RESUMO
In C. elegans, a G(o)/G(q) signaling network regulates locomotion and egg laying [1-8]. Genetic analysis shows that activated Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is suppressed by perturbations of this network, which include loss of the GOA-1 G(o)alpha, DGK-1 diacylglycerol kinase, EAT-16 G protein gamma subunit-like (GGL)-containing RGS protein, or an unidentified protein encoded by the gene eat-11 [9]. We cloned eat-11 and report that it encodes the Gbeta(5) ortholog GPB-2. Gbeta(5) binds specifically to GGL-containing RGS proteins, and the Gbeta(5)/RGS complex can promote the GTP-hydrolyzing activity of Galpha subunits [10, 11]. However, little is known about how this interaction affects G protein signaling in vivo. In addition to EAT-16, the GGL-containing RGS protein EGL-10 participates in G(o)/G(q) signaling; EGL-10 appears to act as an RGS for the GOA-1 G(o)alpha, while EAT-16 appears to act as an RGS for the EGL-30 G(q)alpha [4, 5]. We have combined behavioral, electrophysiological, and pharmacological approaches to show that GPB-2 is a central member of the G(o)/G(q) network and that GPB-2 may interact with both the EGL-10 and EAT-16 RGS proteins to mediate the opposing activities of G(o)alpha and G(q)alpha. These interactions provide a mechanism for the modulation of behavior by antagonistic G protein networks.
Assuntos
Comportamento Animal , Proteínas de Caenorhabditis elegans , Caenorhabditis elegans/fisiologia , Reguladores de Proteínas de Ligação ao GTP , Subunidades beta da Proteína de Ligação ao GTP , Proteínas de Helminto/metabolismo , Proteínas Heterotriméricas de Ligação ao GTP/metabolismo , Sequência de Aminoácidos , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina , Proteínas Quinases Dependentes de Cálcio-Calmodulina/genética , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Bovinos , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP , Proteínas de Helminto/genética , Humanos , Dados de Sequência Molecular , Proteínas RGS/genética , Proteínas RGS/metabolismoRESUMO
Caenorhabditis elegans locomotion is a complex behavior generated by a defined set of motor neurons and interneurons. Genetic analysis shows that UNC-43, the C. elegans Ca(2+)/calmodulin protein kinase II (CaMKII), controls locomotion rate. Elevated UNC-43 activity, from a gain-of-function mutation, causes severely lethargic locomotion, presumably by inappropriate phosphorylation of targets. In a genetic screen for suppressors of this phenotype, we identified multiple alleles of four genes in a G(o)/G(q) G-protein signaling network, which has been shown to regulate synaptic activity via diacylglycerol. Mutations in goa-1, dgk-1, eat-16, or eat-11 strongly or completely suppressed unc-43(gf) lethargy, but affected other mutants with reduced locomotion only weakly. We conclude that CaMKII and G(o)/G(q) pathways act in concert to regulate synaptic activity, perhaps through a direct interaction between CaMKII and G(o).
Assuntos
Caenorhabditis elegans/fisiologia , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Proteínas de Ligação ao GTP/genética , Movimento/fisiologia , Animais , Caenorhabditis elegans/enzimologia , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina , Proteínas Quinases Dependentes de Cálcio-Calmodulina/genética , Cruzamentos Genéticos , Transtornos do Desenvolvimento Sexual , Feminino , Proteínas de Ligação ao GTP/metabolismo , Genes de Helmintos , Locomoção , Masculino , Mutagênese , Oviposição , Supressão GenéticaRESUMO
Using gene targeting in embryonic stem cells, we have derived mice with a null mutation in a DNA mismatch repair gene homolog, PMS2. We observed microsatellite instability in the male germline, in tail, and in tumor DNA of PMS2-deficient animals. We therefore conclude that PMS2 is involved in DNA mismatch repair in a variety of tissues. PMS2-deficient animals appear prone to sarcomas and lymphomas. PMS2-deficient males are infertile, producing only abnormal spermatozoa. Analysis of axial element and synaptonemal complex formation during prophase of meiosis I indicates abnormalities in chromosome synapsis. These observations suggest links among mismatch repair, genetic recombination, and chromosome synapsis in meiosis.