RESUMO
Bone fractures or bones subjected to open conduction and internal fixation are easily infected by bacteria; bacterial lipopolysaccharide (LPS) has been recognized as an important pathogenic factor affecting bone fracture healing. Therefore, the effect of LPS on bone metabolism is relevant for bone healing. In this study, we investigated the effect of LPS on the expression of Toll-like receptor (TLR)-4 (an LPS receptor) by using real-time quantitative PCR and western blotting. We also examined the regulatory role of LPS in osteoblast differentiation by measuring the ALP activity, matrix mineralization, and ALP, OCN, and Runx2 mRNA (essential factors affecting osteoblast differentiation) expression in LPS-treated mouse osteoblast MC3T3-E1 cells. We also evaluated the effect of TLR-4 on LPS-mediated inhibition of osteoblast differentiation using RNA interference. LPS promotes TLR-4 mRNA and protein expression in MC3T3-E1 cells (P < 0.05, P < 0.01 or P < 0.001), and inhibits osteoblast differentiation by downregulating matrix mineralization and ALP activity (P < 0.05, P < 0.01 or P < 0.001), and suppressing the expression ALP, OCN, and Runx2 mRNA in MC3T3-E1 cells (P < 0.05 or P < 0.01). Conversely, RNAi-mediated TLR-4 knockdown abrogates the LPS-mediated inhibition of osteoblast differentiation (P < 0.05 or P < 0.01). In summary, LPS was shown to inhibit osteoblast differentiation by suppressing the expression of ALP, OCN, and Runx2 in a TLR-4-dependent manner. The results of this study may provide insights into the signal pathway of LPS-induced bone loss or delayed bone fracture healing.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Fraturas Ósseas/genética , Osteoblastos/metabolismo , Receptor 4 Toll-Like/biossíntese , Proteínas Adaptadoras de Transdução de Sinal/biossíntese , Animais , Linhagem Celular , Subunidade alfa 1 de Fator de Ligação ao Core/biossíntese , Fraturas Ósseas/tratamento farmacológico , Fraturas Ósseas/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Lipopolissacarídeos/administração & dosagem , Proteínas de Membrana/biossíntese , Camundongos , Osteoblastos/patologia , Osteogênese/efeitos dos fármacos , RNA Mensageiro/genética , Transdução de Sinais/efeitos dos fármacos , Receptor 4 Toll-Like/genéticaRESUMO
Maize (Zea mays L.) kernel width is one of the most important traits that is related to yield and appearance. To understand its genetic mechanisms more clearly, a recombinant inbred line (RIL) segregation population consisting of 239 RILs was used for quantitative trait locus (QTL) mapping for kernel width. We found four QTLs on chromosomes 3 (one), 5 (two), and 10 (one). The QTLs were close to their adjacent markers, with a range of 0-23.8 cM, and explained 6.2-19.7% of the phenotypic variation. The three QTLs on chromosomes 3 and 5 had positive additive effects, and to a certain extent increased kernel width, whereas the one on chromosome 10 exhibited negative additive effects and decreased kernel width. These results can be used for gene cloning and marker-assisted selection in maize-breeding programs.
Assuntos
Mapeamento Cromossômico , Locos de Características Quantitativas/genética , Zea mays/genética , Cruzamento , Cromossomos de Plantas , Fenótipo , Zea mays/crescimento & desenvolvimentoRESUMO
Insulin-like growth factor binding protein-3 (IGFBP-3) exerts anti-proliferative or pro-apoptotic effects through IGF-dependent as well as IGF-independent mechanisms in vitro. The purpose of this study was to examine the association between genetic variants in IGFBP-3 (rs2270628) and the risk of esophageal squamous cell carcinoma (ESCC) in a Chinese Han population. Five hundred ESCC cases and 500 cancer-free controls of the Chinese Han population were involved in this study. The IGFBP-3 single-nucleotide polymorphism (SNP) rs2270628 was genotyped and the estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for its association with the risk of ESCC were determined using unconditional logistic regression analysis. Compared with the rs2270628 CC genotype, TT genotype was associated with a significantly increased ESCC risk with OR (95%CI) of 2.07 (1.05-4.09), but CT genotype was not (OR = 1.25, 95%CI =0.94-1.66). IGFBP-3 SNP rs2270628 may contribute to the risk of ESCC in the Chinese Han population.