Left ventricular hypertrophy (LVH) is a common complication in patients with CKD and an independent risk factor for death. Changes in the levels of uremic solutes or Klotho have been reported to be related to CKD, whereas the relationships between these factors and CKD-associated LVH remain unclear. Here, we investigated the interaction between Klotho and indoxyl sulfate (IS), a typical uremic solute, in CKD-associated LVH. In a survey of 86 patients with CKD, a negative relationship was found between serum levels of IS and Klotho (r=20.59, P,0.001). Furthermore, serum levels of IS and Klotho were independently associated with LVH (for IS: r=0.69, P,0.001; for Klotho: r=20.49, P,0.001). In normal mice, intraperitoneal injection of IS for 8 weeks induced LVH accompanied by substantial downregulation of renal Klotho. Notably, IS-induced LVH was more severe in heterozygous Klotho-deficient (kl/+) mice. In vitro, treatment with Klotho strongly inhibited IS-induced cardiomyocyte hypertrophy by blocking oxidative stress and inhibiting p38 and extracellular signal-regulated protein kinase 1/2 signaling pathways. In a mouse model of CKD-associated LVH, the renal expression of Klotho was lower and the level of serum IS was higher than in healthy controls. Moreover, treatment of CKD mice with Klotho protein significantly restrained the development of LVH. Taken together, these results suggest that Klotho is an endogenous protector against IS-induced LVH, and the imbalance between Klotho and IS may contribute to the development of LVH in CKD.

We demonstrate by yeast two-hybrid, glutathione S-transferase pulldown, and mammalian reporter gene assays that ARNT requires its helix 2 domain but not its transactivation domain to interact with SRC-1. This indicates a novel mechanism of action for SRC-1. SRC-1 does not require its bHLH-PAS domain to interact with ARNT or AHR, but utilizes distinct domains proximal to its p300/CBP interaction domain. Taken together, these data support a role for the SRC family of transcriptional coactivators in TCDD-dependent gene regulation.

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Nuclear beta-catenin is a transcriptional coactivator of LEF-1/TCF DNA-binding proteins in the Wnt/Wg signaling pathway. Casein Kinase 2 (CK2), a positive regulator of Wnt signaling, is present in beta-catenin complexes and activated in Wnt-signaling cells. We show here that CK2 enhances beta-catenin:LEF-1 transactivation in vivo and in vitro and that beta-catenin and CK2 cycle on and off the DNA in an alternating manner with the TLE1 corepressor at Wnt target genes. Interestingly, CK2 phosphorylates hLEF-1 directly and stimulates binding and transactivation of beta-catenin:LEF-1 complexes on chromatin templates in vitro. In vitro, CK2 phosphorylation of hLEF-1 strongly enhances its affinity for beta-catenin and reduces its affinity for TLE1. MALDI-TOF mass spectrometry (MS) identified two CK2 phosphorylation sites (S42, S61) within the amino terminus of hLEF-1, and mutation of these sites reduced binding to beta-catenin in vitro and transactivation in vivo. Remarkably, treatment of cells with TBB, a pharmaceutical inhibitor of CK2, blocked the recruitment and cycling of beta-catenin and TLE1 at Wnt target genes in vivo. Taken together, these data indicate that CK2 is required for the assembly and cycling of Wnt-enhancer complexes in vivo.

Bladder cancer (BCa) is the one of the most common cancers with high incidence, occurrence and low 5-year survival rate. Emerging evidence indicates that DLK1-DIO3 genomic region especially the miRNA cluster in this region is involved in several pathologic processes and various cancers, and miR-323a-3p is a member of this miRNA cluster. In this study, we investigate the function and regulatory network of miR-323a-3p in BCa. miR-323a-3p is frequently downregulated in BCa tissues and three cell lines compared with adjacent non-tumorous tissues and bladder normal cell line (SV-HUC-1). Besides, downregulation of miR-323a-3p is significantly associated with poor overall survival rate of BCa. Methylation of DLK1-MEG3 intergenic DMR (IG-DMR) contributes to the reduction of miR-323a-3p. Overexpression of miR-323a-3p significantly inhibits the epithelial–mesenchymal transition (EMT) progression of BCa. Both upregulated MET and SMAD3 are direct targets of miR-323a-3p, and the knockdown of MET and SMAD3 also represses the EMT progression consistently with overexpression of miR-323a-3p. SNAIL is detected in the last targeted confocal protein of both MET and SMAD3 signaling that trigger EMT consequently. Hence, a miR-323a-3p/MET/SMAD3/SNAIL circuit is established to regulate the EMT progression of BCa. And a mutual regulatory mechanism between miR-323a-3p/miR-433/miR-409 and MET also participates in this circuit. In conclusion, our study demonstrates a novel regulatory mechanism of the miR-323a-3p/MET/SMAD3/SNAIL circuit that is involved in the EMT regulation of BCa, which may be a potential therapy target for BCa.