A novel identified circular RNA, circ_0000491, aggravates the extracellular matrix of diabetic nephropathy glomerular mesangial cells through suppressing miR­101b by targeting TGFßRI.

Circular RNAs (circRNAs) have crucial roles in various diseases; however, the mechanisms of action underlying circRNAs in the occurrence and development of diabetic nephropathy (DN) remains largely unknown. The present study investigated the differentially expressed circRNAs in the DN mice kidney cortex using circRNA sequencing and elucidated the role of circRNAs in mesangial cells. It was revealed that 40 circRNAs were unconventionally expressed, including 18 upregulated circRNAs and 22 downregulated circRNAs. Furthermore, circ_0000491 levels were significantly augmented in both DN mice and high glucose (HG, 30 mM)­induced mouse mesangial cells (MES13 cells). Knockdown of circ_0000491 significantly suppressed the increase of vimentin, fibronectin and α­smooth muscle actin, as well as collagen type I, III and IV, whilst reversing the decrease of E­cadherin in HG­induced MES13 cells. It was further revealed that circRNA_0000491 sponged miR­101b and that miR­101b directly targets TGFßRI. In addition, the expression levels of miR­101b were negatively associated with the transcriptional level of circRNA_0000491 and miR­101b inhibitors reversed the suppression of extracellular matrix (ECM)­associated protein synthesis mediated by knocking­down circRNA_0000491. In conclusion, the present study investigated the circRNA_0000491/miR­101b/TGFßRI axis in ECM accumulation and fibrosis­associated protein expression levels of mesangial cells, which suggested that circRNA_0000491 may be beneficial for the development of an effective therapeutic target for DN.

Antidepressants induce profibrotic responses via the lysophosphatidic acid receptor LPA1.

Preclinical and clinical studies have indicated that antidepressants can promote inflammation and fibrogenesis, particularly in the lung, by mechanisms not fully elucidated. We have previously shown that different classes of antidepressants can activate the lysophosphatidic acid (LPA) receptor LPA1, a major pathogenetic mediator of tissue fibrosis. The aim of the present study was to investigate whether in cultured human dermal and lung fibroblasts antidepressants could trigger LPA1-mediated profibrotic responses. In both cell types amitriptyline, clomipramine and mianserin mimicked the ability of LPA to induce the phosphorylation/activation of extracellular signal -regulated kinases 1 and 2 (ERK1/2), which was blocked by the selective LPA1 receptor antagonist AM966 and the LPA1/3 antagonist Ki16425. Antidepressant-induced ERK1/2 stimulation was absent in fibroblasts stably depleted of LPA1 by short hairpin RNA transfection and was prevented by pertussis toxin, an uncoupler of receptors from Gi/o proteins. Like LPA, antidepressants stimulated fibroblasts proliferation and this effect was blocked by either AM966 or the MEK1/2 inhibitor PD98059. Moreover, by acting through LPA1 antidepressants induced the expression of α-smooth muscle actin (α-SMA), a marker of myofibroblast differentiation, and caused an ERK1/2-dependent increase in the cellular levels of transforming growth factor-ß (TGF-ß)1, a potent fibrogenic cytokine. Pharmacological blockade of TGF-ß receptor type 1 prevented antidepressant- and LPA-induced α-SMA expression. These data indicate that in human dermal and lung fibroblasts different antidepressants can induce proliferative and differentiating responses by activating the LPA1 receptor coupled to ERK1/2 signalling and suggest that this property may contribute to the promotion of tissue fibrosis by these drugs.

Synthesis and evaluation of the HIF-1α inhibitory activity of 3(5)-substituted-4-(quinolin-4-yl)- and 4-(2-phenylpyridin-4-yl)pyrazoles as inhibitors of ALK5.

The transcription factor hypoxia-inducible factor-1α (HIF-1α) plays an important role in apoptosis, metastasis, and proliferation and is recognized as an important potential therapeutic target for cancer. Six series of 3(5)-(6-methylpyridin-2-yl)-4-(quinolin-4-yl)pyrazoles (11a-d, 12a-d, and 18a-d) and 3(5)-(6-methylpyridin-2-yl)-4-(2-phenyl-pyridin-4-yl)pyrazoles (19a-d, 20a-d, and 21a-d) were synthesized and evaluated for activin receptor-like kinase 5 (ALK5) and HIF-1α inhibitory activity at the enzyme and cell levels. The effect of the lead compound 20d (J-1012) on HIF-1α activation in HCT116 cells was investigated. J-1012 markedly decreased the hypoxia-induced or TNF-induced accumulation of HIF-1α protein dose-dependently. Analysis revealed that J-1012 inhibited HIF-1α protein synthesis, without affecting the degradation of HIF-1α protein. Furthermore, by inhibiting the activation of HIF-1α, J-1012 suppressed the metastasis and proliferation and promoted apoptosis of HCT116 cells. These results suggest that J-1012 may be a potential therapeutic agent against human colon cancer.

Proprotein convertase furin inhibits matrix metalloproteinase 13 in a TGFß-dependent manner and limits osteoarthritis in mice.

Cartilage loss in osteoarthritis (OA) results from altered local production of growth factors and metalloproteases (MMPs). Furin, an enzyme involved in the protein maturation of MMPs, might regulate chondrocyte function. Here, we tested the effect of furin on chondrocyte catabolism and the development of OA. In primary chondrocytes, furin reduced the expression of MMP-13, which was reversed by treatment with the furin inhibitor α1-PDX. Furin also promoted the activation of Smad3 signaling, whereas activin receptor-like kinase 5 (ALK5) knockdown mitigated the effects of furin on MMP-13 expression. Mice underwent destabilization of the medial meniscus (DMM) to induce OA, then received furin (1 U/mice), α1-PDX (14 µg/mice) or vehicle. In mice with DMM, the OA score was lower with furin than vehicle treatment (6.42 ± 0.75 vs 9.16 ± 0.6, p < 0.01), and the number of MMP-13(+) chondrocytes was lower (4.96 ± 0.60% vs 20.96 ± 8.49%, p < 0.05). Moreover, furin prevented the increase in ALK1/ALK5 ratio in cartilage induced by OA. Conversely, α1-PDX had no effect on OA cartilage structure. These results support a protective role for furin in OA by maintaining ALK5 receptor levels and reducing MMP-13 expression. Therefore, furin might be a potential target mediating the development of OA.