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Sungsoon Fang 2 Articles
Basic Research
CycloZ Improves Hyperglycemia and Lipid Metabolism by Modulating Lysine Acetylation in KK-Ay Mice
Jongsu Jeon, Dohyun Lee, Bobae Kim, Bo-Yoon Park, Chang Joo Oh, Min-Ji Kim, Jae-Han Jeon, In-Kyu Lee, Onyu Park, Seoyeong Baek, Chae Won Lim, Dongryeol Ryu, Sungsoon Fang, Johan Auwerx, Kyong-Tai Kim, Hoe-Yune Jung
Diabetes Metab J. 2023;47(5):653-667.   Published online April 26, 2023
DOI: https://doi.org/10.4093/dmj.2022.0244
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AbstractAbstract PDFSupplementary MaterialPubReader   ePub   
Background
CycloZ, a combination of cyclo-His-Pro and zinc, has anti-diabetic activity. However, its exact mode of action remains to be elucidated.
Methods
KK-Ay mice, a type 2 diabetes mellitus (T2DM) model, were administered CycloZ either as a preventive intervention, or as a therapy. Glycemic control was evaluated using the oral glucose tolerance test (OGTT), and glycosylated hemoglobin (HbA1c) levels. Liver and visceral adipose tissues (VATs) were used for histological evaluation, gene expression analysis, and protein expression analysis.
Results
CycloZ administration improved glycemic control in KK-Ay mice in both prophylactic and therapeutic studies. Lysine acetylation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha, liver kinase B1, and nuclear factor-κB p65 was decreased in the liver and VATs in CycloZ-treated mice. In addition, CycloZ treatment improved mitochondrial function, lipid oxidation, and inflammation in the liver and VATs of mice. CycloZ treatment also increased the level of β-nicotinamide adenine dinucleotide (NAD+), which affected the activity of deacetylases, such as sirtuin 1 (Sirt1).
Conclusion
Our findings suggest that the beneficial effects of CycloZ on diabetes and obesity occur through increased NAD+ synthesis, which modulates Sirt1 deacetylase activity in the liver and VATs. Given that the mode of action of an NAD+ booster or Sirt1 deacetylase activator is different from that of traditional T2DM drugs, CycloZ would be considered a novel therapeutic option for the treatment of T2DM.
Basic Research
DGAT2 Plays a Crucial Role to Control ESRRAPROX1 Transcriptional Network to Maintain Hepatic Mitochondrial Sustainability
Yoseob Lee, Yeseong Hwang, Minki Kim, Hyeonuk Jeon, Seyeon Joo, Sungsoon Fang, Jae-Woo Kim
Received October 13, 2023  Accepted December 11, 2023  Published online April 22, 2024  
DOI: https://doi.org/10.4093/dmj.2023.0368    [Epub ahead of print]
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AbstractAbstract PDF
Background
Diacylglycerol O-acyltransferase 2 (DGAT2) synthesizes triacylglycerol (TG) from diacylglycerol; therefore, DGAT2 is considered as a therapeutic target for steatosis. However, the consequence of inhibiting DGAT2 is not fully investigated due to side effects including lethality and lipotoxicity. In this article, we observed the role of DGAT2 in hepatocarcinoma.
Methods
The role of DGAT2 is analyzed via loss-of-function assay. DGAT2 knockdown (KD) and inhibitor treatment on HepG2 cell line was analyzed. Cumulative analysis of cell metabolism with bioinformatic data were assessed, and further compared with different cohorts of liver cancer patients and non-alcoholic fatty liver disease (NAFLD) patients to elucidate how DGAT2 is regulating cancer metabolism.
Results
Mitochondrial function is suppressed in DGAT2 KD HepG2 cell along with the decreased lipid droplets. In the aspect of the cancer, DGAT2 KD upregulates cell proliferation. Analyzing transcriptome of NAFLD and hepatocellular carcinoma (HCC) patients highlights negatively correlating expression patterns of 73 lipid-associated genes including DGAT2. Cancer patients with the lower DGAT2 expression face lower survival rate. DGAT2 KD cell and patients’ transcriptome show downregulation in estrogen- related receptor alpha (ESRRA) via integrated system for motif activity response analysis (ISMARA), with increased dimerization with corepressor prospero homeobox 1 (PROX1).
Conclusion
DGAT2 sustains the stability of mitochondria in hepatoma via suppressing ESRRA-PROX1 transcriptional network and hinders HCC from shifting towards glycolytic metabolism, which lowers cell proliferation.

Diabetes Metab J : Diabetes & Metabolism Journal