RESUMEN
The lysosome is the final destination for degradation of endocytic cargo, plasma membrane constituents, and intracellular components sequestered by macroautophagy. Fusion of endosomes and autophagosomes with the lysosome depends on the GTPase Rab7 and the homotypic fusion and protein sorting (HOPS) complex, but adaptor proteins that link endocytic and autophagy pathways with lysosomes are poorly characterized. Herein, we show that Pleckstrin homology domain containing protein family member 1 (PLEKHM1) directly interacts with HOPS complex and contains a LC3-interacting region (LIR) that mediates its binding to autophagosomal membranes. Depletion of PLEKHM1 blocks lysosomal degradation of endocytic (EGFR) cargo and enhances presentation of MHC class I molecules. Moreover, genetic loss of PLEKHM1 impedes autophagy flux upon mTOR inhibition and PLEKHM1 regulates clearance of protein aggregates in an autophagy- and LIR-dependent manner. PLEKHM1 is thus a multivalent endocytic adaptor involved in the lysosome fusion events controlling selective and nonselective autophagy pathways.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/genética , Lisosomas/metabolismo , Fusión de Membrana/genética , Glicoproteínas de Membrana/genética , Proteínas Asociadas a Microtúbulos/genética , Fagosomas/metabolismo , Proteínas Adaptadoras Transductoras de Señales/antagonistas & inhibidores , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Secuencia de Aminoácidos , Animales , Proteínas Reguladoras de la Apoptosis , Autofagia , Proteínas Relacionadas con la Autofagia , Endosomas/metabolismo , Regulación de la Expresión Génica , Células HeLa , Humanos , Glicoproteínas de Membrana/antagonistas & inhibidores , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Transgénicos , Proteínas Asociadas a Microtúbulos/metabolismo , Modelos Moleculares , Datos de Secuencia Molecular , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Transporte de Proteínas , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Alineación de Secuencia , Transducción de Señal , Proteínas de Unión al GTP rab/genética , Proteínas de Unión al GTP rab/metabolismo , Proteínas de Unión a GTP rab7RESUMEN
The host endolysosomal compartment is often manipulated by intracellular bacterial pathogens. Salmonella (Salmonella enterica serovar Typhimurium) secrete numerous effector proteins, including SifA, through a specialized type III secretion system to hijack the host endosomal system and generate the Salmonella-containing vacuole (SCV). To form this replicative niche, Salmonella targets the Rab7 GTPase to recruit host membranes through largely unknown mechanisms. We show that Pleckstrin homology domain-containing protein family member 1 (PLEKHM1), a lysosomal adaptor, is targeted by Salmonella through direct interaction with SifA. By binding the PLEKHM1 PH2 domain, Salmonella utilize a complex containing PLEKHM1, Rab7, and the HOPS tethering complex to mobilize phagolysosomal membranes to the SCV. Depletion of PLEKHM1 causes a profound defect in SCV morphology with multiple bacteria accumulating in enlarged structures and significantly dampens Salmonella proliferation in multiple cell types and mice. Thus, PLEKHM1 provides a critical interface between pathogenic infection and the host endolysosomal system.