N-Acetyl Cysteine improves the diabetic cardiac function: possible role of fibrosis inhibition.

BACKGROUND: Diabetic cardiomyopathy is one of the leading causes of death in diabetes mellitus (DM) patients. This study aimed to explore the therapeutic implication of N-acetyl-L-cysteine (NAC, an antioxidant and glutathione precursor) and the possible underlying mechanism. METHODS: Thirty five 12-week-old male C57BL/6 mice were included. Twenty-five diabetic mice were induced by intraperitoneal injection of streptozocin (STZ, 150 mg/kg, Sigma-Aldrich) dissolved in a mix of citrate buffer after overnight fast. Mice with a blood glucose level above 13.5 mmol/L were considered diabetic. As a non-DM (diabetic) control, mice were injected with equal volume of citrate buffer. The 25 diabetic mice were divided into 5 groups with 5 animals in each group: including DM (diabetes without NAC treatment), and 4 different NAC treatment groups, namely NAC1, NAC3, NAC5 and NAC7, with the number defining the start time point of NAC treatment. In the 10 non-DM mice, mice were either untreated (Ctrl) or treated with NAC for 5 weeks (NAC only). Echocardiography was performed 12 weeks after STZ injection. Heart tissue were collected after echocardiography for Hematoxylin Eosin (HE) and Trichrome staining and ROS staining. Cardiac fibroblast cells were isolated, cultured and treated with high glucose plus NAC or the vehicle. qPCR analysis and CCK-8 assay were performed to observe fibrotic gene expression and cell proliferation. RESULTS: We found that both cardiac systolic function and diastolic function were impaired, coupled with excessive reactive oxygen stress and cardiac fibrosis 12 weeks after STZ induction. NAC significantly reduced ROS generation and fibrosis, together with improved cardiac systolic function and diastolic function. Strikingly, NAC1 treatment, which had the earlier and longer treatment, produced significant improvement of cardiac function and less fibrosis. In the cardiac fibroblasts, NAC blocked cardiac fibroblast proliferation and collagen synthesis induced by hyperglycemia. CONCLUSIONS: Our study indicates that NAC treatment in diabetes effectively protects from diabetic cardiomyopathy, possibly through inhibiting the ROS production and fibrosis, which warrants further clarification.

[Effects of nuclear factor of activated T cells on the promoter activity of constitutively activated SV40].

AIM: To check if the common used constitutively promoters, such as CMV, TK and SV40 could be responded to the nuclear factor of activated T cell (NFAT), and to explore the strategies to choose rational internal control in the dual luciferase reporter assay. METHODS: pCMV-luc vector, in which luciferase activity is driven by CMV promoter, was cloned by amplifying the CMV promoter fragment from the pCDNA3.1 vector and then inserting the CMV promoter region into the pGL3-basic vector using the standard protocol. pTK-Luc reporter was similarly constructed, with the TK promoter from the pRL-TK vector. The constructed pCMV-Luc or pTK-Luc was co-transfected with pBIND or pRL-TK respectively, together with NFAT or constitutively active form named NFATCA. Relative luciferase activity was calculated as instructed by the manual instruction. RESULTS: Both pCMV-Luc and pTK-Luc vectors were successfully constructed. Luciferase activity assay revealed that SV40 promoter responded to active NFAT. CONCLUSION: The common used internal control promoter SV40 could respond to active NFAT, which should be kept in mind for selection of the rational internal control vector in the dual luciferase reporter assay. In addition, our study here also provides a practical strategy for rational selection of the internal control.

Cloning and function analysis of full-length cDNA sequence of Schistosoma japonicum eukaryotic translation initiation factor 2 alpha subunit.

OBJECTIVE: To subclone the novel gene screened from the Schistosoma japonicum cercariae cDNA library through expressed sequence tag (EST) strategy and analyze its functions. METHOD: The cDNA fragment inserted in pTriplEx2 vector was sequenced and the result retrieved with BLASTn program. It was found that this cDNA was highly homologous to Schistosoma mansoni eukaryotic translation initiation factor 2 alpha subunit (eIF2 alpha) mRNA. According to the known EST sequence, the 3'-terminal primer that matched the sequencing primer for the 5'-terminal in pTriplEx2 plasmid was designed and used to amplify the full-length open reading frame (ORF) sequence of the eIF2 alpha from the cDNA Library. After proper purification, the PCR product was linked to pGEM-T vector and the recombinant T-vector was sequenced to obtain the full length ORF, which was retrieved for homologue identification using NCBI blast program. The sequences that were highly homologous underwent comparison at the levels of amino acids and nucleotides using BLAST 2 Sequence program on NCBI BLAST site. The motif and conserved domain were also retrieved with the software available online. RESULT: A novel cDNA sequence coding for a eIF2 alpha was found from the cDNA library of Schistosoma japonicum cercariae, which was highly homologous to the known Schistosoma mansoni eIF2 alpha mRNA, with the homology of 87% at the nucleotide level and 79% at the amino acid level. CONCLUSION: The novel gene found by EST strategy may encode a eIF2 alpha which is highly homologous to Schistosoma mansoni eukaryotic eIF2 alpha mRNA.

[Identification and cloning of adenylate kinase gene, a novel gene of Schistosoma japonicum].

OBJECTIVE: To subclone a novel gene of Schistosoma japonicum (Sj), adenylate kinase (AK) cDNA, which was identified through expressed sequence tag (EST) strategy and homology search, so as to prepare for further functional study of this gene. METHOD: The inserted cDNA fragment was sequenced and searched with BLASTn program. Two PCR primers were designed according to the sequence of this Sj AK cDNA and the cloning sites in pET32a (+) plasmid, with the product purified before linkage with pMD 18-T vector. The recombinant T-vector was digested with EcoRI /XhoI to obtain Sj AK cDNA, which was then introduced into the expression plasmid pET32a (+). RESULTS: The novel gene possessed 86% homology with Sm AK cDNA, and the PCR product is of expected length. Double digestion with EcoR I and Xho I proved that the recombinant T-vector and the expression plasmid had the insert with length identical to that of the target fragment. CONCLUSION: The novel cDNA codes for adenylate kinase of Schistosoma japonicum, and the recombinant expression plasmid pET32a (+)-Sj AK have been successfully constructed.