In situ hybridization of SP-A mRNA in adult human conducting airways.
In our study, surfactant protein (SP)-A was characterized in adult human trachea and bronchi. SP-A mRNA and protein were localized to serous cells in submucosal gland by in situ hybridization and immunohistochemistry, respectively. A 2.2 kb SP-A mRNA transcript was detected in tracheal tissues by Northern blot analysis. Primer extension analysis and gene-specific reverse transcriptase polymerase chain reaction (RT-PCR) revealed the predominance of SP-A2 mRNA. However, using nested PCR, we also detected low amounts of SP-A1 mRNA in the tracheal tissues. A approximately 35 kDa SP-A immunoreactive protein was detected in the tracheal tissues by immunoblot analysis and was shown to be modified by the addition of N-linked oligosaccharides. We conclude that submucosal glands in the conducting airways produce a novel SP-A protein with a molecular weight and post-translational modification similar to the SP-A produced in the distal lung. We speculate that this SP-A2 protein, like other serous secretions from airway submucosal glands, functions in local antimicrobial host defense mechanisms in the conducting airways.
Khubchandani
K R
KR
Department of Anatomy and Cell Biology, University of Iowa College of Medicine, Iowa City 52242, USA.
Goss
K L
KL
Engelhardt
J F
JF
Snyder
J M
JM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015152:Blotting, Northern; D001980:Bronchi / Q000378:metabolism*; D005260:Female; D006031:Glycosylation; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011510:Proteolipids / Q000096:biosynthesis*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012704:Serous Membrane / Q000378:metabolism; D014132:Trachea / Q000378:metabolism*
D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D012333:RNA, Messenger; C445842:SFTPA1 protein, human; C445843:SFTPA2 protein, human