Question

a) LIF (Leukemia Inhibitory factor) belongs to a family of cytokines and has just binded to a GP-130 receptor of a mouse embryonic stem cell. Please describe in relative detail the consequences of this interaction. (8 pts)

Answer 1

ANSWER:

In mouse Embryonic stem cells (ESCs) derived from blastocyts, their in-vitro propagation required the activity of the cytokine LIF (leukemia inhibitory factor). LIF funtions by activating the janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway.

In JAK-STAT signaling LIF first binds to its signaling receptor, LIF and recruits second signaling receptor GP-130, to form a heterodimer which mediates downstream signal transduction. Also, the secretion of GP-130 ligands in mESCs buffers cells combined with the autoregulatory behavior of JAK-STAT signaling and precocious differentiation, supports propogation of mESCs. But in the absence of LIF the secretion of GP-130 ligands is insufficient to keep up pluripotency in balanced mESC conditions.