Pathogenic mutations cause rapid degradation of lysosomal storage disease-related membrane protein CLN6

Kurze, Anna-Katherina; Galliciotti, Giovanna; Heine, Claudia; Mole, Sara; Quitsch, Arne; Braulke, Thomas

doi:10.1002/humu.21184

Cited by 21 publications

(15 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In immortalized cerebellar neuronal precursor cell lines established from P4 nclf mice, expression of the mutant Cln6 mRNA was found to be reduced sixfold (Cao et al,2011). A similar observation was described in the OCLN6 South Hampshire sheep model for CLN6 disease (Tammen et al,2006), suggesting that, in these two animal models and in some human patients, CLN6 protein levels will be low or even unstable, as observed for the human c.307insC mutant CLN6 and the nclf Cln6 protein (Kurze et al,2010; G. Galliciotti, unpublished results). The lack of induced ER stress and the rapid proteasomal degradation of mutant CLN6 render it very unlikely that accumulation/aggregation of toxic Cln6 polypeptides accounts for this neurodegenerative disease.…”

Section: Discussionsupporting

confidence: 70%

High expression of disease‐related Cln6 in the cerebral cortex, purkinje cells, dentate gyrus, and hippocampal ca1 neurons

Thelen

Fehr

Schweizer

et al. 2011

J of Neuroscience Research

Self Cite

View full text Add to dashboard Cite

Mutations in the CLN6 gene cause a variant form of late infantile neuronal ceroid lipofuscinosis, a relentless neurodegenerative disease that is inherited as an autosomal recessive trait in humans and in the naturally occurring nclf mouse strain. The CLN6 protein is localized in the endoplasmic reticulum, but it has an unknown function. To develop a molecular understanding of neurodegeneration induced by mutations in CLN6, we examined the spatial and temporal distribution of Cln6 mRNA expression in murine brain. By using Northern blot and tissue qPCR array techniques, a single Cln6 transcript was detected throughout the adult brain, with greatest expression in the cerebellum and hypothalamus. Real-time qPCR showed 2.4-4-fold increases in Cln6 mRNA levels in the cortex and cerebellum during the first 28 days of life, with less prominent enhancement of expression in the hippocampus. In situ hybridization analyses demonstrated Cln6 expression in brainstem, dentate gyrus, and hippocampal neurons of newborn P0 mice. From P14 onward, Cln6 expression is widely distributed throughout the brain and is most prominent in cells of cortical layers II-VI, the Purkinje cell layer, dentate gyrus, and hippocampal CA1 region of adult mice. In different regions of the brain in P0 and P28 nclf mice, the Cln6 mRNA abundance was reduced by 30-40% compared with control mice. These findings implicate Cln6 in the survival and maturation of specific neuronal populations during development and make it possible to compare regional Cln6 expression with the distribution of subsequent pathology.

show abstract

Section: Discussionsupporting

confidence: 70%

High expression of disease‐related Cln6 in the cerebral cortex, purkinje cells, dentate gyrus, and hippocampal ca1 neurons

Thelen

Fehr

Schweizer

et al. 2011

J of Neuroscience Research

Self Cite

View full text Add to dashboard Cite

show abstract

“…The single cytosine insertion (c.307insC) in the Cln6 gene of nclf mice was also found in three families of Pakistan origin (c.316insC). These mutations are responsible for frameshifts and production of truncated proteins, p.R103PfsX62 and p.R106PfsX26, respectively [8], [9], [12]. The present expression studies showed that the newly synthesized mutant p.R103PfsX62 Cln6 is rapidly degraded similarly to mutant human CLN6 [12].…”

Section: Discussionmentioning

confidence: 52%

“…These mutations are responsible for frameshifts and production of truncated proteins, p.R103PfsX62 and p.R106PfsX26, respectively [8], [9], [12]. The present expression studies showed that the newly synthesized mutant p.R103PfsX62 Cln6 is rapidly degraded similarly to mutant human CLN6 [12]. The comparable half-lives of mutant human CLN6 and murine Cln6 indicate that the GFP-tag does not affect the stability of the mutant Cln6 protein.…”

Section: Discussionmentioning

confidence: 55%

“…Mutations in CLN6 cause variant late-onset neuronal ceroid lipofuscinosis (vLINCL [8], [9]) as well as an adult form of the disease [11]. Among the 55 disease-causing mutations identified in the CLN6 gene (http://www.ucl.ac.uk/ncl/cln6.shtml), a 1-bp insertion in exon 4 (c.316insC) causes a frame shift and a premature stop codon [12] leading to the production of a truncated protein (p.R106PfsX26). In the mouse ortholog, an identical mutation (c.307insC) has been identified in nclf mice [7], [8], a naturally occurring model for CLN6 disease recapitulating the phenotype of the disease [13].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Disruption of the Autophagy-Lysosome Pathway Is Involved in Neuropathology of the nclf Mouse Model of Neuronal Ceroid Lipofuscinosis

et al. 2012

Self Cite

View full text Add to dashboard Cite

Variant late-infantile neuronal ceroid lipofuscinosis, a fatal lysosomal storage disorder accompanied by regional atrophy and pronounced neuron loss in the brain, is caused by mutations in the CLN6 gene. CLN6 is a non-glycosylated endoplasmic reticulum (ER)-resident membrane protein of unknown function. To investigate mechanisms contributing to neurodegeneration in CLN6 disease we examined the nclf mouse, a naturally occurring model of the human CLN6 disease. Prominent autofluorescent and electron-dense lysosomal storage material was found in cerebellar Purkinje cells, thalamus, hippocampus, olfactory bulb and in cortical layer II to V. Another prominent early feature of nclf pathogenesis was the localized astrocytosis that was evident in many brain regions and the more widespread microgliosis. Expression analysis of mutant Cln6 found in nclf mice demonstrated synthesis of a truncated protein with a reduced half-life. Whereas the rapid degradation of the mutant Cln6 protein can be inhibited by proteasomal inhibitors, there was no evidence for ER stress or activation of the unfolded protein response in various brain areas during postnatal development. Age-dependent increases in LC3-II, ubiquitinated proteins, and neuronal p62-positive aggregates were observed, indicating a disruption of the autophagy-lysosome degradation pathway of proteins in brains of nclf mice, most likely due to defective fusion between autophagosomes and lysosomes. These data suggest that proteasomal degradation of mutant Cln6 is sufficient to prevent the accumulation of misfolded Cln6 protein, whereas lysosomal dysfunction impairs constitutive autophagy promoting neurodegeneration.

show abstract

“…Of note, the same frame-shift mutation (c.307insC) is found in CLN6 nclf mice and human CLN6 patients. Cell culture expression studies with mutant CLN6 revealed that the decrease in CLN6 transcripts caused a corresponding decrease in protein levels [35]. Nonsense-mediated decay has also been reported for CLN1, CLN2, and CLN3 and a potential therapeutic option could be treatment with read-through drugs that enhance protein function.…”

Section: Discussionmentioning

confidence: 92%

Progressive Retinal Degeneration and Glial Activation in the CLN6nclf Mouse Model of Neuronal Ceroid Lipofuscinosis: A Beneficial Effect of DHA and Curcumin Supplementation

et al. 2013

View full text Add to dashboard Cite

Neuronal ceroid lipofuscinosis (NCL) is a group of neurodegenerative lysosomal storage disorders characterized by vision loss, mental and motor deficits, and spontaneous seizures. Neuropathological analyses of autopsy material from NCL patients and animal models revealed brain atrophy closely associated with glial activity. Earlier reports also noticed loss of retinal cells and reactive gliosis in some forms of NCL. To study this phenomenon in detail, we analyzed the ocular phenotype of CLN6nclf mice, an established mouse model for variant-late infantile NCL. Retinal morphometry, immunohistochemistry, optokinetic tracking, electroretinography, and mRNA expression were used to characterize retinal morphology and function as well as the responses of Müller cells and microglia. Our histological data showed a severe and progressive degeneration in the CLN6nclf retina co-inciding with reactive Müller glia. Furthermore, a prominent phenotypic transformation of ramified microglia to phagocytic, bloated, and mislocalized microglial cells was identified in CLN6nclf retinas. These events overlapped with a rapid loss of visual perception and retinal function. Based on the strong microglia reactivity we hypothesized that dietary supplementation with immuno-regulatory compounds, curcumin and docosahexaenoic acid (DHA), could ameliorate microgliosis and reduce retinal degeneration. Our analyses showed that treatment of three-week-old CLN6nclf mice with either 5% DHA or 0.6% curcumin for 30 weeks resulted in a reduced number of amoeboid reactive microglia and partially improved retinal function. DHA-treatment also improved the morphology of CLN6nclf retinas with a preserved thickness of the photoreceptor layer in most regions of the retina. Our results suggest that microglial reactivity closely accompanies disease progression in the CLN6nclf retina and both processes can be attenuated with dietary supplemented immuno-modulating compounds.

show abstract

Pathogenic mutations cause rapid degradation of lysosomal storage disease-related membrane protein CLN6

Cited by 21 publications

References 26 publications

High expression of disease‐related Cln6 in the cerebral cortex, purkinje cells, dentate gyrus, and hippocampal ca1 neurons

High expression of disease‐related Cln6 in the cerebral cortex, purkinje cells, dentate gyrus, and hippocampal ca1 neurons

Disruption of the Autophagy-Lysosome Pathway Is Involved in Neuropathology of the nclf Mouse Model of Neuronal Ceroid Lipofuscinosis

Progressive Retinal Degeneration and Glial Activation in the CLN6nclf Mouse Model of Neuronal Ceroid Lipofuscinosis: A Beneficial Effect of DHA and Curcumin Supplementation

Contact Info

Product

Resources

About