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Developmental changes in hepatocyte growth factor mRNA and its receptor in rat liver, kidney and lung
M Kagoshima1, T Kinoshita, K Matsumoto
1Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan.
Abstract:
Hepatocyte growth factor (HGF) is a mesenchymal-derived factor which induces mitosis, cell movement and morphogenesis of tissue-like structure. We analyzed changes in HGF mRNA and its receptor, the c-met proto-oncogene product, in the liver, kidney and lung during late fetal and postnatal development in rats. In the liver, the HGF-mRNA level was very low during late gestation and in neonates, it increased remarkably and reached a maximum two weeks postnatally, to be followed by a decrease to 33% of the maximum. HGF mRNA in the kidney and lung was either undetectable or very low during late gestation and the neonatal period and increased markedly to reach a maximum, respectively, 3-4 weeks postnatally. HGF-mRNA level in the adult rat lung was fivefold higher than that in the liver and kidney. The number of HGF receptors on plasma membranes of these tissues was low in neonates but there was a rapid increase after birth and a maximum was reached within three weeks. The number of HGF receptors/ng plasma membrane protein at the maximal level was highest in the liver and lowest in the lung. c-met/HGF-receptor mRNA in the liver was also low during late-gestation or in early neonatal periods and increased postnatally. Since HGF-mRNA and HGF-receptor levels changed differently in liver, kidney and lung, the expression of HGF and its receptor may be independently regulated in each organ. However, in these organs, HGF mRNA and the HGF receptor increased within a few weeks of birth, HGF may play roles in organ growth, organ maturation and the maintenance of tissue homeostasis during the postnatal period, presumably through its potential to act as mitogen, motogen and morphogen.
Insights
Hepatocyte growth factor (HGF) and its receptor c-met are crucial for postnatal organ development in rats. Their expression levels change significantly after birth, suggesting independent regulation and vital roles in growth and tissue homeostasis.
Area of Science:
- Developmental Biology
- Molecular Biology
- Regenerative Medicine
Background:
- Hepatocyte growth factor (HGF) is a key signaling molecule involved in cell proliferation, migration, and morphogenesis.
- The c-met proto-oncogene product is the primary receptor for HGF.
- Understanding the dynamic expression of HGF and c-met during development is crucial for insights into organogenesis and tissue repair.
Purpose of the Study:
- To investigate the developmental expression patterns of HGF mRNA and its receptor, c-met, in rat liver, kidney, and lung.
- To determine the temporal changes in HGF and c-met levels during late fetal and postnatal development.
- To explore the potential roles of HGF signaling in postnatal organ maturation and homeostasis.
Main Methods:
- Quantitative analysis of HGF mRNA levels using molecular techniques.
- Assessment of c-met receptor expression on plasma membranes.
- Comparison of gene and protein expression across different organs (liver, kidney, lung) and developmental stages (fetal, neonatal, postnatal).
Main Results:
- HGF mRNA levels were low during gestation, increased significantly postnatally, with distinct peak times in liver, kidney, and lung.
- C-met receptor expression also increased rapidly after birth, reaching maximum levels within three weeks.
- Differential expression patterns suggest independent regulation of HGF and c-met in each organ, with significant postnatal increases indicating a role in organ development.
Conclusions:
- HGF and its receptor c-met expression are dynamically regulated during postnatal development in rat liver, kidney, and lung.
- The observed postnatal surge in HGF and c-met suggests critical roles in organ growth, maturation, and maintaining tissue homeostasis.
- HGF likely acts as a mitogen, motogen, and morphogen, contributing to the functional development of these organs after birth.