Comparison of the properties of cholinergic differentiation factors and examination of their possible role in vivo

[摘要] We have compared the immunological, biochemical, and biological properties of three previously described cholinergic factors, cholinergic differentiation factor/Leukemia inhibitory factor (CDF/UF), ciliary neurotrophic factor (CNTF), and membrane-associatedneurotransmitter-inducing substance (MANS). CDF/U F differs from CNTF and MANS in that it does not have any ciliary neurotrophic activity. Further, antibodies generated against the N-terminal sequence of CDF/LIF do not precipitate cholinergic activity from sciatic nerve (CNTF) or spinal cord (MANS) preparations indicating that CDF/UF is a distinct molecule. MANS preparations contain a 24 kD molecule immunologically related to CNTF and CNTF antisera also, immunoprecipitate the cholinergic differentiation activity present in MANS fractions. CNTF, like CDF/LlF, affects neuropeptide expression. Neuropeptide Y levels are reduced and vasoactive intestinal peptide, somatostatin and Substance P levels are elevated in a dose-dependent fashion. Unlike CDF/LlF, the effects of CNTF on cholineacetyltransferase and peptide induction are not antagonized by depolarization. In addition, CNTF, in contrast to CDF/LlF, does not modulate peptide levels in DRG neuronal cultures. Thus, at least two distinct factors, CNTF and CDF/LlF, exist and have distinct but overlapping functions.We have investigated the possible role of CDF (cholinergic differentiation factor from skeletal muscle), CDF/LIF CNTF, and MANS in mediating the target directed noradrenergic to cholinergic switch that characterizes sweat gland innervation. Sweat gland extracts contain a cholinergic and peptidergic differentiation activity for cultured sympathetic neurons. Extracts from tabby mice (which lack sweat glands) and noradrenergic sympathetic targets have significantly reduced cholinergic differentiation activity. Expression of the differentiation activity in footpads occurs at a time period appropriate for a role for this factor(s) in vivo. Comparison with other differentiation molecules suggests that it is distinct from MANS, CDF and the heparin binding cholinergic factor. Immunological and biochemical analysis indicate that the major cholinergic-inducing activity is not LlF but is a CNTF-like molecule. Western blots, northern blot and in situ hybridization analysis fail to detect CNTF or CNTF message in footpads. The possible relationship between CNTF, LlF and sweat gland cholinergic differentiation factor(s) is discussed.

[发布机构] University:California Institute of Technology;Department:Biology

[关键词] Biology