Principal Investigators

Very little is known about the cellular and molecular mechanisms that govern the production of complex proteins by engineered mammalian cells. The majority of the work to date has largely concentrated on optimisation of cell culture conditions (e.g. media formulation), bioreactor design, and improvements in the design of expression vectors. We are undertaking proteomic studies on CHO cells and other industrially relevant cell lines, in order to understand the molecular and cellular mechanisms involved in growth and productivity in mammalian cells used for biopharmaceutical production. Protein profiles generated from both intracellular and extracellular samples from bioreactors may give insights for genetic intervention to possibly create better host cell lines, or even to provide clues to more rational strategies for process development (e.g. media design).

In CHO production cell cultures, the expression of high levels of recombinant biopharmaceuticals is linked to inducing endoplasmic reticulum (ER) stress, causing enhanced unfolded protein response (UPR) levels to maintain cell viability and productivity. ER stress mechanisms are poorly understood in CHO cells, and are a major bottleneck in improving the efficiency of production of high cost recombinant biopharmaceuticals. Advanced high-resolution state-of-the-art mass spectrometry are being used to identify proteomic changes and site-specific post translational modifications on cellular proteins as a result of changes to productivity of CHO cells. This will lead to the identification of engineering targets to improve CHO cell productivity that is of significant relevance to the Biopharmaceutical industry.

Research Group Members

Principal Investigators

Dr. Ciarán Fagan seeks to improve the stability of enzymes. Enzymes are ideal “green” catalysts: they can enable newer processes that are less hazardous and less costly than traditional methods, while producing less waste.

Enzymes’ many industrial applications range from detergents to the food and (bio)pharma industries. Unfortunately, enzymes may become unstable and lose their catalytic abilities under the demands of process conditions, or upon prolonged use or extended storage. Dr. Fagan uses two main strategies to increase the stability of enzymes, namely protein engineering and chemical modification. He has prepared enzymes that are more tolerant of heat, organic solvents or oxidizing conditions, or that give improved biosensor performance.

Although he has worked on numerous enzymes, his special focus is on plant peroxidases (which are used for a variety of purposes). These, together with a “resurrected” ancient plant peroxidase, an evolutionary precursor of the modern-day enzymes, provide opportunities for postgraduate research.