This experiment was designed to construct mouse Smad6 recombinant RNA interference vectors and determine their interference effects on bone marrow mesenchymal stem cells (BMSCs). Three recombinant Smad6 RNA interference vectors were constructed by molecular clone techniques with a lenti-virus vector expressing green fluorescent protein (GFP), and the correctness of recombinant vectors was verified by DNA sequencing. Mouse BMSCs were used for transfection experiments and BMP-2 was in use for osteogenic induction of MSCs. The transfection efficiency of recombinant vectors was examined by Laser confocal scanning microscope and the interference effect of recombinant vectors on Smad6 gene expression was determined by real-time RT-PCR and Western blot, respectively. Three Smad6 recombinant RNA interference vectors were successfully constructed and their correctness was proved by DNA sequencing. After transfection, GFPs were effectively expressed in MSCs and all of three recombinant vectors gained high transfection efficiency (> 95%). Both real-time PCR and Western blot examination indicated that among three recombinant vectors, No. 2 Svector had the best interference effect and the interference effect was nearly 91% at protein level. In conclusion, Mouse recombinant Smad6 RNA interference (RNAi) vector was successfully constructed and it provided an effective tool for further studies on BMP signal pathways.
Animals ; Bone Morphogenetic Proteins ; genetics ; metabolism ; Genetic Vectors ; genetics ; Green Fluorescent Proteins ; biosynthesis ; genetics ; Lentivirus ; genetics ; metabolism ; Mesenchymal Stromal Cells ; metabolism ; Mice ; RNA Interference ; Recombinant Proteins ; biosynthesis ; genetics ; Smad6 Protein ; biosynthesis ; genetics ; Transfection

The present study was designed to observe the expressions of bone morphogenetic protein-7 (BMP-7) and inhibitory Smads in kidney of rats with diabetic nephropathy (DN), and explore the possible mechanism of DN. Male Wistar rats weighing 180-220 g were single injected with streptozocin (STZ, 55 mg/kg body weight) for 2, 4, 8 and 16 weeks to induce DN. Blood glucose, kidney weight/body weight and 24-hour urine protein in the control and DN rats were examined; the expressions of BMP-7, Smad6 and Smad7 were detected by using immunohistochemical techniques, Western blot and real-time PCR. The results showed that blood glucose and 24-hour urine protein in DN rats were higher than that in the control rats and kidney weight/body weight was also elevated in DN rats, especially in 16-week STZ-induced rats. The expressions of BMP-7 and Smad6 proteins in DN rats were elevated, while BMP-7 mRNA expression was increased 2 weeks after STZ injection and decreased 16 weeks after STZ injection. The expressions of Smad7 protein and mRNA were elevated in DN rats 2 weeks after STZ injection and decreased 16 weeks after STZ injection. In addition, the expressions of transforming growth factor-beta1 (TGF-beta1) and collagen type I (COL-I) mRNA were increased in DN rats. These results suggest in the early stage of DN, increase in BMP-7 and inhibitory Smad expression may play a role in the feedback regulation and restrain the development of DN.
Animals ; Bone Morphogenetic Protein 7 ; genetics ; metabolism ; Collagen Type I ; metabolism ; Diabetes Mellitus, Experimental ; metabolism ; Diabetic Nephropathies ; metabolism ; Kidney ; metabolism ; pathology ; Male ; RNA, Messenger ; genetics ; metabolism ; Random Allocation ; Rats ; Rats, Wistar ; Smad6 Protein ; genetics ; metabolism ; Smad7 Protein ; genetics ; metabolism ; Transforming Growth Factor beta1 ; metabolism

The inhibitory Smad6 and Smad7 are responsible for cross-talk between TGF-beta/bone morphogenic protein (BMP) signaling and other cellular signaling pathways, as well as negative feedback on their own signaling functions. Although inhibitory Smads are induced by various stimuli, little is known about the stimuli that increase Smad6 transcription, in contrast to Smad7. Here we demonstrate that etoposide, which induces double strand breaks during DNA replication, significantly up-regulates the transcription of the Smad6 gene in CMT-93 mouse intestinal cells by increasing specific DNA binding proteins. In addition, endogenous inhibition of the Smad6 gene by RNAi interference led to transient accumulation of G1 phase cells and reduction in incorporation of bromodeoxyuridine (BrdU). These findings strongly suggest that Smad6 plays a distinct role in the signaling of etoposide-induced DNA damage.
Animals ; Base Sequence ; Cell Line ; DNA-Binding Proteins/metabolism ; Enterocytes/*cytology/drug effects/*metabolism ; Etoposide/*pharmacology ; G1 Phase/*drug effects ; Mice ; Molecular Sequence Data ; Promoter Regions, Genetic/genetics ; RNA, Small Interfering/metabolism ; S Phase/*drug effects ; Smad6 Protein/*genetics ; Transcriptional Activation/drug effects