In humans, defects in peroxisome biogenesis are the cause of lethal diseases typified by Zellweger syndrome. Here, we show that inactivating mutations in human PEX3 cause Zellweger syndrome, abrogate peroxisome membrane synthesis, and result in reduced abundance of peroxisomal membrane proteins (PMPs) and/or mislocalization of PMPs to the mitochondria. Previous studies have suggested that PEX3 may traffic through the ER en route to the peroxisome, that the COPI inhibitor, brefeldin A, leads to accumulation of PEX3 in the ER, and that PEX3 overexpression alters the morphology of the ER. However, we were unable to detect PEX3 in the ER at early times after expression. Furthermore, we find that inhibition of COPI function by brefeldin A has no effect on trafficking of PEX3 to peroxisomes and does not inhibit PEX3-mediated peroxisome biogenesis. We also find that inhibition of COPII-dependent membrane traffic by a dominant negative SAR1 mutant fails to block PEX3 transport to peroxisomes and PEX3-mediated peroxisome synthesis. Based on these results, we propose that PEX3 targeting to peroxisomes and PEX3-mediated peroxisome membrane synthesis may occur independently of COPI- and COPII-dependent membrane traffic.
The main oil fields in China have gone gradually into the high or extra-high water cut production period, and conventional profile control technologies already cannot meet oilfields’ production requirements. The research and application of new fluid diverting technologies has got many new progresses, but their validity term is relatively short in the aspect of improving the high water cut oil reservoir. Based on the capillary bundle model, a comprehensive performance evaluation method of fluid diverting agents has been proposed, through systematical analysis of the fluid diverting agents evaluation methods at home and abroad and their existing problems, and all-sided understanding of the present reservoir situation. The experimental results showed that this method could effectively and comprehensively evaluate the fluid diverting agents’ diverting effect, shear resistance performance, temperature resistance performance and salt resistance performance, and could optimize injection process parameters. It has the important and practical significance to improve the duty validity of the fluid diverting agents.
Calcium ions (Ca 2+ ) regulate plant growth and development during exposure to multiple biotic and abiotic stresses as the second signaling messenger in cells. The extracellular calcium-sensing receptor (CAS) is a specific protein spatially located on the thylakoid membrane. It regulates the intracellular Ca 2+ responses by sensing changes in extracellular Ca 2+ concentration, thereby affecting a series of downstream signal transduction processes and making plants more resilient to respond to stresses. Here, we summarized the discovery process, structure, and location of CAS in plants and the effects of Ca 2+ and CAS on stomatal functionality, photosynthesis, and various environmental adaptations. Under changing environmental conditions and global climate, our study enhances the mechanistic understanding of calcium-sensing receptors in sustaining photosynthesis and mediating abiotic stress responses in plants. A better understanding of the fundamental mechanisms of Ca 2+ and CAS in regulating stress responses in plants may provide novel mitigation strategies for improving crop yield in a world facing more extreme climate-changed linked weather events with multiple stresses during cultivation.
Abstract Twenty‐three microsatellite markers were developed from an AC‐enriched genomic library of Eucommia ulmoides , an economically important tree species for both herbal medicine and organic chemical industry in China. Nineteen microsatellite loci were found polymorphic by testing 36 individuals from 10 populations, with two to 14 alleles per locus. The expected heterozygosity ranged from 0.054 to 0.874. This set of microsatellite markers has provided a useful tool for the ongoing efforts in studying population genetic structure of E. ulmoides.
Steroidogenesis is an indispensable process that is indirectly associated with spermatogenesis in the Leydig cell (LC) to utilize the lipid droplets (LDs) that are critical to maintaining normal testosterone synthesis. The regulation of LD mobilization, known as lipophagy, in the LC is still largely unknown.In the present study, the LC of the Chinese soft-shelled turtle was investigated to identify the steroidogenic activity and lipophagy during the annual reproductive cycle by light microscopy, immunohistochemistry (IHC), immunofluorescence (IF), and transmission electron microscopy (TEM).The LC showed a dynamic steroidogenic function with strong activity of 3β-HSD, vimentin and tubular ER during hibernation by IHC and TEM. The tubulo-vesicular ER had a weak immunopositive reaction for 3β-HSD in the LC during reproductive phase, suggesting persistent steroidogenic activity. ORO staining and TEM demonstrated that a larger number of LDs had accumulated in the LC during hibernation than in the reproductive phase. These LDs existed in close association with mitochondria and lysosomes by being dynamically surrounded by intermediate filaments to facilitate LD utilization. Lysosomes were found directly attached to large LDs, forming an autophagic tube and engulfing LDs, suggesting that micro-lipophagy occurs during hibernation. Furthermore, the IHC of ATG7 (Autophagy Related Gene 7) and the IF of the LC3 (Microtubule-associated protein light chain 3), p62 (Sequestosome-1 (SQSTM1) and LAMP1(Lysosomal-associated membrane protein 1) results demonstrated strong expression, and further confirmation by TEM showed the existence of an autophagosome and an autolysosome and their fusion during the hibernation season.In conclusion, the present study provides clear evidence of LD consumption in the LC by lipophagy, lysosome and mitochondria during the hibernation period, which is a key aspect of steroidogenesis in the Chinese soft-shelled turtle.
Abstract Background: Mitochondrial quality control (MQC) plays a critical role in the progression of tubulointerstitial injury in diabetic kidney disease (DKD). Mitochondrial unfolded protein response (UPRmt), an important MQC procedure, is activated to maintain mitochondrial protein homeostasis upon mitochondrial stress. Activating transcription factor 5 (ATF5) has been proved to be the key in mammalian UPRmt via its mitochondria-nuclear translocation. In this study, we investigated whether ATF5 activate UPRmt in mammalian DKD to reduce tubule injury. Methods: Eight-week-old db/db mice were injected with ATF5-shRNA lentivirus or negative control lentivirus via the tail vein. Mice were euthanized at 12 weeks, DHE and Tunel assay were performed respectively to evaluate the apoptosis and ROS production of kidney section. And we used western blotting to detect the expression relationship between ATF5 and UPRmt. ATF5-siRNA, ATF5 overexpression plasmid or HSP60-siRNA were transfected into HK-2 cells. Mitosox and DCFH-DA staining methods were used to gauging cell and mitochondial oxidative stress level, while early stage of cell apoptosis was detected by JC-1 kit. Results: We found that UPRmt intensified and exhibited opposite function in HK-2 cells in respond to high glucose intervention. We showed that compared with non-diabetic samples, renal section from patients and mice with diabetes showed increase expression of ATF5 and UPRmt related proteins (HSP60, CLpP, LONP1), which were correlated with tubule damage of kidney. We also established 12-week-old ATF5 knocking-down db/db mice, and found they presented improved biochemical and histological features and lower expression of UPRmt related proteins as compared with db/db mice. Correspondingly, HG-induced oxidative stress damage, apoptosis and UPRmt were reversed by ATF5-siRNA in HK-2 cells and aggravated by ATF5 over-expressing plasmid. Moreover, overexpressing ATF5 and down-regulating HSP60 simultaneously offset the effect of ATF5 overexpressing plasmid. Conclusions: Our findings suggest that ATF5 is closely associated with the progress of damage in diabetic kidney tubule cells by regulating UPRmt.
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