Paradoxical activation of SREBP1c and de novo lipogenesis by hepatocyte-selective ACLY depletion in obese mice [preprint]
Yenilmez, Batuhan ; Kelly, Mark ; Zhang, Guofang ; Wetoska, Nicole ; Ilkayeva, Olga R. ; Min, Kyounghee ; Rowland, Leslie ; DiMarzio, Chloe ; He, Wentao ; Raymond, Naideline ... show 10 more
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Kelly, Mark
Zhang, Guofang
Wetoska, Nicole
Ilkayeva, Olga R.
Min, Kyounghee
Rowland, Leslie
DiMarzio, Chloe
He, Wentao
Raymond, Naideline
Lifshitz, Lawrence
Pan, Meixia
Han, Xianlin
Xie, Jun
Friedline, Randall H.
Kim, Jason K
Gao, Guangping
Herman, Mark A.
Newgard, Christopher B.
Czech, Michael P.
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Abstract
Hepatic steatosis associated with high fat diets, obesity and type 2 diabetes is thought to be the major driver of severe liver inflammation, fibrosis, and cirrhosis. Cytosolic acetyl-coenzyme A (AcCoA), a central metabolite and substrate for de novo lipogenesis (DNL), is produced from citrate by ATP-citrate lyase (ACLY) and from acetate through AcCoA synthase short chain family member 2 (ACSS2). However, the relative contributions of these two enzymes to hepatic AcCoA pools and DNL rates in response to high fat feeding is unknown. We report here that hepatocyte-selective depletion of either ACSS2 or ACLY caused similar 50% decreases in liver AcCoA levels in obese mice, showing that both pathways contribute to generation of this DNL substrate. Unexpectedly however, the hepatocyte ACLY depletion in obese mice paradoxically increased total DNL flux measured by D2O incorporation into palmitate, while in contrast ACSS2 depletion had no effect. The increase in liver DNL upon ACLY depletion was associated with increased expression of nuclear sterol regulatory element-binding protein 1c (SREBP1c) and of its target DNL enzymes. This upregulated DNL enzyme expression explains the increased rate of palmitate synthesis in ACLY depleted livers. Furthermore, this increased flux through DNL may also contribute to the observed depletion of AcCoA levels due to its increased conversion to Malonyl CoA (MalCoA) and palmitate. Together, these data indicate that in HFD fed obese mice, hepatic DNL is not limited by its immediate substrates AcCoA or MalCoA, but rather by activities of DNL enzymes.
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Paradoxical activation of SREBP1c and de novo lipogenesis by hepatocyte-selective ACLY depletion in obese mice Batuhan Yenilmez, Mark Kelly, Guofang Zhang, Nicole Wetoska, Olga R. Ilkayeva, Kyounghee Min, Leslie Rowland, Chloe DiMarzio, Wentao He, Naideline Raymond, Lawrence Lifshitz, Meixia Pan, Xianlin Han, Jun Xie, Randall H. Friedline, Jason K. Kim, Guangping Gao, Mark A. Herman, Christopher B. Newgard, Michael P. Czech bioRxiv 2022.03.21.485183; doi: https://doi.org/10.1101/2022.03.21.485183
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This article is a preprint. Preprints are preliminary reports of work that have not been certified by peer review.
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Now published in Journal of Biological Chemistry, https://doi.org/10.1016/j.jbc.2022.102401