Barrier role of actin filaments in regulated mucin secretion from airway goblet cells.
Airway goblet cells secrete mucin onto mucosal surfaces under the regulation of an apical, phospholipase C/G(q)-coupled P2Y(2) receptor. We tested whether cortical actin filaments negatively regulate exocytosis in goblet cells by forming a barrier between secretory granules and plasma membrane docking sites as postulated for other secretory cells. Immunostaining of human lung tissues and SPOC1 cells (an epithelial, mucin-secreting cell line) revealed an apical distribution of beta- and gamma-actin in ciliated and goblet cells. In goblet cells, actin appeared as a prominent subplasmalemmal sheet lying between granules and the apical membrane, and it disappeared from SPOC1 cells activated by purinergic agonist. Disruption of actin filaments with latrunculin A stimulated SPOC1 cell mucin secretion under basal and agonist-activated conditions, whereas stabilization with jasplakinolide or overexpression of beta- or gamma-actin conjugated to yellow fluorescent protein (YFP) inhibited secretion. Myristoylated alanine-rich C kinase substrate, a PKC-activated actin-plasma membrane tethering protein, was phosphorylated after agonist stimulation, suggesting a translocation to the cytosol. Scinderin (or adseverin), a Ca(2+)-activated actin filament severing and capping protein was cloned from human airway and SPOC1 cells, and synthetic peptides corresponding to its actin-binding domains inhibited mucin secretion. We conclude that actin filaments negatively regulate mucin secretion basally in airway goblet cells and are dynamically remodeled in agonist-stimulated cells to promote exocytosis.
Ehre
Camille
C
Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599-7248, USA.
Rossi
Andrea H
AH
Abdullah
Lubna H
LH
De Pestel
Kathleen
K
Hill
Sandra
S
Olsen
John C
JC
Davis
C William
CW
D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D016764:Cell Polarity / Q000502:physiology; D005089:Exocytosis / Q000502:physiology; D018260:Gelsolin; D015870:Gene Expression / Q000502:physiology; D020397:Goblet Cells / Q000166:cytology / Q000378:metabolism* / Q000637:transplantation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008840:Microfilament Proteins / Q000378:metabolism; D009077:Mucins / Q000378:metabolism*; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D058910:Purinergic P2 Receptor Agonists; D051381:Rats; D058473:Receptors, Purinergic P2Y2; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism; D014132:Trachea / Q000166:cytology* / Q000378:metabolism; D014183:Transplantation, Heterologous
D018260:Gelsolin; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009077:Mucins; C546385:P2RY2 protein, human; C546386:P2ry2 protein, mouse; D058910:Purinergic P2 Receptor Agonists; D058473:Receptors, Purinergic P2Y2; C065395:scinderin; D000076250:Myristoylated Alanine-Rich C Kinase Substrate