An alternatively spliced Muc10 glycoprotein ligand for putative L-selectin binding during mouse embryonic submandibular gland morphogenesis.
Late-gestation (embryonic day 18; E18) mouse submandibular glands (SMG) comprise a network of large and small ducts that terminate in lumen-containing, presumptive acini (terminal buds) expressing unique, cell membrane-associated embryonic mucin. The objective here was to clone and sequence embryonic low molecular-weight SMG mucin, predict its secondary structure, and begin to investigate its possible role in SMG development. Evidence was found that: (1) embryonic low molecular-weight mucin is an alternatively spliced Muc10 gene product, 220 amino acids in size (approximately 25 kDa), rich in potential O-glycosylation sites, and variably glycosylated (approximately 40 and 68 kDa); (2) consensus secondary-structure prediction for embryonic low molecular-weight mucin is consistent with a molecule that is anchored to the plasma membrane, directly or indirectly (via a glycolipid), and has a protein core that serves as a scaffold for carbohydrate presentation; (3) embryonic L-selectin is immunolocalized to the plasma membrane region of terminal-bud epithelial cells in a pattern similar to that seen for embryonic mucin; (4) embryonic, but not adult, mucin is able to bind L-selectin and does so endogenously in E18 SMG. As the primary role of L-selectin is to mediate cell adhesion and its ligands are mucin-like glycoproteins, it is suggested that this embryonic low molecular-weight mucin be termed MucCAM.
Melnick
M
M
Laboratory for Developmental Genetics, University of Southern California, 925 W 34th Street, DEN-4266, CA 90089-0641, Los Angeles, USA. mmelnick@hsc.usc.edu
Chen
H
H
Zhou
Y
Y
Jaskoll
T
T
D000367:Age Factors; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion; D002462:Cell Membrane / Q000648:ultrastructure; D003001:Cloning, Molecular; D004847:Epithelial Cells / Q000648:ultrastructure; D005260:Female; D005865:Gestational Age; D006023:Glycoproteins / Q000235:genetics*; D006031:Glycosylation; D019041:L-Selectin / Q000378:metabolism*; D008024:Ligands; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009024:Morphogenesis / Q000502:physiology; D009077:Mucins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017433:Protein Structure, Secondary; D018987:Salivary Ducts / Q000196:embryology; D013363:Submandibular Gland / Q000196:embryology*
D006023:Glycoproteins; D008024:Ligands; D009077:Mucins; D019041:L-Selectin