Balance of two secretion pathways of nerve growth factor in PC12 cells changes during the progression of their differentiation, with a decrease in constitutive secretion in more differentiated cells.
Proteins are secreted from animal cells by either a constitutive or a regulated pathway. When cDNA of nerve growth factor (NGF) was introduced into PC12 cells, these cells produced and secreted active NGF, where NGF was secreted not only in constitutive but also in activity-dependent regulated way according to the results of pulse-chase and ELISA studies. The regulated secretion was caused by depolarization, cyclic AMP analogue, or beta-adrenergic agonist but not by glutamate or carbachol. Because these transfected cells differentiated into a morphology indistinguishable from that incubated with NGF protein, we next compared the secretion pathways of NGF from PC12 cells at different stages of the differentiation. NGF was secreted in both constitutive and regulated way at 2 and 7 days after the transfection of NGF-cDNA, but the constitutive secretion of NGF from the more differentiated cells of Day 7 was decreased and mature NGF tended to accumulate in the cells. These results indicate that the neurotrophin secretion mechanism is intimately regulated in the course of the differentiation of PC12 cells. Such a change in the protein secretion pathway might have an profound role in the development of neurons.
Nomoto
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Hiroshi Nomoto, Laboratory of Molecular Biology, Gifu Pharmaceutical University, Gifu 502-8585, Japan. hnomoto@gifu-pu.ac.jp
Tomotoshi
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Ito
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Furukawa
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D000818:Animals; D019556:COS Cells; D002454:Cell Differentiation / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D020932:Nerve Growth Factor / Q000378:metabolism*; D016716:PC12 Cells / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
D011994:Recombinant Proteins; D020932:Nerve Growth Factor