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Activins as candidate cholinergic differentiation factors in vivo
Author(s) -
Fann MingJi,
Patterson Paul H.
Publication year - 1995
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/0736-5748(94)00075-e
Subject(s) - biology , endocrinology , medicine , leukemia inhibitory factor , cholinergic , neuropeptide , oncostatin m , cytokine , ciliary neurotrophic factor , acvr2b , transforming growth factor , microbiology and biotechnology , neurotrophic factors , tgf beta signaling pathway , interleukin 6 , immunology , genetics , receptor
A number of cytokine families have been implicated in shaping neuronal survival, growth and gene expression. The neuropoietic and transforming growth factor‐β (TGF‐β) cytokines, in particular, have emerged as candidates for regulating the phenotype of sympathetic neurons. Culture studies have shown that neuropoietic cytokines (such as leukemia inhibitory factor, ciliary neurotrophic factor, oncostatin M, growth promoting activity) can induce the cholinergic enzyme, choline acetyltransferase (ChAT) and several neuropeptides, whereas certain members of the TGF‐β family (activin A, bone morphogenetic proteins‐2 and ‐6) induce partially overlapping but distinct sets of transmitter and neuropeptide genes in sympathetic neurons. Since activins can induce ChAT in cultured neurons, we have investigated whether these cytokines are expressed by the appropriate cells and tissues to make them candidates for the cholinergic differentiation factor that is known to alter the phenotype of sympathetic neurons that innervate the sweat gland in the footpad in vivo. In‐situ hybridization with the anti‐sense probe for activin β B specifically labels the sweat glands but not other tissues in the footpads of developing rats. Ribonuclease protection assays indicate that β B as well as the other activin and inhibin subunit mRNAs are expressed by a number of tissues, including footpad, hairy skin and submaxillary gland. Homogenates of developing rat footpads, however, failed to induce the set of neuropeptide genes in cultured sympathetic neurons that is characteristic for activins, although neuropoietic cytokine activity was readily detectable in this assay. Thus, while activin β B mRNA is expressed in the sweat gland, this tissue does not contain detectable activin protein as assayed by its ability to regulate neuronal gene expression. Moreover, activin subunit mRNAs are expressed by targets of noradrenergic sympathetic neurons in vivo , indicating that activin expression is not limited to targets of cholinergic neurons.