High-level expression of human calmodulin in E. coli and its effects on cell proliferation

• Published in: 世界胃肠病学杂志(英文版) Vol. 6; no. 4; pp. 588 - 592
• Main Authors: Xiao Jun Li, Jian Guo Wu, Jun Ling Si, Da Wen Guo, Jian Ping Xu
• Format: Journal Article
• Language: English
• Published: Department of Immunology, Center of Laboratory Medical Science, Nanjing General Hospital of Nanjing Command, PLA, Nanjing 210002, Jiangsu Province, China 01-08-2000
• Subjects: biological activity; cell proliferation; geneexpression; Escherichia coli; trifluoperazine; calmodulin; polymerase chain reaction; monoclonal antibodies
• ISSN: 1007-9327

Calmodulin (CaM), widely distributed in almost all eukaryotic cells, is a major intracellular calcium receptor responsible for mediating the Ca2 + signal to a multitude of different enzyme systems and is thought to play a vital role in the regulation of cell proliferative cycle[1，2]. Recently, many studies showed that CaM is also present in extracellular fluid such as cell culture media and normal body fluid and has been reported to stimulate proliferation in a range of normal and neoplastic cells, apparently acting as an autocrine growth factor[3-11]. In 1988, Crocker et al reported for the first time that addition of extracellular pure pig brain CaM could promote DNA synthesis and cell
[7]proliferation in K562 human leukaemic lymphocytes[7].After that, more and more research was done on extracellular CaM and evidences demonstrated that extracellular CaM could also stimulate cell proliferation in normal human umbilical vein endothelial cells[5], keratinocytes[4], suspension-cultured cells of Angelica Dahurica, etc[6]. CaM is a monomeric protein of 148 amino acids that contains four homologous Ca2 + -binding domains. CaM has been highly conserved throughout the evolution. Only 1 out of 148 amino acids of human CaM is different from that of fish CaM. Complementary DNAs encoding rat, eel, chicken, human, and trypanosome CaM have been cloned.