Summary
In the neonatal rat lung, alveolar development occurs from postnatal Days 4–13, during which time there is a fourfold increase in interstitial fibroblasts. Factors influencing emergence of new septa and cell proliferation associated with septal elongation have yet to be identified, in part because of difficulties inherent in studying this process in vivo. Using flow cytometric analysis of the DNA content of freshly isolated lung fibroblasts, we found that proliferation, as indicated by the percentage of cells in S plus G2/M phases, peaked on postnatal Day 4 (P<0.04). By Days 9–10 the proliferation rate was lower than on Days 3, 4, 5, or 6 (P<0.005). We then evaluated rates of in vitro proliferation as a function of postnatal age in first passage fibroblasts and found that the proliferative phenotype expressed in vivo persists in vitro. Fibroblasts from 4–5-d-old pups increased in number and incorporated 3H-thymidine at a faster rate than did fibroblasts obtained from pups at other postnatal ages (P<0.0001). Age-dependent differences in cell cycle transit time were compared in fibroblasts synchronized by serum starvation and analyzed by flow cytometry at 2-h intervals from 13–21 h after release from serum starvation. A greater percentage of cells from 5-d-old pups entered S phase during this period than was seen for cells obtained from 2-, 9-, 13-, or 23-d-old rat pups (P=0.0001). Cells from 5-, 9-, and 13-d-old pups reentered G0/G1 by 21 h after release from serum starvation, in contrast to fibroblasts from 2- and 23-d-old rats which did not. Throughout the 15-h period after release from serum starvation, levels of cyclin E, which peaks at the G1/S border, were highest in the 5-d-old cells (P<0.025). Synchronization with 2.5 mM hydroxyurea which inhibits DNA synthesis completely abolished age-related differences in cell cycle transit time, implying that age-dependent differences in lung fibroblast proliferation rates are the result of events occurring before S-phase entry.
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Baldin, V.; Lukas, J.; Marcote, M. J.; Pagano, M.; Draetta, G. Cyclin D1 is a nuclear protein required for cell cycle progression in G1. Genes Dev. 7:812–821; 1993.
Bohmer, R.; Scharf, E.; Assoian, R. Cytoskeletal integrity is required throughout the mitogen stimulation phase of the cell cycle and mediates the anchorage-dependent expression of cyclin D1. Mol. Biol. Cell 7:101–111; 1996.
Bostrom, H.; Willetts, K.; Pekny, M.; Leveen, P.; Lindahl, P.; Hedstrand, H.; Pekna, M.; Hellstrom, M.; Gebre-Medhin, S.; Schalling, M.; Nilsson, M.; Kurland, S.; Tornell, J.; Heath, J. K.; Betsholtz, C. PDGF-A signaling is a critical event in alveolar myofibroblasts development and alveogenesis. Cell 85:863–873; 1996.
Bruce, M. C. Developmental changes in tropoelastin mRNA levels in rat lung: evaluation by in situ hybridization. Am. J. Respir. Cell Mol. Biol. 5:344–350; 1991.
Bucher, J. R.; Roberts, R. J. The development of the newborn rat lung in hyperoxia: a dose-response study of lung growth, maturation, and changes in antioxidant enzyme activities. Pediatr. Res. 15:999–1008; 1981.
Coalson, J. J.; Winter, V.; deLemos, R. A. Decreased alveolarization in baboon survivors with bronchopulmonary dysplasia. Am. J. Respir. Crit. Care Med. 152:640–646; 1995.
Dulic, V.; Lees, E.; Reed, S. I. Association of human cyclin E with a periodic G1-S phase protein kinase. Science (Wash DC) 257:1958–1961; 1992.
Elias, J. A.; Rossman, M. D.; Phillips, P. D. Phenotypic variability among density-fractionated human lung fibroblasts. Am. Rev. Respir. Dis. 135:57–61; 1987.
Fang, F.; Orend, G.; Watanabe, N.; Hunter, T.; Ruoslahti, E. Dependence of cyclin E-cdk2 kinase activity on cell anchorage. Science (Wash DC) 271:499–502; 1996.
Funk, B.; Kessler, U.; Eisenmenger, W.; Hansmann, A.; Kolb, H. J.; Kiess, W. Expression of the insulin-like growth factor-II/mannose-6-phosphate receptor in multiple human tissues during fetal life and early infancy. J. Clin. Endocrinol. Metab. 75:424–431; 1996.
Giarreti, W.; Nusse, M.; Bruno, S.; Di Vinci, A.; Geido, E. A new method to discriminate G1, S, G2, M, and G1 postmitotic cells. Exp. Cell Res. 182:290–295; 1989.
Heichman, K. A.; Roberts, J. M. Rules to replicate by. Cell 79:557–562; 1994.
Kauffman, S. L.; Burri, P. H.; Weibel, E. R. The postnatal growth of the rat lung II. Autoradiography. Anat. Rec. 180:63–76; 1974.
Kauffman, S. L. Cell proliferation in the mammalian lung. Int. Rev. Exp. Pathol. 22:131–191; 1980.
Kida, K.; Thurlbeck, W. M. The effects of β-aminoproprionitrile on the growing rat lung. Am. J. Pathol. 101:693–710; 1980.
Maitre, B.; Clement, A.; Williams, M. C.; Brody, J. S. Expression of insulin-like growth factors 1 and 2 in the developing lung and their relation to epithelial cell differentiation. Am. J. Respir. Cell Mol. Biol. 13:262–270; 1995.
Maksvytis, H. J.; Niles, R. M.; Simanovsky, L.; Minassian, I. A.; Richardson, L. L.; Hamosh, M.; Hamosh, P.; Brody, J. S. In vitro characteristics of the lipid-filled interstitial cell associated with postnatal lung growth: evidence for fibroblast heterogeneity. J. Cell. Physiol. 118:113–123; 1984.
Koff, A.; Giordano, A.; Desai, D.; Yamashita, K.; Harper, J. W.; Elledge, S.; Nishimoto, T.; Morgan, D. O.; Fraza, B. R.; Roberts, J. M. Formation and activation of a cyclin E-cdk2 complex during the G1 phase of the human cell cycle. Science (Wash DC) 257:1689–1694; 1992.
Krakoff, I. H.; Brown, N. C.; Reichard, P. Inhibition of ribonucleotide diphosphate reductase by hydroxyurea. Cancer Res. 28:1559–1565; 1968.
Luck, R. W. L.; Krupinska, K. Repeated probing of Western blots obtained from Coomassie brilliant blue-stained or unstained polyacrylamide gels. Biotechniques 21:418–422; 1996.
Margraf, L. R.; Tomashefski, J. F., Jr.; Bruce, M. C.; Dahms, B. Morphometric analysis of the lung in bronchopulmonary dysplasia. Am. Rev. Respir. Dis. 143:391–400; 1991.
Massaro, D.; Teich, N.; Maxwell, S.; Massaro, G. D.; Whitney, P. Postnatal development of alveoli: regulation and evidence for a critical period in rats. J. Clin. Invest. 76:1297–1305; 1985.
Noguchi, A.; Samaha, H. Developmental changes in tropoelastin gene expression in the rat studied by in situ hybridization. Am. J. Respir. Cell and Molec. Biol. 5:571–578; 1991.
O’Dell, B. L.; Kilburn, K. H.; McKenzie, W. N.; Thurston, R. J. The lung of the copper-deficient rat: a model for developmental pulmonary emphysema. Am. J. Pathol. 91:413–432; 1978.
Ohtsubo, M.; Roberts, J. Cyclin dependent regulation of G1 in mammalian fibroblasts. Science (Wash DC) 259:1908; 1993.
Quelle, D. E.; Ashmun, R. A.; Shurleff, S. A.; Kato, J.-Y.; Bar-Sagi, D.; Roussel, M. F.; Sherr, C. J. Overexpression of mouse D-type cyclins accelerates G1 phase transition in rodent fibroblasts. Genes Dev. 7:1559–1571; 1993.
Reed, S. I.; Bailly, E.; Dulic, V.; Hengst, L.; Resnitzky, D.; Slingerland, J. G1 control in mammalian cells. J. Cell Sci. Suppl. 18:69–73; 1994.
Resnitzsky, D.; Gossens, M.; Bujard, H.; Reed, S. I. Acceleration of the G1/S phase transition by expression of cyclins D1 and E with an inducible system. Mol. Cell. Biol. 14:1669–1679; 1994.
Sastry, S. K.; Horwitz, A. F. Adhesion-growth factor interactions during differentiation: an integrated biological response. Dev. Biol. 180:455–467; 1996.
Sherr, C. J. G1 phase progression: cycling on cue. Cell 79:547–550; 1994.
Sobonya, R. E.; Lovinoff, M. M.; Taussig, L. M.; Theriault, A. Morphometric analysis of the lung in prolonged bronchopulmonary dysplasia. Pediatr. Res. 16:969–972; 1982.
Uhal, B. D.; Rannels, D. E. DNA distribution analysis of type II pneumocytes by laser flow cytometry: technical considerations. Am. J. Physiol. 261 (Lung Cell. Mol. Physiol. 5):L296-L306; 1991.
Virtanen, I.; Laitinen, A.; Tani, T.; Paakko, P.; Laitinen, L. A.; Burgeson, R. E.; Lehto, V.-P. Differential expression of laminins and their integrin receptors in developing and adult human lung. Am. J. Respir. Cell Mol. Biol. 15:184–196; 1996.
Wallen, L. D.; Han, V. K. M. Spatial and temporal distribution of insulinlike growth factors I and II during development of rat lung. Am. J. Physiol. 267 (Lung Cell. Mol. Physiol. 11):L531–542; 1994.
Zhu, X.; Ohtsubo, M.; Bohmer, R. M.; Roberts, J. M.; Assoian, R. K. Adhesion-dependent cell cycle progression linked to the expression of cyclin D1, activation of cyclin E-cdk2, and phosphorylation of the retinoblastoma protein. J. Cell Biol. 133:391–403; 1996.
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Al-Jumaily, W., Bruce, M.C. The postnatal age of rat lung fibroblasts influences G1/S phase transition in vitro . In Vitro Cell.Dev.Biol.-Animal 35, 410–416 (1999). https://doi.org/10.1007/s11626-999-0116-3
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DOI: https://doi.org/10.1007/s11626-999-0116-3