ABSTRACT
Liver regeneration following injury aids the restoration of liver mass and the recovery of liver function. In the present study we investigated the contribution of megakaryocytic leukemia 1 (MKL1), a transcriptional modulator, to liver regeneration. We report that both MKL1 expression and its nuclear translocation correlated with hepatocyte proliferation in cell and animal models of liver regeneration and in liver failure patients. Mice with MKL1 deletion exhibited defective regenerative response in the liver. Transcriptomic analysis revealed that MKL1 interacted with E2F1 to program pro-regenerative transcription. MAPKAPK2 mediated phosphorylation primed MKL1 for its interaction with E2F1. Of interest, phospholipase d2 promoted MKL1 nuclear accumulation and liver regeneration by catalyzing production of phosphatidic acid (PA). PA administration stimulated hepatocyte proliferation and enhanced survival in a MKL1-dependent manner in a pre-clinical model of liver failure. Finally, PA levels was detected to be positively correlated with expression of pro-regenerative genes and inversely correlated with liver injury in liver failure patients. In conclusion, our data reveal a novel mechanism whereby MKL1 contributes to liver regeneration. Screening for small-molecule compounds boosting MKL1 activity may be considered as a reasonable approach to treat acute liver failure.
ABSTRACT
Objective To investigate the significance of the expression of phosphatidic acid phosphatase type 2 domain containing 1A(PPAPDC1A) in human colorectal cancer cell lines.Methods The high metastatic potential cells LOVO,SW620 and low metastatic potential cells SW480,RKO,HCT116 and DLD-1 were cultured,the expression of PPAPDC1A mRNA and protein in different colorectal cancer cells in logarithmic growth period was detected by real-time quantitative polymerase chain reaction and Western blot.Results There were significant differences in the expressions of PPAPDC1A mRNA and protein among the six human colorectal cancer cells (F =41.213,344.1 16;P ＜ 0.05).The expression of PPAPDC1 A mRNA and protein in highly metastatic potential cells LOVO and SW620 was significantly higher than that in DLD-1,HCT116,RKO and SW480 cells (P ＜0.05).The expression of PPAPDC1A protein in LOVO cells with high metastatic potential was significantly higher than that in SW620 cells(P ＜ 0.05).The expression of PPAPDC1A protein in DLD-1 cells was significantly higher than that in HCT116,RKO and SW480 cells (P ＜0.05).The expression of PPAPDC1 A protein in HCT116 cells with low metastatic potential was significantly higher than that in RKO and SW480 cells (P ＜ 0.05).The expression of PPAPDC1 A protein in RKO cells was significantly higher than that in SW480 cells (P ＜ 0.05).There was no significant difference in the expression of PPAPDC1A mRNA between LOVO and SW620 cells (P ＜ 0.05).There was no significant difference in the expression of PPAPDC1A mRNA between SW480,RKO,HCT116 and DLD-1 cells (P＜ 0.05).Conclusion PPAPDC1A expresses differentially in colorectal cancer cell lines,which may be involved in the invasion and metastasis of colorectal cancer.
ABSTRACT
OBJECTIVE: To investigate factors that affected the distribution of rehydrated particle size of freeze-dried docetaxel liposome and develop a technique of producing docetaxel liposome that can meet clinical requirements. METHODS: The single factor method was utilized in this study. Docetaxel liposome were prepared using different types of negatively charged phospholipids, or lecithins with varying phosphatidylcholine (PC) content, or various cryoprotectants at different gradient concentrations, followed by freeze-drying with different protocols. The particle sizes of corresponding rehydrated products were compared and the effects of different factors were analyzed. RESULTS: The optimal liposomal membrane was composed of dipalmitoyl phosphatidic acid (DPPA), 20% trehalose and lecithin containing 92% PC. The best freeze-drying protocol included following steps; flash freezing, 19 h of sublimation-drying and 9 h of desorption-drying. CONCLUSION: The parameters, including negatively charged phospholipids, cryoprotectants, PC content of lecithin and lyophilization protocols, had various effects on the particle sizes of reconstituted docetaxel liposome.
ABSTRACT
Extracellular ATP has been known to modulate various cellular responses including mitogenesis, secretion and morphogenic activity in neuronal cells. In the ATP-induced morphogenic activity, focal adhesion kinase(s) such as Fak have been suggested to play a critical role. Binding of ATP to its specific cell surface receptor in PC12 cells induces phospholipase D (PLD) activity. However, the role of PLD on ATP-induced Fak activation in PC12 cells remains unclear. In this study, we investigated the role of PLD on the ATP-induced Fak activation and paxillin phosphorylation using two established cell lines: wild type PLD2- and lipase-inactive mutant PLD2-inducible PC12 cells. Stimulation of cells with ATP caused PLD2 activation via classical protein kinase C activation. ATP also induced Fak activation, and paxillin phosphorylation, and were dramatically reduced by wild type PLD2 overexpression but not by lipase-inactive mutant PLD2 overexpression. When the PC12 cells were pretreated with propranolol, a specific inhibitor for phosphatidic acid phosphohydrolase resulting in the accumulation of PA, ATP-induced Fak activation and paxillin phosphorylation were also reduced. We found that inhibition of tyrosine phosphatases by pervanadate completely blocked PLD2-dependent Fak and paxillin dephosphorylation. Taken together, we suggest that PLD2 activity might play a negative role in ATP-induced Fak and paxillin phosphorylation possibly through tyrosine phosphatases.