Pim-1 is up-regulated by shear stress and is involved in shear stress-induced proliferation of rat mesenchymal stem cells.

AIMS: Investigation of the response of mesenchymal stem cells (MSCs) to vascular mechanical forces is very important in the field of cardiovascular intervention. Ser/Thr-protein kinase Pim-1 is a novel transducer of cell survival and the cell cycle that promotes signals in the hematopoietic cell system. Current studies aim to foster an understanding of Pim-1 expression and regulation in MSCs in response to different durations and strengths of laminar shear stress (SS) and to investigate the role of Pim-1 in SS-induced cell proliferation. MAIN METHODS: A parallel-plate flow chamber was used to control the strength and duration of SS. Proliferation was measured with the BrdU cell proliferation assay. The expressions of Pim-1 mRNA and protein were evaluated by reverse transcription-polymerase chain reaction and western blotting, respectively. RNA interference was used to knock down the Pim-1 gene. KEY FINDINGS: The results showed that SS up-regulation of Pim-1 mRNA and protein was time-dependent. Pim-1 induction was SS strength-dependent, and the expression level reached a maximum at 30 dynes/cm(2). Inhibitors of p38MAPK and ERK attenuated the SS-induced expression of Pim-1. In addition, SS significantly increased BrdU-uptake, which was effectively blocked by the silencing of Pim-1. SIGNIFICANCE: These results demonstrated that Pim-1 is expressed in MSCs and plays an important role in the SS-induced proliferation of MSCs.

Upregulated expression of GAP-43 mRNA and protein in anterior horn motoneurons of the spinal cord after brachial plexus injury.

BACKGROUND AND AIMS: This study is concerned with the expressions of growth-associated protein-43 (GAP-43) mRNA and protein in the anterior horn of the spinal cord after brachial plexus injury. METHODS: Animals were killed 1, 7, 14 days after injury and were divided into three injury groups: group 1, right C(7) ventral motor root avulsion; group 2, right C(7) ventral motor root avulsion and cut right C(5)-T(1) dorsal sensitive roots; and group 3, right C(7) ventral motor root avulsion plus right hemisection between C(5) and C(6) segment of the spinal cord. The combined behavioral scores (CBS) 1, 7 and 14 days after surgery were used in behavioral testing. Expressions of both GAP-43 mRNA and protein were analyzed using QRT-PCR and immunohistochemistry 14 days after surgery. RESULTS: Among the injury groups, rats in group 3 had the highest score and those in group 1, the lowest score. On day 14 after surgery, the expressions of GAP-43 mRNA and protein were evidently up-regulated compared to the control group, with the highest in group 3 and the lowest in group 1, showing significant differences among the three injury groups (p <0.01). CONCLUSIONS: Our study suggests that the expressions of GAP-43 mRNA and protein may be upregulated after brachial plexus injury, and GAP-43 protein is possibly associated with the axon regeneration and function reconstruction.

Involvement of Akt1/protein kinase Balpha in tumor conditioned medium-induced endothelial cell migration and survival in vitro.

PURPOSE: Endothelial cell migration and survival might be called "major angiogenic responses". Tumor conditioned medium (CM) has been widely used to stimulate endothelial cells to form capillary-like structures in angiogenesis models in vitro. However, the molecular events triggered by tumor CM are not fully understood. Here, we examined the effects of the CM from human lung carcinoma cell lines A549 and SPC-A-1 on cultures of primary human umbilical veins endothelial cells (HUVECs). METHODS: After treatment of HUVECs with the CM, cell migration was assessed by wound-healing assay, cell viability was evaluated by XTT assay, and apoptosis and cell death of HUVECs was analyzed by flow cytometry. Phosphorylation of Akt was assessed by Western blotting. To dissect the direct role of Akt, small interfering RNA (siRNA) against Akt1 was used. RESULTS: Both A549 and SPC-A-1 CM significantly stimulated cell migration. However, only A549 CM promoted cell viability and inhibited low serum-induced apoptosis and cell death of HUVECs, but SPC-A-1-CM showed no effects on survival of HUVECs. Meanwhile, A549 CM was found to be able to induce much more phosphorylation of Akt compared to SPC-A-1 CM treated group. The inhibitor of PI3K (wortmaninn) or Akt1 siRNA blocked A549 CM-induced migration and survival of HUVECs. CONCLUSION: These results indicated that the angiogenic effects of A549 CM are largely mediated through activation of the PI3K-Akt in endothelial cells, and that the Akt1 is crucial in this process, which may provide a therapeutic target for decreasing tumor angiogenesis.