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1.
Chin J Physiol ; 64(4): 202-209, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34472451

RESUMO

Gamma-linolenic acid (GLA), a natural fatty acid obtained from oils of various vegetables and seeds, has been demonstrated as an anticancer agent. In this work, we investigated the anticancer effects of GLA on breast cancer BT-474 cells. GLA at 30 µM, a concentration reportedly within the range of circulating concentrations in clinical studies, caused apoptotic cell death. GLA caused an elevation in mitochondrial Ca2+ level and a decrease in mitochondrial membrane potential. GLA treatment depleted cyclopiazonic acid (CPA)-sensitive Ca2+ store and triggered substantial Ca2+ influx. Intracellular Ca2+ release triggered by GLA was suppressed by 3 µM xestospongin C (XeC, IP3 receptor-channel blocker) and 100 µM ryanodine (ryanodine receptor-channel blocker), suggesting that the Ca2+ release was via IP3 receptor-channel and ryanodine receptor-channel. Increased expressions of p-eIF2α and CHOP were observed in GLA-treated cells, suggesting GLA-treated cells had increased expressions of p-eIF2α and CHOP, which suggest endoplasmic reticulum (ER) stress. In addition, GLA elicited increased production of reactive oxygen species. Taken together, our results suggest a basal level of GLA induced apoptotic cell death by causing Ca2+ overload, mitochondrial dysfunction, Ca2+ store depletion, ER stress, and oxidative stress. This is the first report to show that GLA caused Ca2+ store depletion and ER stress. GLA-induced Ca2+ store depletion resulted from opening of IP3 receptor-channel and ryanodine receptor-channel.


Assuntos
Neoplasias da Mama , Ácido gama-Linolênico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Cálcio/metabolismo , Retículo Endoplasmático/metabolismo , Feminino , Humanos , Estresse Oxidativo , Ácido gama-Linolênico/metabolismo
2.
Adv Exp Med Biol ; 1325: 3-24, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34495528

RESUMO

N-glycosylation is a highly conserved glycan modification, and more than 7000 proteins are N-glycosylated in humans. N-glycosylation has many biological functions such as protein folding, trafficking, and signal transduction. Thus, glycan modification to proteins is profoundly involved in numerous physiological and pathological processes. The N-glycan precursor is biosynthesized in the endoplasmic reticulum (ER) from dolichol phosphate by sequential enzymatic reactions to generate the dolichol-linked oligosaccharide composed of 14 sugar residues, Glc3Man9GlcNAc2. The oligosaccharide is then en bloc transferred to the consensus sequence N-X-S/T (X represents any amino acid except proline) of nascent proteins. Subsequently, the N-glycosylated nascent proteins enter the folding step, in which N-glycans contribute largely to attaining the correct protein fold by recruiting the lectin-like chaperones, calnexin, and calreticulin. Despite the N-glycan-dependent folding process, some glycoproteins do not fold correctly, and these misfolded glycoproteins are destined to degradation by proteasomes in the cytosol. Properly folded proteins are transported to the Golgi, and N-glycans undergo maturation by the sequential reactions of glycosidases and glycosyltransferases, generating complex-type N-glycans. N-Acetylglucosaminyltransferases (GnT-III, GnT-IV, and GnT-V) produce branched N-glycan structures, affording a higher complexity to N-glycans. In this chapter, we provide an overview of the biosynthetic pathway of N-glycans in the ER and Golgi.


Assuntos
Glicoproteínas , Dobramento de Proteína , Retículo Endoplasmático/metabolismo , Glicoproteínas/metabolismo , Glicosilação , Humanos , Lectinas , Polissacarídeos/metabolismo
3.
Int J Mol Sci ; 22(16)2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34445487

RESUMO

Mechanosensitive ion channels are widely expressed in the cardiovascular system. They translate mechanical forces including shear stress and stretch into biological signals. The most prominent biological signal through which the cardiovascular physiological activity is initiated or maintained are intracellular calcium ions (Ca2+). Growing evidence show that the Ca2+ entry mediated by mechanosensitive ion channels is also precisely regulated by a variety of key proteins which are distributed in the cell membrane or endoplasmic reticulum. Recent studies have revealed that mechanosensitive ion channels can even physically interact with Ca2+ regulatory proteins and these interactions have wide implications for physiology and pathophysiology. Therefore, this paper reviews the cross-talk between mechanosensitive ion channels and some key Ca2+ regulatory proteins in the maintenance of calcium homeostasis and its relevance to cardiovascular health and disease.


Assuntos
Canais de Cálcio/metabolismo , Cálcio/metabolismo , Doenças Cardiovasculares/metabolismo , Sistema Cardiovascular/metabolismo , Animais , Membrana Celular/metabolismo , Retículo Endoplasmático/metabolismo , Regulação da Expressão Gênica , Homeostase , Humanos
4.
Int J Mol Sci ; 22(15)2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34360783

RESUMO

Ca2+ ion channels are critical in a variety of physiological events, including cell growth, differentiation, gene transcription and apoptosis. One such essential entry pathway for calcium into the cell is the Ca2+ release-activated Ca2+ (CRAC) channel. It consists of the Ca2+ sensing protein, stromal interaction molecule 1 (STIM1) located in the endoplasmic reticulum (ER) and a Ca2+ ion channel Orai in the plasma membrane. The Orai channel family includes three homologues Orai1, Orai2 and Orai3. While Orai1 is the "classical" Ca2+ ion channel within the CRAC channel complex and plays a universal role in the human body, there is increasing evidence that Orai2 and Orai3 are important in specific physiological and pathophysiological processes. This makes them an attractive target in drug discovery, but requires a detailed understanding of the three Orai channels and, in particular, their differences. Orai channel activation is initiated via Ca2+ store depletion, which is sensed by STIM1 proteins, and induces their conformational change and oligomerization. Upon STIM1 coupling, Orai channels activate to allow Ca2+ permeation into the cell. While this activation mechanism is comparable among the isoforms, they differ by a number of functional and structural properties due to non-conserved regions in their sequences. In this review, we summarize the knowledge as well as open questions in our current understanding of the three isoforms in terms of their structure/function relationship, downstream signaling and physiology as well as pathophysiology.


Assuntos
Canais de Cálcio Ativados pela Liberação de Cálcio , Sinalização do Cálcio , Cálcio , Retículo Endoplasmático , Animais , Cálcio/química , Cálcio/metabolismo , Canais de Cálcio Ativados pela Liberação de Cálcio/química , Canais de Cálcio Ativados pela Liberação de Cálcio/genética , Canais de Cálcio Ativados pela Liberação de Cálcio/metabolismo , Retículo Endoplasmático/química , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Humanos , Proteínas de Neoplasias/química , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Molécula 1 de Interação Estromal/química , Molécula 1 de Interação Estromal/genética , Molécula 1 de Interação Estromal/metabolismo , Relação Estrutura-Atividade
5.
J Cell Sci ; 134(2)2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-34432035

RESUMO

Pharmacological manipulation of lysosome membrane integrity or ionic movements is a key strategy for probing lysosomal involvement in cellular processes. However, we have found an unexpected inhibition of store-operated Ca2+ entry (SOCE) by these agents. Dipeptides [glycyl-L-phenylalanine 2-naphthylamide (GPN) and L-leucyl-L-leucine methyl ester] that are inducers of lysosomal membrane permeabilization (LMP) uncoupled endoplasmic reticulum Ca2+-store depletion from SOCE by interfering with Stim1 oligomerization and/or Stim1 activation of Orai. Similarly, the K+/H+ ionophore, nigericin, that rapidly elevates lysosomal pH, also inhibited SOCE in a Stim1-dependent manner. In contrast, other strategies for manipulating lysosomes (bafilomycin A1, lysosomal re-positioning) had no effect upon SOCE. Finally, the effects of GPN on SOCE and Stim1 was reversed by a dynamin inhibitor, dynasore. Our data show that lysosomal agents not only release Ca2+ from stores but also uncouple this release from the normal recruitment of Ca2+ influx.


Assuntos
Canais de Cálcio , Cálcio , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Sinalização do Cálcio , Retículo Endoplasmático/metabolismo , Lisossomos/metabolismo , Proteína ORAI1/metabolismo , Molécula 1 de Interação Estromal/metabolismo
6.
Science ; 373(6556)2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-34385370

RESUMO

The neurotransmitter acetylcholine (ACh) acts in part through a family of nicotinic ACh receptors (nAChRs), which mediate diverse physiological processes including muscle contraction, neurotransmission, and sensory transduction. Pharmacologically, nAChRs are responsible for tobacco addiction and are targeted by medicines for hypertension and dementia. Nicotinic AChRs were the first ion channels to be isolated. Recent studies have identified molecules that control nAChR biogenesis, trafficking, and function. These nAChR accessories include protein and chemical chaperones as well as auxiliary subunits. Whereas some factors act on many nAChRs, others are receptor specific. Discovery of these regulatory mechanisms is transforming nAChR research in cells and tissues ranging from central neurons to spinal ganglia to cochlear hair cells. Nicotinic AChR-specific accessories also enable drug discovery on high-confidence targets for psychiatric, neurological, and auditory disorders.


Assuntos
Chaperonas Moleculares/metabolismo , Neurônios/metabolismo , Proteínas/metabolismo , Receptores Nicotínicos/metabolismo , Animais , Membrana Celular/metabolismo , Descoberta de Drogas , Retículo Endoplasmático/metabolismo , Humanos , Ligantes , Músculo Esquelético/metabolismo , Neurofarmacologia , Nicotina/metabolismo , Subunidades Proteicas/metabolismo , Receptores Nicotínicos/química
7.
Ageing Res Rev ; 70: 101417, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34339860

RESUMO

One evident hallmark of Alzheimer's disease (AD) is the irregular accumulation of proteins due to changes in proteostasis involving endoplasmic reticulum (ER) stress. To alleviate ER stress and reinstate proteostasis, cells undergo an integrated signaling cascade called the unfolded protein response (UPR) that reduces the number of misfolded proteins and inhibits abnormal protein accumulation. Aging is associated with changes in the expression of ER chaperones and folding enzymes, leading to the impairment of proteostasis, and accumulation of misfolded proteins. The disrupted initiation of UPR prevents the elimination of unfolded proteins, leading to ER stress. In AD, the accumulation of misfolded proteins caused by sustained cellular stress leads to neurodegeneration and neuronal death. Current research has revealed that ER stress can trigger an inflammatory response through diverse transducers of UPR. Although the involvement of a neuroinflammatory component in AD has been documented for decades, whether it is a contributing factor or part of the neurodegenerative events is so far unknown. Besides, a feedback loop occurs between neuroinflammation and ER stress, which is strongly associated with neurodegenerative processes in AD. In this review, we focus on the current research on ER stress and UPR in cellular aging and neuroinflammatory processes, leading to memory impairment and synapse dysfunction in AD.


Assuntos
Doença de Alzheimer , Doença de Alzheimer/metabolismo , Senescência Celular , Retículo Endoplasmático/metabolismo , Estresse do Retículo Endoplasmático , Humanos , Resposta a Proteínas não Dobradas
8.
Int J Mol Sci ; 22(15)2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34360941

RESUMO

Phospholipids (PLs) are amphiphilic molecules that were essential for life to become cellular. PLs have not only a key role in compartmentation as they are the main components of membrane, but they are also involved in cell signaling, cell metabolism, and even cell pathophysiology. Considered for a long time to simply be structural elements of membranes, phospholipids are increasingly being viewed as sensors of their environment and regulators of many metabolic processes. After presenting their main characteristics, we expose the increasing methods of PL detection and identification that help to understand their key role in life processes. Interest and importance of PL homeostasis is growing as pathogenic variants in genes involved in PL biosynthesis and/or remodeling are linked to human diseases. We here review diseases that involve deregulation of PL homeostasis and present a predominantly muscular phenotype.


Assuntos
Músculo Estriado/metabolismo , Fosfolipídeos/metabolismo , Animais , Membrana Celular/metabolismo , Retículo Endoplasmático/metabolismo , Humanos , Mitocôndrias/metabolismo , Músculo Estriado/fisiologia , Fosfolipídeos/química
9.
Int Rev Cell Mol Biol ; 363: 203-269, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34392930

RESUMO

An increase in intracellular Ca2+ concentration ([Ca2+]i) regulates a plethora of functions in the cardiovascular (CV) system, including contraction in cardiomyocytes and vascular smooth muscle cells (VSMCs), and angiogenesis in vascular endothelial cells and endothelial colony forming cells. The sarco/endoplasmic reticulum (SR/ER) represents the largest endogenous Ca2+ store, which releases Ca2+ through ryanodine receptors (RyRs) and/or inositol-1,4,5-trisphosphate receptors (InsP3Rs) upon extracellular stimulation. The acidic vesicles of the endolysosomal (EL) compartment represent an additional endogenous Ca2+ store, which is targeted by several second messengers, including nicotinic acid adenine dinucleotide phosphate (NAADP) and phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2], and may release intraluminal Ca2+ through multiple Ca2+ permeable channels, including two-pore channels 1 and 2 (TPC1-2) and Transient Receptor Potential Mucolipin 1 (TRPML1). Herein, we discuss the emerging, pathophysiological role of EL Ca2+ signaling in the CV system. We describe the role of cardiac TPCs in ß-adrenoceptor stimulation, arrhythmia, hypertrophy, and ischemia-reperfusion injury. We then illustrate the role of EL Ca2+ signaling in VSMCs, where TPCs promote vasoconstriction and contribute to pulmonary artery hypertension and atherosclerosis, whereas TRPML1 sustains vasodilation and is also involved in atherosclerosis. Subsequently, we describe the mechanisms whereby endothelial TPCs promote vasodilation, contribute to neurovascular coupling in the brain and stimulate angiogenesis and vasculogenesis. Finally, we discuss about the possibility to target TPCs, which are likely to mediate CV cell infection by the Severe Acute Respiratory Disease-Coronavirus-2, with Food and Drug Administration-approved drugs to alleviate the detrimental effects of Coronavirus Disease-19 on the CV system.


Assuntos
COVID-19/complicações , COVID-19/tratamento farmacológico , Sinalização do Cálcio/fisiologia , Doenças Cardiovasculares/etiologia , Doenças Cardiovasculares/metabolismo , Sistema Cardiovascular/metabolismo , Lisossomos/metabolismo , SARS-CoV-2 , ADP-Ribosil Ciclase 1/metabolismo , Animais , Encéfalo/irrigação sanguínea , Encéfalo/metabolismo , COVID-19/metabolismo , Canais de Cálcio/metabolismo , Doenças Cardiovasculares/tratamento farmacológico , Retículo Endoplasmático/metabolismo , Células Endoteliais/metabolismo , Humanos , Modelos Cardiovasculares , Miócitos Cardíacos/metabolismo , NADP/análogos & derivados , NADP/metabolismo , Receptores Adrenérgicos beta/metabolismo , Retículo Sarcoplasmático/metabolismo , Canais de Potencial de Receptor Transitório/metabolismo
10.
Cell Mol Life Sci ; 78(16): 6017-6031, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34245311

RESUMO

A precondition for efficient proinsulin export from the endoplasmic reticulum (ER) is that proinsulin meets ER quality control folding requirements, including formation of the Cys(B19)-Cys(A20) "interchain" disulfide bond, facilitating formation of the Cys(B7)-Cys(A7) bridge. The third proinsulin disulfide, Cys(A6)-Cys(A11), is not required for anterograde trafficking, i.e., a "lose-A6/A11" mutant [Cys(A6), Cys(A11) both converted to Ser] is well secreted. Nevertheless, an unpaired Cys(A11) can participate in disulfide mispairings, causing ER retention of proinsulin. Among the many missense mutations causing the syndrome of Mutant INS gene-induced Diabetes of Youth (MIDY), all seem to exhibit perturbed proinsulin disulfide bond formation. Here, we have examined a series of seven MIDY mutants [including G(B8)V, Y(B26)C, L(A16)P, H(B5)D, V(B18)A, R(Cpep + 2)C, E(A4)K], six of which are essentially completely blocked in export from the ER in pancreatic ß-cells. Three of these mutants, however, must disrupt the Cys(A6)-Cys(A11) pairing to expose a critical unpaired cysteine thiol perturbation of proinsulin folding and ER export, because when introduced into the proinsulin lose-A6/A11 background, these mutants exhibit native-like disulfide bonding and improved trafficking. This maneuver also ameliorates dominant-negative blockade of export of co-expressed wild-type proinsulin. A growing molecular understanding of proinsulin misfolding may permit allele-specific pharmacological targeting for some MIDY mutants.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Proinsulina/metabolismo , Adolescente , Células Cultivadas , Cisteína/genética , Cisteína/metabolismo , Diabetes Mellitus Tipo 2/genética , Dissulfetos/metabolismo , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Humanos , Insulina/genética , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Mutação de Sentido Incorreto/genética , Proinsulina/genética , Dobramento de Proteína
11.
J Enzyme Inhib Med Chem ; 36(1): 1436-1453, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34229558

RESUMO

This study describes the synthesis and vacuole-inducing activity of 5-((4-(pyridin-3-yl)pyrimidin-2-yl)amino)-1H-indole-2-carbohydrazide derivatives, including five potent derivatives 12c, 12 g, 12i, 12n, and 12A that exhibit excellent vacuole-inducing activity. Remarkably, 12A effectively induces methuosis in tested cancer cells but not human normal cells. In addition, 12A exhibits high pan-cytotoxicity against different cancer cell lines but is hardly toxic to normal cells. It is found that the 12A-induced vacuoles are derived from macropinosomes but not autophagosomes. The 12A-induced cytoplasmic vacuoles may originate from the endoplasmic reticulum (ER) and be accompanied by ER stress. The MAPK/JNK signalling pathway is involved in the 12A-induced methuotic cell death. Moreover, 12A exhibits significant inhibition of tumour growth in the MDA-MB-231 xenograft mouse model. The excellent potency and selectivity of 12A prompt us to select it as a good lead compound for further development of methuosis inducers and investigation of the molecular and cellular mechanisms underlying methuosis.


Assuntos
Antineoplásicos/farmacologia , Desenho de Fármacos , Hidrazinas/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Humanos , Hidrazinas/síntese química , Hidrazinas/química , Neoplasias Mamárias Experimentais/tratamento farmacológico , Neoplasias Mamárias Experimentais/metabolismo , Neoplasias Mamárias Experimentais/patologia , Camundongos , Modelos Moleculares , Estrutura Molecular , Relação Estrutura-Atividade , Células Tumorais Cultivadas
12.
J Plant Physiol ; 264: 153473, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34298331

RESUMO

Plant endoplasmic reticulum (ER) remodelling is likely to be important for its function in targeted protein secretion, organelle interaction and signal exchange. It has been known for decades that the structure and movement of the ER network is mainly regulated by the actin cytoskeleton through actin motor proteins and membrane-cytoskeleton adaptors. Recent discoveries also revealed alternative pathways that influence ER movement, through a microtubule-based machinery. Therefore, plants utilize both cytoskeletal components to drive ER dynamics, a process that is likely to be dependent on the cell type and the developmental stages. On the other hand, the ER membrane also has a direct effect towards the organization of the cytoskeletal network and disrupting the tethering factors at the ER-PM interface also rearranges the cytoskeletal structure. However, the influence of the ER network on the cytoskeleton organization has not been studied. In this review, we will provide an overview of the ER-cytoskeleton network in plants, and discuss the most recent discoveries in the field.


Assuntos
Citoesqueleto/metabolismo , Retículo Endoplasmático/metabolismo , Plantas/metabolismo , Proteínas de Plantas/metabolismo
13.
Molecules ; 26(12)2021 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-34208277

RESUMO

In human cells, one-third of all polypeptides enter the secretory pathway at the endoplasmic reticulum (ER). The specificity and efficiency of this process are guaranteed by targeting of mRNAs and/or polypeptides to the ER membrane. Cytosolic SRP and its receptor in the ER membrane facilitate the cotranslational targeting of most ribosome-nascent precursor polypeptide chain (RNC) complexes together with the respective mRNAs to the Sec61 complex in the ER membrane. Alternatively, fully synthesized precursor polypeptides are targeted to the ER membrane post-translationally by either the TRC, SND, or PEX19/3 pathway. Furthermore, there is targeting of mRNAs to the ER membrane, which does not involve SRP but involves mRNA- or RNC-binding proteins on the ER surface, such as RRBP1 or KTN1. Traditionally, the targeting reactions were studied in cell-free or cellular assays, which focus on a single precursor polypeptide and allow the conclusion of whether a certain precursor can use a certain pathway. Recently, cellular approaches such as proximity-based ribosome profiling or quantitative proteomics were employed to address the question of which precursors use certain pathways under physiological conditions. Here, we combined siRNA-mediated depletion of putative mRNA receptors in HeLa cells with label-free quantitative proteomics and differential protein abundance analysis to characterize RRBP1- or KTN1-involving precursors and to identify possible genetic interactions between the various targeting pathways. Furthermore, we discuss the possible implications on the so-called TIGER domains and critically discuss the pros and cons of this experimental approach.


Assuntos
Proteínas de Transporte/metabolismo , Retículo Endoplasmático/metabolismo , Membranas Intracelulares/metabolismo , Proteínas de Membrana/metabolismo , RNA Mensageiro/metabolismo , Proteínas de Transporte/genética , Células HeLa , Humanos , Proteínas de Membrana/genética , Proteoma/análise , Proteoma/metabolismo , RNA Mensageiro/genética
14.
Basic Res Cardiol ; 116(1): 42, 2021 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-34224022

RESUMO

Coronavirus disease 2019 (COVID-19) spawned a global health crisis in late 2019 and is caused by the novel coronavirus SARS-CoV-2. SARS-CoV-2 infection can lead to elevated markers of endothelial dysfunction associated with higher risk of mortality. It is unclear whether endothelial dysfunction is caused by direct infection of endothelial cells or is mainly secondary to inflammation. Here, we investigate whether different types of endothelial cells are susceptible to SARS-CoV-2. Human endothelial cells from different vascular beds including umbilical vein endothelial cells, coronary artery endothelial cells (HCAEC), cardiac and lung microvascular endothelial cells, or pulmonary arterial cells were inoculated in vitro with SARS-CoV-2. Viral spike protein was only detected in HCAECs after SARS-CoV-2 infection but not in the other endothelial cells tested. Consistently, only HCAEC expressed the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2), required for virus infection. Infection with the SARS-CoV-2 variants B.1.1.7, B.1.351, and P.2 resulted in significantly higher levels of viral spike protein. Despite this, no intracellular double-stranded viral RNA was detected and the supernatant did not contain infectious virus. Analysis of the cellular distribution of the spike protein revealed that it co-localized with endosomal calnexin. SARS-CoV-2 infection did induce the ER stress gene EDEM1, which is responsible for clearance of misfolded proteins from the ER. Whereas the wild type of SARS-CoV-2 did not induce cytotoxic or pro-inflammatory effects, the variant B.1.1.7 reduced the HCAEC cell number. Of the different tested endothelial cells, HCAECs showed highest viral uptake but did not promote virus replication. Effects on cell number were only observed after infection with the variant B.1.1.7, suggesting that endothelial protection may be particularly important in patients infected with this variant.


Assuntos
Retículo Endoplasmático/virologia , Células Endoteliais/virologia , SARS-CoV-2/patogenicidade , Enzima de Conversão de Angiotensina 2/metabolismo , Calnexina/metabolismo , Células Cultivadas , Retículo Endoplasmático/metabolismo , Estresse do Retículo Endoplasmático , Células Endoteliais/metabolismo , Interações Hospedeiro-Patógeno , Humanos , Proteínas de Membrana/metabolismo , Receptores Virais/metabolismo , SARS-CoV-2/genética , SARS-CoV-2/metabolismo , Glicoproteína da Espícula de Coronavírus/metabolismo
15.
Nat Commun ; 12(1): 4493, 2021 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-34301956

RESUMO

Neuronal function relies on careful coordination of organelle organization and transport. Kinesin-1 mediates transport of the endoplasmic reticulum (ER) and lysosomes into the axon and it is increasingly recognized that contacts between the ER and lysosomes influence organelle organization. However, it is unclear how organelle organization, inter-organelle communication and transport are linked and how this contributes to local organelle availability in neurons. Here, we show that somatic ER tubules are required for proper lysosome transport into the axon. Somatic ER tubule disruption causes accumulation of enlarged and less motile lysosomes at the soma. ER tubules regulate lysosome size and axonal translocation by promoting lysosome homo-fission. ER tubule - lysosome contacts often occur at a somatic pre-axonal region, where the kinesin-1-binding ER-protein P180 binds microtubules to promote kinesin-1-powered lysosome fission and subsequent axonal translocation. We propose that ER tubule - lysosome contacts at a pre-axonal region finely orchestrate axonal lysosome availability for proper neuronal function.


Assuntos
Axônios/metabolismo , Retículo Endoplasmático/metabolismo , Lisossomos/metabolismo , Neurônios/metabolismo , Animais , Transporte Axonal/fisiologia , Células Cultivadas , Feminino , Cinesina/metabolismo , Microtúbulos/metabolismo , Neurônios/citologia , Ligação Proteica , Ratos Wistar
16.
Commun Biol ; 4(1): 828, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-34211117

RESUMO

The heterotrimeric Sec61 complex is a major site for the biogenesis of transmembrane proteins (TMPs), accepting nascent TMP precursors that are targeted to the endoplasmic reticulum (ER) by the signal recognition particle (SRP). Unlike most single-spanning membrane proteins, the integration of type III TMPs is completely resistant to small molecule inhibitors of the Sec61 translocon. Using siRNA-mediated depletion of specific ER components, in combination with the potent Sec61 inhibitor ipomoeassin F (Ipom-F), we show that type III TMPs utilise a distinct pathway for membrane integration at the ER. Hence, following SRP-mediated delivery to the ER, type III TMPs can uniquely access the membrane insertase activity of the ER membrane complex (EMC) via a mechanism that is facilitated by the Sec61 translocon. This alternative EMC-mediated insertion pathway allows type III TMPs to bypass the Ipom-F-mediated blockade of membrane integration that is seen with obligate Sec61 clients.


Assuntos
Retículo Endoplasmático/metabolismo , Membranas Intracelulares/metabolismo , Proteínas de Membrana/metabolismo , Biossíntese de Proteínas , Canais de Translocação SEC/metabolismo , Animais , Retículo Endoplasmático/efeitos dos fármacos , Glicoconjugados/farmacologia , Células HeLa , Humanos , Immunoblotting , Membranas Intracelulares/efeitos dos fármacos , Modelos Biológicos , Transporte Proteico/efeitos dos fármacos , Interferência de RNA , Canais de Translocação SEC/genética , Partícula de Reconhecimento de Sinal/metabolismo
17.
Clin Chim Acta ; 521: 104-106, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34245688

RESUMO

SLC37A4-CDG is an emerging congenital disorder of glycosylation which is characterized by a dominant inheritance and a major coagulopathy originating from the liver. Recent studies took interest in the biochemical alterations found in this CDG and showed that they consisted of multiple glycosylation abnormalities, which result from mislocalization of the endoplasmic reticulum glucose-6-phosphate transporter and associated Golgi homeostasis defects. In this work, we highlight in six affected individuals abnormal patterns for various serum N-glycoproteins and bikunin proteoglycan isoforms, together with specific alterations of the mass spectra of endoglycosidase H-released serum N-glycans. Collectively, these data complement previous findings, help to better delineate SLC37A4-CDG and could present interest in diagnosing this disease.


Assuntos
Defeitos Congênitos da Glicosilação , Antiporters/metabolismo , Defeitos Congênitos da Glicosilação/diagnóstico , Defeitos Congênitos da Glicosilação/genética , Defeitos Congênitos da Glicosilação/metabolismo , Retículo Endoplasmático/metabolismo , Glicosilação , Complexo de Golgi , Humanos , Proteínas de Transporte de Monossacarídeos/genética , Proteínas de Transporte de Monossacarídeos/metabolismo , Polissacarídeos
18.
Int J Mol Sci ; 22(14)2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34299184

RESUMO

Quorum sensing of Acinetobacter nosocomialis for cell-to-cell communication produces N-3-hydroxy dodecanoyl-DL-homoserine lactone (OH-dDHL) by an AnoR/I two-component system. However, OH-dDHL-driven apoptotic mechanisms in hosts have not been clearly defined. Here, we investigated the induction of apoptosis signaling pathways in bone marrow-derived macrophages treated with synthetic OH-dDHL. Moreover, the quorum-sensing system for virulence regulation was evaluated in vivo using wild-type and anoI-deletion mutant strains. OH-dDHL decreased the viability of macrophage and epithelial cells in dose- and time-dependent manners. OH-dDHL induced Ca2+ efflux and caspase-12 activation by ER stress transmembrane protein (IRE1 and ATF6a p50) aggregation and induced mitochondrial dysfunction through reactive oxygen species (ROS) production, which caused cytochrome c to leak. Pretreatment with a pan-caspase inhibitor reduced caspase-3, -8, and -9, which were activated by OH-dDHL. Pro-inflammatory cytokine and paraoxonase-2 (PON2) gene expression were increased by OH-dDHL. We showed that the anoI-deletion mutant strains have less intracellular invasion compared to the wild-type strain, and their virulence, such as colonization and dissemination, was decreased in vivo. Consequently, these findings revealed that OH-dDHL, as a virulence factor, contributes to bacterial infection and survival as well as the modification of host responses in the early stages of infection.


Assuntos
4-Butirolactona/análogos & derivados , Acinetobacter/metabolismo , Retículo Endoplasmático/efeitos dos fármacos , Homosserina/análogos & derivados , Macrófagos/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , 4-Butirolactona/farmacologia , Acinetobacter/isolamento & purificação , Acinetobacter/patogenicidade , Animais , Apoptose/efeitos dos fármacos , Células Cultivadas , Modelos Animais de Doenças , Retículo Endoplasmático/metabolismo , Feminino , Homosserina/farmacologia , Humanos , Macrófagos/metabolismo , Macrófagos/microbiologia , Macrófagos/patologia , Camundongos , Mitocôndrias/metabolismo , Percepção de Quorum , Espécies Reativas de Oxigênio/metabolismo , Fatores de Virulência/farmacologia
19.
Int J Mol Sci ; 22(13)2021 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-34202771

RESUMO

In this article, we review the biological and clinical implication of the Recruitment-Secretory Block ("R-SB") phenomenon. The phenomenon refers to the reaction of the liver with regard to protein secretion in conditions of clinical stimulation. Our basic knowledge of the process is due to the experimental work in animal models. Under basal conditions, the protein synthesis is mainly carried out by periportal (zone 1) hepatocytes that are considered the "professional" synthesizing protein cells. Under stimulation, midlobular and centrolobular (zones 2 and 3) hepatocytes, are progressively recruited according to lobular gradients and contribute to the increase of synthesis and secretion. The block of secretion, operated by exogenous agents, causes intracellular retention of all secretory proteins. The Pi MZ phenotype of Alpha-1-antitrypsin deficiency (AATD) has turned out to be the key for in vivo studies of the reaction of the liver, as synthesis and block of secretion are concomitant. Indeed, the M fraction of AAT is stimulated for synthesis and regularly exported while the Z fraction is mostly retained within the cell. For that reason, the phenomenon has been designated "Recruitment-Secretory Block" ("R-SB"). The "R-SB" phenomenon explains why: (a) the MZ individuals can correct the serum deficiency; (b) the resulting immonohistochemical and electron microscopic (EM) patterns are very peculiar and specific for the diagnosis of the Z mutation in tissue sections in the absence of genotyping; (c) the term carrier is no longer applicable for the heterozygous condition as all Pi MZ individuals undergo storage and the storage predisposes to liver damage. The storage represents the true elementary lesion and consequently reflects the phenotype-genotype correlation; (d) the site and function of the extrahepatic AAT and the relationship between intra and extracellular AAT; (e) last but not least, the concept of Endoplasmic Reticulum Storage Disease (ERSD) and of a new disease, hereditary hypofibrinogenemia with hepatic storage (HHHS). In the light of the emerging phenomenon, described in vitro, namely that M and Z AAT can form heteropolymers within hepatocytes as well as in circulation, we have reviewed the whole clinical and experimental material collected during forty years, in order to evaluate to what extent the polymerization phenomenon occurs in vivo. The paper summarizes similarities and differences between AAT and Fibrinogen as well as between the related diseases, AATD and HHHS. Indeed, fibrinogen gamma chain mutations undergo an aggregation process within the RER of hepatocytes similar to AATD. In addition, this work has clarified the intriguing phenomenon underlying a new syndrome, hereditary hypofibrinogenemia and hypo-APO-B-lipoproteinemia with hepatic storage of fibrinogen and APO-B lipoproteins. It is hoped that these studies could contribute to future research and select strategies aimed to simultaneously correct the hepatocytic storage, thus preventing the liver damage and the plasma deficiency of the two proteins.


Assuntos
Suscetibilidade a Doenças , Retículo Endoplasmático/metabolismo , Sistemas de Translocação de Proteínas/metabolismo , Animais , Animais Geneticamente Modificados , Biomarcadores , Modelos Animais de Doenças , Predisposição Genética para Doença , Humanos , Fígado/metabolismo , Fígado/patologia , Fígado/ultraestrutura , Redes e Vias Metabólicas , Erros Inatos do Metabolismo/genética , Erros Inatos do Metabolismo/metabolismo , Transporte Proteico , alfa 1-Antitripsina/genética , alfa 1-Antitripsina/metabolismo , Deficiência de alfa 1-Antitripsina/genética , Deficiência de alfa 1-Antitripsina/metabolismo
20.
Nat Commun ; 12(1): 4267, 2021 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-34257291

RESUMO

The lipid composition of organelles acts as a landmark to define membrane identity and specify subcellular function. Phosphoinositides are anionic lipids acting in protein sorting and trafficking at the trans-Golgi network (TGN). In animal cells, sphingolipids control the turnover of phosphoinositides through lipid exchange mechanisms at endoplasmic reticulum/TGN contact sites. In this study, we discover a mechanism for how sphingolipids mediate phosphoinositide homeostasis at the TGN in plant cells. Using multiple approaches, we show that a reduction of the acyl-chain length of sphingolipids results in an increased level of phosphatidylinositol-4-phosphate (PtdIns(4)P or PI4P) at the TGN but not of other lipids usually coupled to PI4P during exchange mechanisms. We show that sphingolipids mediate Phospholipase C (PLC)-driven consumption of PI4P at the TGN rather than local PI4P synthesis and that this mechanism is involved in the polar sorting of the auxin efflux carrier PIN2 at the TGN. Together, our data identify a mode of action of sphingolipids in lipid interplay at the TGN during protein sorting.


Assuntos
Fosfatidilinositóis/metabolismo , Esfingolipídeos/metabolismo , Rede trans-Golgi/metabolismo , Animais , Retículo Endoplasmático/metabolismo , Humanos , Fosfatidilinositóis/genética , Esfingolipídeos/genética , Fosfolipases Tipo C/metabolismo , Rede trans-Golgi/genética
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