• Biodesign
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• v.6 no.4
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• pp.100-102
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• 2018

Autophagy is a degradation pathway that targets many cellular components and plays a particularly important role in protein degradation and recycling. This process is very complex and several proteins participate in this process. One of them, P62/SQSTM1, is related to the N-end rule and induces protein degradation through autophagy. The P62/SQSTM1 makes a huge oligomer, and this oligomerization is known to play an important role in its mechanism. This oligomerization takes two steps. First, the PB1 domain of P62/SQSTM1 makes the base oligomer, and then, when the ligand binds to the ZZ domain of P62/SQSTM1, it induces a higher oligomer by the disulfide bond of the two cysteines. To understand the oligomerization mechanism of P62/SQSTM1, we need to know the dimerization of the PB1 domain. In this study, crystals of PB1 dimer were made and the crystals were diffracted by X-ray to collect usable data up to 3.2A. We are analyzing the structure using the molecular replacement (MR) method.

• BMB Reports
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• v.54 no.6
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• pp.305-310
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• 2021

Cereblon (CRBN) is a multi-functional protein that acts as a substrate receptor of the E3 ligase complex and a molecular chaperone. While CRBN is proposed to function in mitochondria, its specific roles are yet to be established. Here, we showed that knockdown of CRBN triggers oxidative stress and calcium overload in mitochondria, leading to disruption of mitochondrial membrane potential. Notably, long-term CRBN depletion using PROteolysis TArgeting Chimera (PROTAC) induced irreversible mitochondrial dysfunction, resulting in cell death. Our collective findings indicate that CRBN is required for mitochondrial homeostasis in cells.

• BMB Reports
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• v.53 no.1
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• pp.28-34
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• 2020

Sphingolipids are ubiquitous building blocks of eukaryotic cell membranes that function as signaling molecules for regulating a diverse range of cellular processes, including cell proliferation, growth, survival, immune-cell trafficking, vascular and epithelial integrity, and inflammation. Recently, several studies have highlighted the pivotal role of sphingolipids in neuroinflammatory regulation. Sphingolipids have multiple functions, including induction of the expression of various inflammatory mediators and regulation of neuroinflammation by directly effecting the cells of the central nervous system. Accumulating evidence points to sphingolipid engagement in neuroinflammatory disorders, including Alzheimer's and Parkinson's diseases. Abnormal sphingolipid alterations, which involves an increase in ceramide and a decrease in sphingosine kinase, are observed during neuroinflammatory disease. These trends are observed early during disease development, and thus highlight the potential of sphingolipids as a new therapeutic and diagnostic target for neuroinflammatory diseases.

• Molecules and Cells
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• v.43 no.1
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• pp.23-33
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• 2020

NF-κB signaling through both canonical and non-canonical pathways plays a central role in immune responses and inflammation. NF-κB-inducing kinase (NIK) stabilization is a key step in activation of the non-canonical pathway and its dysregulation implicated in various hematologic malignancies. The tumor suppressor, p53, is an established cellular gatekeeper of proliferation. Abnormalities of the TP53 gene have been detected in more than half of all human cancers. While the non-canonical NF-κB and p53 pathways have been explored for several decades, no studies to date have documented potential cross-talk between these two cancer-related mechanisms. Here, we demonstrate that p53 negatively regulates NIK in an miRNA-dependent manner. Overexpression of p53 decreased the levels of NIK, leading to inhibition of the non-canonical NF-κB pathway. Conversely, its knockdown led to increased levels of NIK, IKKα phosphorylation, and p100 processing. Additionally, miR-34b induced by nutlin-3 directly targeted the coding sequences (CDS) of NIK. Treatment with anti-miR-34b-5p augmented NIK levels and subsequent non-canonical NF-κB signaling. Our collective findings support a novel cross-talk mechanism between non-canonical NF-κB and p53.

• Molecules and Cells
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• v.43 no.12
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• pp.1035-1045
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• 2020

The Drosophila genome contains four low molecular weight-protein tyrosine phosphatase (LMW-PTP) members: Primo-1, Primo-2, CG14297, and CG31469. The lack of intensive biochemical analysis has limited our understanding of these proteins. Primo-1 and CG31469 were previously classified as pseudophosphatases, but CG31469 was also suggested to be a putative protein arginine phosphatase. Herein, we present the crystal structures of CG31469 and Primo-1, which are the first Drosophila LMW-PTP structures. Structural analysis showed that the two proteins adopt the typical LMW-PTP fold and have a canonically arranged P-loop. Intriguingly, while Primo-1 is presumed to be a canonical LMW-PTP, CG31469 is unique as it contains a threonine residue at the fifth position of the P-loop motif instead of highly conserved isoleucine and a characteristically narrow active site pocket, which should facilitate the accommodation of phosphoarginine. Subsequent biochemical analysis revealed that Primo-1 and CG31469 are enzymatically active on phosphotyrosine and phosphoarginine, respectively, refuting their classification as pseudophosphatases. Collectively, we provide structural and biochemical data on two Drosophila proteins: Primo-1, the canonical LMW-PTP protein, and CG31469, the first investigated eukaryotic protein arginine phosphatase. We named CG31469 as DARP, which stands for Drosophila ARginine Phosphatase.

• Biomolecules & Therapeutics
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• v.30 no.1
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• pp.48-54
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• 2022

GPR43 (also known as FFAR2), a metabolite-sensing G-protein-coupled receptor stimulated by short-chain fatty acid (SCFA) ligands is involved in innate immunity and metabolism. GPR43 couples with Gα_i/o and Gα_q/11 heterotrimeric proteins and is capable of decreasing cyclic AMP and inducing Ca²⁺ flux. The GPR43 receptor has additionally been shown to bind β-arrestin 2 and inhibit inflammatory pathways, such as NF-κB. However, GPR43 shares the same ligands as GPR41, including acetate, propionate, and butyrate, and determination of its precise functions in association with endogenous ligands, such as SCFAs alone, therefore remains a considerable challenge. In this study, we generated novel synthetic agonists that display allosteric modulatory effects on GPR43 and downregulate NF-κB activity. In particular, the potency of compound 187 was significantly superior to that of pre-existing compounds in vitro. However, in the colitis model in vivo, compound 110 induced more potent attenuation of inflammation. These novel allosteric agonists of GPR43 clearly display anti-inflammatory potential, supporting their clinical utility as therapeutic drugs.

• BMB Reports
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• v.50 no.11
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• pp.535-536
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• 2017

A novel approach has been used to identify functional interactions relevant to human disease. Using high-throughput human-yeast genetic interaction screens, a first draft of disease interactome was obtained. This was achieved by first searching for candidate human disease genes that confer toxicity in yeast, and second, identifying modulators of toxicity. This study found potentially disease-relevant interactions by analyzing the network of functional interactions and focusing on genes implicated in amyotrophic lateral sclerosis (ALS), for example. In the subsequent proof-of-concept study focused on ALS, similar functional relationships between a specific kinase and ALS-associated genes were observed in mammalian cells and zebrafish, supporting findings in human-yeast genetic interaction screens. Results of combined analyses highlighted MAP2K5 kinase as a potential therapeutic target in ALS.

• The Journal of the Korea Contents Association
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• v.19 no.6
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• pp.461-470
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• 2019

In diabetes mellitus, renal disease is a common complication, characterized by increased urinary albumin excretion and reduced eGFR. According to KDIGO CKD stage classification, Korean characteristics were analyzed according to urinary albumin and eGFR using the National Health and Nutrition Examination Survey VI raw data. According to KDIGO classification, diabetic patients were classified as Low risk 72.0%, Moderate risk 19.3%, High risk 5.6% and Very high risk 3.0%. Low risk decreased from 74.7% to 52.2%, and moderate to very high risk increased from 25.4% to 47.8% as the duration of diabetes mellitus was prolonged. The risk factors were CKD stage 1 (HR 2.064) to stage 4 (HR 11.049), the highest risk of hypertension. The incidence of renal disease was elevated according to duration of hypertension and HR 0.42 of kidney disease was decreased in the group maintaining proper blood pressure. In the hypertensive patients, the group administered with target blood pressure had a reduction of the kidney disease by 42% than the group with the hypertension. Therefore, controlling and managing hypertension to target blood pressure is important for the prevention of kidney disease.

• Journal of Microbiology and Biotechnology
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• v.32 no.10
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• pp.1355-1355
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• 2022

• Molecules and Cells
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• v.45 no.9
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• pp.640-648
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• 2022

CD133, also known as prominin-1, was first identified as a biomarker of mammalian cancer and neural stem cells. Previous studies have shown that the prominin-like (promL) gene, an orthologue of mammalian CD133 in Drosophila, plays a role in glucose and lipid metabolism, body growth, and longevity. Because locomotion is required for food sourcing and ultimately the regulation of metabolism, we examined the function of promL in Drosophila locomotion. Both promL mutants and pan-neuronal promL inhibition flies displayed reduced spontaneous locomotor activity. As dopamine is known to modulate locomotion, we also examined the effects of promL inhibition on the dopamine concentration and mRNA expression levels of tyrosine hydroxylase (TH) and DOPA decarboxylase (Ddc), the enzymes responsible for dopamine biosynthesis, in the heads of flies. Compared with those in control flies, the levels of dopamine and the mRNAs encoding TH and Ddc were lower in promL mutant and pan-neuronal promL inhibition flies. In addition, an immunostaining analysis revealed that, compared with control flies, promL mutant and pan-neuronal promL inhibition flies had lower levels of the TH protein in protocerebral anterior medial (PAM) neurons, a subset of dopaminergic neurons. Inhibition of promL in these PAM neurons reduced the locomotor activity of the flies. Overall, these findings indicate that promL expressed in PAM dopaminergic neurons regulates locomotion by controlling dopamine synthesis in Drosophila.