Selective developmental regulation of gene expression for insulin-like growth factor-binding proteins in mouse spinal cord

Study Design. Prospective, randomized experimental study in mice. Study Objective. To determine whether insulin-like growth factor binding pr oteins (IGFBPs) are present in mouse spinal cord and, if so, what role they play in its :development. Summary of Background Data. Insulin-like growth factors are well recognized hormonal effecters of growth hormone and are expressed in the mammalian sp inal cord. The IGFBPs are a group of six genetically distinct proteins that bind IGFs and modulate their bioactivity. They appear in the brain during development, localize to the neuromuscular junction, and promote motor neur on survival. The benefit of IGF-I in amyotrophic lateral sclerosis ALS and its potential use in preventing motor neuron apoptosis in spinal cord injur y dictates that studies of the presence and response of IGFBPs in that tiss ue be performed. Methods. The IGFBPs in mouse spinal cord were analyzed by Western ligand bl ot, Western immunoblot, and reverse transcription-polymerase chain reaction at various time points from embryonic day 14 to postnatal day 30. Results. Three IGFBPs with molecular masses of 24, 28, and 32 kDa were foun d, the latter two being the most prominent. The data indicate that these ar e IGFBP-4, -5, and -2. Conclusion. Both IGFBP-2 and BP-5 are development tally regulated in mouse spinal cord, with higher levels of those at early embryonic stages indicati ng their potential role In development of the mouse spinal cord.