RESUMEN
Purpose: The human somatropin is a single-chain polypeptide with a pivotal role in various biological processes. Although Escherichia coli is considered as a preferred host for the production of human somatropin, the high expression of this protein in E. coli results in the accumulation of protein as inclusion bodies. Periplasmic expression using signal peptides could be used to overcome the formation of inclusion bodies; still, the efficiency of each of the signal peptides in periplasmic transportation is varied and often is protein specific. The present study aimed to use in silico analysis to identify an appropriate signal peptide for the periplasmic expression of human somatropin in E. coli. Methods: A library containing 90 prokaryotic and eukaryotic signal peptides were collected from the signal peptide database, and each signal's characteristics and efficiency in connection with the target protein were analyzed by different software. The prediction of the secretory pathway and the cleavage position was determined by the signalP5 server. Physicochemical properties, including molecular weight, instability index, gravity, and aliphatic index, were investigated by ProtParam software. Results: The results of the present study showed that among all the signal peptides studied, five signal peptides ynfB, sfaS, lolA, glnH, and malE displayed high scores for periplasmic expression of human somatropin in E. coli, respectively. Conclusion: In conclusion, the results indicated that in-silico analysis could be used for the identification of suitable signal peptides for the periplasmic expression of proteins. Further laboratory studies can evaluate the accuracy of the results of in silico analysis.
RESUMEN
Purpose: Breast cancer (BC) is globally the main reason of cancer-related deaths in women. Omentin-1, an anti-inflammatory and antioxidant adipokine, plays different roles in tumorigenesis and anti-oncogenic pathways. In present study, we investigated the association of omentin-1 with oxidative stress and clinical significances in healthy controls and BC patients to assess the prognostic and diagnostic value of omentin-1 in this cancer. Methods: This case-control study included 88 BC patients and 86 healthy controls. The serum levels of omentin-1 were assessed by enzyme-linked immunosorbent assays methods. Also, total antioxidant capacity (TAC), total oxidant status (TOS) and malondialdehyde (MDA) serum levels were measured by spectrophotometer. quantitative real-time polymerase chain reaction (qRT-PCR) was applied to the measurement of gene expression of omentin-1. Results: the serum levels of omentin-1 were significantly lower in the BC patients compared to the healthy controls (P<0.001). Moreover, gene expression of omentin-1was significantly downregulated in the BC tissues compared to the adjacent normal tissues (P<0.001). Gene expression of omentin-1and its serum levels were significantly higher in grade I compared with grade II and III (P=0.001, P<0.001, respectively). Additionally, the serum levels of omentin-1 in the p53-positive BC patients were significantly higher than the p53-negative BC patients (P=0.001). There was an inverse correlation between the serum levels of MDA and TOS with the serum levels of omentin-1 (r=-0.436, r=-461, respectively). Conclusion: We conclude that omentin-1 may have a good prognostic and diagnostic roles in the BC patients and decreases oxidative stress in these patients.
