Aberrant upregulation of the glycolytic enzyme PFKFB3 in CLN7 neuronal ceroid lipofuscinosis

Irene López-Fabuel ,Juan P Bolaños,Daniel Jiménez-Blasco ,Paula Alonso-Batan,Jordi Llop,Tristan R Mckay,Rubén Quintana-Cabrera ,Marta Guevara-Ferrer,Ángeles Almeida ,Lorna M Fitzpatrick ,Aseel M Sharaireh ,Brenda Morant-Ferrando,Emilio Fernàndez ,Christopher D Thompton,П О Федичев ,Nicoló Bonora ,Stephan Storch,Diego L Medina,Pedro Ramos‐Cabrer ,Sara Mole ,Olga Burmistrova,Marina Garcia-Macía ,Costantina Buondelmonte,Carlos Vicente-Gutiérrez

doi:10.1038/s41467-022-28191-1

Abstract

CLN7 neuronal ceroid lipofuscinosis is an inherited lysosomal storage neurodegenerative disease highly prevalent in children. CLN7/MFSD8 gene encodes a lysosomal membrane glycoprotein, but the biochemical processes affected by CLN7-loss of function are unexplored thus preventing development of potential treatments. Here, we found, in the Cln7∆ex2 mouse model of CLN7 disease, that failure in autophagy causes accumulation of structurally and bioenergetically impaired neuronal mitochondria. In vivo genetic approach reveals elevated mitochondrial reactive oxygen species (mROS) in Cln7∆ex2 neurons that mediates glycolytic enzyme PFKFB3 activation and contributes to CLN7 pathogenesis. Mechanistically, mROS sustains a signaling cascade leading to protein stabilization of PFKFB3, normally unstable in healthy neurons. Administration of the highly selective PFKFB3 inhibitor AZ67 in Cln7∆ex2 mouse brain in vivo and in CLN7 patients-derived cells rectifies key disease hallmarks. Thus, aberrant upregulation of the glycolytic enzyme PFKFB3 in neurons may contribute to CLN7 pathogenesis and targeting PFKFB3 could alleviate this and other lysosomal storage diseases.

Highlights

CLN7 neuronal ceroid lipofuscinosis is an inherited lysosomal storage neurodegenerative disease highly prevalent in children
Neuronal 7 (CLN7) disease belongs to a group of neuronal ceroid lipofuscinoses (NCLs) that present in late infancy[4–6] and, whereas CLN7/major facilitator superfamily domain containing 8 (MFSD8) gene is known to encode a lysosomal membrane glycoprotein[4,7–9], the biochemical processes affected by CLN7-loss of function are unexplored, which has hampered the development of therapeutic interventions[1,10]
Isolation of mitochondria followed by blue-native gel electrophoresis (BNGE), complex I (CI) in-gel activity assay (IGA), and western blotting, revealed CI disassembly from mitochondrial supercomplexes (SCs) in Cln7Δex[2] neurons (Fig. 1e)

Summary

Introduction

CLN7 neuronal ceroid lipofuscinosis is an inherited lysosomal storage neurodegenerative disease highly prevalent in children. CLN7/MFSD8 gene encodes a lysosomal membrane glycoprotein, but the biochemical processes affected by CLN7-loss of function are unexplored preventing development of potential treatments. Aberrant upregulation of the glycolytic enzyme PFKFB3 in neurons may contribute to CLN7 pathogenesis and targeting PFKFB3 could alleviate this and other lysosomal storage diseases. Neuronal 7 (CLN7) disease belongs to a group of NCLs that present in late infancy[4–6] and, whereas CLN7/major facilitator superfamily domain containing 8 (MFSD8) gene is known to encode a lysosomal membrane glycoprotein[4,7–9], the biochemical processes affected by CLN7-loss of function are unexplored, which has hampered the development of therapeutic interventions[1,10]. Using the Cln7Δex[2] mouse model of CLN7 disease, we found an aberrant upregulation of pro-glycolytic enzyme PFKFB3 in neurons that may contribute to CLN7 pathogenesis

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Conclusion