Cell death in mammalian cell culture: molecular mechanisms and cell line engineering strategies

Abstract

Cell death is a fundamentally important problem in cell lines used by the biopharmaceutical industry. Environmental stress, which can result from nutrient depletion, by-product accumulation and chemical agents, activates through signalling cascades regulators that promote death. The best known key regulators of death process are the Bcl-2 family proteins which constitute a critical intracellular checkpoint of apoptosis cell death within a common death pathway. Engineering of several members of the anti-apoptosis Bcl-2 family genes in several cell types has extended the knowledge of their molecular function and interaction with other proteins, and their regulation of cell death. In this review, we describe the various modes of cell death and their death pathways at molecular and organelle level and discuss the relevance of the growing knowledge of anti-apoptotic engineering strategies to inhibit cell death and increase productivity in mammalian cell culture.

Fig. 1

Sketch showing the morphological features of necrotic, apoptotic and autophagic cell death. Necrosis involves clear swelling of mitochondria and golgi organelles, followed by breakdown of the cellular membrane leading to leakage of intracellular proteins. Apoptotic cells undergo organized destruction of the cellular cytoskeleton and formation of apoptotic bodies. It also involves chromatin condensation and fragmentation into spherical particles. Autophagy sequesters cytosolic proteins and organelles by a double membrane vesicle which docks and fuses with the lysosome

Fig. 2

Simplified apoptotic (and partly autophagic) signalling pathways (adapted pathways from “Cell Signalling Technology”)

Fig. 3

Overview of anti-apoptotic Bcl-2 interaction with molecules involved in apoptosis and cell cycle regulation