RESUMO
Cells extend membrane protrusions like lamellipodia and filopodia from the leading edge to sense, to move and to form new contacts. The Arp2/3 complex sustains lamellipodia formation, and in conjunction with the actomyosin contractile system, provides mechanical strength to the cell. Drosophila p53-related protein kinase (Prpk), a Tsc5p ortholog, has been described as essential for cell growth and proliferation. In addition, Prpk interacts with proteins associated to actin filament dynamics such as α-spectrin and the Arp2/3 complex subunit Arpc4. Here, we investigated the role of Prpk in cell shape changes, specifically regarding actin filament dynamics and membrane protrusion formation. We found that reductions in Prpk alter cell shape and the structure of lamellipodia, mimicking the phenotypes evoked by Arp2/3 complex deficiencies. Prpk co-localize and co-immunoprecipitates with the Arp2/3 complex subunit Arpc1 and with the small GTPase Rab35. Importantly, expression of Rab35, known by its ability to recruit upstream regulators of the Arp2/3 complex, could rescue the Prpk knockdown phenotypes. Finally, we evaluated the requirement of Prpk in different developmental contexts, where it was shown to be essential for correct Arp2/3 complex distribution and actin dynamics required for hemocytes migration, recruitment, and phagocytosis during immune response.
RESUMO
Maintenance of endoplasmic reticulum (ER) proteostasis is controlled by a signalling network known as the unfolded protein response (UPR). Here, we identified filamin A as a major binding partner of the ER stress transducer IRE1α. Filamin A is an actin crosslinking factor involved in cytoskeleton remodelling. We show that IRE1α controls actin cytoskeleton dynamics and affects cell migration upstream of filamin A. The regulation of cytoskeleton dynamics by IRE1α is independent of its canonical role as a UPR mediator, serving instead as a scaffold that recruits and regulates filamin A. Targeting IRE1α expression in mice affected normal brain development, generating a phenotype resembling periventricular heterotopia, a disease linked to the loss of function of filamin A. IRE1α also modulated cell movement and cytoskeleton dynamics in fly and zebrafish models. This study unveils an unanticipated biological function of IRE1α in cell migration, whereby filamin A operates as an interphase between the UPR and the actin cytoskeleton.
Assuntos
Citoesqueleto de Actina/metabolismo , Movimento Celular , Endorribonucleases/metabolismo , Fibroblastos/metabolismo , Filaminas/metabolismo , Neurônios/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Animais , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Endorribonucleases/deficiência , Endorribonucleases/genética , Evolução Molecular , Feminino , Filaminas/genética , Células HEK293 , Humanos , Cinética , Masculino , Camundongos , Camundongos Knockout , Neurônios/patologia , Heterotopia Nodular Periventricular/genética , Heterotopia Nodular Periventricular/metabolismo , Heterotopia Nodular Periventricular/patologia , Fosforilação , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas Serina-Treonina Quinases/deficiência , Proteínas Serina-Treonina Quinases/genética , Transdução de Sinais , Resposta a Proteínas não Dobradas , Peixe-Zebra/genética , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismoRESUMO
In the version of this Article originally published, the competing interests statement was missing. The authors declare no competing interests; this statement has now been added in all online versions of the Article.
RESUMO
Las metástasis óseas son un evento que se produce en el cáncer avanzado y pueden complicar la calidad de vida. Se presentan con dolor, fracturas patológicas, alteraciones neurológicas, hipercalcemia.