Cardiotrophin-1 requires LIFR beta to promote survival of mouse motoneurons purified by a novel technique

The cytokines ciliary neurotrophic factor (CNTF) and leukemia inhibitory fa ctor (LIF) signal through a receptor complex formed between two transmembra ne proteins, gp130 and LIFR beta. In addition, CNTF also uses a ligand-bind ing component which is anchored to the cell membrane. In the case of cardio trophin-l (CT-1), LIFR beta is also required in cardiomyocytes, but this ha s not been proven in neurons, and published data suggest that motoneurons m ay use a different receptor complex. We used Lifr beta knockout mice to ass ess the requirement for this receptor component in the signal transduction of CT-1 in motoneurons. To study purified motoneurons from such mutants, we have developed a method allowing for isolation of highly purified mouse mo toneurons, This protocol is based on the immunoaffinity purification of mot oneurons using antibodies against the extracellular domain of the neurotrop hin receptor, p75, followed by cell sorting using magnetic microbeads, We s how that CNTF, LIF, and CT-1 are unable to promote the survival of motoneur ons derived from homozygous Lifr beta(-/-) mutant embryos. Thus, LIFR beta is absolutely required to transduce the CT-1 survival signal in motoneurons . (C) 1999 Wiley-Liss, Inc.