Kalirin12 interacts with dynamin.
BACKGROUND
Guanine nucleotide exchange factors (GEFs) and their target Rho GTPases regulate cytoskeletal changes and membrane trafficking. Dynamin, a large force-generating GTPase, plays an essential role in membrane tubulation and fission in cells. Kalirin12, a neuronal RhoGEF, is found in growth cones early in development and in dendritic spines later in development.


RESULTS
The IgFn domain of Kalirin12, not present in other Kalirin isoforms, binds dynamin1 and dynamin2. An inactivating mutation in the GTPase domain of dynamin diminishes this interaction and the isolated GTPase domain of dynamin retains the ability to bind Kalirin12. Co-immunoprecipitation demonstrates an interaction of Kalirin12 and dynamin2 in embryonic brain. Purified recombinant Kalirin-IgFn domain inhibits the ability of purified rat brain dynamin to oligomerize in response to the presence of liposomes containing phosphatidylinositol-4,5-bisphosphate. Consistent with this, expression of exogenous Kalirin12 or its IgFn domain in PC12 cells disrupts clathrin-mediated transferrin endocytosis. Similarly, expression of exogenous Kalirin12 disrupts transferrin endocytosis in cortical neurons. Expression of Kalirin7, a shorter isoform which lacks the IgFn domain, was previously shown to inhibit clathrin-mediated endocytosis; the GTPase domain of dynamin does not interact with Kalirin7.


CONCLUSIONS
Kalirin12 may play a role in coordinating Rho GTPase-mediated changes in the actin cytoskeleton with dynamin-mediated changes in membrane trafficking.
Xin
Xiaonan
X
Neuroscience Department, University of Connecticut Health Center, Farmington, USA. xin@nso.uchc.edu
Rabiner
Chana A
CA
Mains
Richard E
RE
Eipper
Betty A
BA
D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D002966:Clathrin / Q000494:pharmacology; D034281:Dynamins / Q000145:classification / Q000378:metabolism*; D004622:Embryo, Mammalian; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology; D020558:GTP Phosphohydrolases / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000235:genetics; D020439:Growth Cones / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D047468:Immunoprecipitation / Q000379:methods; D008081:Liposomes / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D051381:Rats; D014162:Transfection / Q000379:methods; D014168:Transferrin / Q000378:metabolism
D002966:Clathrin; D020662:Guanine Nucleotide Exchange Factors; C102365:Kalrn protein, rat; D008081:Liposomes; D019269:Phosphatidylinositol 4,5-Diphosphate; D020033:Protein Isoforms; D014168:Transferrin; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D020558:GTP Phosphohydrolases; D034281:Dynamins