The developmental regulation of a novel muscle LIM-protein.

Using a cDNA clone derived from a human muscle library we have identified a novel and highly conserved 2.3kb homologue which is highly expressed in skeletal muscle. The partial sequence contains at least three LIM domains and shows greatest homology with the group of LIM-proteins associated with the cytoskeleton and focal adhesion plaques which include zyxin and paxillin. This homologue is maximally expressed in differentiated ovine primary muscle cultures. It is also expressed in the ovine fetus from at least 50 days of gestation and is increasingly upregulated from 120 days of gestation to 8 weeks after birth after which it declines. This period corresponds to the period of greatest muscle fibre hypertrophy and suggests a role for this homologue in either the elaboration of muscle fibre matrix anchorage or the regulation of muscle fibre hypertrophy itself.