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  1. Article ; Online: Crosstalk between Oxidative Stress and Inflammatory Liver Injury in the Pathogenesis of Alcoholic Liver Disease

    Yoon Mee Yang / Ye Eun Cho / Seonghwan Hwang

    International Journal of Molecular Sciences, Vol 23, Iss 774, p

    2022  Volume 774

    Abstract: Alcoholic liver disease (ALD) is characterized by the injury, inflammation, and scarring in the liver owing to excessive alcohol consumption. Currently, ALD is a leading cause for liver transplantation. Therefore, extensive studies (in vitro, in ... ...

    Abstract Alcoholic liver disease (ALD) is characterized by the injury, inflammation, and scarring in the liver owing to excessive alcohol consumption. Currently, ALD is a leading cause for liver transplantation. Therefore, extensive studies (in vitro, in experimental ALD models and in humans) are needed to elucidate pathological features and pathogenic mechanisms underlying ALD. Notably, oxidative changes in the liver have been recognized as a signature trait of ALD. Progression of ALD is linked to the generation of highly reactive free radicals by reactions involving ethanol and its metabolites. Furthermore, hepatic oxidative stress promotes tissue injury and, in turn, stimulates inflammatory responses in the liver, forming a pathological loop that promotes the progression of ALD. Accordingly, accumulating further knowledge on the relationship between oxidative stress and inflammation may help establish a viable therapeutic approach for treating ALD.
    Keywords alcoholic liver disease ; oxidative stress ; inflammatory liver injury ; fatty liver ; alcoholic steatohepatitis ; cirrhosis ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
    Subject code 610
    Language English
    Publishing date 2022-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Type 1 polyisoprenoid diphosphate phosphatase modulates geranylgeranyl-mediated control of HMG CoA reductase and UBIAD1

    Rania Elsabrouty / Youngah Jo / Seonghwan Hwang / Dong-Jae Jun / Russell A DeBose-Boyd

    eLife, Vol

    2021  Volume 10

    Abstract: UbiA prenyltransferase domain-containing protein-1 (UBIAD1) utilizes geranylgeranyl pyrophosphate (GGpp) to synthesize the vitamin K2 subtype menaquinone-4. The prenyltransferase has emerged as a key regulator of sterol-accelerated, endoplasmic reticulum ...

    Abstract UbiA prenyltransferase domain-containing protein-1 (UBIAD1) utilizes geranylgeranyl pyrophosphate (GGpp) to synthesize the vitamin K2 subtype menaquinone-4. The prenyltransferase has emerged as a key regulator of sterol-accelerated, endoplasmic reticulum (ER)-associated degradation (ERAD) of HMG CoA reductase, the rate-limiting enzyme in synthesis of cholesterol and nonsterol isoprenoids including GGpp. Sterols induce binding of UBIAD1 to reductase, inhibiting its ERAD. Geranylgeraniol (GGOH), the alcohol derivative of GGpp, disrupts this binding and thereby stimulates ERAD of reductase and translocation of UBIAD1 to Golgi. We now show that overexpression of Type 1 polyisoprenoid diphosphate phosphatase (PDP1), which dephosphorylates GGpp and other isoprenyl pyrophosphates to corresponding isoprenols, abolishes protein geranylgeranylation as well as GGOH-induced ERAD of reductase and Golgi transport of UBIAD1. Conversely, these reactions are enhanced in the absence of PDP1. Our findings indicate PDP1-mediated hydrolysis of GGpp significantly contributes to a feedback mechanism that maintains optimal intracellular levels of the nonsterol isoprenoid.
    Keywords vesicular transport ; cholesterol metabolism ; isoprenoids ; ER-associated degradation ; prenylation ; Medicine ; R ; Science ; Q ; Biology (General) ; QH301-705.5
    Language English
    Publishing date 2021-11-01T00:00:00Z
    Publisher eLife Sciences Publications Ltd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Distinct histopathological phenotypes of severe alcoholic hepatitis suggest different mechanisms driving liver injury and failure

    Jing Ma / Adrien Guillot / Zhihong Yang / Bryan Mackowiak / Seonghwan Hwang / Ogyi Park / Brandon J. Peiffer / Ali Reza Ahmadi / Luma Melo / Praveen Kusumanchi / Nazmul Huda / Romil Saxena / Yong He / Yukun Guan / Dechun Feng / Pau Sancho-Bru / Mengwei Zang / Andrew MacGregor Cameron / Ramon Bataller /
    Frank Tacke / Zhaoli Sun / Suthat Liangpunsakul / Bin Gao

    The Journal of Clinical Investigation, Vol 132, Iss

    2022  Volume 14

    Abstract: Intrahepatic neutrophil infiltration has been implicated in severe alcoholic hepatitis (SAH) pathogenesis; however, the mechanism underlying neutrophil-induced injury in SAH remains obscure. This translational study aims to describe the patterns of ... ...

    Abstract Intrahepatic neutrophil infiltration has been implicated in severe alcoholic hepatitis (SAH) pathogenesis; however, the mechanism underlying neutrophil-induced injury in SAH remains obscure. This translational study aims to describe the patterns of intrahepatic neutrophil infiltration and its involvement in SAH pathogenesis. Immunohistochemistry analyses of explanted livers identified two SAH phenotypes despite a similar clinical presentation, one with high intrahepatic neutrophils (Neuhi), but low levels of CD8+ T cells, and vice versa. RNA-Seq analyses demonstrated that neutrophil cytosolic factor 1 (NCF1), a key factor in controlling neutrophilic ROS production, was upregulated and correlated with hepatic inflammation and disease progression. To study specifically the mechanisms related to Neuhi in AH patients and liver injury, we used the mouse model of chronic-plus-binge ethanol feeding and found that myeloid-specific deletion of the Ncf1 gene abolished ethanol-induced hepatic inflammation and steatosis. RNA-Seq analysis and the data from experimental models revealed that neutrophilic NCF1-dependent ROS promoted alcoholic hepatitis (AH) by inhibiting AMP-activated protein kinase (a key regulator of lipid metabolism) and microRNA-223 (a key antiinflammatory and antifibrotic microRNA). In conclusion, two distinct histopathological phenotypes based on liver immune phenotyping are observed in SAH patients, suggesting a separate mechanism driving liver injury and/or failure in these patients.
    Keywords Gastroenterology ; Medicine ; R
    Subject code 610
    Language English
    Publishing date 2022-07-01T00:00:00Z
    Publisher American Society for Clinical Investigation
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Schnyder corneal dystrophy-associated UBIAD1 inhibits ER-associated degradation of HMG CoA reductase in mice

    Youngah Jo / Jason S Hamilton / Seonghwan Hwang / Kristina Garland / Gennipher A Smith / Shan Su / Iris Fuentes / Sudha Neelam / Bonne M Thompson / Jeffrey G McDonald / Russell A DeBose-Boyd

    eLife, Vol

    2019  Volume 8

    Abstract: Autosomal-dominant Schnyder corneal dystrophy (SCD) is characterized by corneal opacification owing to overaccumulation of cholesterol. SCD is caused by mutations in UBIAD1, which utilizes geranylgeranyl pyrophosphate (GGpp) to synthesize vitamin K2. ... ...

    Abstract Autosomal-dominant Schnyder corneal dystrophy (SCD) is characterized by corneal opacification owing to overaccumulation of cholesterol. SCD is caused by mutations in UBIAD1, which utilizes geranylgeranyl pyrophosphate (GGpp) to synthesize vitamin K2. Using cultured cells, we previously showed that sterols trigger binding of UBIAD1 to the cholesterol biosynthetic enzyme HMG CoA reductase (HMGCR), thereby inhibiting its endoplasmic reticulum (ER)-associated degradation (ERAD) (Schumacher et al. 2015). GGpp triggers release of UBIAD1 from HMGCR, allowing maximal ERAD and ER-to-Golgi transport of UBIAD1. SCD-associated UBIAD1 resists GGpp-induced release and is sequestered in ER to inhibit ERAD. We now report knockin mice expressing SCD-associated UBIAD1 accumulate HMGCR in several tissues resulting from ER sequestration of mutant UBIAD1 and inhibition of HMGCR ERAD. Corneas from aged knockin mice exhibit signs of opacification and sterol overaccumulation. These results establish the physiological significance of UBIAD1 in cholesterol homeostasis and indicate inhibition of HMGCR ERAD contributes to SCD pathogenesis.
    Keywords ER-associated degradation ; vitamin K ; geranylgeranyl pyrophosphate ; cholesterol ; isoprenoid ; Schnyder corneal dystrophy ; Medicine ; R ; Science ; Q ; Biology (General) ; QH301-705.5
    Language English
    Publishing date 2019-02-01T00:00:00Z
    Publisher eLife Sciences Publications Ltd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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