Cyclic Guanosine Monophosphate Analogs do not Reverse Bacterial Toxin Modulation of Lactogen-Stimulated nb2 Cell Mitogenesis
| Autor: | J. L. Larsen |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Cholera Toxin
medicine.medical_specialty Biology medicine.disease_cause Pertussis toxin chemistry.chemical_compound Endocrinology Internal medicine Dibutyryl Cyclic GMP Tumor Cells Cultured medicine Animals Virulence Factors Bordetella Cyclic GMP Cyclic guanosine monophosphate Cell growth Cholera toxin Guanylate cyclase activity General Medicine Prolactin Rats Pertussis Toxin chemistry Cell culture Growth Hormone Second messenger system PDE10A Cell Division |
| Zdroj: | Endocrine Research. 18:31-40 |
| ISSN: | 1532-4206 0743-5800 |
| Popis: | Pertussis toxin (PT) and cholera toxin (CT) have been shown to modulate lactogenic hormone-stimulated Nb2 cell mitogenesis, a lactogen-dependent cell line. As both toxins have been shown to alter guanylate cyclase activity in other cell systems, cyclic guanosine monophosphate (cGMP) analogs, 8-bromo or dibutyryl cGMP, were added to determine if they could reverse the toxin-mediated effects. In the absence of bacterial toxins, both cGMP analogs enhanced lactogen-stimulated Nb2 cell mitogenesis in a multiphasic pattern. At maximal enhancement, the effect was statistically significant but not marked (113 +/- 5%; p less than 0.01). Neither cGMP analog increased lactogenic binding site number or affinity so cGMP must affect lactogen action following receptor binding. Neither analog could stimulation Nb2 cell mitogenesis in the absence of lactogens so cGMP is not a second messenger for lactogens in this cell system. Finally, neither cGMP analog reversed the inhibitory effects of either bacterial toxin on lactogen-stimulated Nb2 cell proliferation. In summary, although bacterial toxins may be capable of altering guanylate cyclase activity, as addition of cGMP analogs do not reverse toxin-mediated effects on lactogen-stimulated mitogenesis, these toxins' actions must be mediated predominantly through other mechanisms that may have significant importance to lactogen signal transduction. |
| Databáze: | OpenAIRE |
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