Stimulation by epidermal growth factor of phospholipid methyltransferase in isolated rat hepatocytes

Chiva, Vicente Álvarez; Cao, Dolores Marín; Mato, José M.

doi:10.1016/0014-5793(83)80945-4

Cited by 9 publications

(1 citation statement)

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“…The effect of EGF on phosphatidylinosi-to1 and phosphoinositol turnover is still very controversial, since several authors have reported negative results (134-137). In hepatocytes isolated from juvenile or hepatectomized rat, but not from adult rats, EGF induces a dose-and time-dependent activation of phospholipid methyltransferase (138). EGF also increases the phosphorylation of endogenous membrane proteins in A-43 1 cells (139) or isolated membrane preparations, as well as the phosphorylation of exogenous protein substrates (139,140).…”

Section: General Biological Effectsmentioning

confidence: 99%

Biological effects of epidermal growth factor, with emphasis on the gastrointestinal tract and liver: An update

1989

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Epidermal growth factor (EGF) is a 6,000 Da polypeptide hormone produced by glands of the gastrointestinal tract, namely the salivary and Brunner's glands. It is found in a wide variety of external secretions as well as in blood and amniotic fluid. In fetal and neonatal life, EGF appears to play an important role in the development of the oral cavity, lungs, gastrointestinal tract and eyelids. Its presence in cells of the central nervous system suggests that it also plays a role in modulating the development of this system. In adult animals, the function of EGF is much less well understood. In rodents, it apparently modulates acid secretion from parietal cells in the stomach, and it undoubtedly plays an important role in wound healing, either through its localization within skin or by the licking of wounds with EGF-containing saliva. Considerable evidence now suggests that it may be one of the key factors in initiating liver regeneration after partial hepatectomy or chemical injury. The liver appears to be the principal organ which regulates the circulating level of EGF. In fact, EGF is cleared so efficiently by the liver that only the peripheral cells of the lobule (zone 1) sequester EGF, and little remains in the circulation for cells in the more distal zones (zones 2 and 3). In the liver, EGF normally binds to a plasma membrane receptor and is internalized within the liver cell, where the vast majority of EGF and its receptor are destroyed in lysosomes. A small but consistent quantity of EGF enters the bile intact. In the regenerating liver, however, the lysosomal pathway appears to be shut down, and the EGF is diverted to hepatocyte nuclei prior to the initiation of DNA synthesis. Nuclear EGF is found free as well as bound to a high-molecular-weight protein which has many characteristics identical to the plasma membrane EGF receptor. The plasma membrane receptor is a large transmembrane glycoprotein of 170,000 Da containing four domains: an extracellular EGF-binding portion, a hydrophobic membrane-spanning segment, a proximal cytoplasmic domain which binds ATP and protein substrates containing tyrosine for phosphorylation and a terminal cytoplasmic portion with 3 tyrosines which undergo autophosphorylation after EGF binding.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: General Biological Effectsmentioning

confidence: 99%