title: SFTA2--a novel secretory peptide highly expressed in the lung--is modulated by lipopolysaccharide but not hyperoxia.
abstract: Tissue-specific transcripts are likely to be of importance for the corresponding organ. While attempting to define the specific transcriptome of the human lung, we identified the transcript of a yet uncharacterized protein, SFTA2. In silico analyses, biochemical methods, fluorescence imaging and animal challenge experiments were employed to characterize SFTA2. Human SFTA2 is located on Chr. 6p21.33, a disease-susceptibility locus for diffuse panbronchiolitis. RT-PCR verified the abundance of SFTA2-specific transcripts in human and mouse lung. SFTA2 is synthesized as a hydrophilic precursor releasing a 59 amino acid mature peptide after cleavage of an N-terminal secretory signal. SFTA2 has no recognizable homology to other proteins while orthologues are present in all mammals. SFTA2 is a glycosylated protein and specifically expressed in nonciliated bronchiolar epithelium and type II pneumocytes. In accordance with other hydrophilic surfactant proteins, SFTA2 did not colocalize with lamellar bodies but colocalized with golgin97 and clathrin-labelled vesicles, suggesting a classical secretory pathway for its expression and secretion. In the mouse lung, Sfta2 was significantly downregulated after induction of an inflammatory reaction by intratracheal lipopolysaccharides paralleling surfactant proteins B and C but not D. Hyperoxia, however, did not alter SFTA2 mRNA levels. We have characterized SFTA2 and present it as a novel unique secretory peptide highly expressed in the lung.
authors: Neonatology, Dr. von Haunersches Kinderspital, Ludwig-Maximilians-Universität München, Munich, Germany.
authors: Rashmi A
authors: RA
authors: Mittal
authors: Markus
authors: M
authors: Hammel
authors: Johannes
authors: J
authors: Schwarz
authors: Katharina M
authors: KM
authors: Heschl
authors: Nancy
authors: N
authors: Bretschneider
authors: Andreas W
authors: AW
authors: Flemmer
authors: Susanne
authors: S
authors: Herber-Jonat
authors: Melanie
authors: M
authors: Königshoff
authors: Oliver
authors: O
authors: Eickelberg
authors: Andreas
authors: A
authors: Holzinger
mesh_terms: D056809:Alveolar Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001980:Bronchi / Q000473:pathology; D002460:Cell Line; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D005629:Frozen Sections; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D018496:Hyperoxia / Q000235:genetics* / Q000473:pathology; D015151:Immunoblotting; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008168:Lung / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D037662:Pulmonary Surfactant-Associated Protein A / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014162:Transfection
chemical_list: D008070:Lipopolysaccharides; D010455:Peptides; D037662:Pulmonary Surfactant-Associated Protein A; D012333:RNA, Messenger; C576331:SFTA2 protein, mouse; C445843:SFTPA2 protein, human