title: Drosophila protein kinase N (Pkn) is a negative regulator of actin-myosin activity during oogenesis.
abstract: Nurse cell dumping is an actin-myosin based process, where 15 nurse cells of a given egg chamber contract and transfer their cytoplasmic content through the ring canals into the growing oocyte. We isolated two mutant alleles of protein kinase N (pkn) and showed that Pkn negatively-regulates activation of the actin-myosin cytoskeleton during the onset of dumping. Using live-cell imaging analysis we observed that nurse cell dumping rates sharply increase during the onset of fast dumping. Such rate increase was severely impaired in pkn mutant nurse cells due to excessive nurse cell actin-myosin activity and/or loss of tissue integrity. Our work demonstrates that the transition between slow and fast dumping is a discrete event, with at least a five to six-fold dumping rate increase. We show that Pkn negatively regulates nurse cell actin-myosin activity. This is likely to be important for directional cytoplasmic flow. We propose Pkn provides a negative feedback loop to help avoid excessive contractility after local activation of Rho GTPase.
authors.affiliation: Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal.
authors.forename: Tânia
authors.initials: T
authors.lastname: Ferreira
authors.affiliation: Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal; Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; IBB-Institute for Biotechnology and Bioengineering, Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Prudêncio
authors.affiliation: Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal; Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; IBB-Institute for Biotechnology and Bioengineering, Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal. Electronic address: rmartinho@igc.gulbenkian.pt.
authors.forename: Rui Gonçalo
authors.initials: RG
authors.lastname: Martinho
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D048429:Cell Size; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007150:Immunohistochemistry; D009218:Myosins / Q000378:metabolism*; D009866:Oogenesis / Q000502:physiology*; D010063:Ovum / Q000166:cytology; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000199:Actins; C061570:protein kinase N; D011493:Protein Kinase C; D009218:Myosins; D020741:rho GTP-Binding Proteins
keywords: Actin–myosin; Drosophila; Morphogenesis; Oogenesis; Protein kinase N