Cardiotrophin‐1 requires LIFRβ to promote survival of mouse motoneurons purified by a novel technique

The cytokines ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) signal through a receptor complex formed between two transmembrane proteins, gp130 and LIFRβ. In addition, CNTF also uses a ligand-binding component which is anchored to the cell membrane. In the case of cardiotrophin-1 (CT-1), LIFRβ is also required in cardiomyocytes, but this has not been proven in neurons, and published data suggest that motoneurons may use a different receptor complex. We used Lifrβ knockout mice to assess 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 motoneurons. This protocol is based on the immunoaffinity purification of motoneurons using antibodies against the extracellular domain of the neurotrophin receptor, p75, followed by cell sorting using magnetic microbeads. We show that CNTF, LIF, and CT-1 are unable to promote the survival of motoneurons derived from homozygous Lifrβ−/− mutant embryos. Thus, LIFRβ is absolutely required to transduce the CT-1 survival signal in motoneurons. J Neurosci Res 55:119–126, 1999.