ABSTRACT
Cardiomyocyte progenitor cells play essential roles in early heart development, which requires highly controlled cellular organization. microRNAs (miRs) are involved in various cell behaviors by post-transcriptional regulation of target genes. However, the roles of miRNAs in human cardiomyocyte progenitor cells (hCMPCs) remain to be elucidated. Our previous study showed that miR-134 was significantly downregulated in heart tissue suffering from congenital heart disease, underlying the potential role of miR-134 in cardiogenesis. In the present work, we showed that the upregulation of miR-134 reduced the proliferation of hCMPCs, as determined by EdU assay and Ki-67 immunostaining, while the inhibition of miR-134 exhibited an opposite effect. Both up- and downregulation of miR-134 expression altered the transcriptional level of cell-cycle genes. We identified Meis2 as the target of miR-134 in the regulation of hCMPC proliferation through bioinformatic prediction, luciferase reporter assay and western blot. The over-expression of Meis2 mitigated the effect of miR-134 on hCMPC proliferation. Moreover, miR-134 did not change the degree of hCMPC differentiation into cardiomyocytes in our model, suggesting that miR-134 is not required in this process. These findings reveal an essential role for miR-134 in cardiomyocyte progenitor cell biology and provide new insights into the physiology and pathology of cardiogenesis.
Subject(s)
Cell Proliferation , Homeodomain Proteins/metabolism , MicroRNAs/genetics , Myoblasts, Cardiac/metabolism , Myocytes, Cardiac/metabolism , Transcription Factors/metabolism , Cells, Cultured , Homeodomain Proteins/genetics , Humans , Myoblasts, Cardiac/physiology , Myocytes, Cardiac/physiology , Transcription Factors/geneticsABSTRACT
OBJECTIVE: To investigate the effect of 1,25 (OH)2 dihydroxyvitamin D3 on the generation of osteoclasts from mononuclear cells of adult rats. METHODS: With density gradient centrifugation, the mononuclear cells were isolated from rat bone marrow and cultured in the alpha-MEM with 10(-8) mol/L 1,25 (OH)2 dihydroxyvitamin D3. The induced cells were fixed and stained with tartrate-resistant acid phosphatase (TRAP). The bone resorption pits were examined by scanning electron microscope, and the morphology of osteoclasts were examined with inverted phase contrast microscope. RESULTS: The TRAP+ multinucleated cells could be observed on the seventh culturing day of mononuclear cell group. The number of TRAP+ multinucleated cells went up to a peak on the fourteenth culturing day, and then began to decrease on the twenty-first culturing day. The number of osteoclasts induced from mononuclear cell group was more than that from bone marrow group (P < 0.05) when it was during the fourteenth culturing day to the twenty-third culturing day. The number of bone resorption pits in the mononuclear cell group was much more than that in the bone marrow group (P < 0.05) when it was in period from the tenth culturing day to the twenty-third culturing day. The number of osteoclasts induced from mononuclear cell group could keep the peak value of lasting 7 days, but that induced from bone marrow group could only last its peak value for 3 days. CONCLUSION: The method with 1,25(OH)2 dihydroxyvitamin D3 inducing the formation of osteoclasts from the marrow mononuclear cells is better than that from the whole bone marrow.
Subject(s)
Bone Marrow Cells/cytology , Calcitriol/pharmacology , Leukocytes, Mononuclear/cytology , Leukocytes, Mononuclear/drug effects , Osteoclasts/cytology , Acid Phosphatase/metabolism , Animals , Bone Resorption/metabolism , Female , Isoenzymes/metabolism , Osteoclasts/metabolism , Rats , Rats, Sprague-Dawley , Tartrate-Resistant Acid Phosphatase , Time FactorsABSTRACT
OBJECTIVE: To investigate the difference of osteogenic potential of bone marrow mesenchymal stem cells (MSCs) between healthy rats and osteoporotic rats. METHODS: We established the animal model of osteoporosis by performing ovariectom on the 3-month-old female Sprague-Dawley rats. Bone marrow mesenchymal stem cells(MSCs) were isolated from the rats of control group and of ovariectomized (ovx) group by means of the density-gradient centrifugation method, and the 3rd-4th passage MSCs were used in all the experiments. The experiments comprised 4 groups: (1) Marrow mesenchymal stem cells control group (MSCs control group); (2) Marrow mesenchymal stem cells ovx group (MSCs ovx group); (3) Osteogenesis induction control group (OSI control group); (4) Osteogenesis induction ovx group (OSI ovx group). Cell cycle and proliferation index (PI) of MSCs were detected by flow cytometry. The expression of alkaline phosphatase (ALP) was detected by dynamics method with substrate of phosphoric acid para-Nitro benzene. The levels of osteocalcin were detected with the isotope labelling method. RESULTS: (1) PI of MSCs was lower in MSCs ovx group than in MSCs control group. (2) The expression of alkaline phosphatase (ALP) was much higher in OSI control group than in the MSCs control group; the expression of alkaline phosphatase (ALP) was much higher in the OSI control group than in OSI ovx group after 7-day and 14-day osteogenic induction. (3) The level of osteocalcin was much higher in the OSI control group than in the MSCs control group after 14-day, 21-day, 28-day osteogenic induction. The level of osteocalcin was much higher in the OSI control group than in the OSI ovx group. CONCLUSION: Both the proliferative potential and the osteogenic potential of bone marrow mesenchymal stem cells (MSCs) from the ovariectomized osteoporotic rat are decreased.
