RESUMO
In previous work, we found that gain-of-function mutations that hyperactivate GEM-1 (an SLC16A transporter protein) can bypass the requirement for GON-2 (a TRPM channel protein) during the initiation of gonadogenesis in C. elegans. Consequently, we proposed that GEM-1 might function as part of a Mg(2+) uptake pathway that functions in parallel to GON-2. In this study, we report that CATP-6, a C. elegans ortholog of the P5B ATPase, ATP13A2 (PARK9), is necessary for gem-1 gain-of-function mutations to suppress the effects of gon-2 inactivation. One possible explanation for this observation is that GEM-1 serves to activate CATP-6, which then functions as a Mg(2+) transporter. However, we found that overexpression of GEM-1 can alleviate the requirement for CATP-6 activity, suggesting that CATP-6 probably acts as a non-essential upstream positive regulator of GEM-1. Our results are consistent with the notion that P5B ATPases govern intracellular levels of Mg(2+) and/or Mn(2+) by regulating the trafficking of transporters and other proteins associated with the plasma membrane.
Assuntos
Adenosina Trifosfatases/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/química , Caenorhabditis elegans/metabolismo , Transportadores de Ácidos Monocarboxílicos/genética , Transportadores de Ácidos Monocarboxílicos/metabolismo , ATPases Translocadoras de Prótons/química , Homologia de Sequência , Adenosina Trifosfatases/genética , Sequência de Aminoácidos , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Proteínas de Caenorhabditis elegans/genética , Regulação da Expressão Gênica no Desenvolvimento , Genótipo , Gônadas/crescimento & desenvolvimento , Magnésio/metabolismo , Dados de Sequência Molecular , Supressão GenéticaRESUMO
The gon-2 gene of Caenorhabditis elegans encodes a TRPM cation channel required for gonadal cell divisions. In this article, we demonstrate that the gonadogenesis defects of gon-2 loss-of-function mutants (including a null allele) can be suppressed by gain-of-function mutations in the gem-1 (gon-2 extragenic modifier) locus. gem-1 encodes a multipass transmembrane protein that is similar to SLC16 family monocarboxylate transporters. Inactivation of gem-1 enhances the gonadogenesis defects of gon-2 hypomorphic mutations, suggesting that these two genes probably act in parallel to promote gonadal cell divisions. GEM-1GFP is expressed within the gonadal precursor cells and localizes to the plasma membrane. Therefore, we propose that GEM-1 acts in parallel to the GON-2 channel to promote cation uptake within the developing gonad.
Assuntos
Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Genes de Helmintos , Gônadas/crescimento & desenvolvimento , Gônadas/metabolismo , Canais Iônicos/genética , Canais Iônicos/metabolismo , Transportadores de Ácidos Monocarboxílicos/genética , Transportadores de Ácidos Monocarboxílicos/metabolismo , Alelos , Sequência de Aminoácidos , Animais , Animais Geneticamente Modificados , Sequência de Bases , Caenorhabditis elegans/crescimento & desenvolvimento , Proteínas de Caenorhabditis elegans/química , Cálcio/metabolismo , Mapeamento Cromossômico , Primers do DNA/genética , DNA de Helmintos/genética , Genes Supressores , Modelos Biológicos , Dados de Sequência Molecular , Transportadores de Ácidos Monocarboxílicos/química , Mutação , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Homologia de Sequência de AminoácidosRESUMO
The initiation of postembryonic cell divisions by the gonadal precursors of C. elegans requires the activity of gon-2. gon-2 encodes a predicted cation channel (GON-2) of the TRPM subfamily of TRP proteins and is likely to mediate the influx of Ca(2+) and/or Mg(2+). We report here that mutations in gem-4 (gon-2 extragenic modifier) are capable of suppressing loss-of-function alleles of gon-2. gem-4 encodes a member of the copine family of Ca(2+)-dependent phosphatidylserine binding proteins. Overall, our data indicate that GEM-4 antagonizes GON-2. This antagonism could be mediated by a direct inhibition of GON-2 by GEM-4, since both proteins are predicted to be localized to the plasma membrane. Alternatively, GEM-4 could affect GON-2 activity levels by either promoting endocytosis or inhibiting exocytosis of vesicles that carry GON-2. It is also possible that GEM-4 and GON-2 act in parallel to each other. Mutation of gem-4 does not suppress the gonadal defects produced by inactivation of gon-4, suggesting that gon-4 either acts downstream of gem-4 and gon-2 or acts in a parallel regulatory pathway.
