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Proceedings of the National Academy of... Apr 2024Nonalcoholic fatty liver disease, recently renamed metabolic dysfunction-associated steatotic liver disease (MASLD), is a progressive metabolic disorder that begins with...
Nonalcoholic fatty liver disease, recently renamed metabolic dysfunction-associated steatotic liver disease (MASLD), is a progressive metabolic disorder that begins with aberrant triglyceride accumulation in the liver and can lead to cirrhosis and cancer. A common variant in the gene , encoding the protein PNPLA3-I148M, is the strongest known genetic risk factor for MASLD. Despite its discovery 20 y ago, the function of PNPLA3, and now the role of PNPLA3-I148M, remain unclear. In this study, we sought to dissect the biogenesis of PNPLA3 and PNPLA3-I148M and characterize changes induced by endogenous expression of the disease-causing variant. Contrary to bioinformatic predictions and prior studies with overexpressed proteins, we demonstrate here that PNPLA3 and PNPLA3-I148M are not endoplasmic reticulum-resident transmembrane proteins. To identify their intracellular associations, we generated a paired set of isogenic human hepatoma cells expressing PNPLA3 and PNPLA3-I148M at endogenous levels. Both proteins were enriched in lipid droplet, Golgi, and endosomal fractions. Purified PNPLA3 and PNPLA3-I148M proteins associated with phosphoinositides commonly found in these compartments. Despite a similar fractionation pattern as the wild-type variant, PNPLA3-I148M induced morphological changes in the Golgi apparatus, including increased lipid droplet-Golgi contact sites, which were also observed in I148M-expressing primary human patient hepatocytes. In addition to lipid droplet accumulation, PNPLA3-I148M expression caused significant proteomic and transcriptomic changes that resembled all stages of liver disease. Cumulatively, we validate an endogenous human cellular system for investigating PNPLA3-I148M biology and identify the Golgi apparatus as a central hub of PNPLA3-I148M-driven cellular change.
Topics: Humans; Acyltransferases; Golgi Apparatus; Lipase; Lipid Droplets; Membrane Proteins; Non-alcoholic Fatty Liver Disease; Phospholipases A2, Calcium-Independent
PubMed: 38657050
DOI: 10.1073/pnas.2318619121 -
Biology Direct Apr 2024Oocyte quality is critical for the mammalian reproduction due to its necessity on fertilization and early development. During aging, the declined oocytes showing with...
BACKGROUND
Oocyte quality is critical for the mammalian reproduction due to its necessity on fertilization and early development. During aging, the declined oocytes showing with organelle dysfunction and oxidative stress lead to infertility. AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase which is important for energy homeostasis for metabolism. Little is known about the potential relationship between AMPK with oocyte aging.
RESULTS
In present study we reported that AMPK was related with low quality of oocytes under post ovulatory aging and the potential mechanism. We showed the altered AMPK level during aging and inhibition of AMPK activity induced mouse oocyte maturation defect. Further analysis indicated that similar with its upstream regulator PKD1, AMPK could reduce ROS level to avoid oxidative stress in oocytes, and this might be due to its regulation on mitochondria function, since loss of AMPK activity induced abnormal distribution, reduced ATP production and mtDNA copy number of mitochondria. Besides, we also found that the ER and Golgi apparatus distribution was aberrant after AMPK inhibition, and enhanced lysosome function was also observed.
CONCLUSIONS
Taken together, these data indicated that AMPK is important for the organelle function to reduce oxidative stress during oocyte meiotic maturation.
Topics: Animals; Female; Mice; AMP-Activated Protein Kinases; Cellular Senescence; Mitochondria; Oocytes; Organelles; Oxidative Stress; Reactive Oxygen Species
PubMed: 38654312
DOI: 10.1186/s13062-024-00471-4 -
The Journal of Cell Biology May 2024The regulation of intracellular membrane traffic is coupled with the cell's need to respond to environmental stimuli, which ultimately is critical for different...
The regulation of intracellular membrane traffic is coupled with the cell's need to respond to environmental stimuli, which ultimately is critical for different processes such as cell growth and development. In this issue, Wiese et al. (https://www.doi.org/10.1083/jcb.202311125) explore the role of the trans-Golgi network (TGN) in stress response, exposing its role in mediating adaptive growth decisions.
Topics: Adaptation, Physiological; Plant Proteins; Plants; Stress, Physiological; trans-Golgi Network; Vesicular Transport Proteins
PubMed: 38652246
DOI: 10.1083/jcb.202404039 -
International Immunopharmacology May 2024Sepsis is often accompanied by multiple organ dysfunction, in which the incidence of cardiac injury is about 60%, and is closely related to high mortality. Recent...
BACKGROUND
Sepsis is often accompanied by multiple organ dysfunction, in which the incidence of cardiac injury is about 60%, and is closely related to high mortality. Recent studies have shown that Golgi stress is involved in liver injury, kidney injury, and lung injury in sepsis. However, whether it is one of the key mechanisms of sepsis-induced cardiomyopathy (SIC) is still unclear. The aim of this study is to investigate whether Golgi stress mediates SIC and the specific mechanism.
METHODS
Sepsis model of male C57BL/6J mice was established by cecal ligation and puncture. To observe the effect of Golgi stress on SIC, mice were injected with Golgi stimulant (Brefeldin A) or Golgi inhibitor (Glutathione), respectively. The 7-day survival rate of mice were recorded, and myocardial injury indicators including cardiac function, myocardial enzymes, myocardial pathological tissue score, myocardial inflammatory factors, and apoptosis were detected. The morphology of Golgi was observed by immunofluorescence, and the Golgi stress indices including GM-130, GOLPH3 and Goligin97 were detected by WB and qPCR.
RESULTS
After CLP, the cardiac function of mice was impaired and the levels of myocardial enzymes were significantly increased. Golgi stress was accompanied by increased myocardial inflammation and apoptosis. Moreover, the expressions of morphological proteins GM-130 and Golgin97 were decreased, and the expression of stress protein GOLPH3 was increased. In addition, Brefeldin A increased 7-day mortality and the above indicators in mice. The use of glutathione improves all of the above indicators.
CONCLUSION
Golgi stress mediates SIC, and the inhibition of Golgi stress can improve SIC by inhibiting apoptosis and inflammation.
Topics: Animals; Apoptosis; Male; Sepsis; Golgi Apparatus; Mice, Inbred C57BL; Cardiomyopathies; Mice; Brefeldin A; Inflammation; Disease Models, Animal; Glutathione; Myocardium; Membrane Proteins; Humans
PubMed: 38648713
DOI: 10.1016/j.intimp.2024.112103 -
Investigative Ophthalmology & Visual... Apr 2024The cGAS-STING pathway has been shown to be an important mediator of inflammation. There is emerging evidence of the importance of this signaling cascade in a variety of...
PURPOSE
The cGAS-STING pathway has been shown to be an important mediator of inflammation. There is emerging evidence of the importance of this signaling cascade in a variety of inflammatory diseases settings. Here, we present evidence that the mitochondrial DNA (mtDNA) damage-mediated cGAS-STING pathway plays an important role in the induction of inflammation in environmental dry eye (DE).
METHODS
RT-qPCR and Western blot were used to assess the induction of the cGAS-STING pathway and inflammatory cytokines in environmental DE mouse model, primary human corneal epithelial cells (pHCECs), and patients with DE. RNA sequencing was used to determine mRNA expression patterns of high osmotic pressure (HOP)-stimulated pHCECs. mtDNA was detected with electron microscopy, flow cytometry, and immunofluorescent staining. mtDNA was isolated and transfected into pHCECs for evaluating the activation of the cGAS-STING pathway.
RESULTS
The expression levels of cGAS, STING, TBK1, IRF3, and IFNβ were significantly increased in an environmental DE model and HOP-stimulated pHCECs. The STING inhibitor decreased the expression of inflammatory factors in DE. An upregulation of STING-mediated immune responses and IRF3 expression mediated by TBK1 were observed in the HOP group. HOP stimulation induced mitochondrial oxidative damage and the leakage of mtDNA into the cytoplasm. Then, mtDNA activated the cGAS-STING pathway and induced intracytoplasmic STING translocated to the Golgi apparatus. Finally, we also found activated cGAS-STING signaling in the human conjunctival blot cell of patients with DE.
CONCLUSIONS
Our findings suggest that the cGAS-STING pathway is activated by recognizing cytoplasmic mtDNA leading to STING translocation, further exacerbating the development of inflammation in environmental DE.
Topics: Animals; Female; Humans; Mice; Blotting, Western; Cells, Cultured; Disease Models, Animal; DNA, Mitochondrial; Dry Eye Syndromes; Epithelium, Corneal; Flow Cytometry; Membrane Proteins; Mice, Inbred C57BL; Nucleotidyltransferases; Real-Time Polymerase Chain Reaction; Signal Transduction
PubMed: 38648040
DOI: 10.1167/iovs.65.4.33 -
Cureus Mar 2024Overlap syndrome is a clinical challenge and brings together a wide range of treatment options for the treating physician. Addressing each and every complaint of the...
Overlap syndrome is a clinical challenge and brings together a wide range of treatment options for the treating physician. Addressing each and every complaint of the patient is crucial. A 50-year-old female patient presented with skin thickening, blackening, and hyperkeratosis; dysphagia; joint pain; features of myopathy; Raynaud's phenomenon; and dry mouth. Inflammatory markers were raised along with a positive antinuclear antibody (ANA) with Golgi apparatus pattern, anti-Sjögren's-syndrome-related antigen A (anti-SSA)/Ro60 3+, anti-SSA/Ro52 3+, and anti-PM/Scl 2+ antibodies that suggested overlap syndrome. Although the patient had no respiratory complaints, a unique interstitial lung disease (ILD) pattern was noted during the evaluation. Skin manifestations were puzzling, but the histopathology analyses of skin biopsies taken from two different sites revealed distinguishing features of cutaneous lupus and dermatomyositis. Treatment with hydroxychloroquine, pilocarpine, nifedipine, methotrexate, and topical tacrolimus produced a dramatic improvement in the clinical features. This case highlights subtle and florid features of different autoimmune diseases. The hyperkeratotic skin changes were the most striking feature, but the whole evaluation process unveiled many rare presentations of known autoimmune conditions that can open doors to new areas of our understanding toward connective tissue diseases (CTDs). Our case report demonstrates significant heterogeneity in the ANA patterns, ILD patterns, clinical manifestations, and treatment approaches.
PubMed: 38646215
DOI: 10.7759/cureus.56531 -
Clinical Case Reports Apr 2024Plasma cell myeloma is a rare entity in the pediatric population. The peak incidence is in the seventh decade, with less than 2% of cases occurring in patients under the...
KEY CLINICAL MESSAGE
Plasma cell myeloma is a rare entity in the pediatric population. The peak incidence is in the seventh decade, with less than 2% of cases occurring in patients under the age of 40. It is worth noting that any destructive bony lesion in a child should be investigated.
ABSTRACT
Plasma cell myeloma (multiple myeloma) is the most common form of plasma cell neoplasm. It is a rare entity in young patients. The peak incidence is in the seventh decade, with less than 2% of cases occurring in patients under the age of 40. A male patient aged 9 years old with a progressive pain in lower back for about 1 month, aggravated by bending, associated with inability to stand upright, no any history of trauma. He complained about left pin-point chest pain, no any history of febrile illness. MRI showed a mass lesion of the L3 vertebra; CT scan revealed osteolytic lesions in the left T12, S2-sacral region, and left calvarium. Histology report of L3 lesion revealed cells with an eccentric nucleus, prominent Golgi apparatus and Flow cytometry revealed cells stained positive for CD 138 and CD56 and negative for CD45 expression. In situ hybridization identified k-light chain band restriction. Bone marrow evaluation was normal. A small serum monoclonal immunoglobin A spike of k-light chain type was noted. Other tests like complete blood count, lactate dehydrogenase levels, renal functional tests, and B2-microglobulin were normal. A diagnosis of plasma cell myeloma was made and the patient was started on emergent radiation to L3 lesion due to progressive neurological symptoms followed systemic therapy which resulted int reduction of L3 lesion. Plasma cell myeloma is extremely rare form of liquid tumor in the pediatric population, and it is important for any destructive bony lesion in a child to have appropriate work up.
PubMed: 38645602
DOI: 10.1002/ccr3.8801 -
ELife Apr 2024Mapping proteins in and associated with the Golgi apparatus reveals how this cellular compartment emerges in budding yeast and progresses over time.
Mapping proteins in and associated with the Golgi apparatus reveals how this cellular compartment emerges in budding yeast and progresses over time.
Topics: Golgi Apparatus; Saccharomycetales
PubMed: 38629949
DOI: 10.7554/eLife.97430 -
Cellular & Molecular Biology Letters Apr 2024The trafficking of cargoes from endosomes to the trans-Golgi network requires numerous sequential and coordinated steps. Cargoes are sorted into endosomal-derived...
BACKGROUND
The trafficking of cargoes from endosomes to the trans-Golgi network requires numerous sequential and coordinated steps. Cargoes are sorted into endosomal-derived carriers that are transported, tethered, and fused to the trans-Golgi network. The tethering step requires several complexes, including the Golgi-associated retrograde protein complex, whose localization at the trans-Golgi network is determined by the activity of small GTPases of the Arl and Rab family. However, how the Golgi-associated retrograde protein complex recognizes the endosome-derived carriers that will fuse with the trans-Golgi network is still unknown.
METHODS
We studied the retrograde trafficking to the trans-Golgi network by using fluorescent cargoes in cells overexpressing Rab4b or after Rab4b knocked-down by small interfering RNA in combination with the downregulation of subunits of the Golgi-associated retrograde protein complex. We used immunofluorescence and image processing (Super Resolution Radial Fluctuation and 3D reconstruction) as well as biochemical approaches to characterize the consequences of these interventions on cargo carriers trafficking.
RESULTS
We reported that the VPS52 subunit of the Golgi-associated retrograde protein complex is an effector of Rab4b. We found that overexpression of wild type or active Rab4b increased early endosomal to trans-Golgi network retrograde trafficking of the cation-independent mannose-6-phosphate receptor in a Golgi-associated retrograde protein complex-dependent manner. Conversely, overexpression of an inactive Rab4b or Rab4b knockdown attenuated this trafficking. In the absence of Rab4b, the internalized cation-independent mannose 6 phosphate receptor did not have access to VPS52-labeled structures that look like endosomal subdomains and/or endosome-derived carriers, and whose subcellular distribution is Rab4b-independent. Consequently, the cation-independent mannose-6-phosphate receptor was blocked in early endosomes and no longer had access to the trans-Golgi network.
CONCLUSION
Our results support that Rab4b, by controlling the sorting of the cation-independent mannose-6-phosphate receptor towards VPS52 microdomains, confers a directional specificity for cargo carriers en route to the trans-Golgi network. Given the importance of the endocytic recycling in cell homeostasis, disruption of the Rab4b/Golgi-associated retrograde protein complex-dependent step could have serious consequences in pathologies.
Topics: Cations; Endosomes; Golgi Apparatus; Protein Transport; Receptor, IGF Type 2; trans-Golgi Network
PubMed: 38627612
DOI: 10.1186/s11658-024-00574-w -
PLoS Pathogens Apr 2024Kaposi's sarcoma-associated herpesvirus (KSHV) is a double-stranded DNA virus etiologically associated with multiple malignancies. Both latency and sporadic lytic...
Kaposi's sarcoma-associated herpesvirus (KSHV) is a double-stranded DNA virus etiologically associated with multiple malignancies. Both latency and sporadic lytic reactivation contribute to KSHV-associated malignancies, however, the specific roles of many KSHV lytic gene products in KSHV replication remain elusive. In this study, we report that ablation of ORF55, a late gene encoding a tegument protein, does not impact KSHV lytic reactivation but significantly reduces the production of progeny virions. We found that cysteine 10 and 11 (C10 and C11) of pORF55 are palmitoylated, and the palmytoilation is essential for its Golgi localization and secondary envelope formation. Palmitoylation-defective pORF55 mutants are unstable and undergo proteasomal degradation. Notably, introduction of a putative Golgi localization sequence to these palmitoylation-defective pORF55 mutants restores Golgi localization and fully reinstates KSHV progeny virion production. Together, our study provides new insight into the critical role of pORF55 palmitoylation in KSHV progeny virion production and offers potential therapeutic targets for the treatment of related malignancies.
Topics: Herpesvirus 8, Human; Golgi Apparatus; Humans; Lipoylation; Virion; Viral Proteins; Virus Replication; HEK293 Cells
PubMed: 38626263
DOI: 10.1371/journal.ppat.1012141