Feedback-responsive cell factories for dynamic modulation of the unfolded protein response.

Engineering cell factories that support the production of large quantities of protein therapeutics remains a significant biomanufacturing challenge. The overexpression of secretory proteins causes proteotoxic stress, affecting cell viability and protein productivity. Proteotoxic stress leads to the activation of the Unfolded Protein Response (UPR), a series of signal transduction pathways regulating protein quality control mechanisms aimed at restoring homeostasis. Sustained UPR activation culminates with the induction of apoptosis. Current strategies for enhancing the production of therapeutic proteins have focused on the deregulated modulation of key components of the UPR. These strategies have resulted in limited and often protein-specific improvements as they may lead to adaptation and cell toxicity and do not account for natural population heterogeneities. We report here feedback-responsive cell factories that sense proteotoxic stress and, in response, modulate the UPR to enhance stress attenuation and delay cell death, addressing the limitations of current strategies. We demonstrate that our cell engineering approach enables dynamic UPR modulation upon proteotoxic stress. The sense-and-respond systems that mediate dynamic UPR modulation enhance the production of the therapeutic enzyme tissue plasminogen activator and the bispecific antibody blinatumomab. Our feedback-responsive cell factories provide an innovative strategy for dynamically adjusting the innate cellular stress response and enhancing therapeutic protein manufacturing.