Protein Transport Research Articles

A variant of the Hspa8 synaptic chaperone modifies disease in a SOD1G86R mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a relatively common and invariably fatal, paralyzing motor neuron disease for which there are few treatment options. ALS is frequently associated with ubiquitin-positive motor neuronal aggregates, a pathology suggestive of perturbed proteostasis. Indeed, cellular chaperones, which are involved in protein trafficking and degradation often underlie familial ALS. Spinal muscular atrophy (SMA) is a second, common paralytic condition resulting from motor neuron loss and muscle atrophy. While SMA is now effectively treated, mechanisms underlying motor neuron degeneration in the disease remain far from clear. To address mechanistic questions about SMA, we recently identified a genetic modifier of the disease. The factor, a G470R variant in the constitutively expressed cellular chaperone, Hspa8, arrested motor neuron loss, prevented the abnormal accumulation of neurofilament aggregates at nerve terminals and suppressed disease. Hspa8 is best known for its role in autophagy. Amongst its many clients is the ALS-associated superoxide dismutase 1 (SOD1) protein. Given its suppression of the SMA phenotype, we tested potential disease-mitigating effects of Hspa8G470R in a mutant SOD1 mouse model of ALS. Unexpectedly, disease in mutant SOD1 mice expressing the G470R variant was aggravated. Motor performance of the mice deteriorated, muscle atrophy worsened, and lifespan shrunk even further. Paradoxically, SOD1 protein in spinal cord tissue of the mice was dramatically reduced. Our results suggest that Hspa8 modulates the ALS phenotype. However, rather than mitigating disease, the G470R variant exacerbates it.

Retraction: Effect of Photoinduced Size Changes on Protein Refolding and Transport Abilities of Soft Nanotubes.

Retraction: Effect of Photoinduced Size Changes on Protein Refolding and Transport Abilities of Soft Nanotubes.

Functional Diversification of Sec13 Isoforms for Storage Protein Trafficking in Rice Endosperm Cells.

Coat protein complex II (COPII) vesicles play crucial roles in mediating the endoplasmic reticulum (ER) exit of newly synthesized proteins to the Golgi in eukaryotic cells. However, the molecular functions of COPII components and their functional diversifications in plant seeds remain obscure. Here, we showed that the rice (Oryza sativa) glutelin precursor accumulation12 (gpa12) mutant is defective in storage protein export from the ER, resulting in the formation of aggregated protein bodies. Map-based cloning revealed that GPA12 encodes a COPII outer layer protein, Sec13a, that mainly localizes to endoplasmic reticulum exit sites (ERES) and partially localizes to the Golgi. Biochemical experiments verified that Sec13a physically interacts with Sec31 and Sec16, and mutation in Sec13 compromises its interaction with Sec31 and Sec16, thereby affecting the membrane association of the inner complex components Sar1b and Sec23c. Apart from Sec13a, the rice genome encodes two other Sec13 isoforms, Sec13b and Sec13c. Notably, we observed an abnormal accumulation of globular ER structures in the sec13bc double mutant but not in the single mutants, suggesting a functional redundancy of Sec13b and Sec13c in modulating ER morphology. Taken together, our results substantiated that Sec13a plays an important role in regulating storage protein export from the ER, while Sec13b and Sec13c are required for maintaining ER morphology in rice endosperm cells. Our findings provide insights into the functional diversification of COPII components in plants.

Fluorescent Reporters, Imaging, and Artificial Intelligence Toolkits to Monitor and Quantify Autophagy, Heterophagy, and Lysosomal Trafficking Fluxes.

Lysosomal compartments control the clearance of cell-own material (autophagy) or of material that cells endocytose from the external environment (heterophagy) to warrant supply of nutrients, to eliminate macromolecules or parts of organelles present in excess, aged, or containing toxic material. Inherited or sporadic mutations in lysosomal proteins and enzymes may hamper their folding in the endoplasmic reticulum (ER) and their lysosomal transport via the Golgi compartment, resulting in lysosomal dysfunction and storage disorders. Defective cargo delivery to lysosomal compartments is harmful to cells and organs since it causes accumulation of toxic compounds and defective organellar homeostasis. Assessment of resident proteins and cargo fluxes to the lysosomal compartments is crucial for the mechanistic dissection of intracellular transport and catabolic events. It might be combined with high-throughput screenings to identify cellular, chemical, or pharmacological modulators of these events that may find therapeutic use for autophagy-related and lysosomal storage disorders. Here, discuss qualitative, quantitative and chronologic monitoring of autophagic, heterophagic and lysosomal protein trafficking in fixed and live cells, which relies on fluorescent single and tandem reporters used in combination with biochemical, flow cytometry, light and electron microscopy approaches implemented by artificial intelligence-based technology.

A snapshot of the Physcomitrella N-terminome reveals N-terminal methylation of organellar proteins

Key messageAnalysis of the N-terminome of Physcomitrella reveals N-terminal monomethylation of nuclear-encoded, mitochondria-localized proteins.Post- or co-translational N-terminal modifications of proteins influence their half-life as well as mediating protein sorting to organelles via cleavable N-terminal sequences that are recognized by the respective translocation machinery. Here, we provide an overview on the current modification state of the N-termini of over 4500 proteins from the model moss Physcomitrella (Physcomitrium patens) using a compilation of 24 N-terminomics datasets. Our data reveal distinct proteoforms and modification states and confirm predicted targeting peptide cleavage sites of 1,144 proteins localized to plastids and the thylakoid lumen, to mitochondria, and to the secretory pathway. In addition, we uncover extended N-terminal methylation of mitochondrial proteins. Moreover, we identified PpNTM1 (P. patens alpha N-terminal protein methyltransferase 1) as a candidate for protein methylation in plastids, mitochondria, and the cytosol. These data can now be used to optimize computational targeting predictors, for customized protein fusions and their targeted localization in biotechnology, and offer novel insights into potential dual targeting of proteins.Graphical abstract

Prognostic value and anti-tumor immunity role of TMED9 in pan-cancer: a bioinformatics study.

Transmembrane p24 trafficking protein 9 (TMED9) belongs to the TMED family, and its overexpression frequently induces cancer. Studies have demonstrated the association between the overexpression of TMED9 and cancer development and proliferative migration in cancers such as ovarian cancer, hepatocellular carcinoma, and breast cancer. However, there has been no study investigating the clinical value, biological function, and anti-tumor immune effects of TMED9 from a pan-cancer perspective. The aim of this study is to evaluate the prognostic value and anti-tumor immunity role of TMED9 across pan-cancers. We utilized R language along with The Cancer Genome Atlas (TCGA), UCSC Xena (University of California, Santa Cruz Xena Browser), Human Protein Atlas (HPA), and other datasets to investigate TMED9 expression in various tumors. The association between high TMED9 expression and clinical prognosis and patient survival was examined using the Kaplan-Meier method, log-rank test, as well as univariate and multivariate Cox regression analyses. Tumor Immune Estimation Resource 2.0 (TIMER2.0) and various algorithms were employed to explore the relationship between TMED9 and the tumor microenvironment (TME). Additionally, the biological function of TMED9 in cancer was investigated through Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA) analyses. TMED9 was over-expressed in the majority of cancers. Patients exhibiting elevated TMED9 expression typically experienced diminished survival rates and unfavorable clinical outcomes. TMED9 played a role as a mediator in the aggressive phenotype of numerous tumors, actively engaging in various biological and signaling pathways linked to cancer development. TMED9 demonstrated the capacity to modulate the anti-tumor immune response in pan-cancer patients, exerting its influence on the infiltration levels of immune cells and cancer-associated fibroblasts (CAFs). TMED9 serves as a novel "cancer indicator" and "clinical prognostic marker", capable of reshaping the TME, impacting the immunotherapeutic response, and guiding precise treatments for cancers to a certain extent.

Targeting Cholesterol Biosynthesis with Statins Synergizes with AKT Inhibitors in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is responsible for a disproportionate number of breast cancer patient deaths due to extensive molecular heterogeneity, high recurrence rates, and lack of targeted therapies. Dysregulation of the phosphoinositide 3-kinase (PI3K)/AKT pathway occurs in approximately 50% of TNBC patients. Here, we performed a genome-wide CRISPR/Cas9 screen with PI3Kα and AKT inhibitors to find targetable synthetic lethalities in TNBC. Cholesterol homeostasis was identified as a collateral vulnerability with AKT inhibition. Disruption of cholesterol homeostasis with pitavastatin synergized with AKT inhibition to induce TNBC cytotoxicity in vitro in mouse TNBC xenografts and in patient-derived estrogen receptor (ER)-negative breast cancer organoids. Neither ER-positive breast cancer cell lines nor ER-positive organoids were sensitive to combined AKT inhibitor and pitavastatin. Mechanistically, TNBC cells showed impaired sterol regulatory element-binding protein 2 (SREBP-2) activation in response to single-agent or combination treatment with AKT inhibitor and pitavastatin, which was rescued by inhibition of the cholesterol-trafficking protein Niemann-Pick C1 (NPC1). NPC1 loss caused lysosomal cholesterol accumulation, decreased endoplasmic reticulum cholesterol levels, and promoted SREBP-2 activation. Taken together, these data identify a TNBC-specific vulnerability to the combination of AKT inhibitors and pitavastatin mediated by dysregulated cholesterol trafficking. These findings support combining AKT inhibitors with pitavastatin as a therapeutic modality in TNBC. Significance: Two FDA-approved compounds, AKT inhibitors and pitavastatin, synergize to induce cell death in triple-negative breast cancer, motivating evaluation of the efficacy of this combination in clinical trials.

Guilu Erxian glue reduces endoplasmic reticulum stress-mediated apoptosis and restores the balance of extracellular matrix synthesis and degradation in chondrocytes by inhibiting the ATF6/GRP78/CHOP signaling pathway

Knee Osteoarthritis (KOA) is characterized by phenotypic alterations, apoptosis, and the breakdown of the extracellular matrix (ECM) in the superficial articular cartilage cells. The inflammatory response activates the Endoplasmic Reticulum Stress (ERS) signaling pathway, which plays a critical role in the pathophysiology and progression of KOA. Chondrocytes stimulated by thapsigargin(TG)exhibit heightened ERS and significantly increase the expression of ERS-associated proteins. Key mediators of ERS-induced apoptosis include X-box-binding protein 1(XBP1), elevated levels of the protein transport protein Sec61 subunit (SEC61), and C/EBP homologous protein (CHOP).While the precise mechanism of action of Guilu Erxian Glue (GEG), a medication commonly used in the clinical treatment of KOA, remains to be fully elucidated, our research has shown that GEG mitigates the imbalance between ECM synthesis and degradation, as well as chondrocyte apoptosis resulting from ERS. This effect is likely achieved through the suppression of the Activating Transcription Factor 6 (ATF6)/Glucose-Regulatory Protein 78 (GRP78)/CHOP signaling pathway.In summary,our research results indicate that GEG can activate the ATF6/GRP78/CHOP signaling pathway to restore endoplasmic reticulum (ER) homeostasis in chondrocytes, thereby reducing chondrocyte apoptosis and ultimately promoting the balance between ECM synthesis and degradation.

Bi-Allelic Splicing Variant, c.153-2A > C in TOMM7 Is Associated With Leigh Syndrome.

Translocase of the outer mitochondrial membrane (TOMM) complex plays an important role in the transport of proteins from the cytoplasm into the mitochondria. TOMM7, one of the subunits of the TOMM complex, modulates its assembly and stability. Bi-allelic disease-causing variants in TOMM7 (MIM* 607980) have been previously reported in two unrelated families with a diverse phenotype of short stature, lipodystrophy, progeria, developmental delay, hypotonia, and skeletal dysplasia. We report a 4-month-old female child significantly affected with neonatal-onset hypotonia, lactic acidosis, optic atrophy, and neuroimaging findings suggestive of Leigh disease with a novel canonical splice variant, c.153-2A > C in TOMM7 (NM_019059.5). Further work done on cDNA of parents revealed the presence of shorter transcripts secondary to aberrant splicing.

A Fluorogenic Chemogenetic pH Sensor for Imaging Protein Exocytosis.

Fluorescent protein-based pH biosensors enable the tracking of pH changes during protein trafficking and, in particular, exocytosis. The recent development of chemogenetic reporters combining synthetic fluorophores with self-labeling protein tags offers a versatile alternative to fluorescent proteins that combines the diversity of chemical probes and indicators with the selectivity of the genetic encoding. However, this hybrid protein labeling strategy does not avoid common drawbacks of organic fluorophores such as the risk of off-target signal due to unbound molecules. Here, we describe a novel fluorogenic and chemogenetic pH sensor based on a cell-permeable molecular pH indicator called pHluo-Halo-1, whose fluorescence can be locally activated in cells by reaction with HaloTag, ensuring excellent signal selectivity in wash-free imaging experiments. pHluo-Halo-1 was selected out of a series of four fluorogenic molecular rotor structures based on protein chromophore analogues. It displays good pH sensitivity with a pKa of 6.3 well-suited to monitor pH variations during exocytosis and an excellent labeling selectivity in cells. It was applied to follow the secretion of CD63-HaloTag fusion proteins using TIRF microscopy. We anticipate that this strategy based on the combination of a tunable and chemically accessible fluorogenic probe with a well-established protein tag will open new possibilities for the development of versatile alternatives to fluorescent proteins for elucidating the dynamics and regulatory mechanisms of proteins in living cells.

The role of chloroplast SRP54 domains and its C-terminal tail region in post- and co-translational protein transport in vivo.

In the chloroplast, the 54 kDa subunit of the signal recognition particle (cpSRP54) is involved in the post-translational transport of the light-harvesting chlorophyll a/b-binding proteins (LHCPs) and the co-translational transport of plastid-encoded subunits of the photosynthetic complexes to the thylakoid membrane. It forms a high-affinity complex with plastid-specific cpSRP43 for post-translational transport, while a ribosome-associated pool coordinates its co-translational function. CpSRP54 constitutes a conserved multidomain protein, comprising a GTPase (NG) and a methionine-rich (M) domain linked by a flexible region. It is further characterized by a plastid-specific C-terminal tail region containing the cpSRP43-binding motif. To characterize the physiological role of the various regions of cpSRP54 in thylakoid membrane protein transport, we generated Arabidopsis cpSRP54 knockout (ffc1-2) lines producing truncated cpSRP54 variants or a GTPase point mutation variant. Phenotypic characterization of the complementation lines demonstrated that the C-terminal tail region of cpSRP54 plays an important role exclusively in post-translational LHCP transport. Furthermore, we show that the GTPase activity of cpSRP54 plays an essential role in the transport pathways for both nuclear as well as plastid-encoded proteins. In addition, our data revealed that plants expressing cpSRP54 without the C-terminal region exhibit a strongly increased accumulation of a photosystem I assembly intermediate.

Phosphoproteomics-directed manipulation reveals SEC22B as a hepatocellular signaling node governing metabolic actions of glucagon

The peptide hormone glucagon is a fundamental metabolic regulator that is also being considered as a pharmacotherapeutic option for obesity and type 2 diabetes. Despite this, we know very little regarding how glucagon exerts its pleiotropic metabolic actions. Given that the liver is a chief site of action, we performed in situ time-resolved liver phosphoproteomics to reveal glucagon signaling nodes. Through pathway analysis of the thousands of phosphopeptides identified, we reveal “membrane trafficking” as a dominant signature with the vesicle trafficking protein SEC22 Homolog B (SEC22B) S137 phosphorylation being a top hit. Hepatocyte-specific loss- and gain-of-function experiments reveal that SEC22B was a key regulator of glycogen, lipid and amino acid metabolism, with SEC22B-S137 phosphorylation playing a major role in glucagon action. Mechanistically, we identify several protein binding partners of SEC22B affected by glucagon, some of which were differentially enriched with SEC22B-S137 phosphorylation. In summary, we demonstrate that phosphorylation of SEC22B is a hepatocellular signaling node mediating the metabolic actions of glucagon and provide a rich resource for future investigations on the biology of glucagon action.

Chloroplasts with clefts and holes: a reassessment of the chloroplast shape using 3D FE-SEM cellular reconstruction of two species of Chlamydomonas.

Chloroplasts are usually considered spheroid organelles, but this is not the only shape of chloroplasts. The chloroplast of Chlamydomonas has been typically described as cup-shaped. However, in old studies, it was also modeled as a complex shape with "perforations" or windows. Here, we reconstructed the cellular architecture of Chlamydomonas reinhardtii and C. applanata using an array tomography system installed on a field emission scanning electron microscope. C. reinhardtii chloroplasts resembled a baseball glove or a cup without a side, featuring numerous large and small holes that may facilitate the transport of metabolites and proteins produced in the Golgi apparatus fitted in the holes. In a lipid-accumulating, high-light condition, the chloroplast volume increased by filling the side cleft with an entire wall. Many accumulated large lipid droplets were accommodated within the chloroplast holes, which could have been considered as "chloroplast lipid droplets." Mitochondrial meshworks surrounded the chloroplast. C. applanata chloroplasts appeared like a folded starfish or a cup with many side clefts and a few holes. There was a single mitochondrion or two that branched in a complex form. Tight contacts of various organelles were also found in C. applanata. These reconstructions illustrate the complexity of chloroplast shape, which necessitates a revised understanding of the localization of lipid droplets and the evolution of chloroplasts: The prevailing image of the spheroid chloroplasts that reminds us of the similarity between chloroplasts and cyanobacteria is no longer tenable.

Altered glycosylation in cancer: molecular functions and therapeutic potential

AbstractGlycosylation, a key mode of protein modification in living organisms, is critical in regulating various biological functions by influencing protein folding, transportation, and localization. Changes in glycosylation patterns are a significant feature of cancer, are associated with a range of pathological activities in cancer‐related processes, and serve as critical biomarkers providing new targets for cancer diagnosis and treatment. Glycoproteins like human epidermal growth factor receptor 2 (HER2) for breast cancer, alpha‐fetoprotein (AFP) for liver cancer, carcinoembryonic antigen (CEA) for colon cancer, and prostate‐specific antigen (PSA) for prostate cancer are all tumor biomarkers approved for clinical use. Here, we introduce the diversity of glycosylation structures and newly discovered glycosylation substrate—glycosylated RNA (glycoRNA). This article focuses primarily on tumor metastasis, immune evasion, metabolic reprogramming, aberrant ferroptosis responses, and cellular senescence to illustrate the role of glycosylation in cancer. Additionally, we summarize the clinical applications of protein glycosylation in cancer diagnostics, treatment, and multidrug resistance. We envision a promising future for the clinical applications of protein glycosylation.

VPS13C and STING expression in neuropsychiatric systemic lupus erythematosus: unveiling an unbreached territory

ObjectivesTo measure the expression level of the vacuolar protein sorting 13 (VPS13) gene and stimulator of interferon genes (STING) in patients with SLE with and without reported neuropsychiatric symptoms to...

Low Magnetic Field Exposure Alters Prostate Cancer Cell Properties.

Prostate cancer is the second most common neoplasia and fifth-leading cause of cancer death in men worldwide. Electromagnetic and magnetic fields have been classified as possible human carcinogens, but current understanding of molecular and cellular pathways involved is very limited. Effects due to extremely low magnetic/hypomagnetic fields (LMF) are furthermore poorly understood. Extracellular vesicles (EVs) are crucial mediators of cellular communication with multifaceted roles in cancer progression, including via transport and uptake of various protein and microRNA (miRNA) EV-cargoes. miRNAs regulate gene expression and are implicated in cancer-related processes such as proliferation, metastasis, and chemoresistance. This study investigated the effects of LMF exposure (20 nT) by magnetic shielding on the prostate cancer cell line PC3 compared to the prostate epithelial cell line PNT2 under short-term (4 h) conditions. We examined EV profiles following a 4 h LMF exposure alongside associated functional enrichment KEGG and GO pathways for the EV proteomes. The 4 h LMF exposure significantly reduced cellular EV release and modified PC3 EV cargoes to a more inflammatory and metastatic profile, with 16 Disease Pathways and 95 Human Phenotypes associated specifically with the LMF-treated PC3 EV proteomes. These included cancerous, metabolic, blood, skin, cardiac and skeletal Disease Pathways, as well as pain and developmental disorders. In the normal PNT2 cells, less EV protein cargo was observed following LMF exposure compared with cells not exposed to LMF, and fewer associated functional enrichment pathways were identified. This pointed to some differences in various cellular functions, ageing, defence responses, oxidative stress, and disease phenotypes, including respiratory, digestive, immune, and developmental pathways. Furthermore, we analysed alterations in matrix metalloproteinases (MMPs) and miRNAs linked to metastasis, as this is crucial in cancer aggressiveness. The 4 h LMF exposure caused a significant increase in MMP2 and MMP9, as well as in onco-miRs miR-155, miR-210, miR-21, but a significant reduction in tumour-suppressor miRs (miR-200c and miR-126) in the metastatic PC3 cells, compared with normal PNT2 cells. In addition, 4 h LMF exposure significantly induced cellular invasion of PC3 cells. Overall, our findings suggest that changes in magnetic field exposures modulate EV-mediated and miR-regulatory processes in PCa metastasis, providing a basis for exploring novel therapeutic strategies.

Toxoplasma FER1 is a versatile and dynamic mediator of differential microneme trafficking and microneme exocytosis

Toxoplasma gondii is a polarized cell concentrating several secretory organelles at the apical pole. The secretory micronemes come in two sub-populations differentiated by dependence on Rab5A/C in their biogenesis. Calcium-dependent exocytosis of micronemes occurs at the very apical tip and is critical for parasite egress from its host cell, adhesion and invasion of the next cell. Ferlins represent a protein family with roles in exocytosis containing multiple Ca2+-sensing C2 domains. We determined that T. gondii’s ferlin 1 (FER1) localized dynamically to the parasite’s secretory pathway. FER1 function was dissected by dominant negative overexpression strategies. We demonstrated that FER1 traffics microneme organelles along the following trajectories: (1) Along the cortex to the apical end; (2) To the apical tip for fusion with the plasma membrane; (3) Differential microneme sub-population traffic, and that FER1 could putatively be responsible for microneme protein trafficking. (4) From the trans-Golgi-endosomal network to the subpellicular cortex; (5) Retrograde transport allowing microneme recycling from mother to daughter. Finally, FER1 overexpression triggers a microneme exocytosis burst, supporting the notion that the radially organized micronemes at the apical tip comprise a readily-releasable microneme pool. In summary, FER1 is pivotal for dynamic microneme trafficking, acts differently on the two microneme subpopulations, and acts on the plasma membrane fusion step during microneme exocytosis.

CRISPR screen for rAAV production implicates genes associated with infection.

Recombinant adeno-associated virus (rAAV) vectors are an effective and well-established tool in the growing gene therapy field, with five FDA-approved AAV-mediated gene therapies already on the market and numerous more in clinical trials. However, manufacturing rAAV vectors is an expensive, timely, and labor-intensive process that limits the commercial use of AAV-mediated gene therapies. To address this limitation, we screened producer cells for genes that could be targeted to increase rAAV yield. Specifically, we performed a CRISPR-based genome-wide knockout screen in HEK 293 cells using an antibody specific to intact AAV2 capsids coupled with flow cytometry to identify genes that modulate rAAV production. We discovered that the knockout of a group of heparan sulfate biosynthesis genes previously implicated in rAAV infectivity decreased rAAV production. Additionally, we identified several vesicular trafficking proteins for which knockout in HEK 293 cells increased rAAV yields. Our findings provide evidence that host proteins associated with viral infection may have also been co-opted for viral assembly and that the genetic makeup of viral producer cells can be manipulated to increase particle yield.

Targetedprotein relocalization via protein transport coupling.

Subcellular protein localization regulates protein function and can be corrupted in cancers1 and neurodegenerative diseases2,3. The rewiring of localization to address disease-driving phenotypes would be an attractive targeted therapeutic approach. Molecules that harness the trafficking of a shuttle protein to control the subcellular localization of a target protein could enforce targeted protein relocalization and rewire the interactome. Here we identify a collection of shuttle proteins with potent ligands amenable to incorporation into targeted relocalization-activating molecules (TRAMs), and use these to relocalize endogenous proteins. Using a custom imaging analysis pipeline, we show that protein steady-state localization can be modulated through molecular coupling to shuttle proteins containing sufficiently strong localization sequences and expressed in the necessary abundance. We analyse the TRAM-induced relocalization of different proteins and then use nuclear hormone receptors as shuttles to redistribute disease-driving mutant proteins such as SMARCB1Q318X, TDP43ΔNLS and FUSR495X. TRAM-mediated relocalization of FUSR495X to the nucleus from the cytoplasm correlated with a reduction in the number of stress granules in a model of cellular stress. With methionyl aminopeptidase 2 and poly(ADP-ribose) polymerase 1 as endogenous cytoplasmic and nuclear shuttles, respectively, we demonstrate relocalization of endogenous PRMT9, SOS1 and FKBP12. Small-molecule-mediated redistribution of nicotinamide nucleotide adenylyltransferase 1 from nuclei to axons in primary neurons was able to slow axonal degeneration and pharmacologically mimic the genetic WldS gain-of-function phenotype in mice resistant to certain types of neurodegeneration4. The concept of targeted protein relocalization could therefore inspire approaches for treating disease through interactome rewiring.

VPS34 Governs Oocyte Developmental Competence by Regulating Mito/Autophagy: A Novel Insight into the Significance of RAB7 Activity and Its Subcellular Location.

Asynchronous nuclear and cytoplasmic maturation in human oocytes is believed to cause morphological anomalies after controlled ovarian hyperstimulation. Vacuolar protein sorting 34 (VPS34) is renowned for its pivotal role in regulating autophagy and endocytic trafficking. To investigate its impact on oocyte development, oocyte-specific knockout mice (ZcKO) are generated, and these mice are completely found infertile, with embryonic development halted at 2- to 4-cell stage. This infertility is related with a disruption on autophagic/mitophagic flux in ZcKO oocytes, leading to subsequent failure of zygotic genome activation (ZGA) in derived 2-cell embryos. The findings further elucidated the regulation of VPS34 on the activity and subcellular translocation of RAS-related GTP-binding protein 7 (RAB7), which is critical not only for the maturation of late endosomes and lysosomes, but also for initiating mitophagy via retrograde trafficking. VPS34 binds directly with RAB7 and facilitates its activity conversion through TBC1 domain family member 5 (TBC1D5). Consistent with the cytoplasmic vacuolation observed in ZcKO oocytes, defects in multiple vesicle trafficking systems are also identified in vacuolated human oocytes. Furthermore, activating VPS34 with corynoxin B (CB) treatment improved oocyte quality in aged mice. Hence, VPS34 activation may represent a novel approach to enhance oocyte quality in human artificial reproduction.