Recent nobel_g2013_schekman items

Assembly of γ-secretase occurs through stable dimers after exit from the endoplasmic reticulum

Mon, 14 Mar 2022 00:00:00 +0000

γ-Secretase affects many physiological processes through targeting >100 substrates; malfunctioning links γ-secretase to cancer and Alzheimer's disease. The spatiotemporal regulation of its stoichiometric assembly remains unresolved. Fractionation, biochemical assays, and imaging support prior formation of stable dimers in the ER, which, after ER exit, assemble into full complexes. In vitro ER budding shows that none of the subunits is required for the exit of others. However, knockout of any subunit leads to the accumulation of incomplete subcomplexes in COPII vesicles. Mutating a DPE motif in presenilin 1 (PSEN1) abrogates ER exit of PSEN1 and PEN-2 but not nicastrin. We explain this by the preferential sorting of PSEN1 and nicastrin through Sec24A and Sec24C/D, respectively, arguing against full assembly before ER exit. Thus, dimeric subcomplexes aided by Sec24 paralog selectivity support a stepwise assembly of γ-secretase, controlling final levels in post-Golgi compartments.

Selective sorting of microRNAs into exosomes by phase-separated YBX1 condensates

Mon, 20 Dec 2021 00:00:00 +0000

Exosomes may mediate cell-to-cell communication by transporting various proteins and nucleic acids to neighboring cells. Some protein and RNA cargoes are significantly enriched in exosomes. How cells efficiently and selectively sort them into exosomes remains incompletely explored. Previously, we reported that YBX1 is required in sorting of miR-223 into exosomes. Here, we show that YBX1 undergoes liquid-liquid phase separation (LLPS) in vitro and in cells. YBX1 condensates selectively recruit miR-223 in vitro and into exosomes secreted by cultured cells. Point mutations that inhibit YBX1 phase separation impair the incorporation of YBX1 protein into biomolecular condensates formed in cells, and perturb miR-233 sorting into exosomes. We propose that phase separation-mediated local enrichment of cytosolic RNA-binding proteins and their cognate RNAs enables their targeting and packaging by vesicles that bud into multivesicular bodies. This provides a possible mechanism for efficient...

Low-bias ncRNA libraries using ordered two-template relay: Serial template jumping by a modified retroelement reverse transcriptase

Mon, 13 Dec 2021 00:00:00 +0000

Selfish, non-long terminal repeat (non-LTR) retroelements and mobile group II introns encode reverse transcriptases (RTs) that can initiate DNA synthesis without substantial base pairing of primer and template. Biochemical characterization of these enzymes has been limited by recombinant expression challenges, hampering understanding of their properties and the possible exploitation of their properties for research and biotechnology. We investigated the activities of representative RTs using a modified non-LTR RT from Bombyx mori and a group II intron RT from Eubacterium rectale Only the non-LTR RT supported robust and serial template jumping, producing one complementary DNA (cDNA) from several templates each copied end to end. We also discovered an unexpected terminal deoxynucleotidyl transferase activity of the RTs that adds nucleotide(s) of choice to 3' ends of single- and/or double-stranded RNA or DNA. Combining these two types of activity with additional insights...

Extracellular vesicles from neurons promote neural induction of stem cells through cyclin D1

Mon, 30 Aug 2021 00:00:00 +0000

Extracellular vesicles (EVs) are thought to mediate the transport of proteins and RNAs involved in intercellular communication. Here, we show dynamic changes in the buoyant density and abundance of EVs that are secreted by PC12 cells stimulated with nerve growth factor (NGF), N2A cells treated with retinoic acid to induce neural differentiation, and mouse embryonic stem cells (mESCs) differentiated into neuronal cells. EVs secreted from in vitro differentiated cells promote neural induction of mESCs. Cyclin D1 enriched within the EVs derived from differentiated neuronal cells contributes to this induction. EVs purified from cells overexpressing cyclin D1 are more potent in neural induction of mESC cells. Depletion of cyclin D1 from the EVs reduced the neural induction effect. Our results suggest that EVs regulate neural development through sorting of cyclin D1.

Open science takes on Parkinson’s disease

Mon, 29 Mar 2021 00:00:00 +0000

The Aligning Science Across Parkinson's (ASAP) initiative was set up to improve understanding of the biology underlying the onset and progression of Parkinson's disease. With an emphasis on open science and collaboration, we have assembled a research network led by nearly 100 investigators to explore the pathology of Parkinson's disease, and this network will soon expand to include researchers working on relevant (dys)-functional neural circuits. We have also contributed to large-scale genetics and patient cohort initiatives related to the disease. We hope that these actions, and others planned for the future, will deepen our knowledge of the molecular mechanisms underlying the origin and evolution of Parkinson's disease and, ultimately, contribute to the development of novel therapies.

The ER–Golgi intermediate compartment is a key membrane source for the LC3 lipidation step of autophagosome biogenesis

Mon, 1 Feb 2021 00:00:00 +0000

Autophagy is a catabolic process for bulk degradation of cytosolic materials mediated by double-membraned autophagosomes. The membrane determinant to initiate the formation of autophagosomes remains elusive. Here, we establish a cell-free assay based on LC3 lipidation to define the organelle membrane supporting early autophagosome formation. In vitro LC3 lipidation requires energy and is subject to regulation by the pathways modulating autophagy in vivo. We developed a systematic membrane isolation scheme to identify the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) as a primary membrane source both necessary and sufficient to trigger LC3 lipidation in vitro. Functional studies demonstrate that the ERGIC is required for autophagosome biogenesis in vivo. Moreover, we find that the ERGIC acts by recruiting the early autophagosome marker ATG14, a critical step for the generation of preautophagosomal membranes. DOI:http://dx.doi.org/10.7554/eLife.00947.001.

eLife and early career researchers

Mon, 18 Jan 2021 00:00:00 +0000

There are many reasons for submitting your best work to eLife, especially if you are an early career researcher.

Recognizing the importance of new tools and resources for research

Sun, 3 Jan 2021 00:00:00 +0000

eLife is introducing a new article type—called Tools and Resources—to highlight new experimental techniques, datasets, software tools and other resources.

The structure of the COPII transport-vesicle coat assembled on membranes

Sun, 3 Jan 2021 00:00:00 +0000

Coat protein complex II (COPII) mediates formation of the membrane vesicles that export newly synthesised proteins from the endoplasmic reticulum. The inner COPII proteins bind to cargo and membrane, linking them to the outer COPII components that form a cage around the vesicle. Regulated flexibility in coat architecture is essential for transport of a variety of differently sized cargoes, but structural data on the assembled coat has not been available. We have used cryo-electron tomography and subtomogram averaging to determine the structure of the complete, membrane-assembled COPII coat. We describe a novel arrangement of the outer coat and find that the inner coat can assemble into regular lattices. The data reveal how coat subunits interact with one another and with the membrane, suggesting how coordinated assembly of inner and outer coats can mediate and regulate packaging of vesicles ranging from small spheres to large tubular carriers. DOI:http://dx.doi.org/10.7554/eLife.00951....

Advancing research

Mon, 12 Oct 2020 00:00:00 +0000

eLife has introduced a new type of article-the Research Advance-that allows the authors of an eLife paper to publish results that build on their original research paper.

Building a sustainable future for eLife

Mon, 12 Oct 2020 00:00:00 +0000

To support the long-term growth of eLife we are going to introduce a publication fee of $2500.

Progress and promise

Mon, 12 Oct 2020 00:00:00 +0000

As he prepares to step down as the Editor-in-Chief of eLife, Randy Schekman reflects on the origins of the journal, the eLife approach to peer review, and current challenges in scientific publishing.

Room at the top

Mon, 12 Oct 2020 00:00:00 +0000

Five years after eLife published its first papers, we reflect on our consultative approach to peer review, the challenges of reproducibility, and the need to reform how published research is assessed.

How early-career researchers are shaping eLife

Mon, 12 Oct 2020 00:00:00 +0000

Initiatives to improve research communication can benefit from listening to graduate students, postdocs and newly-independent group leaders.

Coordinating a new approach to basic research into Parkinson’s disease