Secramine inhibits Cdc42-dependent functions in cells and Cdc42 activation in vitro.
Inspired by the usefulness of small molecules to study membrane traffic, we used high-throughput synthesis and phenotypic screening to discover secramine, a molecule that inhibits membrane traffic out of the Golgi apparatus by an unknown mechanism. We report here that secramine inhibits activation of the Rho GTPase Cdc42, a protein involved in membrane traffic, by a mechanism dependent upon the guanine dissociation inhibitor RhoGDI. RhoGDI binds Cdc42 and antagonizes its membrane association, nucleotide exchange and effector binding. In vitro, secramine inhibits Cdc42 binding to membranes, GTP and effectors in a RhoGDI-dependent manner. In cells, secramine mimics the effects of dominant-negative Cdc42 expression on protein export from the Golgi and on Golgi polarization in migrating cells. RhoGDI-dependent Cdc42 inhibition by secramine illustrates a new way to inhibit Rho GTPases with small molecules and provides a new means to study Cdc42, RhoGDI and the cellular processes they mediate.
Pelish
Henry E
HE
Department of Cell Biology and the CBR Institute for Biomedical Research, Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA.
Peterson
Jeffrey R
JR
Salvarezza
Susana B
SB
Rodriguez-Boulan
Enrique
E
Chen
Ji-Long
JL
Stamnes
Mark
M
Macia
Eric
E
Feng
Yan
Y
Shair
Matthew D
MD
Kirchhausen
Tomas
T
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001552:Benzazepines / Q000138:chemical synthesis / Q000494:pharmacology*; D002417:Cattle; D018797:Cell Cycle Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006056:Golgi Apparatus / Q000187:drug effects* / Q000378:metabolism; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000138:chemical synthesis / Q000494:pharmacology*; D010091:Oximes / Q000138:chemical synthesis / Q000494:pharmacology*; D013997:Time Factors; D020764:cdc42 GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
D000199:Actins; D001552:Benzazepines; D018797:Cell Cycle Proteins; D020690:GTPase-Activating Proteins; D020730:Guanine Nucleotide Dissociation Inhibitors; D010091:Oximes; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; C508970:secramine A; D020764:cdc42 GTP-Binding Protein