HELQ suppresses migration and proliferation of non-small cell lung cancer cells by repairing DNA damage and inducing necrosis

HELQ as a DNA helicase: Its novel role in normal cell function and tumorigenesis (Review)

Helicase POLQ‑like (HELQ or Hel308), is a highly conserved, 3'‑5' superfamily II DNA helicase that contributes to diverse DNA processes, including DNA repair, unwinding, and strand annealing. HELQ deficiency leads to subfertility, due to its critical role in germ cell stability. In addition, the abnormal expression of HELQ has been observed in multiple tumors and a number of molecular pathways, including the nucleotide excision repair, checkpoint kinase 1‑DNA repair protein RAD51 homolog 1 and ATM/ATR pathways, have been shown to be involved in HELQ. In the present review, the structure and characteristics of HELQ, as well as its major functions in DNA processing, were described. Molecular mechanisms involving HELQ in the context of tumorigenesis were also described. It was deduced that HELQ biology warrants investigation, and that its critical roles in the regulation of various DNA processes and participation in tumorigenesis are clinically relevant.

Functional EGF domain of the human neuregulin 1α produced in Escherichia coli with accurate disulfide bonds

BACKGROUND

Neuregulins comprise a large family of growth factors containing an epidermal growth factor (EGF) domain. NRG1 acts in signaling pathways involved in proliferation, apoptosis, migration, differentiation, and adhesion of many normal cell types and in human diseases. The EGF domain of NRG1 mediates signaling by interaction with members of the ErbB family of receptors. Easy access to correctly folded hNRG1α EGF domain can be a valuable tool to investigate its function in different cell types.

MATERIALS AND METHODS

The EGF domain of hNRG1α was produced in Escherichia coli in fusion with TrxA and purified after cleavage of TrxA. Conformation and stability analyses were performed by using biophysical methods and the disulfide bonds were mapped by mass spectrometry. The activity of the hNRG1α EGF domain was demonstrated in cell proliferation and migration assays.

RESULTS

Approximately 3.3 mg of hNRG1α EGF domain were obtained starting from a 0.5 L of E. coli culture. Correct formation of the three disulfide bonds was demonstrated by mass spectrometry with high accuracy. Heat denaturation assays monitored by circular dichroism and dynamic light scattering revealed that it is a highly stable protein. The recombinant EGF domain of hNRG1α purified in this work is highly active, inducing cell proliferation at concentration as low as 0.05 ng/mL. It induces also cell migration as demonstrated by a gap closure assay.

CONCLUSION

The EGF domain of hNRG1α was produced in E. coli with the correct disulfide bonds and presented high stimulation of HeLa cell proliferation and NDFH cell migration.