Gene Therapy and SUMO

Recombinant adeno associated viruses (rAAV) have become the vehicle of choice to deliver gene therapy for cure genetically inherited diseases but also gene delivery system for many chronic diseases. There are major hurdles in production of safe rAAV. Generally, rAAV is produced by transfecting three plasmid systems: (1) an AAV2 ITR-containing plasmid carrying the gene of interest; (2), a plasmid that carries the AAV2 Rep-Cap proteins; and (3), a plasmid that provides the helper genes isolated from adenovirus. This method of producing therapeutic dose of rAAV is very labor intensive and expensive due to low yield of the rAAV. While progress is being made to manufacture large titers of therapeutic viruses, it is hampered by lack of foreign gene expression or degradation of the targeted protein (step 1). If we can construct a highly potent rAAV that expresses the therapeutic gene, it will solve the problem of large manufacturing batches, decreasing the cost of goods. We believe application of SUMO (Small Ubiquitin-Like Modifiers) fusion with therapeutic gene will solve many of the problems described above.

Click to Read More: The solution to expression

 LifeSensors has established a human SUMOstar based system that allows under expressed or non-expressed genes to be delivered as SUMOstar fusion between AAV2 ITR containing plasmids. Many therapeutic programs are abandoned due to lack of adequate and cost-effective manufacturing of rAAV. Several factors contribute to dramatically enhance protein production and improve quality of quality of gene delivery. Nature designed SUMO to chaperone proteins in the cell. Thus SUMO-fusion enables the protein to be stable for long time to have its biological function. This property allows small doses of rAAV injection to achieve greater therapeutic response. LifeSensors can guide scientists about the most suitable human SUMO tag and the SUMO protease to efficiently remove SUMO to reduce cost of goods. LifeSensors can guide you from your cloning strategy for the best expression and establish a non-GMP process from gene to rAAV production. The process can be easily adapted for downstream GMP production of the rAAV.  

The SUMO Tag

SUMO (Small Ubiquitin-like Modifier) is a member of the ubiquitin family, composed of a flexible N-terminal region followed by a ball-shaped ubiquitin-like fold. SUMO’s hydrophobic core improves correct folding of the fused vaccine, and hydrophilic surface keeps the nanobody soluble. SUMO protease recognizes SUMO structure to cleaves at the junction to generate desired N-terminus of the vaccine.

SUMO protease cleaving target of interest

Figure 2: The rAAV payload, foreign gene, can be expressed as hSUMO-fusion that will be cleaved to generate native gene product. SUMO Protease cleaves the SUMO tag to separate the expressed gene product. hSUMOstar is engineered not to be cleaved in mammalian cells thus preserving the expression enhancing properties of SUMO. Please consult our Therapeutic Protein slide deck.

the protein structure of SUMO

Figure 1: The unique string and ball structure of SUMO allows for improved expression due to a hydrophilic outer surface and a hydrophobic core.

Many Advantages of hSUMO and hSUMOstar Fusion with rAAV and Gene Therapy Including:

  • Under expressed genes are efficiently translated
  • The gene product is stable and accumulates to increase therapeutic response.
  • Development of potent rAAV gene reduces the amount of rAAV required for therapeutic benefit.

LifeSensors has established a Search Sheet (below) that allows you to search a variety of papers that describe the application of SUMO to express proteins in a variety of systems.

Click for: Lifesensors' SUMO Publication Searchable Sheet

To use, simply utilize the drop down arrows in order to search for your target of interest or application category. Lifesensors SUMO technology has been utilized for the expression of many different targets and continues to be utilized worldwide.