All human EF1α promoters are not equal: markedly affect gene expression in constructs from different sources

Area of Science:

• Molecular Biology
• Gene Therapy
• Biotechnology

Background:

• Promoters are critical regulatory elements in gene therapy vectors, influencing transgene expression and target specificity.
• The human elongation factor 1 alpha (EF1α) promoter is commonly used due to its strong activity.

Purpose of the Study:

• To evaluate and compare the expression activity of three different human EF1α promoters.
• To identify potential variations in promoter function that could impact gene therapy efficacy.

Main Methods:

• Three distinct human EF1α promoter variants were cloned into the same expression vector (pAC-luc) driving luciferase cDNA.
• In vitro expression was assessed across four different cell lines.
• In vivo expression was evaluated in rat submandibular glands.

Main Results:

• One EF1α promoter variant (EF1α -3), sourced from a commercial vector, exhibited significantly lower activity compared to the others.
• This reduced activity was observed consistently across all tested cell lines (50-500x lower) and in vivo (~250x lower).
• Sequence variations within the EF1α -3 promoter are hypothesized to be responsible for the observed functional differences.

Conclusions:

• Not all promoters designated by the same name are functionally equivalent, particularly in the context of gene therapy vectors.
• Careful selection and validation of specific promoter sequences are essential for achieving desired transgene expression levels and consistency.
• Sequence differences can lead to substantial variations in gene expression, impacting the success of gene therapy applications.