The neuregulin precursor proARIA is processed to ARIA after expression on the cell surface by a protein kinase C-enhanced mechanism.
We have investigated how the transmembrane precursor proARIA is processed to ARIA (acetylcholine receptor-inducing activity). Pulse-chase labeling in transfected Chinese hamster ovary (CHO) cells showed that proARIA was cleaved to release ARIA into the medium. Cell surface biotin-labeling experiments demonstrated that proARIA was first expressed on the cell surface before being rapidly cleaved to release biotin-labeled ARIA into the medium. While not essential for proteolytic cleavage of proARIA, serum or phorbol-12-myristate-13-acetate (PMA), which activates protein kinase C (PKC), was needed for the efficient release of the processed ARIA. Proteolytic cleavage was blocked by brefeldin A, suggesting that processing occurred distal to Golgi compartments, and by NH4Cl, suggesting a need for intracellular acidic compartments. Serum and PMA also stimulated ARIA release from cultured sensory neurons, suggesting that a similar regulated release mechanism occurs in neurons and may be important in determining where ARIA is released in the developing nervous system.
Loeb
J A
JA
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Susanto
E T
ET
Fischbach
G D
GD
D000818:Animals; D030161:Avian Proteins; D016466:CHO Cells; D002478:Cells, Cultured; D002642:Chick Embryo; D006224:Cricetinae; D003470:Culture Media; D004789:Enzyme Activation; D005727:Ganglia, Spinal; D006023:Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020890:Neuregulin-1; D020880:Neuregulins; D011493:Protein Kinase C / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D011950:Receptors, Cholinergic / Q000378:metabolism*
D030161:Avian Proteins; D003470:Culture Media; D006023:Glycoproteins; D008565:Membrane Proteins; C490582:NRG1 protein, Gallus gallus; D009419:Nerve Tissue Proteins; D020890:Neuregulin-1; D020880:Neuregulins; D011498:Protein Precursors; D011950:Receptors, Cholinergic; D011493:Protein Kinase C