Germline Deletion of Pantothenate Kinases 1 and 2 Reveals the Key Roles for CoA in Postnatal Metabolism

Matthew Garcia,Yong-Mei Zhang,Suzanne Jackowski,Hironori Waki,Jerold E Rehg,Roberta Leonardi

doi:10.1371/journal.pone.0040871

Matthew Garcia, Yong-Mei Zhang + Show 4 more

Open Access

https://doi.org/10.1371/journal.pone.0040871

Copy DOI

Abstract

Pantothenate kinase (PanK) phosphorylates pantothenic acid (vitamin B5) and controls the overall rate of coenzyme A (CoA) biosynthesis. Pank1 gene deletion in mice results in a metabolic phenotype where fatty acid oxidation and gluconeogenesis are impaired in the fasted state, leading to mild hypoglycemia. Inactivating mutations in the human PANK2 gene lead to childhood neurodegeneration, but Pank2 gene inactivation in mice does not elicit a phenotype indicative of the neuromuscular symptoms or brain iron accumulation that accompany the human disease. Pank1/Pank2 double knockout (dKO) mice were derived to determine if the mild phenotypes of the single knockout mice are due to the ability of the two isoforms to compensate for each other in CoA biosynthesis. Postnatal development was severely affected in the dKO mice. The dKO pups developed progressively severe hypoglycemia and hyperketonemia by postnatal day 10 leading to death by day 17. Hyperketonemia arose from impaired whole-body ketone utilization illustrating the requirement for CoA in energy generation from ketones. dKO pups had reduced CoA and decreased fatty acid oxidation coupled with triglyceride accumulation in liver. dKO hepatocytes could not maintain the NADH levels compared to wild-type hepatocytes. These results revealed an important link between CoA and NADH levels, which was reflected by deficiencies in hepatic oleate synthesis and gluconeogenesis. The data indicate that PanK1 and PanK2 can compensate for each other to supply tissue CoA, but PanK1 is more important to CoA levels in liver whereas PanK2 contributes more to CoA synthesis in the brain.

Highlights

Coenzyme A (CoA) is a ubiquitous cofactor that activates acyl groups and participates in several metabolic processes, including fatty acid and lipid synthesis, fatty acid degradation, ketone metabolism and the tricarboxylic acid cycle
Pank2(flox/+) mice were bred with FVB/N-Tg(ACTB-cre)2 Mrt/J transgenic mice (Jackson Laboratories), and pups with a Pank2 allele in which exon 3 was deleted via Cre recombinase-dependent DNA excision were obtained
The postnatal lethality of the Pank1/Pank2 double knockout (dKO) mice coupled with the embryonic lethality of Pank1/Pank3 and Pank2/Pank3 dKO mice illustrate that normal development requires at least two functional Pantothenate kinase (PanK) isoforms

Summary

Introduction

Coenzyme A (CoA) is a ubiquitous cofactor that activates acyl groups and participates in several metabolic processes, including fatty acid and lipid synthesis, fatty acid degradation, ketone metabolism and the tricarboxylic acid cycle. CoA is derived from the vitamin pantothenate, and CoA synthesis is governed by the pantothenate kinases (PanKs), of which there are four active isoforms in mammals: PanK1a, PanK1b, PanK2 and PanK3 [1]. The PanK1a and b isoforms are derived from a single gene by use of alternate initiation exons [2], and PanK2 and PanK3 are encoded by separate, distinct genes [3,4]. PanK1 is the most insensitive among the PanK isoforms to acetyl-CoA feedback inhibition and its expression is highest in liver and kidney. PanK2 is the most stringently regulated among the PanK isoforms, being the most sensitive to inhibition by acetyl-CoA [10], and its expression is highest in testes [11], explaining the observed defect in sperm production in PanK2-null mice [12]

Methods

Results

Conclusion