Tissue Proteome of 2-Hydroxyacyl-CoA Lyase Deficient Mice Reveals Peroxisome Proliferation and Activation of ω-Oxidation.

Youssef Khalil,Francesca Mazzacuva,Fujun Lin,Sara Falcone,Heena V Lad,Anna Ferlin,Daniel P Gale,Gareth Banks,Danilo Concas,Natalie Rivers,Kevin Mills,Sara Carrino,Andrew Blease ,Carlos Aguilar ,Andrew R Haynes ,Paul K Potter ,Raya Al‐Shawi ,Wendy Heywood ,T Nicol ,Peter T Clayton

doi:10.3390/ijms23020987

Abstract

Peroxisomal fatty acid α-oxidation is an essential pathway for the degradation of β-carbon methylated fatty acids such as phytanic acid. One enzyme in this pathway is 2-hydroxyacyl CoA lyase (HACL1), which is responsible for the cleavage of 2-hydroxyphytanoyl-CoA into pristanal and formyl-CoA. Hacl1 deficient mice do not present with a severe phenotype, unlike mice deficient in other α-oxidation enzymes such as phytanoyl-CoA hydroxylase deficiency (Refsum disease) in which neuropathy and ataxia are present. Tissues from wild-type and Hacl1−/− mice fed a high phytol diet were obtained for proteomic and lipidomic analysis. There was no phenotype observed in these mice. Liver, brain, and kidney tissues underwent trypsin digestion for untargeted proteomic liquid chromatography-mass spectrometry analysis, while liver tissues also underwent fatty acid hydrolysis, extraction, and derivatisation for fatty acid gas chromatography-mass spectrometry analysis. The liver fatty acid profile demonstrated an accumulation of phytanic and 2-hydroxyphytanic acid in the Hacl1−/− liver and significant decrease in heptadecanoic acid. The liver proteome showed a significant decrease in the abundance of Hacl1 and a significant increase in the abundance of proteins involved in PPAR signalling, peroxisome proliferation, and omega oxidation, particularly Cyp4a10 and Cyp4a14. In addition, the pathway associated with arachidonic acid metabolism was affected; Cyp2c55 was upregulated and Cyp4f14 and Cyp2b9 were downregulated. The kidney proteome revealed fewer significantly upregulated peroxisomal proteins and the brain proteome was not significantly different in Hacl1−/− mice. This study demonstrates the powerful insight brought by proteomic and metabolomic profiling of Hacl1−/− mice in better understanding disease mechanism in fatty acid α-oxidation disorders.

Highlights

The primary mechanism for fatty acid degradation involves β-oxidation, in which a multistep enzymatic pathway converts fatty acid chains into acetyl-CoAs and 2-carbon shorter fatty acyl-CoAs which can in turn undergo further β-oxidation
Hacl1protein apparently nowhen ob−/− mice were apparently healthy, with no analysed by Western blot
In agreement with the results obtained by Mezzar et al [11], this study found that Hacl1 deficient mice fed a high phytol diet had significantly higher hepatic levels of phytanic and

Summary

Introduction

The primary mechanism for fatty acid degradation involves β-oxidation, in which a multistep enzymatic pathway converts fatty acid chains into acetyl-CoAs and 2-carbon shorter fatty acyl-CoAs which can in turn undergo further β-oxidation. This mechanism is prevented in the presence of a methyl group on the β-carbon such as with the 3-methylbranched phytanic acid (3,7,11,15-tetramethyl hexadecanoic acid). Pristanic acid with a C-2 in an (R)-configuration requires conversation to an (S)-configuration by α-methylacyl-CoA racemase (AMACR) in order to undergo β-oxidation [1] Another pathway for fatty acid degradation is through ω-oxidation, in which dicarboxylic acids are formed and subsequently undergo β-oxidation from the

Methods

Results

Conclusion