Modulation of guanylate cyclase-coupled atrial natriuretic factor receptor activity by mastoparan and ANF in murine Leydig tumor cells: role of G-proteins.

Abstract

Mastoparan potently stimulated catalytic activity of guanylate cyclase-coupled atrial natriuretic factor receptor (GC-A/ANF-R), both in the plasma membranes and intact Leydig tumor (MA-10) cells. In plasma membrane preparations, a maximum of 5-fold GC catalytic activity was stimulated by 100 microM mastoparan and the half maximum stimulation (EC50) was achieved at 40 microM concentration. Mastoparan potentiated GC activity by more than 40%, above the level, stimulated by ANF. Mas 7, an active analog of mastoparan, stimulated the GC activity in a similar manner to mastoparan whereas Mas 17, an inactive analog, did not enhance GC activity. In membranes prepared from mastoparan-treated intact MA-10 cells, GC catalytic activity was enhanced by more than 4-fold as compared with untreated control cells. Pretreatment of membranes with either anti-Gs alpha or anti-Gi alpha antibodies had no effect on mastoparan-stimulated GC activity, however, anti-Go alpha antibodies inhibited the stimulatory effect of mastoparan by almost 50%. Agents known to modulate the effect of mastoparan such as EGTA (Ca2+ chelator), W7 (calmodulin inhibitor) and staurosporine (protein kinase C inhibitor) had no effect on the mastoparan-stimulated GC activity. Mastoparan enhanced the ANF-stimulated GC activity in detergent solubilized membrane preparations without a significant change in ANF-binding capacity. The data establish a role for mastoparan in the ANF-dependent stimulation of GC-A/ANF-R catalytic activity, both in the plasma membrane preparations and intact Leydig tumor (MA-10) cells. Furthermore, these findings provide new evidence that mastoparan (isolated from wasp venom) potently stimulates guanylate cyclase activity of GC-A/ANF-R by activating G-proteins.

• Authors: M L Khurana, K N Pandey
• Journal: Biochimica et biophysica acta (Biochim Biophys Acta) Vol. 1224 Issue 1 Pg. 61-7 (Oct 20 1994) ISSN: 0006-3002 [Print] Netherlands
• PMID: 7948043 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Intercellular Signaling Peptides and Proteins
• Peptides
• Wasp Venoms
• mastoparan
• Atrial Natriuretic Factor
• GTP-Binding Proteins
• Guanylate Cyclase
• Receptors, Atrial Natriuretic Factor

Topics

• Animals
• Atrial Natriuretic Factor (pharmacology)
• Cell Line
• Cell Membrane (metabolism)
• GTP-Binding Proteins (physiology)
• Guanylate Cyclase (metabolism)
• Intercellular Signaling Peptides and Proteins
• Leydig Cell Tumor (metabolism)
• Mice
• Peptides
• Receptors, Atrial Natriuretic Factor (drug effects, metabolism)
• Wasp Venoms (pharmacology)