Both human SP-A1 and Sp-A2 genes are expressed in small and large intestine.
The human SP-A locus consists of two functional genes and one pseudogene, and SP-A is shown to play a role in local host defense and the regulation of inflammation in lung. Because the intestine, like the lung, is constantly exposed to foreign and potentially harmful substances, we investigated the hypothesis that both human SP-A genes are expressed in intestine. We demonstrate that both SP-A genes are expressed in human small and large intestine. The presence of SP-A mRNA in human intestine was detected by reverse transcription polymerase chain reaction (RT-PCR), Northern blot analysis, and immunohistochemistry. The size of intestinal SP-A mRNA is the same as that in human lung, but the level of expression, compared with that in the lung, is very low in both the small and large intestine. Immunohistochemical analysis revealed positive reactivity for SP-A in a subgroup of epithelial cells in the intestine. Expression of both SP-A1 and SP-A2 genes was established by gene-specific PCR amplification, PCR-based converted RFLP discrimination, and direct sequencing of RT-PCR products. We speculate that SP-A in the intestine plays a role in local host defense and inflammation.
Lin
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Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey 17033-0850, USA. zlin@psu.edu
deMello
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Phelps
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Koltun
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Floros
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D015152:Blotting, Northern; D018076:DNA, Complementary / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism; D007420:Intestine, Large / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D008168:Lung / Q000378:metabolism; D012150:Polymorphism, Restriction Fragment Length; D011510:Proteolipids / Q000096:biosynthesis* / Q000235:genetics*; D011544:Pseudogenes; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000096:biosynthesis* / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D018076:DNA, Complementary; 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