IPTG-induced high protein expression for whole-cell biosynthesis of L-phosphinothricin

BACKGROUND

Biocatalytic production of L-phosphinothricin (L-PPT) is currently the most promising method. In this work, we use an Escherichia coli strain coexpressing of D-amino acid oxidase and catalase (E. coli DAAO-CAT) to oxidation biocatalytic D-PPT to PPO, then use the second E. coli strain coexpressing glutamate dehydrogenase and formate dehydrogenase (E. coli GluDH-FDH) to reduce biocatalytic PPO to L-PPT.

MAIN METHODS AND MAJOR RESULTS

We compared the effects of different concentrations of IPTG or lactose on protein expression and enzyme activity in 5 L fermenter. The best induction conditions for E. coli DAAO-CAT were 0.05 mM IPTG, induction for 18 h at 28°C. The specific enzyme activities of DAAO and CAT were 153.20 U g-1 and 896.23 U g-1 , respectively. The optimal induction conditions for E. coli GluDH-FDH were 0.2 mM IPTG, induction for 19 h at 28°C. The specific enzyme activities of GluDH and FDH were 41.72 U g-1 and 109.70 U g-1 , respectively. The 200 mM D-PPT was biocatalyzed by E. coli DAAO-CAT for 4 h with space-time yield of 9.0 g·L-1 ·h-1 and conversion rate of over 99.0%. Then 220 mM PPO was converted to L-PPT by E. coli GluDH-FDH for 3 h with space-time yield of 14.5 g·L-1 ·h-1 and conversion rate of over 99.0%. To our knowledge, this is the most efficient biocatalytic reaction for L-PPT production.

CONCLUSIONS AND IMPLICATIONS

We found that IPTG has advantages compared with lactose in the enzyme activity and biomass of E. coli DAAO-CAT and E. coli GluDH-FDH, and IPTG is more environmentally friendly. Our data implicated that IPTG can replace lactose in terms of economic feasibility and effectiveness for scaled-up industrial fermentations.

[Propensity-matched comparison of laparoscopic and open radical cystectomy for female patients with bladder cancer]

OBJECTIVE

To compare the perioperative and oncologic outcomes of female patients receiving laparoscopic radical cystectomy (LRC) and open radical cystectomy (ORC).

METHODS

Retrospective review of 91 consecutive female patients with urothelial carcinoma of bladder undergoing radical cystectomy at a single academic institution from 2006 to 2017. Those female patients received open radical cystectomy were matched to the patients who underwent laparoscopic radical cystectomy by using propensity score matching in 1 ∶1 ratio. The matching factors included age, body mass index (BMI), American Society of Anesthesiologists (ASA) score, pathologic stage and pathologic nodal stage. The perioperation and oncology characteristics were compared, and Kaplan-Meier method was used to analyze the overall survival (OS), cancer specific survival (CSS) and progression-free survival (PFS) estimates. Finally, we did a sensitive analysis by using multivariable COX regression of all the patients, adjusting for the matching factors.

RESULTS

There were 65 ORC and 26 LRC patients identified in this cohort with urothelial carcinoma of bladder, the median follow-up time was 38 months (interquartile range 18-69). The age (P<0.001) and ASA scores (P=0.018) were less for LRC before being matched. There were 22 LRC and 22 ORC patients matching successfully. Before being matched, the estimate blood loss (P=0.005), transfusion rate (P<0.001) and total complications rate (P=0.015) were less for LRC, and the lymph nodes yield was greater for LRC, but there were no differences in OS (P=0.698), CSS (P=0.942) and PFS (P=0.837) between the two groups. After being matched, the estimate blood loss (P=0.009), transfusion rate (P=0.001) and total complications rate (P=0.040) were less for LRC, but there was no difference in the lymph nodes yield. Besides, there were no statistic differences in OS (P=0.432), CSS (P=0.429) and PFS (P=0.284) between the two groups. In addition, in multivariable COX regression analysis, surgical approaches (LRC/ORC) were not found to be a predictor of OS (HR 1.134, 95%CI 0.335-3.835, P=0.839), CSS (HR 1.051, 95%CI 0.234-4.719, P=0.949) and PFS (HR 0.538, 95%CI 0.138-2.095, P=0.371) of the female patients with urothelial carcinoma of bladder.

CONCLUSION

It is advantageous for laparoscopic radical cystectomy in terms of estimating blood loss, transfusion rate and complication rate. But there was no evidence that laparoscopic radical cystectomy for female patients with bladder cancer had a better oncologic prognosis than open radical cystectomy from this study.

[Chloroquine inhibits viability of renal carcinoma cells and enhances sunitinib-induced caspase-dependent apoptosis]

OBJECTIVE

To determine whether chloroquine (CQ), an often used inhibitor of late autophagy and autophagosome/lyosome fusion, can inhibit proliferation of renal carcinoma cells and investigate its effect on sunitinib (ST)-induced apoptosis.

METHODS

Renal carcinoma cell line 786 O and ACHN had been used as cellular model and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay was carried out to detect the cell viability in response to CQ or ST treatment. Both transmission electron microscope and immunoblotting had been employed to observe apoptotic and autophagic process. To examine the involvement of autophagy in ST-dependent apoptosis, autophagy had been inhibited either chemically or genetically via utilizing autophagy inhibitor or specific small interference RNA (siRNA) targeted to either Ulk1 (unc-51-like kinase 1) or LC3 (microtubule associated protein 1 light chain 3 fusion protein), two essential autophagic proteins.

RESULTS

Both ST and CQ induced cell viability loss, indicating that either of them could inhibit renal cancer cell proliferation. Clone formation experiments confirmed the aforementioned results. Furthermore, the combined ST with CQ synergistically promoted the loss of cell viability. By transmission electron microscopy and immunoblotting, we found that the ST induced both autophagy and caspase-dependent apoptosis. While 3-MA, an early autophagy inhibitor, reduced the ST-induced cleavage of poly (ADP-ribose) polymerase-1 (PARP-1), a substrate of caspase 3/7 and often used marker of caspase-dependent apoptosis, CQ promoted the ST-dependent PARP-1 cleavage, indicating that the early and late autophagy functioned differentially on the ST-activated apoptotic process. Moreover, the knock down of either Ulk1 or LC3 decreased the ST-caused apoptosis.Interestingly, we observed that rapamycin, a specific inhibitor of mTOR (mammalian target of rapamycin) and an inducer of autophagy, also showed to inhibit cell viability and increased the cleavage of PARP-1 in the ST-treated cells, suggesting that autophagy was likely to play a dual role in the regulation of the ST-induced apoptosis.

CONCLUSION

ST activates both apoptotic and autophagic process in renal carcinoma cells. Although autophagy precedes the ST-induced apoptosis, however, early and late autophagy functions differentially on the apoptotic process induced by this compound. Additionally, ST can coordinate with the inducer of autophagy to inhibit the cell proliferation. Further research in this direction will let us illuminate to utilize CQ as a potential drug in the treatment of renal carcinoma.

[Sunitinib induces autophagy via suppressing Akt/mTOR pathway in renal cell carcinoma]

OBJECTIVE

To determine the mechanism of sunitinib-induced autophagy in renal cell carcinoma cells.

METHODS

MTS assay was applied to detect the cell viability alteration under the treatment of sunitinib (2, 8 μmol/L). The sunitinib-induced autophagy as well as cell apoptosis was measured and compared after knocking down autophagy-related protein Beclin1 and microtubule associated protein 1 light chain 3 fusion protein (LC3) by RNA interference. The transmission electron microscope was used to observe the formation of autophagosomes in ACHN cells. The fluorescence microscope was used to monitor distribution and aggregation of endogenous LC3-II. The expressions of protein such as LC3-II, the autophagic regulation molecules protein kinase B/ mammalian target of rapamycin (Akt/mTOR) and the symbol of apoptosis poly ADP-ribose polymerase (PARP) were capable to be detected by immunoblotting assay.

RESULTS

Sunitinib was able to significantly trigger cell viability loss in the renal carcinoma cell ACHN, which was both in a concentration-dependent and time-dependent manner (P<0.05). After reducing the autophagy by knocking down Beclin1 and LC3, the number of cleavage of PARP was increased remarkably, whereas there was nearly not any cleavage in the mock group. By the transmission electron microscope, there were more autophagic vacuoles in ACHN cells after being administrated with sunitininb compared with the control. And the nuclear-to-cytosol translocation as well as aggregation of LC3-II was presented after sunitinib treatment by the fluorescence microscope, which was the proof of the enhanced autophagy. According to the immunoblotting, sunitinib was able to increase the accumulation of LC3-II . At the same time, the result of sunitinib combined with chloroquine, a drug which blocked the fusion of autophagosomes and lysosomes, demonstrated that the increasing amount of LC3-II was due to the enhanced autophagy flux by sunitinib treatment in ACHN cells. However, phosphorylation of Akt as well as mTOR was decreased at the same time. The rapamycin (mTOR inhibitor) or knocking down Akt subunits could change the sunitinib-induced LC3 -II accumulation, whereas overexpression of Akt subunits decreased the autophagic flux, indicating that Akt/mTOR was the target of sunitinib in autophagy.

CONCLUSION

Sunitinib induced autophagy via suppressing Akt/mTOR pathway, and the autophagy was involved in apopotosis.

[Sunitinib induces autophagy via suppressing Akt/mTOR pathway in renal cell carcinoma]

OBJECTIVE

To determine the mechanism of sunitinib-induced autophagy in renal cell carcinoma cells.

METHODS

MTS assay was applied to detect the cell viability alteration under the treatment of sunitinib (2, 8 μmol/L). The sunitinib-induced autophagy as well as cell apoptosis was measured and compared after knocking down autophagy-related protein Beclin1 and microtubule associated protein 1 light chain 3 fusion protein (LC3) by RNA interference. The transmission electron microscope was used to observe the formation of autophagosomes in ACHN cells. The fluorescence microscope was used to monitor distribution and aggregation of endogenous LC3-II. The expressions of protein such as LC3-II, the autophagic regulation molecules protein kinase B/ mammalian target of rapamycin (Akt/mTOR) and the symbol of apoptosis poly ADP-ribose polymerase (PARP) were capable to be detected by immunoblotting assay.

RESULTS

Sunitinib was able to significantly trigger cell viability loss in the renal carcinoma cell ACHN, which was both in a concentration-dependent and time-dependent manner (P<0.05). After reducing the autophagy by knocking down Beclin1 and LC3, the number of cleavage of PARP was increased remarkably, whereas there was nearly not any cleavage in the mock group. By the transmission electron microscope, there were more autophagic vacuoles in ACHN cells after being administrated with sunitininb compared with the control. And the nuclear-to-cytosol translocation as well as aggregation of LC3-II was presented after sunitinib treatment by the fluorescence microscope, which was the proof of the enhanced autophagy. According to the immunoblotting, sunitinib was able to increase the accumulation of LC3-II . At the same time, the result of sunitinib combined with chloroquine, a drug which blocked the fusion of autophagosomes and lysosomes, demonstrated that the increasing amount of LC3-II was due to the enhanced autophagy flux by sunitinib treatment in ACHN cells. However, phosphorylation of Akt as well as mTOR was decreased at the same time. The rapamycin (mTOR inhibitor) or knocking down Akt subunits could change the sunitinib-induced LC3 -II accumulation, whereas overexpression of Akt subunits decreased the autophagic flux, indicating that Akt/mTOR was the target of sunitinib in autophagy.

CONCLUSION

Sunitinib induced autophagy via suppressing Akt/mTOR pathway, and the autophagy was involved in apopotosis.

The expression of osteoprotegerin is required for maintaining the intervertebral disc endplate of aged mice

OBJECTIVE

Human chondrocytes and annulus fibrosus cells of intervertebral disc (IVD) express osteoprotegerin (OPG), but the effect of OPG on the pathogenesis of IVD degeneration remains unknown. Here we assessed the phenotype change of IVD in OPG(-/-) mice.

METHODS

The IVDs from 12-, 20-, and 28-week-old OPG(-/-) mice and WT controls were subjected to histologic analyses including TRAP staining for osteoclasts, immunostaining for OPG and type I collagen protein expression, and TUNEL staining for apoptosis. The IVD tissues were also subjected to real time RT-PCR for mRNA expression of genes for osteoblast-osterix, ALP, and osteocalcin; for osteoclasts-trap, rank, mmp9 and cathepsin K, and for chondrocytes-aggrecan, mmp13 and Col10.

RESULTS

OPG protein expresses at the cells of endplate cartilage and annulus fibrosis in IVDs of WT mice. Compared to WT mice, OPG(-/-) mice developed aging related cartilage loss and bony tissue appearance at the endplate. Stating from 20 weeks of age, IVDs from OPG(-/-) mice expressed significantly increased mmp13 and Col10 levels, which is associated with increased osteoblast number and elevated expression of osteoblast marker genes. Furthermore, TRAP+ osteoclasts were presented in the endplate cartilage of OPG(-/-) mice. These osteoclasts localized adjacently to and erosion into the cartilage. Increased expression of RANK, mmp9 and cathepsin k was detected in OPG(-/-) IVDs.

CONCLUSIONS

OPG at IVD plays an important role for maintaining the integrity of endplate cartilage during aging by preventing endplate cartilage from osteoclast-mediated resorption.

Sequence homology of a canine brain calcium-binding protein with calregulin and the human Ro/SS-A antigen

A 60 kDa calcium-binding protein (CBP) was purified from canine brain and its N-terminal sequence determined to be: Glu-Pro-Ala-Ile-Tyr-Phe-Lys-Glu-Gln-Phe-Leu-Asp-Gly-Asp-Gly-X-Thr-Arg-X- Ile- Glu-Ser-Lys. This sequence is very similar to that of "Ccalregulin", a CBP of unknown function which is similar in size and appears to be present in most animal tissues. An unexpected and even more striking similarity was found with the N-terminal sequence of the human Ro/SS-A antigen, a 60 kDa protein which has long been implicated in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus. These findings suggest that the Ro/SS-A antigen is probably also a CBP.