Department of Molecular and Cell Biology, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA.
Sci Adv. 2023 May 3;9(18):eadf0138. doi: 10.1126/sciadv.adf0138.
Proliferating cells rely on acetyl-CoA to support membrane biogenesis and acetylation. Several organelle-specific pathways are available for provision of acetyl-CoA as nutrient availability fluctuates, so understanding how cells maintain acetyl-CoA homeostasis under such stresses is critically important. To this end, we applied C isotope tracing cell lines deficient in these mitochondrial [ATP-citrate lyase (ACLY)]-, cytosolic [acetyl-CoA synthetase (ACSS2)]-, and peroxisomal [peroxisomal biogenesis factor 5 (PEX5)]-dependent pathways. ACLY knockout in multiple cell lines reduced fatty acid synthesis and increased reliance on extracellular lipids or acetate. Knockout of both ACLY and ACSS2 (DKO) severely stunted but did not entirely block proliferation, suggesting that alternate pathways can support acetyl-CoA homeostasis. Metabolic tracing and PEX5 knockout studies link peroxisomal oxidation of exogenous lipids as a major source of acetyl-CoA for lipogenesis and histone acetylation in cells lacking ACLY, highlighting a role for inter-organelle cross-talk in supporting cell survival in response to nutrient fluctuations.
增殖细胞依赖乙酰辅酶 A 来支持膜生物发生和乙酰化。随着营养物质可用性的波动，有几种细胞器特异性途径可提供乙酰辅酶 A，因此了解细胞在这些应激下如何维持乙酰辅酶 A 稳态至关重要。为此，我们应用 C 同位素示踪方法，研究了这些线粒体 [三磷酸柠檬酸裂合酶 (ACLY)]、细胞质 [乙酰辅酶 A 合成酶 (ACSS2)] 和过氧化物酶体 [过氧化物酶体生物发生因子 5 (PEX5)] 依赖性途径缺陷的细胞系。在多种细胞系中敲除 ACLY 会减少脂肪酸合成并增加对细胞外脂质或醋酸盐的依赖。同时敲除 ACLY 和 ACSS2（双敲除，DKO）严重抑制但并未完全阻止增殖，表明替代途径可以维持乙酰辅酶 A 稳态。代谢追踪和 PEX5 敲除研究将过氧化物酶体氧化外源性脂质与 lipogenesis 和组蛋白乙酰化的乙酰辅酶 A 的主要来源联系起来，这突出了细胞器间相互作用在支持细胞对营养物质波动的生存反应中的作用。
