|
2
|
Hsu J, Fatuzzo N, Weng N, Michno W, Dong W, Kienle M, Dai Y, Pasca A, Abu-Remaileh M, Rasgon N, Bigio B, Nasca C, Khosla C. Carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-L-carnitine into acetyl-CoA in mammalian cells. J Biol Chem 2023; 299:102848. [PMID: 36587768 PMCID: PMC9898754 DOI: 10.1016/j.jbc.2022.102848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 12/20/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022] Open
Abstract
In eukaryotes, carnitine is best known for its ability to shuttle esterified fatty acids across mitochondrial membranes for β-oxidation. It also returns to the cytoplasm, in the form of acetyl-L-carnitine (LAC), some of the resulting acetyl groups for posttranslational protein modification and lipid biosynthesis. While dietary LAC supplementation has been clinically investigated, its effects on cellular metabolism are not well understood. To explain how exogenous LAC influences mammalian cell metabolism, we synthesized isotope-labeled forms of LAC and its analogs. In cultures of glucose-limited U87MG glioma cells, exogenous LAC contributed more robustly to intracellular acetyl-CoA pools than did β-hydroxybutyrate, the predominant circulating ketone body in mammals. The fact that most LAC-derived acetyl-CoA is cytosolic is evident from strong labeling of fatty acids in U87MG cells by exogenous 13C2-acetyl-L-carnitine. We found that the addition of d3-acetyl-L-carnitine increases the supply of acetyl-CoA for cytosolic posttranslational modifications due to its strong kinetic isotope effect on acetyl-CoA carboxylase, the first committed step in fatty acid biosynthesis. Surprisingly, whereas cytosolic carnitine acetyltransferase is believed to catalyze acetyl group transfer from LAC to coenzyme A, CRAT-/- U87MG cells were unimpaired in their ability to assimilate exogenous LAC into acetyl-CoA. We identified carnitine octanoyltransferase as the key enzyme in this process, implicating a role for peroxisomes in efficient LAC utilization. Our work has opened the door to further biochemical investigations of a new pathway for supplying acetyl-CoA to certain glucose-starved cells.
Collapse
Affiliation(s)
- Jake Hsu
- Department of Chemical Engineering, Stanford University, Stanford, California, USA
| | - Nina Fatuzzo
- Department of Chemistry, Stanford University, Stanford, California, USA
| | - Nielson Weng
- Department of Chemistry, Stanford University, Stanford, California, USA
| | - Wojciech Michno
- Division of Neonatology, Department of Pediatrics, Stanford University, Stanford, California, USA
| | - Wentao Dong
- Department of Chemical Engineering, Stanford University, Stanford, California, USA; Department of Genetics, Stanford University, Stanford, California, USA
| | - Maryline Kienle
- Department of Chemistry, Stanford University, Stanford, California, USA
| | - Yuqin Dai
- Sarafan ChEM-H, Stanford, California, USA
| | - Anca Pasca
- Division of Neonatology, Department of Pediatrics, Stanford University, Stanford, California, USA
| | - Monther Abu-Remaileh
- Department of Chemical Engineering, Stanford University, Stanford, California, USA; Department of Genetics, Stanford University, Stanford, California, USA; Sarafan ChEM-H, Stanford, California, USA
| | - Natalie Rasgon
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, USA
| | - Benedetta Bigio
- Department of Psychiatry, Grossman School of Medicine, New York University, New York, New York, USA
| | - Carla Nasca
- Department of Psychiatry, Grossman School of Medicine, New York University, New York, New York, USA; Department of Neuroscience and Physiology, New York University Neuroscience Institute, Grossman School of Medicine, New York University, New York, New York, USA; Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, The Rockefeller University, New York, New York, USA
| | - Chaitan Khosla
- Department of Chemical Engineering, Stanford University, Stanford, California, USA; Department of Chemistry, Stanford University, Stanford, California, USA; Sarafan ChEM-H, Stanford, California, USA.
| |
Collapse
|
|
3
|
Abstract
In this full article, a detailed study of a distal alkenyl C-H arylation and alkylation through the palladium/norbornene (NBE) cooperative catalysis is described. Both aminopyridine- and oxime ether-type directing groups have been found effective for this transformation, allowing functionalization of diverse allyl amines and homoallyl alcohols. In addition, the C5,C6-substititued NBEs show optimal reactivity and selectivity. Various cis-olefins can be transformed to the corresponding arylated or alkylated trisubstituted alkenes with excellent regio- and stereoselectivity. Preliminary mechanistic studies support the Catellani pathway instead of the Heck pathway.
Collapse
Affiliation(s)
- Zhao Wu
- Department of Chemistry, The University of Chicago, 5735 S Ellis Ave, Chicago, IL, 60637, USA
| | - Nina Fatuzzo
- Department of Chemistry, The University of Chicago, 5735 S Ellis Ave, Chicago, IL, 60637, USA
| | - Guangbin Dong
- Department of Chemistry, The University of Chicago, 5735 S Ellis Ave, Chicago, IL, 60637, USA
| |
Collapse
|
|
4
|
Abstract
A distal-selective alkenyl C-H arylation method is reported through a directed palladium/norbornene (Pd/NBE) cooperative catalysis. The key is to use an appropriate combination of the directing group and the NBE cocatalyst. A range of acyclic and cyclic cis-olefins are suitable substrates, and the reaction is operated under air with excellent site-selectivity. Preliminary mechanistic studies are consistent with the proposed Pd/NBE-catalyzed C-H activation instead of the Heck pathway. Initial success on distal alkylation has also been achieved using MeI and methyl bromoacetate as electrophiles.
Collapse
Affiliation(s)
- Zhao Wu
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Nina Fatuzzo
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Guangbin Dong
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| |
Collapse
|
|
5
|
Abstract
Checkpoint blockade immunotherapy (CBI) elicits durable therapeutic responses by blocking T cell inhibitory pathways of tumors with pre-infiltrated T cells and/or high mutational burden to activate antitumor immunity but is ineffective against poorly immunogenic tumors. Immunogenic radiotherapy, photodynamic therapy (PDT), and chemotherapy have thus been examined as immunomodulatory adjuvants to augment CBI. Dysregulated hormone production has long been linked to tumorigenesis and poor prognosis of various cancers. Herein, we report the use of a Cu-porphyrin nanoscale metal-organic framework (nMOF) to mediate synergistic hormone-triggered chemodynamic therapy (CDT) and light-triggered PDT. The combination of CDT/PDT-based radical therapy with a programmed cell-death ligand 1 blockade effectively extends the local therapeutic effects of CDT/PDT to distant tumors via abscopal effects on mouse tumor models with high levels of estradiol. Our work thus establishes the feasibility of combining nMOF-mediated radical therapy with CBI to elicit systemic antitumor immunity in hormonally dysregulated tumor phenotypes.
Collapse
Affiliation(s)
- Kaiyuan Ni
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- These authors contributed equally to this work
| | - Theint Aung
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- These authors contributed equally to this work
| | - Shuyi Li
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- Laboratory of Controllable Nanopharmaceuticals, Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience and CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, No. 11 First North Road, Zhongguancun, Beijing 100190, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Nina Fatuzzo
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
| | - Xingjie Liang
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- Laboratory of Controllable Nanopharmaceuticals, Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience and CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, No. 11 First North Road, Zhongguancun, Beijing 100190, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Wenbin Lin
- Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
- Department of Radiation and Cellular Oncology and The Ludwig Center for Metastasis Research, The University of Chicago, Chicago, IL 60637, USA
| |
Collapse
|