Regulatory Elements in Vectors for Efficient Generation of Cell Lines Producing Target Proteins

Abstract

To date, there has been an increasing number of drugs produced in mammalian cell cultures. In order to enhance the expression level and stability of target recombinant proteins in cell cultures, various regulatory elements with poorly studied mechanisms of action are used. In this review, we summarize and discuss the potential mechanisms of action of such regulatory elements.

Keywords: S/MAR; STAR; UCOE; insulators; protein production in mammalian cells; recombinant proteins.

Fig. 1

A – Model of establishing specific long-range interactions between regulatory elements. Several IAP (insulator architectural proteins) bind with each element. As a result, two identical elements are capable of providing highly specific and efficient ultra long-range interactions between regulatory elements, but only weak contacts are formed upon partial overlap of IAP-binding sites in regulatory elements. Grey rectangles represent regulatory elements binding with IAP; colored ellipses depict combinations of IAP that specifically bind their own sites and interact with each other. B – Specific integration of a transgenic construct into a particular genomic region. The transgenic construct is presented as a circle. Black triangles correspond to P element end repeats; grey rectangle, –elements comprising a transgenic construct. Orange ellipses –regulatory elements that bind with IAP. Brown rectangle – a genome region

Fig. 2

Schematic representation of β-globin locus and adjacent sequences. Designations ρ, β^H, β^A, ε correspond to the genes β-globin locus; FR – folate receptor gene; OR – olfactory receptor gene. Arrows indicate the direction of gene transcription. HSA, 5’HS4, 3’HS – insulators; LCR, βA/ε – enhancers of β-globin locus. Insulator HS4 is represented schematically in detail. FI, FIII, FV –binding sites for protein Vezf1/BGP1. FII and FIV – protein CTCF- and heterodimer USF1/2-binding sites, respectively