Cyclin D1 Gene Silencing Promotes IL‐1β‐Induced Apoptosis in Rat Chondrocytes

This study investigated the effects of cyclin D1 gene silencing on cell proliferation and apoptosis of interleukin‐1β (IL‐1β)‐induced osteoarthritis (OA) chondrocytes. Chondrocytes from healthy sprague‐dawley rats were divided into blank, OA model (chondrocytes underwent IL‐1β inducement), OA trial (chondrocytes underwent IL‐1β inducement with cyclin D1‐shRNA treatment), and negative control (NC; chondrocytes underwent IL‐1β inducement and control‐shRNA treatment) groups. Cell proliferation was assessed by CCK‐8 assay, and cell cycle and apoptosis by flow cytometry. qRT‐PCR and Western blotting were performed to detect cyclin D1 and apoptosis‐related factors expression levels. Chondrocyte proliferation increased after 72–96 h after incubation. The OA trial group exhibited reduced cell proliferation at 48, 72, and 96 h after treatment. The OA model, OA trial, and NC groups all contained more cells arrested in G1 phase and had higher apoptosis rates than the blank group. Additionally, the OA trial group contained more cells arrested in G1 phase, with increased apoptosis rates compared to the OA model and NC groups. The OA model group had lowest expression of cyclin D1 whereas the blank group contained the highest among the four groups. qRT‐PCR also showed that the OA model, OA trial, and NC groups all had increased expression levels of Bax and reduced expression levels of Bcl‐2 and P53 compared to the blank group, whereby by the OA group had the most significant change. The combined evidence in our study shows that cyclin D1 gene silencing suppresses proliferation and induces apoptosis of rat chondrocytes in IL‐1β‐induced OA. J. Cell. Biochem. 119: 290–299, 2018. © 2017 Wiley Periodicals, Inc.     

β‐Hairpin stabilization in a 28‐residue peptide derived from the β‐subunit sequence of human chorionic gonadotropin hormone

The β‐subunit of the human chorionic gonadotropin (hCG) hormone, which is believed to be related to certain types of cancer, contains three hairpin‐like fragments. To investigate the role of β‐hairpin formation in the early stages of the hCGβ folding, a 28‐residue peptide with the sequence RDVRFESIRLPGSPRGVNPVVSYAVALS, corresponding to the H3‐β hairpin fragment (residues 60–87) of the hCGβ subunit, was studied under various conditions using three optical spectroscopic methods: Fourier transform ir spectroscopy, electronic CD, and vibrational CD. Environmental conditions are critical factors for formation of secondary structure in this peptide. TFE : H₂O mixed solvents induced helical formation. Formation of β‐structure in this peptide, which may be related to the native β‐hairpin formation in the intact hormone, was found to be induced only under conditions such as high concentration, high temperature, and the presence of nonmicellar sodium dodecyl sulfate concentrations. These findings support a protein folding mechanism for the hCGβ subunit in which an initial hydrophobic collapse, which increases intermolecular interactions in hCGβ, is needed to induce the H3‐β hairpin formation. © 1999 John Wiley & Sons, Inc. Biopoly 50: 413–423, 1999     

Syntheses and anti‐tubercular activity of β‐substituted and α,β‐disubstituted peptidyl β‐aminoboronates and boronic acids

Tuberculosis is still affecting millions of people worldwide, and new resistant strains of Mycobacterium tuberculosis are being found. It is therefore necessary to find new compounds for treatment. In this paper, we report the synthesis and in vitro testing of peptidyl β‐aminoboronic acids and β‐aminoboronates with anti‐tubercular activity. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Depletion of β‐arrestin2 in hepatic stellate cells reduces cell proliferation via ERK pathway

β‐Arrestins are multifunctional adaptor proteins. Recently, some new roles of β‐arrestins in regulating intracellular signaling networks have been discovered, which regulate cell growth, proliferation, and apoptosis. Though, the role of β‐arrestins expression in the pathology of hepatic fibrosis remains unclear. In this study, the possible relationship between the expression of β‐arrestins with the experimental hepatic fibrosis and the proliferation of hepatic stellate cells (HSCs) were investigated. Porcine serum induced liver fibrosis was established in this study. At five time points, the dynamic expression of β‐arrestin1, β‐arrestin2, and α‐smooth muscle actin (α‐SMA) in rat liver tissues, was measured by immunohistochemical staining, double immunofluorescent staining, and Western blotting. This study showed that aggravation of hepatic fibrosis with gradually increasing expression of β‐arrestin2 in the hepatic tissues, but not β‐arrestin1. Further, as hepatic fibrosis worsens, β‐arrestin2‐expressing activated HSCs accounts for an increasingly larger percentage of all activated HSCs. And the expression of β‐arrestin2 had a significant positive correlation with the expression of α‐SMA, an activated HSCs marker. In vitro studies, the dynamic expression of β‐arrestin1 and β‐arrestin2 in platelet derived growth factor‐BB (PDGF‐BB) stimulated HSCs was assessed by Western blotting. The expression of β‐arrestin2 was remarkably increased in PDGF‐BB stimulated HSCs. Furthermore, the small interfering RNA (siRNA) technique was used to explore the effect of β‐arrestins on the proliferation of HSCs and the activation of ERK1/2. Transfection of siRNA targeting β‐arrestin2 mRNA (siβ‐arrestin2) into HSCs led to a 68% and 70% reduction of β‐arrestin2 mRNA and protein expression, respectively. siβ‐arrestin2 abolished the effect of PDGF‐BB on the proliferation of HSCs. In addition, siβ‐arrestin2 exerted the inhibition of the activation of ERK1/2 in HSCs. The present study provided strong evidence for the participation of the β‐arrestin2 in the pathogenesis of hepatic fibrosis. The β‐arrestin2 depletion diminishes HSCs ERK1/2 signaling and proliferation stimulated by PDGF‐BB. Selective targeting of β‐arrestin2 inhibitors to HSCs might present as a novel strategy for the treatment of hepatic fibrosis. J. Cell. Biochem. 114: 1153–1162, 2013. © 2012 Wiley Periodicals, Inc.     

Biotransformation of (−)‐(R)‐α‐Phellandrene: Antimicrobial Activity of Its Major Metabolite

Terpene derivatives converted by microbial biotransformation constitute an important resource for natural pharmaceutical, fragrance, and aroma substances. In the present study, the monoterpene α‐phellandrene was biotransformed by 16 different strains of microorganisms (bacteria, fungi, and yeasts). The transformation metabolites were initially screened by TLC and GC/MS, and then further characterized by NMR spectroscopic techniques. Among the six metabolites characterized, 6‐hydroxypiperitone, α‐phellandrene epoxide, cis‐p‐menth‐2‐en‐1‐ol, and carvotanacetone, which originated from (?)‐(R)‐α‐phellandrene, are reported for the first time in this study. Additionally, the substrate and the metabolite 5‐p‐menthene‐1,2‐diol were subjected to in vitro antibacterial and anticandidal tests. The metabolite showed moderate‐to‐good inhibitory activities (MICs=0.125 to >4 mg/ml) against various bacteria and especially against Candida species in comparison with its substrate (?)‐(R)‐α‐phellandrene and standard antimicrobial agents.     

Biglycan Intensifies ALK5–Smad2/3 Signaling by TGF‐β1 and Downregulates Syndecan‐4 in Cultured Vascular Endothelial Cells

Proteoglycans are macromolecules that consist of a core protein and one or more glycosaminoglycan side chains. A small leucine‐rich dermatan sulfate proteoglycan, biglycan, is one of the predominant types of proteoglycans synthesized by vascular endothelial cells; however, the physiological functions of biglycan are not completely understood. In the present study, bovine aortic endothelial cells in culture were transfected with small interfering RNAs for biglycan, and the expression of other proteoglycans was examined. Transforming growth factor‐β₁ signaling was also investigated, because the interaction of biglycan with cytokines has been reported. Biglycan was found to form a complex with either transforming growth factor‐β₁ or the transforming growth factor‐β₁ type I receptor, ALK5, and to intensify the phosphorylation of Smad2/3, resulting in a lower expression of the transmembrane heparan sulfate proteoglycan, syndecan‐4. This is the first report to clarify the function of biglycan as a regulatory molecule of the ALK5–Smad2/3 TGF‐β₁ signaling pathway that mediates the suppression of syndecan‐4 expression in vascular endothelial cells. J. Cell. Biochem. 118: 1087–1096, 2017. © 2016 Wiley Periodicals, Inc.