Manumycin-induced apoptosis in U937 human myeloid leukemia cells via blocking PI3K/Akt signaling pathway / 实用医学杂志

Objective To explore the effects of manumycin on U937 cells and its mechanisms.Methods Apoptosis was detected by flow cytometry using annexin V and propidium iodide (PI) after treatment with manumycin (2 μmol/L) for different time.The reactive oxygen species (ROS) was detected by flow cytometry using Reactive Oxygen Species Assay Kit.The expressions of PI3K,P-Akt and Akt were detected by Western blotting.Results Compared with the 0 h treatment,manumycin treatment resulted in apoptosis (P ＜ 0.05) and ROS generation (P ＜ 0.05) gradually in U937 cell lines.Furthermore,manumycin also inhibited the activation of phosphatidylinositol-3 kinase (PI3K)/Akt pathway.Moreover,NAC could decrease manumycin-induced ROS generation and inhibit the effects of manumycin on the PI3K/Akt pathway and protect U937 cells from apoptosis induced by manumycin.Conclusion Manumycin induces apoptosis in U937 human leukemia cells through the regulation of the PI3K/Akt pathway and ROS production plays a critical role in the progress.

Role of tumor necrosis factor-αin the regulation of T-type calcium channel current in HL-1 cells / 中国病理生理杂志

AIM:Increasing evidence indicates that inflammation contributes to the initiation and perpetuation of atrial fibrillation ( AF) .Al-though tumor necrosis factor ( TNF)-αlevels are increased in patients with AF , the role of TNF-αin the pathogenesis of AF remains unclear.Recent research has revealed that T-type Ca2+currents ( ICa,T ) play an important role in the pathogenesis of AF .METH-ODS:In this study , we used the whole-cell voltage-clamp technique and biochemical assays to explore the role of TNF-αin the regula-tion of ICa,T in atrial myocytes.RESULTS:We found that compared with sinus rhythm (SR) controls, T-type calcium channel (TCC) subunit mRNA levels were decreased , while TNF-αexpression levels were increased , in human atrial tissue from patients with AF .In murine atrial myocyte HL-1 cells, after cultured for 24 h, 12.5, 25 and 50 μg/L TNF-αsignificantly reduced the protein expression levels of the TCC α1G subunit in a concentration-dependent manner .The peak current was reduced by the application of 12.5 or 25μg/L TNF-αin a concentration-dependent manner [from ( -15.08 ±1.11) pA/pF in controls to ( -11.89 ±0.83) pA/pF and (-8.54 ±1.55) pA/pF in 12.5 and 25 μg/L TNF-αgroups, respectively].TNF-αapplication also inhibited voltage-dependent inactivation of ICa,T shifted the inactivation curve to the left .CONCLUSION:These results suggest that TNF-αis involved in the path-ogenesis of AF, probably via decreasing ICa,T function in atrium-derived myocytes through impaired channel function and down -regula-tion of channel protein expression .This pathway thus represents a potential pathogenic mechanism in AF .

Cx43 is involved in electrical remodeling of atrial myocytes through regu-lating L-type calcium current / 中国病理生理杂志

AIM:To investigate whether the association of connexin 43 ( Cx43 ) and L-type calcium channel involved in the pathogenesis of atrial fibrillation ( AF) .METHODS:The biochemical assays and whole-cell patch-clamp technique were used to study the expression of Cx43 in human atrial tissue.The co-localization of Cx43 and L-type calcium channel, and the regulation of L-type calcium current in atrial myocytes were investigated.RESULTS:The expression of Cx43 at mRNA and protein levels was decreased in human atrial tissues of AF patients.In cultured atrium-derived myocytes ( HL-1 cells) , knockdown of Cx43 significantly inhibited the mRNA expression of L-type calcium channelα1c subunit, as well as L-type calcium current.Co-localization of Cx43 with L-type calcium channel α1c subunit in mouse atrial myocytes was observed.CONCLUSION:The decrease in Cx43 is involved in the pathogenesis of AF, probably through reducing the L-type calcium current in atrial myoctyes by co-localization with L-type calcium channel, thus representing the potential pathogenesis in atrial fibrillation.

Sodium-calcium exchanger promoter promotes differentiation of mouse induced pluripotent stem cells into cardiomyocytesin vitro / 中国组织工程研究

BACKGROUND:Inducing pluripotent stem cels has been considered as a promising treatment for ischemic heart disease. However, an ideal inducing method has not been found yet. OBJECTIVE:To investigate the role of sodium-calcium exchanger (NCX1) promoter in the differentiation of mouse induced pluriptent stem cels (miPS) into cardiomyocytes. METHODS: The pLVX-IRES-ZsGreen1 vectors which contain NCX1 promoter constructed by recombinant DNA technology were co-transfected to 293FT cels with ViraPowerTM Lentiviral Packaging Mix. The recombinant lentiviruses infected with miPS were selected and purified by puromycin. miPS were recovered and passaged to form embryoid bodies. The embryoid bodies were induced by differentiation medium containing various concentrations of the virus titer. The number of beating embryoid bodies were calculated. The expression profiles of the myocardial intra-markers were tested to determine the differentiation efficiency of iPSC by RT-PCR and immunofluorescence analysis. RESULTS AND CONCLUSION:pLVX-IRES-ZsGreen1 vectors which contain NCX1 promoter were constructed and confirmed by PCR. Virus could be packaged, purified and concentrated successfuly. The recombinant lentivirus to transduce miPS was sorted by flow cytometry. In contrast to NCX1-/GFP- cels, NCX1+/GFP+ cels were differentiated and developed prominent beating areas with sustained contractile activity for additional 4 days, and demonstrated positive expression of gap communication marker CX43 and cardiac troponin. The expressions of GATA4, MEF2c and Nkx2.5 in the NCX1+ cels were 4.2, 7.5, and 2.5 times those in NCX1- cels. Results showed the NCX1 promoter can promote the cardiac differentiation of miPS .

Expression of thioredoxin-2 for monitoring minimal residual disease in acute leukemia / 中南大学学报(医学版)

OBJECTIVE@#To investigate the significance of human thioredoxin-2 (TRX-2) in monitoring minimal residual disease (MRD) in acute leukemia (AL).@*METHODS@#We used real-time quantitative PCR to serially quantitize TRX-2 expression levels in the bone marrow of AL patients at diagnosis (n=68), at complete hematologic remission (CHR, n=57) and at relapse (n=25). Another 25 normal donors served as normal controls. The upper limit of the bone marrow at 91 was regarded as the reference. TRX-2 expression level at CHR with 91). TRX-2 level was correlated to the expression level of MRD.@*CONCLUSION@#TRX-2 may be the marker for AL and used in MRD monitoring.

Construction of recombinant retroviral vector of short interfering RNAs specific for macrophage migration inhibitory factor (MIF) and establishment of stable HeLa cell line with a persistent knockdown of MIF / 中国病理生理杂志

AIM:To construct recombinant retroviral vector of short interfering RNAs (siRNA) specific for macrophage migration inhibitory factor (MIF) and to establish the stable knockdown of MIF cell line of mammalian cells by transfecting the recombinant retroviral vectors. METHODS: We synthesized oligo-nucleotides for MIF in vitro, and cloned them into retroviral vector pSuper.retro. Subsequently the plasmids were sequenced and digested to identify the construction of the recombinant retroviral vectors. The vectors RNAi were transfected into packing cell line PHOENIX, which was selected by puromycin later. HeLa cell line was infected by the virus supernatant of stable PHOENIX cell lines, and the stable HeLa cell line showed significantly to silence MIF was established by selecting with puromycin. We also compare the characters of HeLa-pSuper-mock to HeLa-pSuper-MIF cells by using migration assay, adhesion assay, soft agar assay and FACS analysis of the cell-cycle progression. RESULTS: The recombinant retroviral vectors were constructed successfully. The HeLa cell line infected by the supernatant containing the retrovirus of package PHOENIX cells was persistent knockdown of MIF confirmed by Western blotting. Knockdown of MIF in HeLa cells inhibited the migration and adhesion, and decreased the clone formation. FACS analysis revealed that knockdown of MIF arrested HeLa cells in G0/G1 phase. CONCLUSION: We establish the stable HeLa cell line with a persistent knockdown of MIF. Our current studies reveal that MIF is necessary for HeLa cell migration and anchorage-independent growth.