Purification and partial biochemical characterization of recombinant lactate dehydrogenase 1 (LDH-1) of the white shrimp Litopenaeus vannamei

Comprehensive evaluation of recombinant lactate dehydrogenase production from inclusion bodies

A broad application spectrum ranging from clinical diagnostics to biosensors in a variety of sectors, makes the enzyme Lactate dehydrogenase (LDH) highly interesting for recombinant protein production. Expression of recombinant LDH is currently mainly carried out in uncontrolled shake-flask cultivations leading to protein that is mostly produced in its soluble form, however in rather low yields. Inclusion body (IB) processes have gathered a lot of attention due to several benefits like increased space-time yields and high purity of the target product. Thus, to investigate the suitability of this processing strategy for ldhL1 production, a fed-batch fermentation steering the production of IBs rather than soluble product formation was developed. It was shown that the space-time-yield of the fermentation could be increased almost 3-fold by increasing qs to 0.25 g g-1 h-1 which corresponds to 21% of qs,max, and keeping the temperature at 37°C after induction. Solubilization and refolding unit operations were developed to regain full bioactivity of the ldhL1. The systematic approach in screening for solubilization and refolding conditions revealed buffer compositions and processing strategies that ultimately resulted in 50% product recovery in the refolding step, revealing major optimization potential in the downstream processing chain. The recovered ldhL1 showed an optimal activity at pH 5.5 and 30∘C with a high catalytic activity and KM values of 0.46 mM and 0.18 mM for pyruvate and NADH, respectively. These features, show that the here produced LDH is a valuable source for various commercial applications, especially considering low pH-environments.

Transcriptomic analysis reveals the role of Glycolysis pathway in Litopenaeus vannamei during DIV1 infection

In recent years, shrimp farming has experienced significant losses due to the emergence of DIV1 (Decapod iridescent virus 1), an infectious virus with a high fatality rate among shrimp. In this study, we conducted transcriptomic analyses on shrimp Litopenaeus vannamei hemocytes following DIV1 infection and focused on the function of genes in the Glycolysis pathway during DIV1 infection. A total of 2197 differentially expressed genes (DEGs) were identified, comprising 1506 up-regulated genes and 691 down-regulated genes. These genes were primarily associated with Phagosome, ECM-Receptor Interaction, Drug Metabolism-Other Enzymes, and the AGE-RAGE signaling pathway in diabetic complications. KEGG pathway enrichment analysis of the DEGs revealed a noteworthy correlation with metabolic pathways, with a specific focus on glucose metabolism. Specifically, the Glycolysis/Gluconeogenesis pathway exhibited significant upregulation following DIV1 infection. In line with this, we observed an augmented accumulation of glycolytic-related metabolites in the hemolymph following DIV1 challenge along with upregulation of the relative mRNA expression of several glycolytic-related genes. Moreover, we found that the inhibition of lactate dehydrogenase (LDH) activity through RNAi or the use of an inhibitor resulted in reduced lactate production, effectively safeguarding shrimp from DIV1 infection. These findings not only provide a comprehensive dataset for further investigation into DIV1 pathogenesis but also offer valuable insights into the immunometabolism mechanisms that govern shrimp responses to DIV1 infection.

Recombinant production, purification, and biochemical characterization of a novel L-lactate dehydrogenase from Bacillus cereus NRC1 and inhibition study of mangiferin

Lactate dehydrogenase (LDH, EC 1.1.1.27) is one of the vital glycolytic conditions, especially during anaerobic conditions. It is a significant diagnostic, prognostic, and monitoring biomarker parameter. A 950-bp DNA fragment containing the gene (LDH) encoding LDH was amplified from Bacillus cereus NRC1. The deduced amino acid sequence reveals that B. cereus LDH (Bc-LDH) is highly homologous to the LDHs of Bacillus organisms. All LDH enzymes have a significant degree of conservation in their active site and several additional domains with unidentified functions. The gene for LDH, which catalyzes lactate synthesis, was cloned, sequenced (accession number: LC706200.1), and expressed in Escherichia coli BL21 (DE3). In this investigation, Bc-LDH was purified to homogeneity with a specific activity of 22.7 units/mg protein and a molecular weight of 35 kDa. It works optimally at pH 8.0. The purified enzyme was inhibited by FeCl2, CuCl2, ZnCl2, and NiCl, whereas CoCl2 was found to boost the activity of Bc-LDH. The molecular docking of the 3D model of the Bc-LDH structure with a natural inhibitor, mangiferin, demonstrated excellent LDH inhibition, with a free binding energy of −10.2 kcal/mol. Moreover, mangiferin is a potent Bc-LDH inhibitor that inhibits Bc-LDH competitively and has one binding site with a Ki value of 0.075 mM. The LDH-mangiferin interaction exhibits a low RMSF value (>1.5 Å), indicating a stable contact at the residues. This study will pave the way for more studies to improve the understanding of mangiferin, which could be considered an intriguing candidate for creating novel and improved LDH inhibitors.

LncRNA LINC00461 exacerbates myocardial ischemia-reperfusion injury via microRNA-185-3p/Myd88

OBJECTIVE

Long non-coding RNAs (lncRNAs) play critically in the pathogenesis of myocardial ischemia-reperfusion (I/R) injury. Thus, it was proposed to investigate the mechanism of LINC00461 in the disease through mediating microRNA-185-3p (miR-185-3p)/myeloid differentiation primary response gene 88 (Myd88) axis.

METHODS

miR-185-3p, LINC00461 and Myd88 expression in mice with I/R injury was measured. Mice with I/R injury were injected with the gene expression-modified vectors, after which cardiac function, hemodynamics, myocardial enzyme, oxidative stress, and cardiomyocyte apoptosis were analyzed.

RESULTS

I/R mice showed LINC00461 and Myd88 up-regulation and miR-185-3p down-regulation. Down-regulating LINC00461 or up-regulating miR-185-3p recovered cardiac function, reduced myocardial enzyme levels, and attenuated oxidative stress and cardiomyocyte apoptosis in mice with I/R. miR-185-3p overexpression rescued the promoting effect of LINC00461 upregulation on myocardial injury in I/R mice.

CONCLUSION

LINC00461 knockdown attenuates myocardial I/R injury via elevating miR-185-3p expression to suppress Myd88 expression.

microRNA-193-3p attenuates myocardial injury of mice with sepsis via STAT3/HMGB1 axis

Objective

Little is known regarding the functional role of microRNA-193-3p (miR-193-3p) in sepsis. Hence, the aim of the present study was to investigate the effect of miR-193-3p on myocardial injury in mice with sepsis and its mechanism through the regulation of signal transducers and activators of transcription 3 (STAT3).

Methods

The mice model of sepsis was established by cecal ligation and puncture (CLP), septic mice were injected with miR-193-3p agomir, miR-193-3p antagomir or siRNA-STAT3. The expression of miR-193-3p, STAT3 and HMGB1 in the myocardial tissue of septic mice were detected. Cardiac ultrasound, hemodynamics, myocardial injury markers, inflammatory factors and cardiomyocyte apoptosis in septic mice were measured.

Results

MiR-193-3p expression was reduced while STAT3 expression was increased in septic mice. Down-regulated STAT3 or up-regulated miR-193-3p improved cardiac function, attenuated myocardial injury, inflammation and cardiomyocyte apoptosis in septic mice. Knockdown STAT3 reversed the role of inhibited miR-193-3p for mice with sepsis. miR-193-3p targeted STAT3, thereby inhibiting HMGB1 expression.

Conclusion

This study provides evidence that miR-193-3p targets STAT3 expression to reduce HMGB1 expression, thereby reducing septic myocardial damage. MiR-193-3p might be a potential candidate marker and therapeutic target for sepsis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03022-x.