An A-kinase anchoring protein is required for protein kinase A regulatory subunit localization and morphology of actin structures during oogenesis in Drosophila.
Protein kinase A (PKA) holoenzyme is anchored to specific subcellular regions by interactions between regulatory subunits (Pka-R) and A-kinase anchoring proteins (AKAPs). We examine the functional importance of PKA anchoring during Drosophila oogenesis by analyzing membrane integrity and actin structures in mutants with disruptions in Akap200, an AKAP. In wild-type ovaries, Pka-RII and Akap200 localized to membranes and to the outer rim of ring canals, actin-rich structures that connect germline cells. In Akap200 mutant ovaries, Pka-RII membrane localization decreased, leading to a destabilization of membrane structures and the formation of binucleate nurse cells. Defects in membrane integrity could be mimicked by expressing a constitutively active PKA catalytic subunit (Pka-C) throughout germline cells. Unexpectedly, nurse cells in Akap200 mutant ovaries also had enlarged, thin ring canals. In contrast, overexpressing Akap200 in the germline resulted in thicker, smaller ring canals. To investigate the role of Akap200 in regulating ring canal growth, we examined genetic interactions with other genes that are known to regulate ring canal morphology. Akap200 mutations suppressed the small ring canal phenotype produced by Src64B mutants, linking Akap200 with the non-receptor tyrosine kinase pathway. Together, these results provide the first evidence that PKA localization is required for morphogenesis of actin structures in an intact organism.
Jackson
Stephen M
SM
Department of Genome Sciences, Box 357730, University of Washington, 1705 Pacific Street, Seattle, WA 98195-7730, USA. sjackson@u.washington.edu
Berg
Celeste A
CA
D054758:A Kinase Anchor Proteins; D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004251:DNA Transposable Elements; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D009866:Oogenesis / Q000502:physiology*; D010641:Phenotype; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins
D054758:A Kinase Anchor Proteins; D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; C121679:Akap200 protein, Drosophila; D002352:Carrier Proteins; D004251:DNA Transposable Elements; D029721:Drosophila Proteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D011505:Protein-Tyrosine Kinases; C075699:Src64B protein, Drosophila; D017868:Cyclic AMP-Dependent Protein Kinases