scholarly journals Sirtuins Modulation: A Promising Strategy for HIV-Associated Neurocognitive Impairments

2022 ◽  
Vol 23 (2) ◽  
pp. 643
Author(s):  
Izchel Figarola-Centurión ◽  
Martha Escoto-Delgadillo ◽  
Gracia Viviana González-Enríquez ◽  
Juan Ernesto Gutiérrez-Sevilla ◽  
Eduardo Vázquez-Valls ◽  
...  
Keyword(s):  
Viral Proteins ◽  
People Living With Hiv ◽  
Apoptosis Pathway ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
Neurocognitive Impairments ◽  
Intrinsic Apoptosis Pathway ◽  
Neuronal Alteration ◽  
Protein Response ◽  
Living With Hiv

HIV-Associated neurocognitive disorder (HAND) is one of the major concerns since it persists in 40% of this population. Nowadays, HAND neuropathogenesis is considered to be caused by the infected cells that cross the brain–blood barrier and produce viral proteins that can be secreted and internalized into neurons leading to disruption of cellular processes. The evidence points to viral proteins such as Tat as the causal agent for neuronal alteration and thus HAND. The hallmarks in Tat-induced neurodegeneration are endoplasmic reticulum stress and mitochondrial dysfunction. Sirtuins (SIRTs) are NAD+-dependent deacetylases involved in mitochondria biogenesis, unfolded protein response, and intrinsic apoptosis pathway. Tat interaction with these deacetylases causes inhibition of SIRT1 and SIRT3. Studies revealed that SIRTs activation promotes neuroprotection in neurodegenerative diseases such Alzheimer’s and Parkinson’s disease. Therefore, this review focuses on Tat-induced neurotoxicity mechanisms that involve SIRTs as key regulators and their modulation as a therapeutic strategy for tackling HAND and thereby improving the quality of life of people living with HIV.

scholarly journals Molecular architecture of the human tRNA ligase complex

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Alena Kroupova ◽  
Fabian Ackle ◽  
Igor Asanović ◽  
Stefan Weitzer ◽  
Franziska M Boneberg ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Strand Break ◽  
Molecular Architecture ◽  
Rna Repair ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
Terminal Domain ◽  
Structural Framework ◽  
Dna Double Strand Break ◽  
Protein Response

RtcB enzymes are RNA ligases that play essential roles in tRNA splicing, unfolded protein response, and RNA repair. In metazoa, RtcB functions as part of a five-subunit tRNA ligase complex (tRNA-LC) along with Ddx1, Cgi-99, Fam98B and Ashwin. The human tRNA-LC or its individual subunits have been implicated in additional cellular processes including microRNA maturation, viral replication, DNA double-strand break repair and mRNA transport. Here we present a biochemical analysis of the inter-subunit interactions within the human tRNA-LC along with crystal structures of the catalytic subunit RTCB and the N-terminal domain of CGI-99. We show that the core of the human tRNA-LC is assembled from RTCB and the C-terminal alpha-helical regions of DDX1, CGI-99, and FAM98B, all of which are required for complex integrity. The N-terminal domain of CGI-99 displays structural homology to calponin-homology domains, and CGI-99 and FAM98B associate via their N-terminal domains to form a stable subcomplex. The crystal structure of GMP-bound RTCB reveals divalent metal coordination geometry in the active site, providing insights into its catalytic mechanism. Collectively, these findings shed light on the molecular architecture and mechanism of the human tRNA ligase complex, and provide a structural framework for understanding its functions in cellular RNA metabolism.

scholarly journals Alzheimer’s-Like Pathology at the Crossroads of HIV-Associated Neurological Disorders

Vaccines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 930
Author(s):  
Divya T. Chemparthy ◽  
Muthukumar Kannan ◽  
Lila Gordon ◽  
Shilpa Buch ◽  
Susmita Sil
Keyword(s):  
Neurological Disorders ◽  
Disease Process ◽  
Amyloid Β ◽  
Viral Proteins ◽  
Epidemiological Studies ◽  
Model Systems ◽  
People Living With Hiv ◽  
Living With Hiv ◽  
The Brain

Despite the widespread success of combined antiretroviral therapy (cART) in suppressing viremia, the prevalence of human immunodeficiency virus (HIV)-associated neurological disorders (HAND) and associated comorbidities such as Alzheimer’s disease (AD)-like symptomatology is higher among people living with HIV. The pathophysiology of observed deficits in HAND is well understood. However, it has been suggested that it is exacerbated by aging. Epidemiological studies have suggested comparable concentrations of the toxic amyloid protein, amyloid-β42 (Aβ42), in the cerebrospinal fluid (CSF) of HAND patients and in the brains of patients with dementia of the Alzheimer’s type. Apart from abnormal amyloid-β (Aβ) metabolism in AD, a better understanding of the role of similar pathophysiologic processes in HAND could be of substantial value. The pathogenesis of HAND involves either the direct effects of the virus or the effect of viral proteins, such as Tat, Gp120, or Nef, as well as the effects of antiretrovirals on amyloid metabolism and tauopathy, leading, in turn, to synaptodendritic alterations and neuroinflammatory milieu in the brain. Additionally, there is a lack of knowledge regarding the causative or bystander role of Alzheimer’s-like pathology in HAND, which is a barrier to the development of therapeutics for HAND. This review attempts to highlight the cause–effect relationship of Alzheimer’s-like pathology with HAND, attempting to dissect the role of HIV-1, HIV viral proteins, and antiretrovirals in patient samples, animal models, and cell culture model systems. Biomarkers associated with Alzheimer’s-like pathology can serve as a tool to assess the neuronal injury in the brain and the associated cognitive deficits. Understanding the factors contributing to the AD-like pathology associated with HAND could set the stage for the future development of therapeutics aimed at abrogating the disease process.

Andrographolide Mitigates Unfolded Protein Response Pathway andApoptosis Involved in Chikungunya virus Infection

2020 ◽  
Vol 23 ◽  
Author(s):  
Swati Gupta ◽  
KP Mishra ◽  
Bhuvnesh Kumar ◽  
SB Singh ◽  
Lilly Ganju
Keyword(s):  
Protein Expression ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Chikungunya Virus ◽  
Rna Virus ◽  
Apoptosis Pathway ◽  
Unfolded Protein ◽  
Induced Apoptosis ◽  
Protein Response ◽  
Upr Pathway

Background: Chikungunya virus (CHIKV) is an arthropod-borne RNA virus which induces host endoplasmic reticulum (ER) stress by accumulating unfolded or misfolded proteins. ER stress activates the unfolded protein response (UPR) pathway to enable proper protein folding and maintain cellular homeostasis. There is no approved drug or vaccine available for CHIKV treatment, therefore, a pharmacological countermeasure is warranted for preventing CHIKV infection. Objective: With a view to find a treatment modality for chikungunya infection, “andrographolide”; a plant-derived diterpenoid with reported antiviral, anti-inflammatory and immunomodulatory effects, was used to investigate its role in chikungunya induced unfolded protein stress and apoptosis. Methods: Cells and supernatant collected on andrographolide and VER-155008; a GRP78 inhibitor, treatment in CHIKV infected and mock-infected THP-1 cells were tested for differential expression of UPR pathway proteins including GRP78, PERK, EIF-2α, IRE-1α, XBP-1 and ATF6. Further, the inflammasome and apoptosis pathway proteins i.e. caspase-1, caspase-3 and PARP were tested by immunoblotting and cytokines i.e. IL-1β, IL-6 and IFN-γ were tested by ELISA. Results: Andrographolide treatment in CHIKV infected THP-1 cells significantly reduced IRE1α and downstream spliced XBP1 protein expression. Further, CHIKV induced apoptosis and viral protein expression was also reduced on andrographolide treatment. A comparative analysis of andrographolide verses VER-155008, confirmed that andrographolide surpasses the effects of VER-155008 in suppressing the CHIKV induced ER stress. Conclusion: The study, therefore, confirms that andrographolide is a potential remedy for chikungunya infection and suppresses CHIKV induced ER stress and apoptosis.

scholarly journals Molecular architecture of the human tRNA ligase complex

2021 ◽  
Author(s):  
Alena Kroupova ◽  
Fabian Ackle ◽  
Franziska M Boneberg ◽  
Alessia Chui ◽  
Stefan Weitzer ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Strand Break ◽  
Molecular Architecture ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
Terminal Domain ◽  
Structural Framework ◽  
Dna Double Strand Break ◽  
Protein Response ◽  
Intersubunit Interactions

RtcB enzymes are RNA ligases that play essential roles in tRNA splicing, unfolded protein response, and RNA repair. In metazoa, RtcB functions as part of a five-subunit tRNA ligase complex (tRNA-LC) along with Ddx1, Cgi-99, Fam98B and Ashwin. The human tRNA-LC or its individual subunits have been implicated in additional cellular processes including microRNA maturation, viral replication, DNA double-strand break repair and mRNA transport. Here we present a biochemical analysis of the intersubunit interactions within the human tRNA-LC along with crystal structures of the catalytic subunit RTCB and the N-terminal domain of CGI-99. We show that the core of the human tRNA-LC is assembled from RTCB and the C-terminal alpha-helical regions of DDX1, CGI-99, and FAM98B, all of which are required for complex integrity. The N-terminal domain of CGI-99 displays structural homology to calponin-homology domains, and CGI-99 and FAM98B associate via their N-terminal domains to form a stable subcomplex. The crystal structure of GMP-bound RTCB reveals divalent metal coordination geometry in the active site, providing insights into its catalytic mechanism. Collectively, these findings shed light on the molecular architecture and mechanism of the human tRNA ligase complex, and provide a structural framework for understanding its functions in cellular RNA metabolism.

scholarly journals Recent advances in signal integration mechanisms in the unfolded protein response

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1840 ◽  
Author(s):  
G. Elif Karagöz ◽  
Tomás Aragón ◽  
Diego Acosta-Alvear
Keyword(s):  
Unfolded Protein Response ◽  
New Developments ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
Integration Mechanisms ◽  
Physiological Demands ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Er Homeostasis ◽  
Made In

Since its discovery more than 25 years ago, great progress has been made in our understanding of the unfolded protein response (UPR), a homeostatic mechanism that adjusts endoplasmic reticulum (ER) function to satisfy the physiological demands of the cell. However, if ER homeostasis is unattainable, the UPR switches to drive cell death to remove defective cells in an effort to protect the health of the organism. This functional dichotomy places the UPR at the crossroads of the adaptation versus apoptosis decision. Here, we focus on new developments in UPR signaling mechanisms, in the interconnectivity among the signaling pathways that make up the UPR in higher eukaryotes, and in the coordination between the UPR and other fundamental cellular processes.

scholarly journals Structure and Function of Mitochondria-Associated Endoplasmic Reticulum Membranes (MAMs) and Their Role in Cardiovascular Diseases

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Yi Luan ◽  
Ying Luan ◽  
Rui-Xia Yuan ◽  
Qi Feng ◽  
Xing Chen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Vascular Endothelial Cells ◽  
Mitochondrial Dynamics ◽  
Cellular Functions ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
Associated Proteins ◽  
Apoptosis And Inflammation ◽  
And Function ◽  
Protein Response

Abnormal function of suborganelles such as mitochondria and endoplasmic reticulum often leads to abnormal function of cardiomyocytes or vascular endothelial cells and cardiovascular disease (CVD). Mitochondria-associated membrane (MAM) is involved in several important cellular functions. Increasing evidence shows that MAM is involved in the pathogenesis of CVD. MAM mediates multiple cellular processes, including calcium homeostasis regulation, lipid metabolism, unfolded protein response, ROS, mitochondrial dynamics, autophagy, apoptosis, and inflammation, which are key risk factors for CVD. In this review, we discuss the structure of MAM and MAM-associated proteins, their role in CVD progression, and the potential use of MAM as the therapeutic targets for CVD treatment.

scholarly journals The Cross-Links of Endoplasmic Reticulum Stress, Autophagy, and Nurodegeneration in Parkinson’s Disease

2021 ◽  
Vol 13 ◽  
Author(s):  
Haigang Ren ◽  
Wanqing Zhai ◽  
Xiaojun Lu ◽  
Guanghui Wang
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Substantia Nigra Pars Compacta ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
Cross Links ◽  
Main Component ◽  
Protein Response

Parkinson’s disease (PD) is the most common neurodegenerative movement disorder, and it is characterized by the selective loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc), as well as the presence of intracellular inclusions with α-synuclein as the main component in surviving DA neurons. Emerging evidence suggests that the imbalance of proteostasis is a key pathogenic factor for PD. Endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) and autophagy, two major pathways for maintaining proteostasis, play important roles in PD pathology and are considered as attractive therapeutic targets for PD treatment. However, although ER stress/UPR and autophagy appear to be independent cellular processes, they are closely related to each other. In this review, we focused on the roles and molecular cross-links between ER stress/UPR and autophagy in PD pathology. We systematically reviewed and summarized the most recent advances in regulation of ER stress/UPR and autophagy, and their cross-linking mechanisms. We also reviewed and discussed the mechanisms of the coexisting ER stress/UPR activation and dysregulated autophagy in the lesion regions of PD patients, and the underlying roles and molecular crosslinks between ER stress/UPR activation and the dysregulated autophagy in DA neurodegeneration induced by PD-associated genetic factors and PD-related neurotoxins. Finally, we indicate that the combined regulation of ER stress/UPR and autophagy would be a more effective treatment for PD rather than regulating one of these conditions alone.

scholarly journals What Is the Sweetest UPR Flavor for the β-cell? That Is the Question

2021 ◽  
Vol 11 ◽  
Author(s):  
Alina Lenghel ◽  
Alina Maria Gheorghita ◽  
Andrei Mircea Vacaru ◽  
Ana-Maria Vacaru
Keyword(s):  
Molecular Mechanisms ◽  
Secretory Cells ◽  
Insulin Production ◽  
Β Cells ◽  
Β Cell ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
Specific Outcome ◽  
A Cell ◽  
Protein Response

Unfolded protein response (UPR) is a process conserved from yeasts to mammals and, based on the generally accepted dogma, helps the secretory performance of a cell, by improving its capacity to cope with a burden in the endoplasmic reticulum (ER). The ER of β-cells, “professional secretory cells”, has to manage tremendous amounts of insulin, which elicits a strong pressure on the ER intrinsic folding capacity. Thus, the constant demand for insulin production results in misfolded proinsulin, triggering a physiological upregulation of UPR to restore homeostasis. Most diabetic disorders are characterized by the loss of functional β-cells, and the pathological side of UPR plays an instrumental role. The transition from a homeostatic to a pathological UPR that ultimately leads to insulin-producing β-cell decay entails complex cellular processes and molecular mechanisms which remain poorly described so far. Here, we summarize important processes that are coupled with or driven by UPR in β-cells, such as proliferation, inflammation and dedifferentiation. We conclude that the UPR comes in different “flavors” and each of them is correlated with a specific outcome for the cell, for survival, differentiation, proliferation as well as cell death. All these greatly depend on the way UPR is triggered, however what exactly is the switch that favors the activation of one UPR as opposed to others is largely unknown. Substantial work needs to be done to progress the knowledge in this important emerging field as this will help in the development of novel and more efficient therapies for diabetes.

scholarly journals XBP1s activation can globally remodel N-glycan structure distribution patterns

2018 ◽  
Vol 115 (43) ◽  
pp. E10089-E10098 ◽  
Author(s):  
Madeline Y. Wong ◽  
Kenny Chen ◽  
Aristotelis Antonopoulos ◽  
Brian T. Kasper ◽  
Mahender B. Dewal ◽  
...  
Keyword(s):  
Secretory Pathway ◽  
Distribution Patterns ◽  
Surface Proteins ◽  
Glycan Structure ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
A Cell ◽  
Wide Scale ◽  
The Unfolded Protein Response ◽  
Protein Response

Classically, the unfolded protein response (UPR) safeguards secretory pathway proteostasis. The most ancient arm of the UPR, the IRE1-activated spliced X-box binding protein 1 (XBP1s)-mediated response, has roles in secretory pathway maturation beyond resolving proteostatic stress. Understanding the consequences of XBP1s activation for cellular processes is critical for elucidating mechanistic connections between XBP1s and development, immunity, and disease. Here, we show that a key functional output of XBP1s activation is a cell type-dependent shift in the distribution of N-glycan structures on endogenous membrane and secreted proteomes. For example, XBP1s activity decreased levels of sialylation and bisecting GlcNAc in the HEK293 membrane proteome and secretome, while substantially increasing the population of oligomannose N-glycans only in the secretome. In HeLa cell membranes, stress-independent XBP1s activation increased the population of high-mannose and tetraantennary N-glycans, and also enhanced core fucosylation. mRNA profiling experiments suggest that XBP1s-mediated remodeling of the N-glycome is, at least in part, a consequence of coordinated transcriptional resculpting of N-glycan maturation pathways by XBP1s. The discovery of XBP1s-induced N-glycan structural remodeling on a glycome-wide scale suggests that XBP1s can act as a master regulator of N-glycan maturation. Moreover, because the sugars on cell-surface proteins or on proteins secreted from an XBP1s-activated cell can be molecularly distinct from those of an unactivated cell, these findings reveal a potential new mechanism for translating intracellular stress signaling into altered interactions with the extracellular environment.

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