Bone marrow transplantation corrects haemolytic anaemia in a novel ENU mutagenesis mouse model of TPI deficiency.

Ashlee J Conway,Elinor J Hortle,Stephen M Jane,David J Curtis,Fiona C Brown,Gaetan Burgio,Craig J Morton,Simon J Foote

doi:10.1242/dmm.034678

Abstract

ABSTRACTIn this study, we performed a genome-wide N-ethyl-N-nitrosourea (ENU) mutagenesis screen in mice to identify novel genes or alleles that regulate erythropoiesis. Here, we describe a recessive mouse strain, called RBC19, harbouring a point mutation within the housekeeping gene, Tpi1, which encodes the glycolysis enzyme, triosephosphate isomerase (TPI). A serine in place of a phenylalanine at amino acid 57 severely diminishes enzyme activity in red blood cells and other tissues, resulting in a macrocytic haemolytic phenotype in homozygous mice, which closely resembles human TPI deficiency. A rescue study was performed using bone marrow transplantation of wild-type donor cells, which restored all haematological parameters and increased red blood cell enzyme function to wild-type levels after 7 weeks. This is the first study performed in a mammalian model of TPI deficiency, demonstrating that the haematological phenotype can be rescued.

Highlights

Triosephosphate isomerase (TPI or TIM) is an anaerobic glycolysis enzyme encoded by the TPI1 gene at chromosomal position 12p13 in humans (Ralser et al, 2008)
Characterisation of a homozygous mouse strain with macrocytic haemolytic anaemia In an ENU mutagenesis screen designed to identify novel genes or alleles regulating erythropoiesis, we identified a mouse with macrocytic red cells, named RBC19
A phenylalanine-to-serine substitution at amino acid 57 severely reduced enzyme activity in multiple tissues, those with a high dependence on anaerobic glycolysis, such as red blood cells, bone marrow, and neurons. This novel model of triosephosphate isomerase (TPI) deficiency was utilised to demonstrate that the haematological phenotype could be rescued by transplantation using wildtype donor bone marrow

Summary

Introduction

Triosephosphate isomerase (TPI or TIM) is an anaerobic glycolysis enzyme encoded by the TPI1 gene at chromosomal position 12p13 in humans (Ralser et al, 2008). Of the approximate 13 pathological TPI1 mutations identified in humans so far, the Glu104Asp substitution has been the most commonly-identified variant, believed to be responsible for up to 80% of all reported cases of TPI deficiency (Arya et al, 1997; Schneider and Cohen-Solal, 1996). This mutation is believed to cause impaired dimerisation of the enzyme, which is crucial for its catalytic activity, while other variants can impair substrate binding to the active site (Ralser et al, 2006; Mainford et al, 1996; Oliver and Timson, 2017). No treatment is available nor has been trialled for TPI deficiency, likely owing to its rarity and fast mortality

Methods

Results

Conclusion