Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Because surfactant proteins A, B, and C (SP-A, SP-B, and SP-C) are putative markers for alveolar epithelial type II cells, we investigated their expression in embryonic rat lung (12 to 15 days, term = 22 days). The expression of the messages for SP-A, SP-B, and SP-C was assessed by the reverse-transcriptase polymerase chain reaction (RT-PCR). Embryonic rat lung at 12 days' gestation lacked detectable mRNAs for all three surfactant proteins. Messages for SP-A, SP-B, and SP-C were, however, present in embryonic rat lung at 13 days' gestation. Expression of SP-A mRNA increased in embryonic rat lung with advancing gestation. Surfactant protein mRNA expression during the embryonic period of lung development was limited to the epithelial cells. The expression of SP-A mRNA, while limited to the lung, did not appear to be a marker for cells destined to become type II cells, since it was detected in the trachea and the presumptive main bronchial ducts of embryonic rat lung at 13 days' gestation, as well as in the distal lung prealveolar region. Expression of both SP-B and SP-C mRNAs in embryonic lung was confined to the distal portion of the ductal system, although message of SP-C was also found in brain and kidney. These results suggest that none of the three surfactant protein mRNAs studied are, at this early stage of lung development, specific for cells destined to become type II pneumocytes.
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PMID:Expression of surfactant proteins in embryonic rat lung. 750 64

Reverse transcriptase (RT)-PCR with primers specific for surfactant protein A (SP-A), B (SP-B), C (SP-C), and D (SP-D) genes was applied to detect metastatic non-small cell lung carcinomas. Forty-one paratracheal and subcarinal lymph nodes obtained from 41 patients with non-small cell lung carcinomas, 11 lymph nodes from 11 patients with extrapulmonary adenocarcinomas, and eight control lymph nodes from patients without cancer were analyzed using RT-PCR. PCR products corresponding to SP-B gene products were found in all eight control lymph nodes, offering evidence of SP-B gene expression in cells of lymphatic tissue. SP-A, SP-C, and/or SP-D transcripts were detected in 11 (84.6%) of 13 lymph nodes with histologically identifiable metastases of pulmonary adenocarcinomas and in 10 (55.5%) of 18 lymph nodes that were tumor free on routine histological examination. These findings provide evidence of micrometastatic nodal involvement which remains undetectable by conventional light microscopy but can be evaluated by surfactant RT-PCR. Gene expression of SP-A and SP-C was restricted to metastatic pulmonary adenocarcinomas but SP-D gene activity has been also detected in two of four metastases of pulmonary large cell carcinomas, one adenosquamous carcinoma, and nine extrapulmonary adenocarcinomas as well.
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PMID:Surfactant protein gene expression in metastatic and micrometastatic pulmonary adenocarcinomas and other non-small cell lung carcinomas: detection by reverse transcriptase-polymerase chain reaction. 767 Dec 36

Primary lung adenocarcinomas originate from the progenitor cells of peripheral airway cells. Alveolar type II cells and Clara cells are the major progenitor cells of peripheral airway cells. Alveolar type II cells produce a lipid-protein complex called surfactant, which contains surfactant proteins SP-A, SP-B, SP-C and SP-D. Phosphatidylcholine (PC) and phosphatidylglycerol (PG) are believed to be essential for the surfactant function. Clara cells also express SP-A, SP-B and SP-D but not SP-C. In this study we examined the properties of the cancer cells isolated from the pleural effusion of a patient with primary lung adenocarcinoma by analyzing lipids, proteins and mRNAs. The cancer cells, designated as LC117 cells, were isolated from the pleural effusion of a patient with primary lung adenocarcinoma. The percent distributions of [14C]-acetate incorporated into PC and PG in the cancer cells were 55.7 and 1.1%, respectively. The disaturated species in total PC was 46.2%. Immunoblotting analysis using anti-SP-D monoclonal antibody revealed that the pleural effusion from a patient with lung adenocarcinoma contained SP-D. We determined the concentrations of SP-A and SP-D by enzyme-linked immunosorbent assay. The pleural effusions from this patient and the media incubated with cancer cells exhibited significant levels of SP-D as well as SP-A. Reverse transcriptase-polymerase chain reaction demonstrated that the tumor cells expressed mRNAs for SP-C as well as the other surfactant proteins. The results demonstrate that tumor cells from lung adenocarcinoma express all of surfactant-associated proteins, indicating that LC117 cells originate from alveolar type II cells. This study indicates that the combination of analyses of lipids, proteins and mRNAs in the cancer cells isolated from pleural effusion is useful to understand the property of lung adenocarcinoma.
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PMID:Lipid analysis and surfactant-associated protein expression in lung adenocarcinoma cells from pleural effusion. 893 61

Surfactant protein (SP)-B is essential for lamellar body genesis and for the final steps in proSP-C post-translational processing. The mature SP-B protein is derived from multistep processing of the primary translation product proSP-B; however, the enzymes required for these events are currently unknown. Recent ultrastructural colocalization studies have suggested that the cysteine protease Cathepsin H may be involved in proSP-B processing. Using models of isolated human type 2 cells in culture, we describe the effects of cysteine protease inhibition by E-64 on SP-B processing and type 2 cell differentiation. Pulse-chase labeling and Western immunoblotting studies showed that the final step of SP-B processing, specifically cleavage of SP-B(9) to SP-B(8), was significantly inhibited by E-64, resulting in delayed accumulation of SP-B(8) without adverse effects on SP-A or glyceraldehyde phosphate dehydrogenase expression. E-64 treatment during type 2 cell differentiation mimicked features of inherited SP-B deficiency in humans and mice, specifically disrupted lamellar body genesis, and aberrant processing of proSP-C. Reverse transcriptase-polymerase chain reaction and Western immunoblotting studies showed that Cathepsin H is induced during in vitro differentiation of type 2 cells and localizes with SP-B in multivesicular bodies, composite bodies, and lamellar bodies by immunoelectron microscopy. Furthermore, Cathepsin H activity was specifically inhibited in a dose-dependent fashion by E-64. Our data show that a cysteine protease is involved in SP-B processing, lamellar body genesis, and SP-C processing, and suggest that Cathepsin H is the most likely candidate protease.
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PMID:Cysteine protease activity is required for surfactant protein B processing and lamellar body genesis. 1249 34