Mitophagy is a selective autophagy for the degradation of damaged or excessive mitochondria to maintain intracellular homeostasis. In Magnaporthe oryzae, a filamentous ascomycetous fungus that causes rice blast, the most devastating disease of rice, mitophagy occurs in the invasive hyphae to promote infection. To date, only a few proteins are known to participate in mitophagy and the mechanisms of mitophagy are largely unknown in pathogenic fungi.
View Article and Find Full Text PDFThe primary cilium is an antenna-like projection from the plasma membrane that serves as a sensor of the extracellular environment and a crucial signaling hub. Primary cilia are generated in most mammalian cells, and their physiological significance is highlighted by the large number of severe developmental disorders or ciliopathies that occur when primary ciliogenesis is impaired. Primary ciliogenesis is a tightly regulated process, and a central early regulatory step is the removal of a key mother centriole capping protein, CP110 (also known as CCP110).
View Article and Find Full Text PDFRice false smut caused by is becoming one of the most devastating diseases in rice production areas in the world. Revealing potential pathogenic mechanisms provides ideas for formulating more effective prevention and control strategies. Sucrose non-fermenting 1 (Snf1) protein kinase plays a critical role in activating transcription and suppressing gene expression, as well as in cellular response to various stresses, such as nutrient limitation.
View Article and Find Full Text PDFPrimary cilia are sensory organelles that coordinate diverse signaling pathways, controlling development and homeostasis. Progression beyond the early steps of ciliogenesis requires the removal of a distal end protein, CP110, from the mother centriole, a process mediated by Eps15 Homology Domain protein 1 (EHD1). We show that EHD1 regulates CP110 ubiquitination during ciliogenesis, and identify two E3 ubiquitin ligases, HECT domain and RCC1-like domain 2 (HERC2) and mindbomb homolog 1 (MIB1), that interact with and ubiquitinate CP110.
View Article and Find Full Text PDFThe mammalian retromer consists of subunits VPS26 (either VPS26A or VPS26B), VPS29 and VPS35, and a loosely associated sorting nexin (SNX) heterodimer or a variety of other SNX proteins. Despite involvement in yeast and mammalian cell trafficking, the role of retromer in development is poorly understood, and its impact on primary ciliogenesis remains unknown. Using CRISPR/Cas9 editing, we demonstrate that vps-26-knockout worms have reduced brood sizes, impaired vulval development and decreased body length, all of which have been linked to ciliogenesis defects.
View Article and Find Full Text PDFOnce internalized, receptors reach the sorting endosome and are either targeted for degradation or recycled to the plasma membrane, a process mediated at least in part by tubular recycling endosomes (TREs). TREs may be efficient for sorting owing to the ratio of large surface membrane area to luminal volume; following receptor segregation, TRE fission likely releases receptor-laden tubules and vesicles for recycling. Despite the importance of TRE networks for recycling, these unique structures remain poorly understood, and unresolved questions relate to their lipid and protein composition and biogenesis.
View Article and Find Full Text PDFThe endocytic protein EHD1 plays an important role in ciliogenesis by facilitating fusion of the ciliary vesicle and removal of CP110 (also known as CCP110) from the mother centriole, as well as removal of Cep215 (also known as CDK5RAP2) from centrioles to permit disengagement and duplication. However, the mechanism of its centrosomal recruitment remains unknown. Here, we address the role of the EHD1 interaction partner MICAL-L1 in ciliogenesis.
View Article and Find Full Text PDFCentrosomes are the major microtubule-nucleating and microtubule-organizing centers of cells and play crucial roles in microtubule anchoring, organelle positioning, and ciliogenesis. At the centrosome core lies a tightly associated or "engaged" mother-daughter centriole pair. During mitotic exit, removal of centrosomal proteins pericentrin and Cep215 promotes "disengagement" by the dissolution of intercentriolar linkers, ensuring a single centriole duplication event per cell cycle.
View Article and Find Full Text PDFMitochondria play essential roles in cellular energy processes, including ATP production, control of reactive oxygen species (ROS) and apoptosis. While mitochondrial function is regulated by the dynamics of fusion and fission, mitochondrial homeostasis remains incompletely understood. Recent studies implicate dynamin-2 and dynamin-related protein-1 (Drp1, also known as DNM1L), as GTPases involved in mitochondrial fission.
View Article and Find Full Text PDFAn elaborate network of dynamic lipid membranes, termed tubular recycling endosomes (TRE), coordinates the process of endocytic recycling in mammalian cells. The C-terminal Eps15 homology domain (EHD)-containing proteins have been implicated in the bending and fission of TRE, thus regulating endocytic recycling. EHD proteins have an EH domain that interacts with proteins containing an NPF motif.
View Article and Find Full Text PDFDiacylglycerol kinases (DGKs) belong to a family of cytosolic kinases that regulate the phosphorylation of diacylglycerol (DAG), converting it into phosphatidic acid (PA). There are 10 known mammalian DGK isoforms, each with a different tissue distribution and substrate specificity. These differences allow regulation of cellular responses by fine-tuning the delicate balance of cellular DAG and PA.
View Article and Find Full Text PDFThe endocytic recycling compartment (ERC) is a series of perinuclear tubular and vesicular membranes that regulates recycling to the plasma membrane. Despite evidence that cargo is sorted at the early/sorting endosome (SE), whether cargo mixes downstream at the ERC or remains segregated is an unanswered question. Here we use three-dimensional (3D) structured illumination microscopy and dual-channel and 3D direct stochastic optical reconstruction microscopy (dSTORM) to obtain new information about ERC morphology and cargo segregation.
View Article and Find Full Text PDFEndocytosis, which encompasses the internalization and sorting of plasma membrane (PM) lipids and proteins to distinct membrane-bound intracellular compartments, is a highly regulated and fundamental cellular process by which eukaryotic cells dynamically regulate their PM composition. Indeed, endocytosis is implicated in crucial cellular processes that include proliferation, migration, and cell division as well as maintenance of tissue homeostasis such as apical-basal polarity. Once PM constituents have been taken up into the cell, either via clathrin-dependent endocytosis (CDE) or clathrin-independent endocytosis (CIE), they typically have two fates: degradation through the late-endosomal/lysosomal pathway or returning to the PM via endocytic recycling pathways.
View Article and Find Full Text PDFThe biogenesis of tubular recycling endosomes (TREs) and their subsequent vesiculation after cargo-sorting has occurred, is essential for receptor and lipid recycling to the plasma membrane. Although recent studies have implicated the C-terminal Eps15 Homology Domain (EHD) protein, EHD1, as a key regulator of TRE vesiculation, additional proteins involved in this process have been largely uncharacterized. In the present study, we identify the GTPase Regulator Associated with Focal adhesion kinase-1 (GRAF1) protein in a complex with EHD1 and the TRE hub protein, Molecules Interacting with CasL-Like1 (MICAL-L1).
View Article and Find Full Text PDFMajor histocompatibility complex class I (MHC I) presents intracellular-derived peptides to cytotoxic T lymphocytes and its subcellular itinerary is important in regulating the immune response. While a number of diacylglycerol kinase isoforms have been implicated in clathrin-dependent internalization, MHC I lacks the typical motifs known to mediate clathrin-dependent endocytosis. Here we show that depletion of diacylglycerol kinase α (DGKα), a kinase devoid of a clathrin-dependent adaptor protein complex 2 binding site, caused a delay in MHC I recycling to the plasma membrane without affecting the rate of MHC I internalization.
View Article and Find Full Text PDFThere is increased interest in immune-based monoclonal antibody therapies for different malignancies because of their potential specificity and limited toxicity. The activity of some therapeutic monoclonal antibodies is partially dependent on complement-dependent cytolysis (CDC), in which the immune system surveys for invading pathogens, infected cells, and malignant cells and facilitates their destruction. CD59 is a ubiquitously expressed cell-surface glycosylphosphatidylinositol-anchored protein that protects cells from CDC.
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