Primary cilia/intraflagellar transport mediates mechanics-responsive signaling pathway and promotes osteogenic differentiation of bone marrow stromal stem cells / 中国组织工程研究

BACKGROUND:Mechanical stimulation has been confirmed to promote osteogenic differentiation of bone marrow stromal stem cells,but the mechanism is unknown.Primary cilia are important mechanoreceptors and regulate various signaling pathways such as TGF-β1/BMP-2/SMAD.They are likely to be important targets for mechanical regulation of bone marrow stromal stem cells. OBJECTIVE:To investigate the effect and mechanism of fluid shear stress on osteogenic differentiation of bone marrow stromal stem cells. METHODS:Rat bone marrow stromal stem cells were divided into control group,mechanical stimulation group(fluid shear mechanics intervention by shaking table),mechanical stimulation + IFT88 silencing group(mechanical stimulation + silencing IFT88 expression with siRNA).After 24 hours of intervention,qRT-PCR was utilized to determine the expression of transforming growth factor β1 and bone morphogenetic protein 2.Western blot assay was used to detect the expression of phosphorylated SMAD2/3 protein.Immunofluorescent staining of primary cilia was conducted and morphology was analyzed. RESULTS AND CONCLUSION:Shear stress stimulation could promote the transcriptional activity of transforming growth factor β1 and bone morphogenetic protein 2 genes,and increase the expression of phosphorylated SMAD2/3 protein.After siRNA interfered with primary cilia,this mechanical response effect was significantly reduced.There was a Spearman correlation between the change ratio of the primary cilium area of bone marrow stromal stem cells and the increased ratio of transforming growth factor β1 and bone morphogenetic protein 2 gene transcription.These findings indicate that primary cilia/intraflagellar transport mediates the activation of fluid shear stress-responsive transforming growth factor β1/bone morphogenetic protein 2/SMAD signaling pathway and promotes osteogenic differentiation of bone marrow stromal stem cells.

The roles of intraflagellar transport (IFT) protein 25 in mammalian signaling transduction and flagellogenesis / 亚洲男科学杂志(英文版)

Cilium, an organelle with a unique proteome and organization, protruding from the cell surface, generally serves as a force generator and signaling compartment. During ciliogenesis, ciliary proteins are synthesized in cytoplasm and transported into cilia by intraflagellar transport (IFT) particles, where the inner counterparts undergo reverse trafficking. The homeostasis of IFT plays a key role in cilial structure assembly and signaling transduction. Much progress has been made on the mechanisms and functions of IFT; however, recent studies have revealed the involvement of IFT particle subunits in organogenesis and spermatogenesis. In this review, we discuss new concepts concerning the molecular functions of IFT protein IFT25 and how its interactions with other IFT particle subunits are involved in mammalian development and fertility.

Intraflagellar transport is essential for spermiogenesis / 中华男科学杂志

Intra flagellar transport (IFT) is an evolutionarily conserved mechanism thought to be essential for the assembly and maintenance of most eukaryotic cilia and flagella. Development of the sperm tail axoneme resembles the cilia formation, which is organized by intraflagellar transport (IFT). Of all mammalian cells, sperm have the longest motile cilia, but few studies are reported on the role of IFT in the formation of sperm flagella and the mechanisms of IFT in spermiogenesis. This article focuses on the role of IFT in spermatogenesis and the importance of IFT in male fertility.

The expression of IFT20 protein in lung cancer tissues and its effect on the proliferation of lung cancer A549 cells / 肿瘤

Objective: To investigate the expression of intraflagellar transport 20 (IFT20) protein in lung cancer tissues and its effect on the proliferation of lung cancer A549 cells. Methods: The expressions of IFT20 protein in 20 specimens of lung cancer tissues and 4 specimens of normal lung tissues were detected by immunohistochemistry. After the small interfering RNA (siRNA) targeting IFT20 gene was transfected into A549 cells, the expression level of IFT20 mRNA was detected by real-time fluorescence-based quantitative-PCR, the proliferation of A549 cells was determined by MTT assay, the number and length of cilia were observed by immunofluorescence staining, and the proteins expressions in A549 cells were measured by protein chip detection. Results: The expression of IFT20 protein was weakly positive in lung cancer tissues and moderately positive in normal lung tissues. The expression level of IFT20 mRNA in lung cancer A549 cells after transfection with IFT20-targeted siRNA was lower than those in the negative control cells (A549 cells were transfected with control siRNA) and the blank control cells (A549 cells with no transfection) (P < 0.05). The proliferation of A549 cells after transfection with IFT20-targeted siRNA was accelerated (P < 0.05), the expression level of IFT20 protein was down-regulated, the number of cilia was reduced, the length of cilia was shorterned, or the cilia was disappeared (all P < 0.05). The expression levels of X-linked inhibitor of apoptosis protein (XIAP), survivin, high temperature requirment A (HTRA), heat shock protein (Hsp) 27, Hsp70 and second mitochondria-derived activator of caspase (SMAC) were up-regulated (all P < 0.05). Conclusion: The IFT20 protein is lowly expressed in lung cancer tissues. After the inhibition of IFT20 expression, the cilia become less and shorter, which promotes the proliferation of lung cancer A549 cells.