SMDF and GGF neuregulin splice variant isoforms and uses thereof

Abstract

Distinct cDNAs encoding six cysteine-rich domain-NRGs and four glial growth factor isoforms were identified and sequenced. Additional heterogeneity is found in the EGF-like (α- and β-isoforms) and carboxy terminal (a and b variant) regions of CRD-NRGs. Furthermore, the predicted GGF proteins contain glycosylation domains previously found only in mesenchymal NRGs. GGF mRNAs accumulate in axotomized nerve, a subpopulation of DRG neurons and most spinal cord motoneurons. CRD-NRGs, however, are undetectable in injured nerve except by RT-PCR. In contrast, the majority of DRG and spinal cord motor neurons express CRD-NRGs, with a β1 isoform being most abundant and at least some of these proteins are secreted in a form capable of activating erbB receptors. Thus, GGF and CRD-NRG subfamilies are more structurally diverse than previously appreciated. NRG actions during Wallerian degeneration may be modulated by the action of distinct splice variants.

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