Loss of CLN3 in microglia leads to impaired lipid metabolism and myelin turnover.

Loss-of-function mutations in CLN3 cause juvenile Batten disease, featuring neurodegeneration and early-stage neuroinflammation. How loss of CLN3 function leads to early neuroinflammation is not yet understood. Here, we have comprehensively studied microglia from Cln3 mice, a genetically accurate disease model.

TPC2 rescues lysosomal storage in mucolipidosis type IV, Niemann-Pick type C1, and Batten disease.

Lysosomes are cell organelles that degrade macromolecules to recycle their components. If lysosomal degradative function is impaired, e.g.

Autophagy in the Neuronal Ceroid Lipofuscinoses (Batten Disease).

The neuronal ceroid lipofuscinoses (NCLs), also referred to as Batten disease, are a family of neurodegenerative diseases that affect all age groups and ethnicities around the globe. At least a dozen NCL subtypes have been identified that are each linked to a mutation in a distinct ceroid lipofuscinosis neuronal () gene. Mutations in genes cause the accumulation of autofluorescent lipoprotein aggregates, called ceroid lipofuscin, in neurons and other cell types outside the central nervous system.

CLN3, at the crossroads of endocytic trafficking.

The CLN3 gene was identified over two decades ago, but the primary function of the CLN3 protein remains unknown. Recessive inheritance of loss of function mutations in CLN3 are responsible for juvenile neuronal ceroid lipofuscinosis (Batten disease, or CLN3 disease), a fatal childhood onset neurodegenerative disease causing vision loss, seizures, progressive dementia, motor function loss and premature death. CLN3 is a multipass transmembrane protein that primarily localizes to endosomes and lysosomes.

Differential accumulation of storage bodies with aging defines discrete subsets of microglia in the healthy brain.

To date, microglia subsets in the healthy CNS have not been identified. Utilizing autofluorescence (AF) as a discriminating parameter, we identified two novel microglia subsets in both mice and non-human primates, termed autofluorescence-positive (AF) and negative (AF). While their proportion remained constant throughout most adult life, the AF signal linearly and specifically increased in AF microglia with age and correlated with a commensurate increase in size and complexity of lysosomal storage bodies, as detected by transmission electron microscopy and LAMP1 levels.

An Autophagy Modifier Screen Identifies Small Molecules Capable of Reducing Autophagosome Accumulation in a Model of CLN3-Mediated Neurodegeneration.

Alterations in the autophagosomal-lysosomal pathway are a major pathophysiological feature of CLN3 disease, which is the most common form of childhood-onset neurodegeneration. Accumulating autofluorescent lysosomal storage material in CLN3 disease, consisting of dolichols, lipids, biometals, and a protein that normally resides in the mitochondria, subunit c of the mitochondrial ATPase, provides evidence that autophagosomal-lysosomal turnover of cellular components is disrupted upon loss of CLN3 protein function. Using a murine neuronal cell model of the disease, which accurately mimics the major gene defect and the hallmark features of CLN3 disease, we conducted an unbiased search for modifiers of autophagy, extending previous work by further optimizing a GFP-LC3 based assay and performing a high-content screen on a library of ~2000 bioactive compounds.

Moving towards a new era of genomics in the neuronal ceroid lipofuscinoses.

The neuronal ceroid lipofuscinoses (NCL) are a group of disorders defined by shared clinical and pathological features, including seizures and progressive decline in vision, neurocognition, and motor functioning, as well as accumulation of autofluorescent lysosomal storage material, or 'ceroid lipofuscin'. Research has revealed thirteen distinct genetic subtypes. Precisely how the gene mutations lead to the clinical phenotype is still incompletely understood, but recent research progress is starting to shed light on disease mechanisms, in both gene-specific and shared pathways.

Lysosomal proteome analysis reveals that CLN3-defective cells have multiple enzyme deficiencies associated with changes in intracellular trafficking.

Numerous lysosomal enzymes and membrane proteins are essential for the degradation of proteins, lipids, oligosaccharides, and nucleic acids. The gene encodes a lysosomal membrane protein of unknown function, and mutations cause the fatal neurodegenerative lysosomal storage disorder CLN3 (Batten disease) by mechanisms that are poorly understood. To define components critical for lysosomal homeostasis that are affected by this disease, here we quantified the lysosomal proteome in cerebellar cell lines derived from a CLN3 knock-in mouse model of human Batten disease and control cells.

Novel DNA Aptamers that Bind to Mutant Huntingtin and Modify Its Activity.

The CAG repeat expansion that elongates the polyglutamine tract in huntingtin is the root genetic cause of Huntington's disease (HD), a debilitating neurodegenerative disorder. This seemingly slight change to the primary amino acid sequence alters the physical structure of the mutant protein and alters its activity. We have identified a set of G-quadruplex-forming DNA aptamers (MS1, MS2, MS3, MS4) that bind mutant huntingtin proximal to lysines K2932/K2934 in the C-terminal CTD-II domain.

Altered Expression of Ganglioside Metabolizing Enzymes Results in GM3 Ganglioside Accumulation in Cerebellar Cells of a Mouse Model of Juvenile Neuronal Ceroid Lipofuscinosis.

Juvenile neuronal ceroid lipofuscinosis (JNCL) is caused by mutations in the gene. Most JNCL patients exhibit a 1.02 kb genomic deletion removing exons 7 and 8 of this gene, which results in a truncated CLN3 protein carrying an aberrant C-terminus.

Individuals with progranulin haploinsufficiency exhibit features of neuronal ceroid lipofuscinosis.

Heterozygous mutations in the gene lead to progranulin (PGRN) haploinsufficiency and cause frontotemporal dementia (FTD), a neurodegenerative syndrome of older adults. Homozygous mutations, on the other hand, lead to complete PGRN loss and cause neuronal ceroid lipofuscinosis (NCL), a lysosomal storage disease usually seen in children. Given that the predominant clinical and pathological features of FTD and NCL are distinct, it is controversial whether the disease mechanisms associated with complete and partial PGRN loss are similar or distinct.

Aberrant adhesion impacts early development in a Dictyostelium model for juvenile neuronal ceroid lipofuscinosis.

Neuronal ceroid lipofuscinosis (NCL), also known as Batten disease, refers to a group of severe neurodegenerative disorders that primarily affect children. The most common subtype of the disease is caused by loss-of-function mutations in CLN3, which is conserved across model species from yeast to human. The precise function of the CLN3 protein is not known, which has made targeted therapy development challenging.

Diagnosis and misdiagnosis of adult neuronal ceroid lipofuscinosis (Kufs disease).

Objective: To critically re-evaluate cases diagnosed as adult neuronal ceroid lipofuscinosis (ANCL) in order to aid clinicopathologic diagnosis as a route to further gene discovery.

Methods: Through establishment of an international consortium we pooled 47 unsolved cases regarded by referring centers as ANCL. Clinical and neuropathologic experts within the Consortium established diagnostic criteria for ANCL based on the literature to assess each case.

Genetics of the neuronal ceroid lipofuscinoses (Batten disease).

The neuronal ceroid lipofuscinoses (NCLs) are a group of inherited neurodegenerative disorders that affect children and adults and are grouped together by similar clinical features and the accumulation of autofluorescent storage material. More than a dozen genes containing over 430 mutations underlying human NCLs have been identified. These genes encode lysosomal enzymes (CLN1, CLN2, CLN10, CLN13), a soluble lysosomal protein (CLN5), a protein in the secretory pathway (CLN11), two cytoplasmic proteins that also peripherally associate with membranes (CLN4, CLN14), and many transmembrane proteins with different subcellular locations (CLN3, CLN6, CLN7, CLN8, CLN12).

Unbiased Cell-based Screening in a Neuronal Cell Model of Batten Disease Highlights an Interaction between Ca2+ Homeostasis, Autophagy, and CLN3 Protein Function.

Abnormal accumulation of undigested macromolecules, often disease-specific, is a major feature of lysosomal and neurodegenerative disease and is frequently attributed to defective autophagy. The mechanistic underpinnings of the autophagy defects are the subject of intense research, which is aided by genetic disease models. To gain an improved understanding of the pathways regulating defective autophagy specifically in juvenile neuronal ceroid lipofuscinosis (JNCL or Batten disease), a neurodegenerative disease of childhood, we developed and piloted a GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3) screening assay to identify, in an unbiased fashion, genotype-sensitive small molecule autophagy modifiers, employing a JNCL neuronal cell model bearing the most common disease mutation in CLN3.

Future perspectives: Moving towards NCL treatments.

Clinicians, basic researchers, representatives from pharma and families from around the world met in Cordoba, Argentina in October, 2014 to discuss recent research progress at the 14th International Congress on Neuronal Ceroid Lipofuscinoses (NCLs; Batten disease), a group of clinically overlapping fatal, inherited lysosomal disorders with primarily neurodegenerative symptoms. This brief review article will provide perspectives on the anticipated future directions of NCL basic and clinical research as we move towards improved diagnosis, care and treatment of NCL patients. This article is part of a Special Issue entitled: Current Research on the Neuronal Ceroid Lipofuscinoses (Batten Disease).

Partial correction of the CNS lysosomal storage defect in a mouse model of juvenile neuronal ceroid lipofuscinosis by neonatal CNS administration of an adeno-associated virus serotype rh.10 vector expressing the human CLN3 gene.

Juvenile neuronal ceroid lipofuscinosis (JNCL or CLN3 disease) is an autosomal recessive lysosomal storage disease resulting from mutations in the CLN3 gene that encodes a lysosomal membrane protein. The disease primarily affects the brain with widespread intralysosomal accumulation of autofluorescent material and fibrillary gliosis, as well as the loss of specific neuronal populations. As an experimental treatment for the CNS manifestations of JNCL, we have developed a serotype rh.

A broad phenotypic screen identifies novel phenotypes driven by a single mutant allele in Huntington's disease CAG knock-in mice.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the expansion of a CAG trinucleotide repeat in the HTT gene encoding huntingtin. The disease has an insidious course, typically progressing over 10-15 years until death. Currently there is no effective disease-modifying therapy.

Human iPSC models of neuronal ceroid lipofuscinosis capture distinct effects of TPP1 and CLN3 mutations on the endocytic pathway.

Neuronal ceroid lipofuscinosis (NCL) comprises ∼13 genetically distinct lysosomal disorders primarily affecting the central nervous system. Here we report successful reprograming of patient fibroblasts into induced pluripotent stem cells (iPSCs) for the two most common NCL subtypes: classic late-infantile NCL, caused by TPP1(CLN2) mutation, and juvenile NCL, caused by CLN3 mutation. CLN2/TPP1- and CLN3-iPSCs displayed overlapping but distinct biochemical and morphological abnormalities within the endosomal-lysosomal system.

Neuronal ceroid lipofuscinosis: impact of recent genetic advances and expansion of the clinicopathologic spectrum.

Neuronal ceroid lipofuscinosis (NCL), first clinically described in 1826 and pathologically defined in the 1960s, refers to a group of disorders mostly diagnosed in the childhood years that involve the accumulation of lysosomal storage material with characteristic ultrastructure and prominent neurodegenerative features including vision loss, seizures, motor and cognitive function deterioration, and often times, psychiatric disturbances. All NCL disorders evidence early morbidity and treatment options are limited to symptomatic and palliative care. While distinct genetic forms of NCL have long been recognized, recent genetic advances are considerably widening the NCL genotypic and phenotypic spectrum, highlighting significant overlap with other neurodegenerative diseases.

A homozygous mutation in KCTD7 links neuronal ceroid lipofuscinosis to the ubiquitin-proteasome system.

Neuronal ceroid lipofuscinosis (NCL) is a genetically heterogeneous group of lysosomal diseases that collectively compose the most common Mendelian form of childhood-onset neurodegeneration. It is estimated that ∼8% of individuals diagnosed with NCL by conservative clinical and histopathologic criteria have been ruled out for mutations in the nine known NCL-associated genes, suggesting that additional genes remain unidentified. To further understand the genetic underpinnings of the NCLs, we performed whole-exome sequencing on DNA samples from a Mexican family affected by a molecularly undefined form of NCL characterized by infantile-onset progressive myoclonic epilepsy (PME), vision loss, cognitive and motor regression, premature death, and prominent NCL-type storage material.

An atypical case of neuronal ceroid lipofuscinosis with co-inheritance of a variably penetrant POLG1 mutation.

Background: The neuronal ceroid lipofuscinoses (NCLs, or Batten disease) comprise the most common Mendelian form of childhood-onset neurodegeneration, but the functions of the known underlying gene products remain poorly understood. The clinical heterogeneity of these disorders may shed light on genetic interactors that modify disease onset and progression.

Case Presentation: We describe a proband with congenital hypotonia and an atypical form of infantile-onset, biopsy-proven NCL.