An altered secretome is an early marker of the pathogenesis of CLN6 Batten disease. Issue 3 (16th January 2021)

• Record Type: Journal Article
• Authors: Best, Hannah L.; Clare, Alison J.; McDonald, Kirstin O.; Wicky, Hollie E.; Hughes, Stephanie M.
• Is Part Of: Journal of neurochemistry. Volume 157:Issue 3(2021)
• Page Start: 764
• Page End: 780
• Publication Date: 2021-01-16
• Subjects: Batten disease -- CLN6 -- gene therapy -- neuronal ceroid lipofuscinosis -- secretome; Neurochemistry -- Periodicals; 616.8042
• DOI: 10.1111/jnc.15285
• Languages: English
• ISSNs: 0022-3042

Abstract

Abstract: Neuronal ceroid lipofuscinoses (NCLs) are a group of inherited childhood neurodegenerative disorders. In addition to the accumulation of auto‐fluorescent storage material in lysosomes, NCLs are largely characterised by region‐specific neuroinflammation that can predict neuron loss. These phenotypes suggest alterations in the extracellular environment—making the secretome an area of significant interest. This study investigated the secretome in the CLN6 (ceroid‐lipofuscinosis neuronal protein 6) variant of NCL. To investigate the CLN6 secretome, we co‐cultured neurons and glia isolated from Cln6 nclf or Cln6 ± mice, and utilised mass spectrometry to compare protein constituents of conditioned media. The significant changes noted in cathepsin enzymes, were investigated further via western blotting and enzyme activity assays. Viral‐mediated gene therapy was used to try and rescue the wild‐type phenotype and restore the secretome—both in vitro in co‐cultures and in vivo in mouse plasma. In Cln6 nclf cells, proteomics revealed a marked increase in catabolic and cytoskeletal‐associated proteins—revealing new similarities between the pathogenic signatures of NCLs with other neurodegenerative disorders. These changes were, in part, corrected by gene therapy intervention, suggesting these proteins as candidate in vitro biomarkers. Importantly, these in vitro changes show promise for in vivo translation, with Cathepsin L (CTSL) activity reduced in both co‐cultures and Cln6 nclf plasma samples post gene‐therapy. This work suggests the secretome plays a role in CLN6 pathogenesis and highlights its potential use as an in vitro model. Proteomic changes present a list of candidate biomarkers for monitoring disease and assessing potential therapeutics in future studies. Abstract : Primary cultures isolated from a mouse model ( Cln6 nclf ) of the CLN6 variant of Neuronal Ceroid Lipofuscinoses have a significantly different secreted protein profile to that of healthy controls—such as a marked increase in Cathepsin secretion. Gene therapy treatment to Cln6 nclf cells partially restores the secretome profile. Furthermore, the increased Cathepsin L activity identified in diseased primary cultures is restored in vitro and in vivo post gene therapy. This work increases our understanding of disease processes in CLN6 NCL, identifies new similarities with other neurodegenerative disorders, and presents candidate biomarkers for future investigations into CLN6.