Page 37 - N. Metabolism and metabolic diseases

Loss of the E3 ubiquitin ligase MKRN1 represses NAFLD
(Non-alcoholic fatty liver disease) through AMPK activation

Hyun-Ji Han*, Jaewhan Song
Department of Biochemistry, College of Life science and Biotechnology,
Yonsei University, Seoul, Korea
BACKGROUND AIM

Non-alcoholic fatty liver disease (NAFLD) is an important risk MKRN1-depleted mice showed AMPK activation in the liver,
factor for chronic metabolic syndrome. Makorin ring finger resulting in the significant suppression of diet-induced
protein 1 (MKRN1) acts as an E3 ubiquitin ligase for the AMP- metabolic syndrome. Moreover, we demonstrated the
activated protein kinase (AMPK). AMPK is a master regulator of therapeutic effect of MKRN1 using MKRN1-depleted high-
energy metabolism in response to nutritional status. Here, we nutrient-fed mice that reversed the non-alcoholic fatty liver
report the identification of MKRN1 as a novel regulator to disease. We suggest that MKRN1 repression could be a
prevent NAFLD. potential therapeutic strategy for metabolic disorders.

METHODS
MKRN1-null mice and their WT littermates (MKRN1+/+) were bred from MKRN1+/− mice and were randomly grouped for all the
experiments. For HFD induced obesity experiments, male MKRN1+/+ and MKRN1−/− mice were placed on either an HFD (60%
calories from fat; D12492, Research DIET Inc., NJ, USA) or a standard chow diet (17% calories from fat; 38057, Cargill Agri
Purina Inc., Republic of Korea) for 20 weeks starting at 6–8 weeks of age. For HFHF induced NASH experiments, male
MKRN1+/+ and MKRN1 -/- mice were placed on HFD with 30% High Froctose water for 20 weeks at 6-8 weeks of age. All the
mice were maintained under temperature-controlled and light-controlled (standard 12-h light–dark cycles) conditions and provided
with food and water ad libitum.
RESULTS

Figure 1 Figure 2 Figure 3
a a a

b b c d b

Figure 1. A lack of MKRN1 expression reduces obesity in mice placed on an HFD for 16weeks
(a) Male WT and MK1-/- mice fed a chow diet or an HFD for 16 weeks. (a) Representative images of male WT and MK1-/- mice fed a chow diet (left) or an HFD
(right). (b) H&E staining of livers. Scale bar = left; 250µm, middle; 100µm and right; 25µm.

Figure 2. A lack of MKRN1 expression reduces obesity in mice placed on an HFD for 20weeks
(a) Male WT and MK1-/- mice fed an HFD for 20 weeks. Representative images of male WT and MK1-/- mice fed an HFD. (b-c) Body weight gain in male mice fed an
HFD for 20 weeks (HFD, WT n = 7 and MK1-/- n = 5).(d) MK1-/- male mice exhibited a reduced liver weight.

Figure 3. A lack of MKRN1 expression reduces obesity and NASH in mice placed on an HFHF for 20weeks
(a) Male WT and MK1-/- mice fed an HFHF for 20 weeks. (b) Representative images of male WT and MK1-/- mice fed an HFHF. (b) H&E staining of livers. Scale bar
= left; 250µm, middle; 100µm and right; 25µm.
CONCLUSION REFERENCES ACKNOWLEDGEMENTS
• MKRN1 knock-out mice reduces Gray, T. A., Wilson, A., Fortin, P. J. & We specifically thank Deyu Feng
High fat diet induced obesity and Nicholls, R. D. The putatively functional (Northwestern University) and T. A. Gray
NAFLD. Mkrn1-p1 pseudogene is neither expressed (David Axelrod Institute) for their support in
nor imprinted, nor does it regulate its source providing MKRN1-null mice.
• Loss of MKRN1 result in benefit gene in trans. Proc. Natl Acad. Sci. USA 103,
effect on various NASH induced diet 12039–12044 (2006). Contact information
in mice.
Lee, M. S & Han, H. J et al. Loss of the E3 Hyun-Ji Han
• MKRN1 could be a potential ubiquitin ligase MKRN1 represses diet- hyunji89@yonsei.ac.kr
therapeutic target for alleviating the induced metabolic syndrome through AMPK Department of Biochemistry, College of Life Science
symptoms of NASH. activation. Nat Commun. 9, 3404 (2018) and Biotechnology, Yonsei University, Seoul, 03722,
Republic of Korea