipients with chronic allograft nephropathy (CAN). Here, we studied the effect of an intronic SNP in SHROOM3, which has previously been linked to CKD, on the development of CAN in a prospective cohort of renal allograft recipients. The presence of the rs17319721 allele at the SHROOM3 locus in the donor correlated with increased SHROOM3 expression in the allograft. In vitro, we determined that the sequence containing the risk allele at rs17319721 is a transcription factor 7–like 2–dependent (TCF7L2-dependent) enhancer element that functions to increase SHROOM3 transcription. In renal tubular cells, TGF-β1 administration upregulated SHROOM3 expression in a β-catenin/TCF7L2–mediated manner, while SHROOM3 in turn facilitated canonical TGF-β1 signaling and increased α1 collagen (COL1A1) expression. Inducible and tubular cell–specific knockdown of Shroom3 markedly abrogated interstitial fibrosis in mice with unilateral ureteric obstruction. Moreover, SHROOM3 expression in allografts at 3 months after transplant and the presence of the SHROOM3 risk allele in the donor correlated with increased allograft fibrosis and with reduced estimated glomerular filtration rate at 12 months after transplant. Our findings suggest that rs17319721 functions as a cis-acting expression quantitative trait locus of SHROOM3 that facilitates TGF-β1 signaling and contributes to allograft injury.

Authors

Madhav C. Menon, Peter Y. Chuang, Zhengzhe Li, Chengguo Wei, Weijia Zhang, Yi Luan, Zhengzi Yi, Huabao Xiong, Christopher Woytovich, Ilana Greene, Jessica Overbey, Ivy Rosales, Emilia Bagiella, Rong Chen, Meng Ma, Li Li, Wei Ding, Arjang Djamali, Millagros Saminego, Philip J. O’Connell, Lorenzo Gallon, Robert Colvin, Bernd Schroppel, John Cijiang He, Barbara Murphy

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Figure 1

The A allele of rs17319721 in the donor is associated with higher allograft SHROOM3 expression at 3 months and confers significantly higher CAN risk at 12 months.

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The A allele of rs17319721 in the donor is associated with higher allogr...
(A) Allele distribution at rs17319721 in Caucasian and non-Caucasian allograft donors and recipients in the GoCAR cohort, expressed as a percentage. ***P < 0.0001, χ2 test. (B) Allograft SHROOM3-3M, grouped according to donor genotype. *P < 0.05 among groups, ANOVA; P < 0.05, A/A vs. G/G, unpaired t test. (C) SHROOM3-3M in allografts with 1 or 2 copies of the risk allele (A/A or A/G) compared with those without the risk allele (G/G). The presence of the A allele in the donor was associated with significantly greater CADI-12≥2 risk in all allografts (OR, 1.98; CI, 1.10–3.59) and in live donor allografts of Caucasian origin (OR, 5.41; CI, 1.56–18.39) (see Supplemental Table 1). *P = 0.02, unpaired t test. (B and C) SHROOM3-3M values are presented as log-transformed fluorescence relative to normal preperfusion biopsies. Line represents median; boxes represent interquartile range; whiskers represent 5th to 95th percentile; individual dots represent outliers.