BMC Cell Biology最新文献

Background: Diapause is a form of dormancy that is genetically predetermined to allow animals to overcome harsh environmental conditions. It is induced by predictive environmental cues bringing cellular activity levels into a state of suspended animation. Entering diapause requires organismal, molecular and cellular adaptation to severely reduced energy flows. Cells must therefore have evolved strategies that prepare them for periods with limited metabolic resources. However, changes that occur on the (sub-)cellular level have not been thoroughly described.

Results: We investigated mitotic activity and we monitored cytoskeletal network changes in successive stages of diapausing and non-diapausing Daphnia magna embryos using (immuno-)fluorescent labeling. We find that embryos destined to diapause show a delayed and 2.5x slower mitotic activity in comparison to continuously developing embryos. Development is halted when D. magna embryos reach ~ 3500 cells, whereupon mitotic activity is absent and cytoskeletal components are severely reduced, rendering diapause cells compact and condensed.

Conclusion: In the initiation phase of diapause, the slower cell division rate points to prolonged interphase duration, preparing the cells for diapause maintenance. During diapause, cytoskeletal depletion and cellular condensation may be a means to save energy resources. Our data provide insights into the sub-cellular change of diapause in Daphnia.

Background: TRAIL, tumor necrosis factor-related apoptosis-inducing ligand, can selectively kill cancer cells with little or no cytotoxicity toward normal human cells and is regarded as a potential relatively safe antitumor drug. However, some cancer cells are resistant to TRAIL-induced apoptosis. Thus, reagents that potentiate TRAIL-induced cytotoxicity are needed. Herein, we investigated whether shikonin, a natural compound from the root of Lithospermum erythrorhizon, can sensitize TRAIL-resistant cells to TRAIL-induced cytotoxicity.

Results: The viability of A549 cells, which were resistant to TRAIL, was significantly decreased after treatment with TRAIL followed by shikonin. The underlying mechanisms by which shikonin sensitizes cells to TRAIL-induced cytotoxicity were also examined. Combined treatment with shikonin and TRAIL activated the caspase and JNK pathways, inhibited the STAT3 and AKT pathways, downregulated the expression of Mcl-1, Bcl-2, Bcl-xL, c-FLIP and XIAP and upregulated the expression of Bid.

Conclusions: In conclusion, the results indicated that shikonin sensitized resistant cancer cells to TRAIL-induced cytotoxicity via the modulation of the JNK, STAT3 and AKT pathways, the downregulation of antiapoptotic proteins and the upregulation of proapoptotic proteins.

Background: Dasatinib (Sprycel) was developed as a tyrosine kinase inhibitor targeting Bcr-Abl and the family of Src kinases. Dasatinib is commonly used for the treatment of acute lymphoblastic and chronic myelogenous leukemia. Previous clinical studies in melanoma returned inconclusive results and suggested that patients respond highly heterogeneously to dasatinib as single agent or in combination with standard-of-care chemotherapeutic dacarbazine. Reliable biomarkers to predict dasatinib responsiveness in melanoma have not yet been developed.

Results: Here, we collected comprehensive in vitro data from experimentally well-controlled conditions to study the effect of dasatinib, alone and in combination with dacarbazine, on cell proliferation and cell survival. Sixteen treatment conditions, covering therapeutically relevant concentrations ranges of both drugs, were tested in 12 melanoma cell lines with diverse mutational backgrounds. Melanoma cell lines responded heterogeneously and, importantly, dasatinib and dacarbazine did not synergize in suppressing proliferation or inducing cell death. Since dasatinib is a promiscuous kinase inhibitor, possibly affecting multiple disease-relevant pathways, we also determined if basal phospho-protein amounts and treatment-induced changes in phospho-protein levels are indicative of dasatinib responsiveness. We found that treatment-induced de-phosphorylation of p53 correlates with dasatinib responsiveness in malignant melanoma.

Conclusions: Loss of p53 phosphorylation might be an interesting candidate for a kinetic marker of dasatinib responsiveness in melanoma, pending more comprehensive validation in future studies.

Background: Within the past years, umbilical cord (UC) and amniotic membrane (AM) expanded in human platelet lysate (PL) have been found to become increasingly candidate of mesenchymal stromal cells (MSCs) in preclinical and clinical studies. Different sources of MSCs have different properties, and lead to different therapeutic applications. However, the similarity and differences between the AMMSCs and UCMSCs in PL remain unclear.

Results: In this study, we conduct a direct head-to-head comparison with regard to biological characteristics (morphology, immunophenotype, self-renewal capacity, and trilineage differentiation potential) and immunosuppression effects of AMMSCs and UCMSCs expanded in PL. Our results indicated that AMMSCs showed similar morphology, immunophenotype, proliferative capacity and colony efficiency with UCMSCs. Moreover, no significantly differences in osteogenic, chondrogenic and adipogenic differentiation potential were observed between the two types of cells. However, AMMSCs exhibited higher PGE₂ expression and IDO activity compared with UCMSCs when primed by IFN-γ and (or) TNF-α induction, and AMMSCs showed a higher inhibitory effect on PBMCs proliferation than UCMSCs.

Conclusion: The results suggest that AMMSCs expanded in PL showed similar morphology, immunophenotype, self-renewal capacity, and trilineage differentiation potential with UCMSCs. However, AMMSCs possessed superior immunosuppression effects in comparison with UCMSCs. These results suggest that AMMSCs in PL might be more suitable than UCMSCs for treatment of immune diseases. This work provides a novel insight into choosing the appropriate source of MSCs for treatment of immune diseases.

Background: Endothelial cells provide a barrier between blood and tissues, which is regulated to allow molecules and cells in out of tissues. Patients with cerebral cavernous malformations (CCM) have dilated leaky blood vessels, especially in the central nervous system. A subset of these patients has loss-of-function mutations in CCM3. CCM3 is part of the STRIPAK protein complex that includes the little-characterized proteins FAM40A and FAM40B.

Results: We show here that FAM40A and FAM40B can interact with CCM3. Knockdown of CCM3, FAM40A or FAM40B in endothelial cells by RNAi causes an increase in stress fibers and a reduction in loop formation in an in vitro angiogenesis assay, which can be reverted by inhibiting the Rho-regulated ROCK kinases. FAM40B depletion also increases endothelial permeability.

Conclusions: These results demonstrate the importance of the FAM40 proteins for endothelial cell physiology, and suggest that they act as part of the CCM3-containing STRIPAK complex.

Background: KIF17, a kinesin-2 motor that functions in intraflagellar transport, can regulate the onset of photoreceptor outer segment development. However, the function of KIF17 in a mature photoreceptor remains unclear. Additionally, the ciliary localization of KIF17 is regulated by a C-terminal consensus sequence (KRKK) that is immediately adjacent to a conserved residue (mouse S1029/zebrafish S815) previously shown to be phosphorylated by CaMKII. Yet, whether this phosphorylation can regulate the localization, and thus function, of KIF17 in ciliary photoreceptors remains unknown.

Results: Using transgenic expression in zebrafish photoreceptors, we show that phospho-mimetic KIF17 has enhanced localization along the cone outer segment. Importantly, expression of phospho-mimetic KIF17 is associated with greatly enhanced turnover of the photoreceptor outer segment through disc shedding in a cell-autonomous manner, while genetic mutants of kif17 in zebrafish and mice have diminished disc shedding. Lastly, cone expression of constitutively active tCaMKII leads to a kif17-dependent increase in disc shedding.

Conclusions: Taken together, our data support a model in which phosphorylation of KIF17 promotes its photoreceptor outer segment localization and disc shedding, a process essential for photoreceptor maintenance and homeostasis. While disc shedding has been predominantly studied in the context of the mechanisms underlying phagocytosis of outer segments by the retinal pigment epithelium, this work implicates photoreceptor-derived signaling in the underlying mechanisms of disc shedding.

Background: Myocardial ischemia-reperfusion injury (IRI) has become one of the most serious complications after reperfusion therapy in patients with acute myocardial infarction. Small ubiquitin-like modification (SUMOylation) is a reversible process, including SUMO E1-, E2-, and E3-mediated SUMOylation and SUMO-specific protease-mediated deSUMOylation, with the latter having been shown to play a vital role in myocardial IRI previously. However, little is known about the function and regulation of SUMO E3 ligases in myocardial IRI.

Results: In this study, we found dramatically decreased expression of PIAS1 after ischemia/reperfusion (I/R) in mouse myocardium and H9C2 cells. PIAS1 deficiency aggravated apoptosis and inflammation of cardiomyocytes via activating the NF-κB pathway after I/R. Mechanistically, we identified PIAS1 as a specific E3 ligase for PPARγ SUMOylation. Moreover, H9C2 cells treated with hypoxia/reoxygenation (H/R) displayed reduced PPARγ SUMOylation as a result of down-regulated PIAS1, and act an anti-apoptotic and anti-inflammatory function through repressing NF-κB activity. Finally, overexpression of PIAS1 in H9C2 cells could remarkably ameliorate I/R injury.

Conclusions: Collectively, our findings demonstrate the crucial role of PIAS1-mediated PPARγ SUMOylation in protecting against myocardial IRI.

Background: The gap junction protein, Connexin32 (Cx32), is expressed in various tissues including liver, exocrine pancreas, gastrointestinal epithelium, and the glia of the central and peripheral nervous system. Gap junction-mediated cell-cell communication and channel-independent processes of Cx32 contribute to the regulation of physiological and cellular activities such as glial differentiation, survival, and proliferation; maintenance of the hepatic epithelium; and axonal myelination. Mutations in Cx32 cause X-linked Charcot-Marie-Tooth disease (CMT1X), an inherited peripheral neuropathy. Several CMT1X causing mutations are found in the cytoplasmic domains of Cx32, a region implicated in the regulation of gap junction assembly, turnover and function. Here we investigate the roles of acetylation and ubiquitination in the C-terminus on Cx32 protein function. Cx32 protein turnover, ubiquitination, and response to deacetylase inhibitors were determined for wild-type and C-terminus lysine mutants using transiently transfected Neuro2A (N2a) cells.

Results: We report here that Cx32 is acetylated in transfected N2a cells and that inhibition of the histone deacetylase, HDAC6, results in an accumulation of Cx32. We identified five lysine acetylation targets in the C-terminus. Mutational analysis demonstrates that these lysines are involved in the regulation of Cx32 ubiquitination and turnover. While these lysines are not required for functional Cx32 mediated cell-cell communication, BrdU incorporation studies demonstrate that their relative acetylation state plays a channel-independent role in Cx32-mediated control of cell proliferation.

Conclusion: Taken together these results highlight the role of post translational modifications and lysines in the C-terminal tail of Cx32 in the fine-tuning of Cx32 protein stability and channel-independent functions.

Background: Disruption to the blood brain barrier (BBB) is a leading factor associated with the development of postoperative cognitive dysfunction (POCD). Despite this, the underlying mechanism by which BBB disruption promotes POCD in the elderly population has not yet been not fully elucidated.

Results: In this study, we established a POCD mice model using isoflurane, and observed the highly expressed occludin and claudin 5 in brain tissues concomitant with the increased enrichment of CD4 positive cells and NK cells in the hippocampus of POCD mice compared to normal and non-POCD control.

Conclusions: Our data suggests that peripheral immune cells may participate in the inflammatory reaction within the hippocampus, following the administration of anesthesia via inhalation with the destruction of the blood-brain barrier.

Background: Mitochondrial homeostasis has been increasingly viewed as a potential target of cancer therapy, and mitochondrial fission is a novel regulator of mitochondrial function and apoptosis. The aim of our study was to determine the detailed role of mitochondrial fission in SW837 colorectal cancer cell viability, mobility and proliferation. In addition, the current study also investigated the therapeutic impact of Tanshinone IIA (Tan IIA), a type of anticancer adjuvant drug, on cancer mitochondrial homeostasis.

Results: The results of our data illustrated that Tan IIA promoted SW837 cell death, impaired cell migration and mediated cancer proliferation arrest in a dose-dependent manner. Functional investigation exhibited that Tan IIA treatment evoked mitochondrial injury, as witnessed by mitochondrial ROS overproduction, mitochondrial potential collapse, antioxidant factor downregulation, mitochondrial pro-apoptotic protein upregulation, and caspase-9-dependent apoptotic pathway activation. Furthermore, we confirmed that Tan IIA mediated mitochondrial damage by activating mitochondrial fission, and the inhibition of mitochondrial fission abrogated the proapoptotic effects of Tan IIA on SW837 cells. To this end, our results demonstrated that Tan IIA modulated mitochondrial fission via the JNK-Mff pathways. The blockade of the JNK-Mff axis inhibited Tan IIA-mediated mitochondrial fission and promoted the survival of SW837 cells.

Conclusions: Altogether, our results identified mitochondrial fission as a new potential target to control cancer viability, mobility and proliferation. Furthermore, our findings demonstrate that Tan IIA is an effective drug to treat colorectal cancer by activating JNK-Mff-mitochondrial fission pathways.