Identification of a novel targeting sequence for regulated secretion in the serine protease inhibitor neuroserpin.
Ns (neuroserpin) is a member of the serpin (serine protease inhibitor) gene family that is primarily expressed within the central nervous system. Its principal target protease is tPA (tissue plasminogen activator), which is thought to contribute to synaptic plasticity and to be secreted in a stimulus-dependent manner. In the present study, we demonstrate in primary neuronal cultures that Ns co-localizes in LDCVs (large dense core vesicles) with the regulated secretory protein chromogranin B. We also show that Ns secretion is regulated and can be specifically induced 4-fold by secretagogue treatment. A novel 13-amino-acid sorting signal located at the C-terminus of Ns is identified that is both necessary and sufficient to target Ns to the regulated secretion pathway. Its deletion renders Ns no longer responsive to secretagogue stimulation, whereas PAI-Ns [Ns (neuroserpin)-PAI-1 (plasminogen activator inhibitor-1) chimaera appending the last 13 residues of Ns sequence to the C-terminus of PAI-1] shifts PAI-1 secretion into a regulated secretory pathway.
Ishigami
Shoji
S
Center for Vascular and Inflammatory Diseases, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.
Sandkvist
Maria
M
Tsui
Foon
F
Moore
Elizabeth
E
Coleman
Timothy A
TA
Lawrence
Daniel A
DA
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002478:Cells, Cultured; D053378:Chromogranin B / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D015843:Serpins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000235:genetics / Q000378:metabolism; D000097522:Neuroserpin
D053378:Chromogranin B; D009479:Neuropeptides; D011993:Recombinant Fusion Proteins; D015842:Serine Proteinase Inhibitors; D015843:Serpins; D010959:Tissue Plasminogen Activator; D000097522:Neuroserpin