ABSTRACT
Osteoporosis (OP) is a systemic skeletal disease that primarily affects the elderly population, which greatly increases the risk of fractures. Here we report that Kindlin-2 expression in adipose tissue increases during aging and high-fat diet fed and is accompanied by decreased bone mass. Kindlin-2 specific deletion (K2KO) controlled by Adipoq-Cre mice or adipose tissue-targeting AAV (AAV-Rec2-CasRx-sgK2) significantly increases bone mass. Mechanistically, Kindlin-2 promotes peroxisome proliferator-activated receptor gamma (PPARγ) activation and downstream fatty acid binding protein 4 (FABP4) expression through stabilizing fatty acid synthase (FAS), and increased FABP4 inhibits insulin expression and decreases bone mass. Kindlin-2 inhibition results in accelerated FAS degradation, decreased PPARγ activation and FABP4 expression, and therefore increased insulin expression and bone mass. Interestingly, we find that FABP4 is increased while insulin is decreased in serum of OP patients. Increased FABP4 expression through PPARγ activation by rosiglitazone reverses the high bone mass phenotype of K2KO mice. Inhibition of FAS by C75 phenocopies the high bone mass phenotype of K2KO mice. Collectively, our study establishes a novel Kindlin-2/FAS/PPARγ/FABP4/insulin axis in adipose tissue modulating bone mass and strongly indicates that FAS and Kindlin-2 are new potential targets and C75 or AAV-Rec2-CasRx-sgK2 treatment are potential strategies for OP treatment.
ABSTRACT
Objective@#To assess the effect of viral macrophage inflammatory protein (vMIP) -Ⅱ on the expression of apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (APOBEC3G) , and to explore the mechanisms.@*Methods@#A recombinant plasmid pEGFP-N3-K4 (vMIP-Ⅱ plasmid group) and an empty plasmid pEGFP-N3 (empty plasmid group) were separately transfected into 293T cells, and quantitative PCR and Western blot analysis were performed to evaluate the effect of transfection with vMIP-Ⅱ gene on the APOBEC3G expression in 293T cells. Some 293T cells in the empty plasmid group and vMIP-Ⅱ plasmid group were treated with 1 000 IU/ml interferon (IFN) -α for 36 hours, and then Western blot analysis was conducted to determine the APOBEC3G expression in the empty plasmid group and vMIP-Ⅱ plasmid group with or without IFN-α treatment. Some 293T cells transfected with vMIP-Ⅱ plasmids were treated with 75 μmol/L AG490 (a JAK/STAT signaling pathway inhibitor) and 20 μmol/L U0126 (an ERK signaling pathway inhibitor) separately; after 24 hours, total protein was extracted from 293T cells, and Western blot analysis was conducted to determine the expression of APOBEC3G. A recombinant plasmid containing APOBEC3G promoter was constructed by using a luciferase reporter gene, and the promoter fragment included the full-length promoter sequence (POS) of APOBEC3G, sequences with the lengths of 1 560, 960, 720, 480, 420, 360, 330 and 240 bp, and the regulatory element-free region (NEG) of APOBEC3G, separately. Some 293T cells were co-transfected with the recombinant plasmid carrying luciferase reporter gene and vMIP-Ⅱ plasmid (experimental group), or the recombinant plasmid and empty plasmid (control group). Subsequently, the activity of the APOBEC3G promoter was evaluated, and the key promoter region through which the transcriptional activity of APOBEC3G was regulated by vMIP-Ⅱ was analyzed. Statistical analysis was carried out by using t test, one-way analysis of variance and least significant difference (LSD) -t test.@*Results@#The mRNA and protein expression of APOBEC3G was significantly higher in the vMIP-Ⅱ plasmid group (2.500 ± 0.013, 1.472 ± 0.013 respectively) than in the control group (1, 0.364 ± 0.030 respectively; t = 6.22, 6.54 respectively, both P < 0.05) . The APOBEC3G expression significantly differed among the empty plasmid group, vMIP-Ⅱ plasmid group, empty plasmid + IFN-α group and vMIP-Ⅱ plasmid + IFN-α group (1, 2.030 ± 0.108, 2.700 ± 0.081 and 2.600 ± 0.099 respectively; F = 67.026, P < 0.001) , but there was no significant difference between the vMIP-Ⅱ plasmid group and empty plasmid + IFN-α group (t = 3.46, P > 0.05) . The APOBEC3G expression also significantly differed among the vMIP-Ⅱ plasmid group, vMIP-Ⅱ plasmid + AG490 group and vMIP-Ⅱ plasmid + U0126 group (0.617 ± 0.025, 0.179 ± 0.061, 0.359 ± 0.012 respectively; F = 70.019, P < 0.001) , and was significantly lower in the vMIP-Ⅱ plasmid + AG490 group and vMIP-Ⅱ plasmid + U0126 group than in the vMIP-Ⅱ plasmid group (t = 9.66, 11.836 respectively, both P < 0.01) . Luciferase activity assay showed that the promoter activity significantly differed among the vMIP-Ⅱ plasmid groups transfected with POS, 1 560-, 960-, 720-, 480-, 420-, 360-, 330-, 240-bp or NEG sequences (F = 81.092, P < 0.001) , and the APOBEC3G promoter activity decreased greatly from the 720-bp group to 480-bp group.@*Conclusion@#vMIP-Ⅱ upregulates the expression of APOBEC3G, likely through the JAK/STAT signaling pathway or the key promoter region regulating the transcriptional activity of APOBEC3G.
ABSTRACT
Objective To assess the effect of viral macrophage inflammatory protein (vMIP)-Ⅱ on the expression of apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (APOBEC3G),and to explore the mechanisms.Methods A recombinant plasmid pEGFP-N3-K4 (vMIP-Ⅱ plasmid group) and an empty plasmid pEGFP-N3 (empty plasmid group) were separately transfected into 293T cells,and quantitative PCR and Western blot analysis were performed to evaluate the effect of transfection with vMIP-]Ⅱ gene on the APOBEC3G expression in 293T cells.Some 293T cells in the empty plasmid group and vMIP-Ⅱ plasmid group were treated with 1 000 IU/ml interferon (IFN)-α for 36 hours,and then Western blot analysis was conducted to determine the APOBEC3G expression in the empty plasmid group and vMIP-Ⅱ plasmid group with or without IFN-α treatment.Some 293T cells transfected with vMIP-Ⅱplasmids were treated with 75 μ mol/L AG490 (a JAK/STAT signaling pathway inhibitor) and 20 μ mol/L U0126 (an ERK signaling pathway inhibitor) separately;after 24 hours,total protein was extracted from 293T cells,and Western blot analysis was conducted to determine the expression of APOBEC3G.A recombinant plasmid containing APOBEC3G promoter was constructed by using a luciferase reporter gene,and the promoter fragment included the full-length promoter sequence (POS) of APOBEC3G,sequences with the lengths of 1 560,960,720,480,420,360,330 and 240 bp,and the regulatory element-free region (NEG) of APOBEC3G,separately.Some 293T cells were co-transfected with the recombinant plasmid carrying luciferase reporter gene and vMIP-Ⅱ plasmid (experimental group),or the recombinant plasmid and empty plasmid (control group).Subsequently,the activity of the APOBEC3G promoter was evaluated,and the key promoter region through which the transcriptional activity of APOBEC3G was regulated by vMIP -Ⅱ was analyzed.Statistical analysis was carried out by using t test,one-way analysis of variance and least significant difference (LSD)-t test.Results The mRNA and protein expression of APOBEC3G was significantly higher in the vMIP-Ⅱ plasmid group (2.500 ± 0.013,1.472 ± 0.013 respectively) than in the control group (1,0.364 ± 0.030 respectively;t =6.22,6.54 respectively,both P ＜ 0.05).The APOBEC3G expression significantly differed among the empty plasmid group,vMIP-Ⅱ plasmid group,empty plasmid + IFN-oα group and vMIP-Ⅱ plasmid + IFN-α group (1,2.030 ± 0.108,2.700 ± 0.081 and 2.600 ± 0.099 respectively;F =67.026,P ＜ 0.001),but there was no significant difference between the vMIP-Ⅱ plasmid group and empty plasmid + IFN-α group (t =3.46,P ＞ 0.05).The APOBEC3G expression also significantly differed among the vMIP-Ⅱ plasmid group,vMIP-Ⅱ plasmid + AG490 group and vMIP-Ⅱplasmid + U0126 group (0.617 ± 0.025,0.179 ± 0.061,0.359 ± 0.012 respectively;F =70.019,P ＜ 0.001),and was significantly lower in the vMIP-Ⅱ plasmid + AG490 group and vMIP-Ⅱ plasmid + U0126 group than in the vMIP-Ⅱ plasmid group (t =9.66,11.836 respectively,both P ＜ 0.01).Luciferase activity assay showed that the promoter activity significantly differed among the vMIP-Ⅱ plasmid groups transfected with POS,1 560-,960-,720-,480-,420-,360-,330-,240-bp or NEG sequences (F =81.092,P ＜ 0.001),and the APOBEC3G promoter activity decreased greatly from the 720-bp group to 480-bp group.Conclusion vMIP-Ⅱ upregulates the expression of APOBEC3G,likely through the JAK/STAT signaling pathway or the key promoter region regulating the transcriptional activity of APOBEC3G.
ABSTRACT
APOBEC3B is one member of APOBEC with the activity of cytosine deaminase.Researches show that APOBEC3B can take park in the development and progression of breast cancer by means of mediating the genome mutations,which can promote cancer metastasis and drug resistance,thus influencing the treatment effect of patients with cancers.APOBEC3B is closely related with clinical prognosis of breast cancer,which has a potential value in the early diagnosis and biological therapy of breast cancer and provides a new hope for the treatment of breast cancer.
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Objective To investigate mRNA expressions of apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 family (APOBEC3s or A3s) as well as expressions and subcellular distribution of major A3 proteins in HaCaT keratinocytes carrying the genome of human papillomavirus type 11 (HPV11.HaCaT),and to evaluate regulatory effects of exogenous interferon-alpha (IFN-α) on the expressions of A3s.Methods The basal levels of A3A,A3B,A3C and A3H mRNA expressions were measured by real-time fluorescence-based quantitative PCR (qRT-PCR) in HPV11.HaCaT cells and normal HaCaT cells.Cultured HaCaT,HPV11.HaCaT and Hela cells were treated with recombinant human IFN-α 2b (rhIFN-α2b) at concentrations of 104,105 and 106 IU/ml for 6,24 and 48 hours separately,and those receiving no treatment served as the normal control groups.Then,qRT-PCR was performed to measure mRNA expressions of A3A,A3B,A3C and A3H in these cells.Immunofluorescence staining was conducted to observe the expression and distribution of A3A protein in cells after the treatment with rhIFN-α2b for 6 hours.Results As qRT-PCR showed,the basal levels of A3A,A3B and A3C mRNA expressions were all significantly higher in HPV11.HaCaT cells than in normal HaCaT cells (all P ＜ 0.05).After stimulation,the mRNA expressions of the four A3 members increased to different extents with the increase in rhIFN-α2b concentrations,and the increase in A3A mRNA was the most significant.Compared with corresponding normal control groups,the mRNA expression of A3A was significantly increased in HaCaT cells (35.77 ± 5.01 vs.1.00 ± 0.05,P ＜ 0.05),HPV 11.HaCaT cells (15.34 ± 2.14 vs.0.99 ± 0.01,P ＜ 0.05) and Hela cells (24.60 ± 5.45 vs.0.97 ± 0.03,P ＜ 0.05) after the treatment with rhIFN-α2b at 106 IU/ml for 6 hours,while the increase in A3B,A3C and A3H mRNA expressions was no more than 9-fold in these cell lines after that.Enhanced staining for A3A was observed in nuclei and cytoplasm of the 3 cell lines after the treatment with rhIFN-α2b at 106 IU/ml for 6 hours.Conclusions HPV11 transfected into HaCaT cells can activate intracellular A3s,especially A3A.IFN-α may play an immunoregulatory role by inducing high levels of A3A expression.
ABSTRACT
Apolipoprotein B mRNA editing enzyme,catalytic polypeptide-like (APOBECs) is a group of cytidine deaminases,which represents somewhat unusual protein family that can insert mutations in DNA and RNA as a result of their ability to deaminate cytidine to uridine.APOBECs seem to have diverse roles,such as lipid transport,antigen-driven antibody diversification and acting an innate defense system against retroviruses.In recent years,other functions of APOBECs were identified.Notably,APOBECs can cause host genome mutations and are upregulated in multiple cancers,such as breast,cervix,lung,liver cancers and so on.The researches on APOBEC and its relations with in tumors were reviewed.
ABSTRACT
Objective To study the impact of HIV and hepatitis C virus ( HCV ) infection on peripheral expression of antiviral protein A3G and plasma IFN-αlevels.Methods Untreated patients with chronic hepatitis C(HCV infection group, n=43), AIDS(HIV infection group, CD4 +T0.05).There was no significant correlation between plasma IFN-αlevel and A3G mRNA expression (rs =0.04, P>0.05), and the levels of A3G mRNA and IFN-αshowed no correlation with HIV RNA and HCV RNA (all P>0.05).Conclusions A3G is highly expressed in PBMCs from HIV infected patients, and it may not be affected by the infection of HCV.A3G mRNA is not closely correlated with IFN-α, and it has not significant influence on HIV RNA and HCV RNA replication.