|
|
|
| Untersuchte Arbeit: Seite: 18, Zeilen: 1-8 |
Quelle: Fehrenbach 2001 Seite(n): 35, Zeilen: 35: r.col: last paragraph; 38: r.col: 22-26, 41-43 |
|---|---|
| [Although the bronchiolar Clara cells and submucosal cells also synthesize and release the mature proteins SP-A, SP-B and SP-D (Kalina et al., 1992; Voorhout et al., 1992) the alveolar type II epithelial cell is the only type of pulmonary cell that] produces all surfactant components including phospholipids as well as all four surfactant proteins. The mature 3.5-3.7 kDa small SP-C is thought to be exclusively released by AECII cells (Beers et al., 1994; Phelps and Floros et al., 1991).
About 85% of the secreted surfactant is taken up again, metabolised and re-secreted by AECII. Re-uptake and recycling have been demonstrated for all surfactant lipids and for all four surfactant proteins. The degradation of surfactant is accomplished by alveolar macrophages with only minimal contribution (Herbein et al., 2000; Nicholas, 1996; Young et al., 1993). Beers MF, Kim CY, Dodia C, Fisher AB. Localization, synthesis, and processing of surfactant protein SP-C in rat lung analyzed by epitope-specific antipeptide antibodies. J Biol Chem. 1994 Aug 12; 269 (32): 20318-28. Herbein JF, Savov J, Wright JR. Binding and uptake of surfactant protein D by freshly isolated rat alveolar type II cells. Am J Physiol Lung Cell Mol Physiol. 2000 Apr; 278 (4): L830-9. Kalina M, Mason RJ, Shannon JM. Surfactant protein C is expressed in alveolar type II cells but not in Clara cells of rat lung. Am J Respir Cell Mol Biol. 1992 Jun; 6 (6): 594-600. Nicholas TE. Pulmonary surfactant: no mere paint on the alveolar wall. Respirology. 1996 Dec; 1 (4): 247-57. Review. Phelps DS, Floros J. Localization of pulmonary surfactant proteins using immunohistochemistry and tissue in situ hybridization. Exp Lung Res. 1991 Nov-Dec; 17 (6): 985-95. Voorhout WF, Veenendaal T, Kuroki Y, Ogasawara Y, van Golde LM, Geuze HJ. Immunocytochemical localization of surfactant protein D (SP-D) in type II cells, Clara cells, and alveolar macrophages of rat lung. J Histochem Cytochem. 1992 Oct; 40 (10): 1589-97. Young SL, Fram EK, Larson E, Wright JR. Recycling of surfactant lipid and apoprotein-A studied by electron microscopic autoradiography. Am J Physiol. 1993 Jul; 265 (1Pt1): L19-26. |
[page 35]
Synthesis Although the bronchiolar Clara cells synthesise and release the mature proteins SP-A, SP-B, and SP-D (Fig. 2a) [37,38], the AE2 cell is the only type of pulmonary cell that produces all the surfactant components (phospholipids [Fig. 3] as well as all four surfactant proteins). The mature 3.5-3.7 kDa small SP-C (Fig. 2b) is thought to be released by AE2 cells only [39,40]. [page 38] Today it is established that most of the secreted surfactant — estimated at about 85% [24] — is taken up again, metabolised and re-secreted by the AE2 cells. Re-uptake and recycling have been demonstrated for surfactant lipids [58] and all four surfactant proteins [51,58,96,97]. [...] The degradation of surfactant is accomplished by the alveolar macrophages with only minimal contribution, if any, from AE2 cells. 24. Nicholas TE: Pulmonary surfactant: no mere paint on the alveolar wall. Respirology 1996, 1:247–257. 37. Kalina M, Mason RJ, Shannon JM: Surfactant protein C is expressed in alveolar type II cells but not in Clara cells of rat lung. Am J Respir Cell Mol Biol 1992, 6:594–600. 38. Voorhout WF, Veenendaal T, Kuroki Y, Ogasawara Y, van Golde LM, Geuze HJ: Immunocytochemical localization of surfactant protein D (SP-D) in type II cells, Clara cells, and alveolar macrophages of rat lung. J Histochem Cytochem 1992, 40: 1589–1597. 39. Phelps DS, Floros J: Localization of pulmonary surfactant proteins using immunohistochemistry and tissue in situ hybridization. Exp Lung Res 1991, 17:985–995. 40. Beers MF, Kim CY, Dodia C, Fisher AB: Localization, synthesis, and processing of surfactant protein SP-C in rat lung analyzed by epitope-specific antipeptide antibodies. J Biol Chem 1994, 269:20318–20328. 51. Herbein JF, Savov J, Wright JR: Binding and uptake of surfactant protein D by freshly isolated rat alveolar type II cells. Am J Physiol 2000, 278:L830–839. 58. Young SL, Fram EK, Larson E, Wright JR: Recycling of surfactant lipid and apoprotein-A studied by electron microscopic autoradiography. Am J Physiol 1993, 265:L19–L26. 96. Breslin JS, Weaver TE: Binding, uptake, and localization of surfactant protein B in isolated rat alveolar type II cells. Am J Physiol 1992, 262:L699–707. 97. Pinto RA, Wright JR, Lesikar D, Benson BJ, Clements JA: Uptake of pulmonary surfactant protein C into adult rat lung lamellar bodies. J Appl Physiol 1993, 74:1005–1011. |
The source is mentioned further up on the previous page, but without any indication that the here documented passage might have been taken from it. See Mag/Fragment_017_18. |
|