scholarly journals A Rab3a-dependent complex essential for lysosome positioning and plasma membrane repair

2016 ◽  
Vol 213 (6) ◽  
pp. 631-640 ◽  
Author(s):  
Marisa Encarnação ◽  
Lília Espada ◽  
Cristina Escrevente ◽  
Denisa Mateus ◽  
José Ramalho ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Cell Periphery ◽  
Perinuclear Region ◽  
Nonmuscle Myosin ◽  
Membrane Repair ◽  
Rab Family ◽  
Plasma Membrane Repair ◽  
Molecular Machinery

Lysosome exocytosis plays a major role in resealing plasma membrane (PM) disruptions. This process involves two sequential steps. First, lysosomes are recruited to the periphery of the cell and then fuse with the damaged PM. However, the trafficking molecular machinery involved in lysosome exocytosis and PM repair (PMR) is poorly understood. We performed a systematic screen of the human Rab family to identify Rabs required for lysosome exocytosis and PMR. Rab3a, which partially localizes to peripheral lysosomes, was one of the most robust hits. Silencing of Rab3a or its effector, synaptotagmin-like protein 4a (Slp4-a), leads to the collapse of lysosomes to the perinuclear region and inhibition of PMR. Importantly, we have also identified a new Rab3 effector, nonmuscle myosin heavy chain IIA, as part of the complex formed by Rab3a and Slp4-a that is responsible for lysosome positioning at the cell periphery and lysosome exocytosis.

scholarly journals Rab11 is required for lysosome exocytosis through the interaction with Rab3a, Sec15 and GRAB

2021 ◽  
Author(s):  
Cristina Escrevente ◽  
Liliana Bento-Lopes ◽  
José S. Ramalho ◽  
Duarte C. Barral
Keyword(s):  
Plasma Membrane ◽  
Cell Periphery ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Cellular Functions ◽  
Membrane Repair ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Plasma Membrane Repair ◽  
Molecular Machinery

Lysosomes are dynamic organelles, capable of undergoing exocytosis. This process is crucial for several cellular functions, namely plasma membrane repair. Nevertheless, the molecular machinery involved in this process is poorly understood. Here, we identify Rab11a and Rab11b as regulators of calcium-induced lysosome exocytosis. Interestingly, Rab11-positive vesicles transiently interact with lysosomes at the cell periphery, indicating that this interaction is required for the last steps of lysosome exocytosis. Additionally, we found that the silencing of the exocyst subunit Sec15, a Rab11 effector, impairs lysosome exocytosis, suggesting that Sec15 acts together with Rab11 in the regulation of lysosome exocytosis. Furthermore, we show that Rab11 binds the guanine nucleotide exchange factor for Rab3a (GRAB) and also Rab3a, which we described previously as a regulator of the positioning and exocytosis of lysosomes. Thus, our study identifies new players required for lysosome exocytosis and suggest the existence of a Rab11-Rab3a cascade involved in this process.

scholarly journals A novel Rab11-Rab3a cascade required for lysosome exocytosis

2021 ◽  
Author(s):  
Cristina Escrevente ◽  
Liliana Bento-Lopes ◽  
José S Ramalho ◽  
Duarte C Barral
Keyword(s):  
Plasma Membrane ◽  
Cell Periphery ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Cellular Functions ◽  
Membrane Repair ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Plasma Membrane Repair ◽  
Molecular Machinery

AbstractLysosomes are dynamic organelles, capable of undergoing exocytosis. This process is crucial for several cellular functions, namely plasma membrane repair. Nevertheless, the molecular machinery involved in this process is poorly understood.Here, we identify Rab11a and Rab11b as regulators of calcium-induced lysosome exocytosis. Interestingly, Rab11-positive vesicles transiently interact with lysosomes at the cell periphery, indicating that this interaction is required for the last steps of lysosome exocytosis. Additionally, we found that the silencing of the exocyst subunit Sec15, a Rab11 effector, impairs lysosome exocytosis independently of the exocyst complex, suggesting that Sec15 acts together with Rab11 in the regulation of lysosome exocytosis. Furthermore, we show that Rab11 binds the guanine nucleotide exchange factor for Rab3a (GRAB) and also Rab3a, which we described previously as a regulator of the positioning and exocytosis of lysosomes.Thus, our studies suggest that Rab11-positive vesicles transport GRAB to activate Rab3a on lysosomes, establishing a Rab11-Rab3 cascade that is essential for lysosome exocytosis.

scholarly journals Plasma Membrane Repair: A Central Process for Maintaining Cellular Homeostasis

Physiology ◽  
2015 ◽  
Vol 30 (6) ◽  
pp. 438-448 ◽  
Author(s):  
Alisa D. Blazek ◽  
Brian J. Paleo ◽  
Noah Weisleder
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Cell Membrane ◽  
Cellular Response ◽  
Cellular Functions ◽  
Membrane Repair ◽  
Central Process ◽  
Plasma Membrane Repair ◽  
Molecular Machinery ◽  
Membrane Resealing

Plasma membrane repair is a conserved cellular response mediating active resealing of membrane disruptions to maintain homeostasis and prevent cell death and progression of multiple diseases. Cell membrane repair repurposes mechanisms from various cellular functions, including vesicle trafficking, exocytosis, and endocytosis, to mend the broken membrane. Recent studies increased our understanding of membrane repair by establishing the molecular machinery contributing to membrane resealing. Here, we review some of the key proteins linked to cell membrane repair.

scholarly journals Xenopus nonmuscle myosin heavy chain isoforms have different subcellular localizations and enzymatic activities.

1996 ◽  
Vol 134 (3) ◽  
pp. 675-687 ◽  
Author(s):  
C A Kelley ◽  
J R Sellers ◽  
D L Gard ◽  
D Bui ◽  
R S Adelstein ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Myosin Heavy Chain Isoforms ◽  
Enzymatic Activities ◽  
Cell Cortex ◽  
Cell Periphery ◽  
Nonmuscle Myosin ◽  
In Vitro Motility Assay ◽  
Interphase Cells

There are two isoforms of the vertebrate nonmuscle myosin heavy chain, MHC-A and MHC-B, that are encoded by two separate genes. We compared the enzymatic activities as well as the subcellular localizations of these isoforms in Xenopus cells. MHC-A and MHC-B were purified from cells by immunoprecipitation with isoform-specific peptide antibodies followed by elution with their cognate peptides. Using an in vitro motility assay, we found that the velocity of movement of actin filaments by MHC-A was 3.3-fold faster than that by MHC-B. Likewise, the Vmax of the actin-activated Mg(2+)-ATPase activity of MHC-A was 2.6-fold greater than that of MHC-B. Immunofluorescence microscopy demonstrated distinct localizations for MHC-A and MHC-B. In interphase cells, MHC-B was present in the cell cortex and diffusely arranged in the cytoplasm. In highly polarized, rapidly migrating interphase cells, the lamellipodium was dramatically enriched for MHC-B suggesting a possible involvement of MHC-B based contractions in leading edge extension and/or retraction. In contrast, MHC-A was absent from the cell periphery and was arranged in a fibrillar staining pattern in the cytoplasm. The two myosin heavy chain isoforms also had distinct localizations throughout mitosis. During prophase, the MHC-B redistributed to the nuclear membrane, and then resumed its interphase localization by metaphase. MHC-A, while diffuse within the cytoplasm at all stages of mitosis, also localized to the mitotic spindle in two different cultured cell lines as well as in Xenopus blastomeres. During telophase both isoforms colocalized to the contractile ring. The different subcellular localizations of MHC-A and MHC-B, together with the data demonstrating that these myosins have markedly different enzymatic activities, strongly suggests that they have different functions.

scholarly journals An actin-dependent annexin complex mediates plasma membrane repair in muscle

2016 ◽  
Vol 213 (6) ◽  
pp. 705-718 ◽  
Author(s):  
Alexis R. Demonbreun ◽  
Mattia Quattrocelli ◽  
David Y. Barefield ◽  
Madison V. Allen ◽  
Kaitlin E. Swanson ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Muscle Fibers ◽  
Membrane Repair ◽  
Muscle Plasma Membrane ◽  
Shoulder Region ◽  
Plasma Membrane Repair ◽  
Molecular Machinery ◽  
Membrane Resealing ◽  
Efficient Recovery ◽  
High Resolution Microscopy

Disruption of the plasma membrane often accompanies cellular injury, and in muscle, plasma membrane resealing is essential for efficient recovery from injury. Muscle contraction, especially of lengthened muscle, disrupts the sarcolemma. To define the molecular machinery that directs repair, we applied laser wounding to live mammalian myofibers and assessed translocation of fluorescently tagged proteins using high-resolution microscopy. Within seconds of membrane disruption, annexins A1, A2, A5, and A6 formed a tight repair “cap.” Actin was recruited to the site of damage, and annexin A6 cap formation was both actin dependent and Ca2+ regulated. Repair proteins, including dysferlin, EHD1, EHD2, MG53, and BIN1, localized adjacent to the repair cap in a “shoulder” region enriched with phosphatidlyserine. Dye influx into muscle fibers lacking both dysferlin and the related protein myoferlin was substantially greater than control or individual null muscle fibers, underscoring the importance of shoulder-localized proteins. These data define the cap and shoulder as subdomains within the repair complex accumulating distinct and nonoverlapping components.

scholarly journals Plasma membrane repairs by small GTPase Rab3a

2016 ◽  
Vol 213 (6) ◽  
pp. 613-615 ◽  
Author(s):  
Camilla Raiborg ◽  
Harald Stenmark
Keyword(s):  
Plasma Membrane ◽  
Small Gtpase ◽  
Membrane Repair ◽  
Cell Biol ◽  
Plasma Membrane Repair

Lysosomes fuse with the plasma membrane to help repair membrane lesions, but how they are positioned close to these lesions is not fully understood. Now, Encarnação et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201511093) demonstrate that the lysosomal GTPase Rab3a and its effectors orchestrate lysosome positioning and plasma membrane repair.

scholarly journals Mitochondrial fragmentation enables localized signaling required for cell repair

2020 ◽  
Vol 219 (5) ◽  
Author(s):  
Adam Horn ◽  
Shreya Raavicharla ◽  
Sonna Shah ◽  
Dan Cox ◽  
Jyoti K. Jaiswal
Keyword(s):  
Plasma Membrane ◽  
Calcium Influx ◽  
Cell Damage ◽  
Mitochondrial Fission ◽  
Adaptor Protein ◽  
Mitochondrial Fragmentation ◽  
Membrane Repair ◽  
Membrane Injury ◽  
Mitochondrial Signaling ◽  
Plasma Membrane Repair

Plasma membrane injury can cause lethal influx of calcium, but cells survive by mounting a polarized repair response targeted to the wound site. Mitochondrial signaling within seconds after injury enables this response. However, as mitochondria are distributed throughout the cell in an interconnected network, it is unclear how they generate a spatially restricted signal to repair the plasma membrane wound. Here we show that calcium influx and Drp1-mediated, rapid mitochondrial fission at the injury site help polarize the repair response. Fission of injury-proximal mitochondria allows for greater amplitude and duration of calcium increase in these mitochondria, allowing them to generate local redox signaling required for plasma membrane repair. Drp1 knockout cells and patient cells lacking the Drp1 adaptor protein MiD49 fail to undergo injury-triggered mitochondrial fission, preventing polarized mitochondrial calcium increase and plasma membrane repair. Although mitochondrial fission is considered to be an indicator of cell damage and death, our findings identify that mitochondrial fission generates localized signaling required for cell survival.

scholarly journals Annexin A7 is required for ESCRT III-mediated plasma membrane repair

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Stine Lauritzen Sønder ◽  
Theresa Louise Boye ◽  
Regine Tölle ◽  
Jörn Dengjel ◽  
Kenji Maeda ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Repair ◽  
Plasma Membrane Repair ◽  
Annexin A7
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