An efficient large-scale refolding technique for recovering biologically active recombinant human FGF-21 from inclusion bodies

Double promoter and tandem gene strategy for efficiently expressing recombinant FGF21

BACKGROUND

Fibroblast growth factor 21 (FGF21) is a promising candidate for treating metabolic disorder diseases and has been used in phase II clinical trials. Currently, metabolic diseases are prevalent worldwide, underscoring the significant market potential of FGF21. Therefore, the production of FGF21 must be effectively improved to meet market demand.

RESULTS

Herein, to investigate the impact of vectors and host cells on FGF21 expression, we successfully engineered strains that exhibit a high yield of FGF21. Surprisingly, the data revealed that vectors with various copy numbers significantly impact the expression of FGF21, and the results showed a 4.35-fold increase in expression levels. Furthermore, the performance of the double promoter and tandem gene expression construction design surpassed that of the conventional construction method, with a maximum difference of 2.67 times.

CONCLUSION

By exploring engineered vectors and host cells, we successfully achieved high-yield production of the FGF21 strain. This breakthrough lays a solid foundation for the future industrialization of FGF21. Additionally, FGF21 can be easily, quickly and efficiently expressed, providing a better tool and platform for the research and application of more recombinant proteins.

Fibroblast growth factor 21 alleviates idiopathic pulmonary fibrosis by inhibiting PI3K-AKT-mTOR signaling and stimulating autophagy

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive pulmonary disease with an unclear pathogenesis and no available specific drug treatment. The principal etiological factors are lung inflammation caused by environmental factors, damage to alveolar epithelial cells, leading to epithelial-mesenchymal transition (EMT), and the abnormal proliferation of fibroblasts. Here, we have demonstrated that fibroblast growth factor 21 (FGF21) ameliorates IPF via the autophagy pathway. We administered FGF21 to bleomycin (BLM)-treated mice, which ameliorated their defects in lung function, reduced the accumulation of collagen, restored tissue structure, reduced the deposition of hydroxyproline, reduced the expression of collagen I and α-SMA and increased the expression of E-cadherin. The expression of LC3BII and the number of autophagosomes were significantly higher in the lungs. The expression of AKT and mTOR was significantly reduced by FGF21 treatment. We also determined the effects of FGF21 in A549 cells treated with TGF-β, and found that FGF21 significantly inhibits activation of the AKT signaling pathway, thereby reducing TGF-β-induced EMT and preventing the uncontrolled proliferation of fibroblasts. We conclude that FGF21 ameliorates IPF by inhibiting the PI3K-AKT-mTOR signaling pathway and activating autophagy, which provides a theoretical basis for FGF21 to be used for the treatment of IPF.

Enhanced bioactivity and stability of a long-acting FGF21: A novel variant for the treatment of NASH

Fibroblast growth factor 21 (FGF21) is pivotal in regulating energy metabolism, highlighting substantial therapeutic potential for non-alcoholic steatohepatitis (NASH). Previously, we reported a long-acting FGF21 fusion protein, PsTag-FGF21, which was prepared by genetically fusing human FGF21 with a 648-residue polypeptide (PsTag). While this fusion protein demonstrated therapeutic efficacy against NASH, our final product analysis revealed the presence of fixed impurities resistant to effective removal, indicating potential degradation of PsTag-FGF21. Here, we enriched and analyzed the impurities, confirming our hypothesis regarding the C-terminal degradation of PsTag-FGF21. We now describe a new variant developed to eliminate the C-terminal degradation. By introducing one mutation located at the C-terminal of PsTag-FGF21(V169L), we demonstrated that the new molecule, PsTag-FGF21(V169L), exhibits many improved attributes. Compared with PsTag-FGF21, PsTag-FGF21(V169L) displayed elevated bioactivity and stability, along with a twofold enhanced binding affinity to the coreceptor β-Klotho. In vivo, the circulating half-life of PsTag-FGF21(V169L) was further enhanced compared with that of PsTag-FGF21. In NASH mice, PsTag-FGF21(V169L) demonstrated efficacy with sustained improvements in multiple metabolic parameters. Besides, PsTag-FGF21(V169L) demonstrated the ability to alleviate NASH by decreasing hepatocyte apoptosis. The superior biophysical, pharmacokinetic, and pharmacodynamic properties, along with the positive metabolic effects, imply that further clinical development of PsTag-FGF21(V169L) as a metabolic therapy for NASH patients may be warranted.

Therapeutic effect of long-acting FGF21 with controlled site-specific modification on nonalcoholic steatohepatitis

FGF21 plays an active role in the treatment of type 2 diabetes, obesity, nonalcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH). However, the short half-life and poor stability of wild-type FGF21 limit its clinical application. Previous studies found that PEGylation can significantly increase the stability of FGF21. However, the uneven distribution of PEGylation sites in FGF21 makes it difficult to purify PEG-FGF21, thereby affecting its yield, purity, and activity. To obtain long-acting FGF21 with controlled site-specific modification, we mutated lysine residues in FGF21, resulting in PEGylation only at the N-terminus of FGF21 (mFGF21). In addition, we modified mFGF21 molecules with different PEG molecules and selected the PEG-mFGF21 moiety with the highest activity. The yield of PEG-mFGF21 in this study reached 1 g/L (purity >99 %), and the purification process was simple and efficient with strong quality controllability. The half-life of PEG-mFGF21 in rats reached 40.5-67.4 h. Pharmacodynamic evaluation in mice with high-fat, high-cholesterol- and methionine and choline deficiency-induced NASH illustrated that PEG-mFGF21 exhibited long-term efficacy in improving liver steatosis and reducing liver cell damage, inflammation, and fibrosis. Taken together, PEG-mFGF21 could represent a potential therapeutic drug for the treatment of NASH.

Recent Advances in Overexpression of Functional Recombinant Lipases

Heterologous functional expression of the recombinant lipases is typically a bottleneck due to the expression in the insoluble fraction as inclusion bodies (IBs) which are in inactive form. Due to the importance of lipases in various industrial applications, many investigations have been conducted to discover suitable approaches to obtain functional lipase or increase the expressed yield in the soluble fraction. The utilization of the appropriate prokaryotic and eukaryotic expression systems, along with the suitable vectors, promoters, and tags, has been recognized as a practical approach. One of the most powerful strategies to produce bioactive lipases is using the molecular chaperones co-expressed along with the target protein's genes into the expression host to produce the lipase in soluble fraction as a bioactive form. The refolding of expressed lipase from IBs (inactive) is another practical strategy which is usually carried out through chemical and physical methods. Based on recent investigations, the current review simultaneously highlights strategies to express the bioactive lipases and recover the bioactive lipases from the IBs in insoluble form.

Inclusion Bodies: Status Quo and Perspectives

Multiple E. coli cultivations, producing recombinant proteins, lead to the formation of inclusion bodies (IBs). IBs historically were considered as nondesired by-products, due to their time- and cost-intensive purification. Nowadays, many obstacles in IB processing can be overcome. As a consequence, several industrial processes with E. coli favor IB formation over soluble production options due to the high space time yields obtained. Within this chapter, we discuss the state-of-the art biopharmaceutical IB process, review its challenges, highlight the recent developments and perspectives, and also propose alternative solutions, compared to the state-of-the art processing.

Recent Developments of Liquid Chromatography Stationary Phases for Compound Separation: From Proteins to Small Organic Compounds

Compound separation plays a key role in producing and analyzing chemical compounds. Various methods are offered to obtain high-quality separation results. Liquid chromatography is one of the most common tools used in compound separation across length scales, from larger biomacromolecules to smaller organic compounds. Liquid chromatography also allows ease of modification, the ability to combine compatible mobile and stationary phases, the ability to conduct qualitative and quantitative analyses, and the ability to concentrate samples. Notably, the main feature of a liquid chromatography setup is the stationary phase. The stationary phase directly interacts with the samples via various basic mode of interactions based on affinity, size, and electrostatic interactions. Different interactions between compounds and the stationary phase will eventually result in compound separation. Recent years have witnessed the development of stationary phases to increase binding selectivity, tunability, and reusability. To demonstrate the use of liquid chromatography across length scales of target molecules, this review discusses the recent development of stationary phases for separating macromolecule proteins and small organic compounds, such as small chiral molecules and polycyclic aromatic hydrocarbons (PAHs).

Production of active human FGF21 using tobacco mosaic virus-based transient expression system

Fibroblast growth factor (FGF) family has a wide range of metabolic processes. FGF21 exerts critical physiological functions in clinical application. This study aimed to explore a convenient and highly efficient approach for rhFGF21 expression using TMV-TES. Firstly, the vector pTTEV-GFP was constructed, followed by optimisation of the expression parameters in Nicotiana benthamiana. Then, the rhFGF21 encoding gene harbouring vector pTTEV-rhFGF21 was constructed. Agrobacterium-mediated vacuum infiltration was performed with the optimised parameters and the expression of rhFGF21 was confirmed by the immunoblotting analysis. ELISA revealed that the protein accumulation of rhFGF21 accounts for 0.11% of total soluble proteins. The biological activity was evaluated and the results suggested that tobacco-expressed rhFGF21 could stimulate the glucose uptake in swiss 3T3-L1 adipocytes, which was similar to the activity of commercial products, suggesting its native biological activity. Therefore, using TMV-TES to express rhFGF21 will be a feasible approach for the mass production of rhFGF21.

Active tyrosine phenol-lyase aggregates induced by terminally attached functional peptides in Escherichia coli

The formation of inclusion bodies (IBs) without enzyme activity in bacterial research is generally undesirable. Researchers have attempted to recovery the enzyme activities of IBs, which are commonly known as active IBs. Tyrosine phenol-lyase (TPL) is an important enzyme that can convert pyruvate and phenol into 3,4-dihydroxyphenyl-L-alanine (L-DOPA) and IBs of TPL can commonly occur. To induce the correct folding and recover the enzyme activity of the IBs, peptides, such as ELK16, DKL6, L6KD, ELP10, ELP20, L6K2, EAK16, 18A, and GFIL16, were fused to the carboxyl terminus of TPL. The results showed that aggregate particles of TPL-DKL6, TPL-ELP10, TPL-EAK16, TPL-18A, and TPL-GFIL16 improved the enzyme activity by 40.9%, 50.7%, 48.9%, 86.6%, and 97.9%, respectively. The peptides TPL-DKL6, TPL-EAK16, TPL-18A, and TPL-GFIL16 displayed significantly improved thermostability compared with TPL. L-DOPA titer of TPL-ELP10, TPL-EAK16, TPL-18A, and TPL-GFIL16, with cells reaching 37.8 g/L, 53.8 g/L, 37.5 g/L, and 29.1 g/L, had an improvement of 111%, 201%, 109%, and 63%, respectively. A higher activity and L-DOPA titer of the TPL-EAK16 could be valuable for its industrial application to biosynthesize L-DOPA.