In vitro refolding with simultaneous purification of recombinant human parathyroid hormone (rhPTH 1-34) from Escherichia coli directed by protein folding size exclusion chromatography (PF-SEC): implication of solution additives and their role on aggregates and renaturation.

Recombinant proteins are frequently hampered by aggregation during the refolding and purification process. A simple and rapid method for in vitro refolding and purification of recombinant human parathyroid hormone (rhPTH 1-34) expressed in Escherichia coli with protein folding size exclusion chromatography (PF-SEC) was developed in the present work. Discrete effects of potential solution additives such as urea, polypolyethylene glycol, proline, and maltose on the refolding with simultaneous purification of rhPTH were investigated. The results of individual additives indicated that both maltose and proline had remarkable influences on the efficiency of refolding with a recovery yield of 65 and 66% respectively. Further, the synergistic effect of these additives on refolding was also explored. These results demonstrate that the additive combinations are more effective for inhibiting protein aggregation during purification of rhPTH in terms of recovery yield, purity, and specific activity. The maltose and proline combination system achieved the highest renatured rhPTH having a recovery yield of 78%, a purity of ≥99%, and a specific activity of 3.31 × 10(3) cAMP pM/cell respectively, when compared to the classical dilution method yield (41%) and purity (97%). In addition, the role of maltose and proline in a combined system on protein aggregation and refolding has been explained. The molecular docking (in silico) scores of maltose (-10.91) and proline (-9.0) support the in vitro results.

Characterization of recombinant human granulocyte colony-stimulating factor expression by FT-IR spectroscopy: Studies on thermal induction and media formulation on the stability of the protein secondary structure.

The Fourier-transform infrared (FT-IR) spectroscopic approach has been employed to understand the recombinant human G-CSF (rhG-CSF) protein accumulation, secondary structure, and thermal stability in Escherichia coli grown under a temperature shift strategy (37 and 28°C) in various media formulations. The choline + sodium pyruvate (37°C) and sodium pyruvate (28°C) formulations have shown the highest inclusion body (IB) accumulation of 0.41 and 0.46 mg/mL, respectively. Furthermore, insights on the structure of the rhG-CSF within IBs and intact cells have been investigated through secondary structure analysis. Thermal stability experiments were also carried out to explain the pattern of the second derivative structure of rhG-CSF. The studies showed that choline + sodium pyruvate formulation has preserved the protein secondary structure even at 82°C. Overall, the FT-IR spectroscopic technique can also be adopted to accelerate the characterization of other recombinant therapeutic proteins of E. coli origin.

Improved Production and Characterization of Recombinant Human Granulocyte Colony Stimulating Factor from E. coli under Optimized Downstream Processes.

This work reports the upstream and downstream process of recombinant human granulocyte colony stimulating factor (rhG-CSF) expressed in Escherichia coli BL21 (DE3)pLysS. The fed batch mode was selected for the maximum output of biomass (6.4g/L) and purified rhG-CSF (136mg/L) under suitable physicochemical environment. The downstream processing steps viz., recovery, solubilization, refolding and concentration were optimized in this study. The maximum rhG-CSF inclusion bodies recovery yield (97%) was accomplished with frequent homogenization and sonication procedure. An efficient solubilization (96%) of rhG-CSF inclusion bodies were observed with 8M urea at pH 9.5. Refolding efficiency studies showed maximum refolding ⩾86% and ⩾84% at 20°C and pH 9 respectively. The renatured protein solution was concentrated, clarified and partially purified (⩾95%) by the cross flow filtration technique. The concentrated protein was further purified by a single step size exclusion chromatography with ⩾98% purity. The characterization of purified rhG-CSF molecular mass as evidenced by SDS-PAGE, western blot and LC/MS analysis was shown to be 18.8kDa. The secondary structure of rhG-CSF was evaluated by the CD spectroscopic technique based on the helical structural components. The biological activity of the purified rhG-CSF showed a similar activity of cell proliferation with the standard rhG-CSF. Overall, the results demonstrate an optimized downstream process for obtaining high yields of biologically active rhG-CSF.

Environmentally sensitive hotspots in the methylome of the early human embryo.

In humans, DNA methylation marks inherited from gametes are largely erased following fertilisation, prior to construction of the embryonic methylome. Exploiting a natural experiment of seasonal variation including changes in diet and nutritional status in rural Gambia, we analysed three datasets covering two independent child cohorts and identified 259 CpGs showing consistent associations between season of conception (SoC) and DNA methylation. SoC effects were most apparent in early infancy, with evidence of attenuation by mid-childhood. SoC-associated CpGs were enriched for metastable epialleles, parent-of-origin-specific methylation and germline differentially methylated regions, supporting a periconceptional environmental influence. Many SoC-associated CpGs overlapped enhancers or sites of active transcription in H1 embryonic stem cells and fetal tissues. Half were influenced but not determined by measured genetic variants that were independent of SoC. Environmental 'hotspots' providing a record of environmental influence at periconception constitute a valuable resource for investigating epigenetic mechanisms linking early exposures to lifelong health and disease.

Babies of South Asian and European Ancestry Show Similar Associations With Genetic Risk Score for Birth Weight Despite the Smaller Size of South Asian Newborns.

Size at birth is known to be influenced by various fetal and maternal factors, including genetic effects. South Asians have a high burden of low birth weight and cardiometabolic diseases, yet studies of common genetic variations underpinning these phenotypes are lacking. We generated independent, weighted fetal genetic scores (fGSs) and maternal genetic scores (mGSs) from 196 birth weight-associated variants identified in Europeans and conducted an association analysis with various fetal birth parameters and anthropometric and cardiometabolic traits measured at different follow-up stages (5-6-year intervals) from seven Indian and Bangladeshi cohorts of South Asian ancestry. The results from these cohorts were compared with South Asians in UK Biobank and the Exeter Family Study of Childhood Health, a European ancestry cohort. Birth weight increased by 50.7 g and 33.6 g per SD of fGS (P = 9.1 × 10-11) and mGS (P = 0.003), respectively, in South Asians. A relatively weaker mGS effect compared with Europeans indicates possible different intrauterine exposures between Europeans and South Asians. Birth weight was strongly associated with body size in both childhood and adolescence (P = 3 × 10-5 to 1.9 × 10-51); however, fGS was associated with body size in childhood only (P < 0.01) and with head circumference, fasting glucose, and triglycerides in adults (P < 0.01). The substantially smaller newborn size in South Asians with comparable fetal genetic effect to Europeans on birth weight suggests a significant role of factors related to fetal growth that were not captured by the present genetic scores. These factors may include different environmental exposures, maternal body size, health and nutritional status, etc. Persistent influence of genetic loci on size at birth and adult metabolic syndrome in our study supports a common genetic mechanism that partly explains associations between early development and later cardiometabolic health in various populations, despite marked differences in phenotypic and environmental factors in South Asians.

Effect of maternal preconceptional and pregnancy micronutrient interventions on children's DNA methylation: Findings from the EMPHASIS study.

BACKGROUND: Maternal nutrition in pregnancy has been linked to offspring health in early and later life, with changes to DNA methylation (DNAm) proposed as a mediating mechanism. OBJECTIVE: We investigated intervention-associated DNAm changes in children whose mothers participated in 2 randomized controlled trials of micronutrient supplementation before and during pregnancy, as part of the EMPHASIS (Epigenetic Mechanisms linking Preconceptional nutrition and Health Assessed in India and sub-Saharan Africa) study (ISRCTN14266771). DESIGN: We conducted epigenome-wide association studies with blood samples from Indian (n = 698) and Gambian (n = 293) children using the Illumina EPIC array and a targeted study of selected loci not on the array. The Indian micronutrient intervention was food based, whereas the Gambian intervention was a micronutrient tablet. RESULTS: We identified 6 differentially methylated CpGs in Gambians [2.5-5.0% reduction in intervention group, all false discovery rate (FDR) <5%], the majority mapping to ESM1, which also represented a strong signal in regional analysis. One CpG passed FDR <5% in the Indian cohort, but overall effect sizes were small (<1%) and did not have the characteristics of a robust signature. We also found strong evidence for enrichment of metastable epialleles among subthreshold signals in the Gambian analysis. This supports the notion that multiple methylation loci are influenced by micronutrient supplementation in the early embryo. CONCLUSIONS: Maternal preconceptional and pregnancy micronutrient supplementation may alter DNAm in children measured at 7-9 y. Multiple factors, including differences between the nature of the intervention, participants, and settings, are likely to have contributed to the lack of replication in the Indian cohort. Potential links to phenotypic outcomes will be explored in the next stage of the EMPHASIS study.

Simplified in vitro refolding and purification of recombinant human granulocyte colony stimulating factor using protein folding cation exchange chromatography.

Protein folding-strong cation exchange chromatography (PF-SCX) has been employed for efficient refolding with simultaneous purification of recombinant human granulocyte colony stimulating factor (rhG-CSF). To acquire a soluble form of renatured and purified rhG-CSF, various chromatographic conditions, including the mobile phase composition and pH was evaluated. Additionally, the effects of additives such as urea, amino acids, polyols, sugars, oxidizing agents and their amalgamations were also investigated. Under the optimal conditions, rhG-CSF was efficaciously solubilized, refolded and simultaneously purified by SCX in a single step. The experimental results using ribose (2.0M) and arginine (0.6M) combination were found to be satisfactory with mass yield, purity and specific activity of 71%, ≥99% and 2.6×10(8)IU/mg respectively. Through this investigation, we concluded that the SCX refolding method was more efficient than conventional methods which has immense potential for the large-scale production of purified rhG-CSF.