Search Results (51)

Ischemic stroke induces complex molecular responses that disrupt subcellular organelles’ function and contribute to brain injury, yet the temporal changes of organelle-specific transcriptomic remodeling remain to be investigated. In this study, we performed in silico analysis of publicly available transcriptomic data from isolated brain microvessels of transient middle cerebral artery occlusion (tMCAO) mouse model. Using in silico approaches, we analyzed differential gene expression at 24 h (acute phase) and 7 d (intermediate phase) post-stroke, focusing on mitochondria, endoplasmic reticulum (ER), and Golgi apparatus. Functional enrichment (Gene Ontology, KEGG) and protein–protein interaction network analyses were performed. Our analysis of the data revealed that at 24 h post-stroke, all three organelles exhibited marked transcriptional remodeling, where mitochondrial pathways showed disrupted metabolic and redox regulation; ER pathways indicated activation of biosynthetic processes, stress signaling, and ferroptosis; and Golgi-related genes reflected altered vesicular trafficking and glycosylation. By 7 d, mitochondrial alterations subsided, whereas ER and Golgi pathways displayed downregulation of metabolic and neuronal signaling processes, indicating persistent dysfunction and incomplete microvascular recovery. Phase-specific drug–gene interaction analysis will be useful to understand temporal organelle-associated transcriptional organization and to guide future investigations of neurovascular remodeling after ischemic stroke. Full article

The coatomer complex has been implicated in cancer progression; however, a comprehensive pan-cancer analysis is lacking. Therefore, it is essential to identify the critical roles and essentiality of coatomer genes across pan-cancer. We systematically profiled the genetic alterations, expression patterns, prognostic relevance, and functional dependencies of all coatomer subunits across multiple cancers using more than 10,000 tumor samples from The Cancer Genome Atlas, complemented by functional perturbation data from CRISPR (n = 1178) and RNAi (n = 707) screens in DepMap. Functional validation was also performed to identify the essentiality of selectively essential coatomer genes in hepatocellular carcinoma (HCC). Gene amplification, most notably of COPB2, was the most frequent alteration and was associated with poor survival in bladder and esophageal cancers. Mutations in COPA and SEC31A also demonstrated prognostic significance in endometrial carcinoma. Expression analyses revealed broad upregulation of coatomer genes across cancer types, with COPG1 and COPB1 emerging as strong risk-associated genes (HR > 2). Integrative functional dependency analyses identified COPG1 as selectively essential in multiple cancers, and its loss was associated with increased drug sensitivity. Functional validation in hepatocellular carcinoma revealed that COPG1 knockdown impaired malignant phenotypes and reduced tumorigenicity in vivo. Mechanistically, COPG1 depletion induced Golgi disruption and ER stress, increased ROS production, and suppressed PI3K–AKT signaling, thereby sensitizing cells to sorafenib and doxorubicin. Collectively, this pan-cancer analysis reveals the context-dependent roles of coatomer subunits and identifies COPG1 as a novel oncogenic driver and potential therapeutic target in HCC, mediating chemoresistance through redox modulation and PI3K–AKT pathway inhibition. Full article

The incidence and mortality of hepatocellular carcinoma (HCC) are increasing worldwide, underscoring the need for novel therapeutic strategies. Synthetic 2-naphthyl 2-butanamido-2-deoxy-1-thio-β-d-glucopyranoside (612) is a selective inhibitor of β1,4-galactosyltransferase 1 (β4GalT1). In this study, we investigated the cytotoxic effects of 612 across multiple cancer cell lines, with a focus on HCC, and explored the underlying mechanisms. We demonstrate that 612 preferentially exhibits cytotoxicity toward cancer cells with elevated expression of β4GalT family members, while human umbilical vein endothelial cells and immortalized human embryonic kidney epithelial cells are comparatively less sensitive. Treatment with 612 suppresses cancer cell migration and invasion and induces pronounced endoplasmic reticulum and Golgi stress, accompanied by G2/M cell cycle arrest. Furthermore, 612 activates apoptosis through ER stress–associated pathways by downregulating the anti-apoptotic protein Bcl-2 and upregulating pro-apoptotic proteins Bax and Bak, along with activation of caspase-3, -8, and -9. Collectively, these findings identify 612 as a promising anti-cancer candidate targeting β4GalTs-overexpressing HCC cells and warrant further therapeutic development. Full article

The synthesis of the melanin pigment in melanocytes plays a crucial role in protecting the body from ultraviolet radiation. Tyrosinase, a key enzyme in melanogenesis, catalyzes the conversion of tyrosine to melanin in the melanosomes of melanocytes. During melanogenesis, Tyrosinase is abundantly synthesized in the lumen of the endoplasmic reticulum (ER) and subsequently transported from the ER to the melanosomes via the Golgi apparatus. In the present study, we demonstrate that Box B-binding factor 2 human homolog on chromosome 7 (BBF2H7), an ER-resident transmembrane transcription factor that functions as an ER stress sensor, is activated by mild ER stress caused by abundant Tyrosinase synthesis. Activated BBF2H7 enhances COPII-mediated anterograde transport by inducing the expression of Sec23a, which is a COPII component and transcriptional target of BBF2H7. Loss of BBF2H7 attenuates the transport of Tyrosinase, leading to its accumulation in the ER lumen and reduced melanin production. Restoration of BBF2H7 or Sec23a expression in Bbf2h7-deficient melanocytes rescues anterograde transport of Tyrosinase from the ER and melanin pigmentation. Collectively, these findings reveal that the BBF2H7-Sec23a axis is essential for the ER-to-melanosome transport of Tyrosinase and subsequent melanin synthesis. Thus, it may be a prospective therapeutic target for disorders related to melanin pigmentation. Full article

Autophagy is an important catabolic process to maintain cellular homeostasis and antagonize cellular stresses. The initiation and activation are two of the most important aspects of the autophagic process. This review focuses on mechanisms underlying autophagy initiation and activation and signaling pathways regulating the activation of autophagy found in recent years. These findings include autophagy initiation by liquid–liquid phase separation (LLPS), autophagy initiation in the endoplasmic reticulum (ER) and Golgi apparatus, and the signaling pathways mediated by the ULK1 complex, the mTOR complex, the AMPK complex, and the PI3KC3 complex. Through the review, we attempt to present current research progress in autophagy regulation and forward our understanding of the regulatory mechanisms and signaling pathways of autophagy initiation and activation. Full article

Small GTP-binding proteins of the Rab family regulate intracellular vesicle trafficking across many aspects of the transport system. Among these, Rab9 is recognized for its role in controlling the transport system not only around the trans-Golgi network but also around the late endosome. However, the specific functions across different cell types and tissues remain unclear. Here, for the first time, we report that Rab9 negatively regulates morphological changes in the FBD-102b cell line, an oligodendroglial precursor cell line undergoing morphological differentiation. The knockdown of Rab9 led to an increase in cell shape alterations characterized by widespread membrane extensions. These changes were accompanied by increased expression levels of oligodendroglial cell differentiation and myelination marker proteins. Notably, the knockdown of Rab9 was capable of recovering defective cell morphological changes induced by tunicamycin, an inducer of endoplasmic reticulum (ER) stress, which is one of the major causes of oligodendroglial cell diseases such as Pelizaeus–Merzbacher disease (PMD, currently known as hypomyelinating leukodystrophy type 1 [HLD1]). In addition, Rab9 knockdown recovered levels of ER stress marker proteins and differentiation markers. Similar results were obtained in the cases of dithiothreitol (DTT), another chemical ER stress inducer, as well as HLD1-associated proteolipid protein 1 (PLP1) mutant protein. These results indicate a unique role for Rab9 in oligodendroglial cell morphological changes, suggesting its potential as a therapeutic target for mitigating diseases such as HLD1 at the molecular and cellular levels. Full article

The plant hormone ethylene is a key regulator of plant growth, development, and stress adaptation. Many ethylene-related responses, such as abscission, seed germination, or ripening, are of great importance to global agriculture. Ethylene perception and response are mediated by a family of integral membrane receptors (ETRs), which form dimers and higher-order oligomers in their functional state as determined by the binding of Cu(I), a cofactor to their transmembrane helices in the ER-Golgi endomembrane system. The molecular structure and signaling mechanism of the membrane-integral sensor domain are still unknown. In this article, we report on the crystallization of transmembrane (TM) and membrane-adjacent domains of plant ethylene receptors by Lipidic Cubic Phase (LCP) technology using vapor diffusion in meso crystallization. The TM domain of ethylene receptors ETR1 and ETR2, which is expressed in E. coli in high quantities and purity, was successfully crystallized using the LCP approach with different lipids, lipid mixtures, and additives. From our extensive screening of 9216 conditions, crystals were obtained from identical crystallization conditions for ETR1 (aa 1-316) and ETR2 (aa 1-186), diffracting at a medium–high resolution of 2–4 Å. However, data quality was poor and not sufficient for data processing or further structure determination due to rotational blur and high mosaicity. Metal ion loading and inhibitory peptides were explored to improve crystallization. The addition of Zn(II) increased the number of well-formed crystals, while the addition of ripening inhibitory peptide NIP improved crystal morphology. However, despite these improvements, further optimization of crystallization conditions is needed to obtain well-diffracting, highly-ordered crystals for high-resolution structural determination. Overcoming these challenges will represent a major breakthrough in structurally determining plant ethylene receptors and promote an understanding of the molecular mechanisms of ethylene signaling. Full article

Dilated cardiomyopathy (DCM) is a common heart muscle disorder that frequently leads to heart failure, arrhythmias, and death. While DCM is often heritable, disease-causing mutations are identified in only ~30% of cases. In a forward genetic mutagenesis screen, we identified a novel zebrafish mutant, heart and head (hah^vcc43), characterized by early-onset cardiomyopathy and craniofacial defects. Linkage analysis and next-generation sequencing identified a nonsense variant in the highly conserved scfd1 gene, also known as sly1, that encodes sec1 family domain-containing 1. Sec1/Munc18 proteins, such as Scfd1, are involved in membrane fusion regulating endoplasmic reticulum (ER)/Golgi transport. CRISPR/Cas9-engineered scfd1^vcc44 null mutants showed severe cardiac and craniofacial defects and embryonic lethality that recapitulated the phenotype of hah^vcc43 mutants. Electron micrographs of scfd1-depleted cardiomyocytes showed reduced myofibril width and sarcomere density, as well as reticular network disorganization and fragmentation of Golgi stacks. Furthermore, quantitative PCR analysis showed upregulation of ER stress response and apoptosis markers. Both heterozygous hah^vcc43 mutants and scfd1^vcc44 mutants survived to adulthood, showing chamber dilation and reduced ventricular contraction. Collectively, our data implicate scfd1 loss-of-function as the genetic defect at the hah^vcc43 locus and provide new insights into the role of scfd1 in cardiac development and function. Full article

This comprehensive review article dives deep into the Golgi apparatus, an essential organelle in cellular biology. Beginning with its discovery during the 19th century until today’s recognition as an important contributor to cell function. We explore its unique organization and structure as well as its roles in protein processing, sorting, and lipid biogenesis, which play key roles in maintaining homeostasis in cellular biology. This article further explores Golgi biogenesis, exploring its intricate processes and dynamics that contribute to its formation and function. One key focus is its role in neurodegenerative diseases like Parkinson’s, where changes to the structure or function of the Golgi apparatus may lead to their onset or progression, emphasizing its key importance in neuronal health. At the same time, we examine the intriguing relationship between Golgi stress and endoplasmic reticulum (ER) stress, providing insights into their interplay as two major cellular stress response pathways. Such interdependence provides a greater understanding of cellular reactions to protein misfolding and accumulation, hallmark features of many neurodegenerative diseases. In summary, this review offers an exhaustive examination of the Golgi apparatus, from its historical background to its role in health and disease. Additionally, this examination emphasizes the necessity of further research in this field in order to develop targeted therapeutic approaches for Golgi dysfunction-associated conditions. Furthermore, its exploration is an example of scientific progress while simultaneously offering hope for developing innovative treatments for neurodegenerative disorders. Full article

The toxicity of aluminum (Al) in acidic soils poses a significant limitation to crop productivity. In this study, we found a notable increase in DnaJ (HSP40) expression in the roots of Al-tolerant alfalfa (WL-525HQ), which we named MsDjB4. Transient conversion assays of tobacco leaf epidermal cells showed that MsDjB4 was targeted to the membrane system including Endoplasmic Reticulum (ER), Golgi, and plasma membrane. We overexpressed (MsDjB4-OE) and suppressed (MsDjB4-RNAi) MsDjB4 in alfalfa hairy roots and found that MsDjB4-OE lines exhibited significantly better tolerance to Al stress compared to wild-type and RNAi hairy roots. Specifically, MsDjB4-OE lines had longer root length, more lateral roots, and lower Al content compared to wild-type and RNAi lines. Furthermore, MsDjB4-OE lines showed lower levels of lipid peroxidation and ROS, as well as higher activity of antioxidant enzymes SOD, CAT, and POD compared to wild-type and RNAi lines under Al stress. Moreover, MsDjB4-OE lines had higher soluble protein content compared to wild-type and RNAi lines after Al treatment. These findings provide evidence that MsDjB4 contributes to the improved tolerance of alfalfa to Al stress by facilitating protein synthesis and enhancing antioxidant capacity. Full article

Gumboro illness is caused by the highly contagious immunosuppressive infectious bursal disease virus (IBDV), which affects the poultry industry globally. We have previously shown that IBDV hijacks the endocytic pathway to construct viral replication complexes on endosomes linked to the Golgi complex (GC). Then, analyzing crucial proteins involved in the secretory pathway, we showed the essential requirement of Rab1b, the Rab1b downstream effector Golgi-specific BFA resistance factor 1 (GBF1), and its substrate, the small GTPase ADP-ribosylation factor 1 (ARF1), for IBDV replication. In the current work, we focused on elucidating the IBDV assembly sites. We show that viral assembly occurs within single-membrane compartments closely associated with endoplasmic reticulum (ER) membranes, though we failed to elucidate the exact nature of the virus-wrapping membranes. Additionally, we show that IBDV infection promotes the stress of the ER, characterized by an accumulation of the chaperone binding protein (BiP) and lipid droplets (LDs) in the host cells. Overall, our results represent further original data showing the interplay between IBDV and the secretory pathway, making a substantial contribution to the field of birnaviruses–host cell interactions. Full article

Activating transcription factor 6α (ATF6α) is an endoplasmic reticulum protein known to participate in unfolded protein response (UPR) during ER stress in mammals. Herein, we show that in mouse C2C12 myoblasts induced to differentiate, ATF6α is the only pathway of the UPR activated. ATF6α stimulation is p38 MAPK-dependent, as revealed by the use of the inhibitor SB203580, which halts myotube formation and, at the same time, impairs trafficking of ATF6α, which accumulates at the cis-Golgi without being processed in the p50 transcriptional active form. To further evaluate the role of ATF6α, we knocked out the ATF6α gene, thus inhibiting the C2C12 myoblast from undergoing myogenesis, and this occurred independently from p38 MAPK activity. The expression of exogenous ATF6α in knocked-out ATF6α cells recover myogenesis, whereas the expression of an ATF6α mutant in the p38 MAPK phosphorylation site (T166) was not able to regain myogenesis. Genetic ablation of ATF6α also prevents the exit from the cell cycle, which is essential for muscle differentiation. Furthermore, when we inhibited differentiation by the use of dexamethasone in C2C12 cells, we found inactivation of p38 MAPK and, consequently, loss of ATF6α activity. All these findings suggest that the p-p38 MAPK/ATF6α axis, in pathophysiological conditions, regulates myogenesis by promoting the exit from the cell cycle, an essential step to start myoblasts differentiation. Full article

Antiviral protease inhibitors are peptidomimetic molecules that block the active catalytic center of viral proteases and, thereby, prevent the cleavage of viral polyprotein precursors into maturation. They continue to be a key class of antiviral drugs that can be used either as boosters for other classes of antivirals or as major components of current regimens in therapies for the treatment of infections with human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, sustained/lifelong treatment with the drugs or drugs combined with other substance(s) often leads to severe hepatic side effects such as lipid abnormalities, insulin resistance, and hepatotoxicity. The underlying pathogenic mechanisms are not fully known and are under continuous investigation. This review focuses on the general as well as specific molecular mechanisms of the protease inhibitor-induced hepatotoxicity involving transporter proteins, apolipoprotein B, cytochrome P450 isozymes, insulin-receptor substrate 1, Akt/PKB signaling, lipogenic factors, UDP-glucuronosyltransferase, pregnane X receptor, hepatocyte nuclear factor 4α, reactive oxygen species, inflammatory cytokines, off-target proteases, and small GTPase Rab proteins related to ER-Golgi trafficking, organelle stress, and liver injury. Potential pharmaceutical/therapeutic solutions to antiviral drug-induced hepatic side effects are also discussed. Full article

Sec bodies are membraneless stress-induced assemblies that form by the coalescence of endoplasmic reticulum exit sites (ERES). Through APEX2 tagging of Sec24AB, we biotinylated and identified the full complement of Sec body proteins. In the presence of biotin-phenol and H₂O₂ (APEX on), APEX2 facilitates the transfer of a biotin moiety to nearby interactors of chimeric Sec24AB. Using this unbiased approach comparing APEX on and off (−H₂O₂) conditions, we identified 52 proteins specifically enriched in Sec bodies. These include a large proportion of ER and Golgi proteins, packaged without defined stoichiometry, which we could selectively verify by imaging. Interestingly, Sec body components are neither transcriptionally nor translationally regulated under the conditions that induce Sec body formation, suggesting that incorporation of these proteins into granules may be driven instead by the aggregation of nucleating proteins with a high content of intrinsically disordered regions. This reinforces the notion that Sec bodies may act as storage for ERES, ER and Golgi components during stress. Full article

Leishmaniasis and Chagas disease affect millions of people worldwide. The available treatments against these parasitic diseases are limited and display multiple undesired effects. The brown alga belonging to the genus Gongolaria has been previously reported as a source of compounds with different biological activities. In a recent study from our group, Gongolaria abies-marine was proven to present antiamebic activity. Hence, this brown alga could be a promising source of interesting molecules for the development of new antiprotozoal drugs. In this study, four meroterpenoids were isolated and purified from a dichloromethane/ethyl acetate crude extract through a bioguided fractionation process targeting kinetoplastids. Moreover, the in vitro activity and toxicity were evaluated, and the induction of programmed cell death was checked in the most active and less toxic compounds, namely gongolarone B (2), 6Z-1′-methoxyamentadione (3) and 1′-methoxyamentadione (4). These meroterpenoids triggered mitochondrial malfunction, oxidative stress, chromatin condensation and alterations of the tubulin network. Furthermore, a transmission electron microscopy (TEM) image analysis showed that meroterpenoids (2–4) induced the formation of autophagy vacuoles and ER and Golgi complex disorganization. The obtained results demonstrated that the mechanisms of action at the cellular level of these compounds were able to induce autophagy as well as an apoptosis-like process in the treated parasites. Full article