Novel long-range regulatory mechanisms controlling PKD2 gene expression

Transcription factor FoxM1 promotes cyst growth in PKD1 mutant ADPKD

Autosomal dominant polycystic kidney disease (ADPKD) is driven by mutations in the PKD1 and PKD2 genes, and it is characterized by renal cyst formation, inflammation and fibrosis. Forkhead box protein M1 (FoxM1), a transcription factor of the Forkhead box (Fox) protein super family, has been reported to promote tumor formation, inflammation and fibrosis in many organs. However, the role and mechanism of FoxM1 in regulation of ADPKD progression is still poorly understood. Here, we show that FoxM1 is an important regulator of cyst growth in ADPKD. FoxM1 is upregulated in cyst-lining epithelial cells in Pkd1 mutant mouse kidneys and human ADPKD kidneys. FoxM1 promotes cystic renal epithelial cell proliferation by increasing the expression of Akt and Stat3 and the activation of ERK and Rb. FoxM1 also regulates cystic renal epithelial cell apoptosis through NF-κB signaling pathways. In addition, FoxM1 regulates the recruitment and retention of macrophages in Pkd1 mutant mouse kidneys, a process that is associated with FoxM1-mediated upregulation of monocyte chemotactic protein 1. Targeting FoxM1 with its specific inhibitor, FDI-6, delays cyst growth in rapidly progressing and slowly progressing Pkd1 mutant mouse kidneys. This study suggests that FoxM1 is a central and upstream regulator of ADPKD pathogenesis and provides a rationale for targeting FoxM1 as a therapeutic strategy for ADPKD treatment.

Silencing of long non-coding RNA H19 downregulates CTCF to protect against atherosclerosis by upregulating PKD1 expression in ApoE knockout mice

This study aimed to explore the interactions among long non-coding RNA H19, transcriptional factor CCCTC-binding factor (CTCF) and polycystic kidney disease 1 (PKD1), and to investigate its potentially regulatory effect on vulnerable plaque formation and angiogenesis of atherosclerosis. We established an atherosclerosis mouse model in ApoE knockout mice, followed by gain- and loss-of-function approaches. H19 was upregulated in aortic tissues of atherosclerosis mice, but silencing of H19 significantly inhibited atherosclerotic vulnerable plaque formation and intraplaque angiogenesis, accompanied by a downregulated expression of MMP-2, VEGF, and p53 and an upregulated expression of TIMP-1. Moreover, opposite results were found in the aortic tissues of atherosclerosis mice treated with H19 or CTCF overexpression. H19 was capable of recruiting CTCF to suppress PKD1, thus promoting atherosclerotic vulnerable plaque formation and intraplaque angiogenesis in atherosclerosis mice. The present study provides evidence that H19 recruits CTCF to downregulate the expression of PKD1, thereby promoting vulnerable plaque formation and intraplaque angiogenesis in mice with atherosclerosis.

Characterization of GJB2 cis-regulatory elements in the DFNB1 locus

Although most disease-causing variants are within coding region of genes, it is now well established that cis-acting regulatory sequences, depending on 3D-chromatin organization, are required for temporal and spatial control of gene expression. Disruptions of such regulatory elements and/or chromatin conformation are likely to play a critical role in human genetic disease. Hence, recurrent monoallelic cases, who present the most common hereditary type of nonsyndromic hearing loss (i.e., DFNB1), carry only one identified pathogenic allele. This strongly suggests the presence of uncharacterized distal cis-acting elements in the missing allele. Here within, we study the spatial organization of a large DFNB1 locus encompassing the gap junction protein beta 2 (GJB2) gene, the most frequently mutated gene in this inherited hearing loss phenotype, with the chromosome conformation capture carbon copy technology (5C). By combining this approach with functional activity reporter assays and mapping of CCCTC-binding factor (CTCF) along the DFNB1 locus, we identify a novel set of cooperating GJB2 cis-acting elements and suggest a DFNB1 three-dimensional looping regulation model.