A Murine Model of Variant Late Infantile Ceroid Lipofuscinosis Recapitulates Behavioral and Pathological Phenotypes of Human Disease

Abstract

Neuronal ceroid lipofuscinoses (NCLs; also known collectively as Batten Disease) are a family of autosomal recessive lysosomal storage disorders. Mutations in as many as 13 genes give rise to ∼10 variants of NCL, all with overlapping clinical symptomatology including visual impairment, motor and cognitive dysfunction, seizures, and premature death. Mutations in CLN6 result in both a variant late infantile onset neuronal ceroid lipofuscinosis (vLINCL) as well as an adult-onset form of the disease called Type A Kufs. CLN6 is a non-glycosylated membrane protein of unknown function localized to the endoplasmic reticulum (ER). In this study, we perform a detailed characterization of a naturally occurring Cln6 mutant (Cln6nclf) mouse line to validate its utility for translational research. We demonstrate that this Cln6nclf mutation leads to deficits in motor coordination, vision, memory, and learning. Pathologically, we demonstrate loss of neurons within specific subregions and lamina of the cortex that correlate to behavioral phenotypes. As in other NCL models, this model displays selective loss of GABAergic interneuron sub-populations in the cortex and the hippocampus with profound, early-onset glial activation. Finally, we demonstrate a novel deficit in memory and learning, including a dramatic reduction in dendritic spine density in the cerebral cortex, which suggests a reduction in synaptic strength following disruption in CLN6. Together, these findings highlight the behavioral and pathological similarities between the Cln6nclf mouse model and human NCL patients, validating this model as a reliable format for screening potential therapeutics.

A CLN6-CLN8 complex recruits lysosomal enzymes at the ER for Golgi transfer

“…Commonly associated symptoms include cognitive decline, seizures, retinopathy and gait difficulties with patients first reporting to the clinic between two and eight years of age (14)(15)(16). Naturally occurring mouse models for CLN6 and CLN8 diseases have been widely characterized and have been shown to mimic many of the disease phenotypes (17). Like human patients, mutant mice die prematurely and exhibit dysfunctional lysosomal metabolism in multiple tissues and organs (18,19).…”

Neuron–astrocyte interactions in neurodegenerative diseases: Role of neuroinflammation

“…Reactive astrocytes have also been described in LINCL and variant late infantile NCL forms (i.e. CLN5 and CLN6), which often precedes neurodegeneration …”

A multimodal approach to identify clinically relevant parameters to monitor disease progression in a preclinical model of neuropediatric disease

“…The selective vulnerability of various populations of neurons is a key feature of many neurodegenerative diseases, including Batten disease ( 27, 28 ). Prior studies have demonstrated that thinning of select anatomical regions and different cortical layers is present in Cln6 nclf mice ( 9, 12, 14, 19 ), however, all of these measurements are based on invasive, histopathological analysis of post-mortem tissues. To identify progressive changes in brain architecture, we examined cohorts of mice longitudinally up to one year of age with T2 weighted magnetic resonance (T2-MRI) and diffusion tensor imaging (DTI).…”

“…We hypothesized that by looking at various non-invasive disease markers as a system, rather than individually, we could provide a highly sensitive tool that may be translatable to the clinic. Sample size, endpoints, and rules for stopping data collection were determined based on our previously published studies on this model ( 83 ). No outliers were removed from any data sets.…”

“…As the disease progresses, patients lose vision, develop seizures and ultimately succumb to the disease around 10-12 years of life. The spontaneously occurring Cln6 nclf mouse model of CLN6 disease has been shown to faithfully recapitulate many of the hallmarks of the human disease both behaviorally and pathologically ( 9, 10 ), but noninvasive, clinically relevant assays have not yet been employed to characterize longitudinal changes in this model. Various scientists, our lab included, have performed a very comprehensive pathological assessment of Batten disease rodent and large animal models to reveal how different brain regions change over time, however, these experiments were all conducted on post-mortem brain samples ( 11-20 ).…”