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Klotho is a gene associated with aging, the transmembrane protein encoded by this gene is highly expressed in the kidney, and is also expressed in tissues such as the brain, parathyroid and pituitary glands. The extracellular domain of Klotho can also be cleaved and shed to form soluble Klotho, which acts as a circulating hormone and can be detected in blood, cerebrospinal fluid, and urine. More and more studies have shown that Klotho protein plays an important role in the complex regulation of growth hormone (GH)-insulin-like growth factor 1(IGF1) axis. The interaction between Klotho protein and GH-IGF1 axis is bidirectional, which regulates each other, and then regulates the normal linear growth of children. In addition, Klotho protein can also affect the growth and development of fetus and newborn through different ways, and its mechanism is not very clear.
ABSTRACT
Objective@#To explore the effects of microRNA-34a on regulating silent information regulator 1 (SIRT1) and influence of SIRT1 on myocardial damage of rats with severe burns at early stage.@*Methods@#(1) Twenty-four Sprague-Dawley (SD) rats were divided into sham injury (SI) group, simple burns (SB) group and SIRT1 agonist (SA) group according to the random number table (the same grouping method below), with 8 rats in each group. Rats in groups SB and SA were inflicted with 30% total body surface area full-thickness scald (hereinafter referred to as burns) on the back, and rats in group SI were sham injuried on the back. Immediately after injury, rats in groups SI and SB were intraperitoneally injected with normal saline of 50 mL/kg, and rats in group SA were intraperitoneally injected with normal saline of 50 mL/kg and 1 mg/mL resveratrol of 50 mg/kg. At 6 h post injury, abdominal aortic blood was collected to make serum and myocardial tissue of rats was collected. (2) Myocardial cells of twelve neonatal SD rats were collected and divided into microRNA-34a mimic control (MMC) group, microRNA-34a mimic (MM) group, microRNA-34a inhibitor control (MIC) group, and microRNA-34a inhibitor (MI) group, which were respectively transfected with gene sequences of mimic control, mimic, inhibitor control, and inhibitor of microRNA-34a. The microRNA-34a expression level and protein expression level of SIRT1 in myocardial cells were respectively detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. Another batch of myocardial cells were divided into microRNA-34a inhibitor control+ burn serum (MCB) group, microRNA-34a inhibitor+ burn serum (MB) group, and microRNA-34a inhibitor+ burn serum + EX527 (MBE) group. Myocardial cells in group MCB were transfected with gene sequence of inhibitor control, and myocardial cells in the later groups were transfected with gene sequence of inhibitor of microRNA-34a. After transfection of 48 h, myocardial cells in group MBE were cultured in Dulbecco′s modified Eagle′s medium (DMEM) solution for 6 hours, with serum in group SB of volume fraction of 10% and final amount-of-substance concentration of 1 mol/L, and myocardial cells in the other 2 groups were cultured in DMEM solution with serum from rats of group SB of volume fraction of 10%. The protein expression levels of myocardial cells of SIRT1, cleaved-caspase-3, and Bax were detected by Western blotting. (3) Myocardial tissue from (1) was collected to detect expression levels of microRNA-34a and mRNA of SIRT1 in groups SI and SB by real-time fluorescence quantitative RT-PCR. Morphology of myocardial tissue of rats in groups SI, SB, and SA was observed with biological image navigator. The mRNA expression levels of interleukin 1β (IL-1β) and tumor necrosis factor (TNF-α) of rats in groups SI, SB, and SA were detected by real-time fluorescence quantitative RT-PCR. The expression levels of cleaved-caspase-3, and Bax of myocardial tissue of rats in groups SI, SB, and SA were detected by Western blotting. Data were processed with one-way analysis of variance and least-significant difference test.@*Results@#(1) After transfection of 48 h, the expression level of microRNA-34a of myocardial cells in group MM was 4.67±0.92, significantly higher than 1.03±0.04 in group MMC (P<0.01); the protein expression level of SIRT1 of myocardial cells in group MM was 0.35±0.06, significantly lower than 1.12±0.11 in group MMC (P<0.01). After transfection of 48 h, the expression level of microRNA-34a of myocardial cells in group MI was 0.26±0.07, significantly lower than 1.33±0.07 in group MIC (P<0.01); the protein expression level of SIRT1 of myocardial cells in group MIC was 1.12±0.16, significantly lower than 1.74±0.34 in group MI (P<0.01). At 6 h after culture, compared with those in group MCB, the SIRT1 protein expression level of myocardial cells in group MB was significantly increased (P<0.05), while cleaved-caspase-3 and Bax protein expression levels of myocardial cells in group MB were significantly decreased (P<0.05). Compared with those in group MB, the SIRT1 protein expression level of myocardial cells in group MBE was with no significantly statistical difference (P>0.05), and cleaved-caspase-3 and Bax protein expression levels were significantly increased (P<0.05). (2) At 6 h post injury, compared with that in group SI, the microRNA-34a expression level of myocardial tissue in group SB was significantly increased (P<0.01), and the mRNA expression level of SIRT1 of myocardial tissue in group SB was significantly decreased (P<0.01). At 6 h post injury, myocardial cells in group SI arranged neatly with normal nucleus and no inflammatory cells infiltration; myocardial cells in group SB arranged disorderly, with no abnormal nucleus, and obvious inflammatory cells infiltration; myocardial cells in group SA arranged neatly, with normal nucleus and little inflammatory cells infiltration. At 6 h post injury, compared with those in group SB, the mRNA expression levels of IL-1β and TNF-α, and the protein expression levels of cleaved-caspase-3 and Bax of myocardial tissue in groups SI and SA were significantly decreased (P<0.01).@*Conclusions@#The microRNA-34a expression level of myocardial tissue of rats with severe burns at early stage increases, which decreases the expression level of SIRT1, and increases the expression levels of IL-1β, TNF-α, cleaved-caspase-3 and Bax, leading to obvious myocardial damage. Activation of SIRT1 can alleviate myocardial damage of rats with severe burns at early stage through decreasing expression levels of IL-1β, TNF-α, cleaved-caspase-3, and Bax.
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Objective To discuss the feasibility and effect of labeled antibody on targeting therapy of systemic lupus erythematosus(SLE) associated thrombocytopenia.Methods MTX-IVIG conjugate was prepared by indirect and direct cross linking,and the binding ability of it to Fc fragment was detected by indirect immunofluor-escence.The killing activity of the conjugate was detected by MTT method using murine macrophage with Fc receptor and strain U937 of human monocytic leukemia cell as targets.Results Conjugation showed stronger cytotoxicity upon target cells than free MTX,and it showed less cytotoxic effect on Fc receptor negative cells compared with the positive ones.IVIG-HSA-MTX restrained the phagocyte of macrophage.The killing effect of IVIG-HSA-MTX was significantly stronger than that of IVIG-MTX.Conclusion The conjugation can show a highly specific cytotoxicity upon mononuclear-macrophage in vitro.