Kamal Prashad Segar's Talk

Jun 26, 2014 - 17:00

Jun 26, 2014 - 18:00

Creativity Hall Room 118 Chemical Engineering

Seminars

Kamal Prashad Segar PhD Student Department of Chemical Engineering IIT Bombay

Abstract: Technological breakthrough in recombinant DNA technology combined with advanced bioprocesses has made commercial production of recombinant biologics possible at a large scale. Nearly 70% of the biologics are produced using Chinese Hamster Ovary (CHO) cells as the hosts. Investing quite a huge amount of money and time in creating a "producer cell line" biopharmaceutical industries focus on enhancing productivity to gain higher profits. To enhance productivity it is essential to understand productivity at the molecular level. Productivity is a multifaceted phenomenon involving different metabolic pathways inside the cell. Engineering growth apoptosis and energy metabolism leads to an increase in total cell numbers and high product titres. In contrast engineering protein secretion increases the protein production per cell by enhancing the protein processing efficiency of the cell. Different cell engineering approaches had been tried in the past to increase the productivity using this pathway. Though promising the results from these studies are conflicting and are often cell line and protein dependent. The objective of this project is to understand the relationship between productivity and protein processing inside the Endoplasmic Reticulum (ER) using a systems approach. Two recombinant CHO cell lines secreting anti-rhesus D IgG with a 10-fold difference in their productivities were compared at their growth and recombinant mRNA levels. Specific protein processing pathway genes of ER were also compared at their mRNA levels between these cell lines. IgG heavy chain mRNA was limiting productivity with dynamic expression of chaperones and UPR genes. Interestingly mRNA levels of IgG HC and key UPR genes showed a higher correlation with productivities. Further the expression of recombinant mRNA and UPR activity were perturbed using chemical modulators. Perturbing recombinant mRNA expression lead to an increase in productivity with transient induction of major ER stress response genes. Artificial induction of ER stress did not increase productivity suggesting that both recombinant mRNA expression and higher UPR activity are essential to increase productivity in recombinant CHO cells. With the availability of huge amount of growth kinetic productivity and mRNA levels of different UPR genes in different cell lines a multivariate regression analysis was done to identify key factors influencing productivity. These factors may be of vital importance in the process of creating a "super producer".