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Neuronal Ceroid Lipofuscinosis (NCL), also known as Batten disease, is an incurable childhood brain disease. The thirteen forms of NCL are caused by mutations in thirteen CLN genes. Mutations in one CLN gene, CLN5, cause variant late-infantile NCL, with an age of onset between 4 and 7 years. The CLN5 protein is ubiquitously expressed in the majority of tissues studied and in the brain, CLN5 shows both neuronal and glial cell expression. Mutations in CLN5 are associated with the accumulation of autofluorescent storage material in lysosomes, the recycling units of the cell, in the brain and peripheral tissues. CLN5 resides in the lysosome and its function is still elusive. Initial studies suggested CLN5 was a transmembrane protein, which was later revealed to be processed into a soluble form. Multiple glycosylation sites have been reported, which may dictate its localisation and function. CLN5 interacts with several CLN proteins, and other lysosomal proteins, making it an important candidate to understand lysosomal biology. The existing knowledge on CLN5 biology stems from studies using several model organisms, including mice, sheep, cattle, dogs, social amoeba and cell cultures. Each model organism has its advantages and limitations, making it crucial to adopt a combinatorial approach, using both human cells and model organisms, to understand CLN5 pathologies and design drug therapies. In this comprehensive review, we have summarised and critiqued existing literature on CLN5 and have discussed the missing pieces of the puzzle that need to be addressed to develop an efficient therapy for CLN5 Batten disease.

Gliomas are highly malignant tumors with a rapid progression and poor prognosis. The present study investigated the cellular effects of CLN5-knockdown in the glioblastoma (GBM) U251 and U87MG cell lines. The Cell Counting Kit-8 and colony formation assays indicated that CLN5-knockdown inhibited the proliferation of GBM cells. Additionally, the results of the Transwell and scratch assays revealed that CLN5-knockdown significantly inhibited migration and invasion, and the flow cytometry analysis confirmed that apoptosis was promoted. Knockdown of CLN5 downregulated the expression levels of MMP-2, Bcl-2, cyclin D1, CDK4 and CDK6, and upregulated the expression levels of Bax and activated caspase-9. Additionally, it blocked GBM cells in the G1-phase and induced early apoptosis. Knockdown of CLN5 inhibited the activation of the Akt and mTOR signaling pathways in GBM by decreasing the levels of phosphorylated (p)-Akt and p-mTOR. The present data suggested that downregulation of CLN5 may be a potential treatment option for GBM. Knockdown of CLN5 inhibited the development of GBM via the inhibition of the Akt and mTOR signaling pathways.

Mutations in CLN5 cause a subtype of neuronal ceroid lipofuscinosis (NCL) called CLN5 disease. While the precise role of CLN5 in NCL pathogenesis is not known, recent work revealed that the protein has glycoside hydrolase activity. Previous work on the Dictyostelium discoideum homolog of human CLN5, Cln5, revealed its secretion during the early stages of development and its role in regulating cell adhesion and cAMP-mediated chemotaxis. Here, we used Dictyostelium to examine the effect of cln5-deficiency on various growth and developmental processes during the life cycle. During growth, cln5– cells displayed reduced cell proliferation, cytokinesis, viability, and folic acid-mediated chemotaxis. In addition, the growth of cln5– cells was severely impaired in nutrient-limiting media. Based on these findings, we assessed autophagic flux in growth-phase cells and observed that loss of cln5 increased the number of autophagosomes suggesting that the basal level of autophagy was increased in cln5– cells. Similarly, loss of cln5 increased the amounts of ubiquitin-positive proteins. During the early stages of multicellular development, the aggregation of cln5– cells was delayed and loss of the autophagy genes, atg1 and atg9, reduced the extracellular amount of Cln5. We also observed an increased amount of intracellular Cln5 in cells lacking the Dictyostelium homolog of the human glycoside hydrolase, hexosaminidase A (HEXA), further supporting the glycoside hydrolase activity of Cln5. This observation was also supported by our finding that CLN5 and HEXA expression are highly correlated in human tissues. Following mound formation, cln5– development was precocious and loss of cln5 affected spore morphology, germination, and viability. When cln5– cells were developed in the presence of the autophagy inhibitor ammonium chloride, the formation of multicellular structures was impaired, and the size of cln5– slugs was reduced relative to WT slugs. These results, coupled with the aberrant autophagic flux observed in cln5– cells during growth, support a role for Cln5 in autophagy during the Dictyostelium life cycle. In total, this study highlights the multifaceted role of Cln5 in Dictyostelium and provides insight into the pathological mechanisms that may underlie CLN5 disease.

Neuronal ceroid lipofuscinoses (NCLs) are a group of autosomal recessive inherited neurodegenerative disorders mainly affecting children, and at least 13 causative genes (CLN1 to CLN8 and CLN10 to CLN14) have been identified. Here, we reported a novel homozygous missense mutation (c.434G > C, p.Arg145Pro) identified in CLN5 gene via whole exome sequencing in a 5-year-old girl. The patient first presented paroxysmal epilepsy associated with vomiting, followed by progressive regression in walking, vision, intelligence and speaking. Combining the molecular and clinical analysis, the diagnosis of NCL could be made, although the missense mutation (c.434G > C, p.Arg145Pro) in CLN5 was evaluated to be a variant of uncertain significance according to American College of Medical Genetics and Genomics (ACMG) standard. We further performed expression and localization studies and our results provide evidence of impaired cellular trafficking of CLN5 to lysosome, indicating that this mutation might be deleterious to the function of CLN5 for its mislocalization. Our study demonstrated the efficacy of next generation sequencing in molecular diagnosis, and a deleterious effect of the variant discovered in our patient on CLN5, triggering the NCL disease.

Batten disease (neuronal ceroid lipofuscinosis) refers to a group of neurodegenerative lysosomal storage diseases predominantly affecting children. There are currently no effective treatments, and the functions of many of the associated gene products are unknown. Here we characterise fetal neural cultures from two genetically distinct sheep forms of Batten disease, with mutations in the lysosomal protein encoding gene CLN5 and endoplasmic reticulum membrane protein encoding gene CLN6, respectively. We found similar reductions in autophagy, acidic organelles and synaptic recycling in both forms compared to unaffected cells. We then developed a high-throughput screen and tested for correction of deficient cells with lentiviral-mediated CLN5 or CLN6 gene transfer and fibrate drugs, gemfibrozil and fenofibrate in CLN6 deficient neural cultures. These assays provide a simple system to rapidly screen candidate therapies or libraries of drugs prior to in vivo testing.

Neuronal Ceroid Lipofuscinoses (NCLs) are progressive degenerative diseases mainly affect brain and retina. They are characterized by accumulation of autofluorescent storage material, mitochondrial ATPase subunit C, or sphingolipid activator proteins A and D in lysosomes of most cells. Heterogenous storage material in NCLs is not completely disease-specific. Most of CLN proteins and their natural substrates are not well-characterized. Studies have suggested variants of Late-Infantile NCLs (LINCLs) include the major type CLN2 and minor types CLN5, CLN6, CLN7, and CLN8. Therefore, combination of clinical and molecular analysis has become a more effective diagnosis method. We studied 4 late-infantile NCL siblings characterized by seizures, ataxia as early symptoms, followed by progressive regression in intelligence and behavior, but mutations are located in different genes. Symptoms and progression of 4 types of LINCLs are compared. Pathology of LINCLs is also discussed. We performed Nest-Generation Sequencing on these phenotypically similar families. Three novel variants c.1551+1insTGAT in TPP1, c.244G>T in CLN6, c.554-5A>G in MFSD8 were identified. Potential outcome of the mutations in structure and function of proteins are studied. In addition, we observed some common and unique clinical features of Chinese LINCL patient as compared with those of Western patients, which greatly improved our understanding of the LINCLs.

The neuronal ceroid lipofuscinoses (NCLs) are a group of devastating neurological disorders that have a global distribution and affect people of all ages. Commonly known as Batten disease, this form of neurodegeneration is linked to mutations in 13 genetically distinct genes. The precise mechanisms underlying the disease are unknown, in large part due to our poor understanding of the functions of NCL proteins. The social amoeba Dictyostelium discoideum has proven to be an exceptional model organism for studying a wide range of neurological disorders, including the NCLs. The Dictyostelium genome contains homologs of 11 of the 13 NCL genes. Its life cycle, comprised of both single-cell and multicellular phases, provides an excellent system for studying the effects of NCL gene deficiency on conserved cellular and developmental processes. In this review, we highlight recent advances in NCL research using Dictyostelium as a biomedical model.

Background Neuronal ceroid lipofuscinosis (NCL) is a hereditary lysosomal storage disease with progressive brain neurodegeneration. Mutations in ceroid lipofuscinosis neuronal protein 5 (CLN5) cause CLN5 disease, a severe condition characterized by seizures, visual failure, motor decline, and progressive cognitive deterioration. This study aimed to identify causative gene variants in Pakistani consanguineous families diagnosed with NCL. Methods After a thorough clinical and neuroradiological characterization, whole exome sequencing (WES) was performed in 3 patients from 2 unrelated families. Segregation analysis was subsequently performed through Sanger sequencing Analysis WES led to the identification of the 2 novel homozygous variants c.925_926del, (p.Leu309AlafsTer4) and c.477 T > C, (p.Cys159Arg). Conclusion In this study, we report two novel CLN5 cases in the Punjab region of Pakistan. Our observations will help clinicians observe and compare common and unique clinical features of NCL patients, further improving our current understanding of NCL., Highlights • Neuronal ceroid lipofuscinosis is a hereditary lysosomal storage disease. • It is characterized by progressive brain neurodegeneration. • WES was performed in 3 patients from 2 unrelated Pakistani families. • WES led to the identification of the 2 novel homozygous variants. • We report a novel CLN5 case in the Punjab region of Pakistan.

Studies on naturally occurring New Zealand and Australian ovine models of the neuronal ceroid-lipofuscinoses (Batten disease, NCLs) have greatly aided our understanding of these diseases. Close collaborations between the New Zealand groups at Lincoln University and the University of Otago, Dunedin, and a group at the University of Sydney, Australia, led to the formation of BARN, the Batten Animal Research Network. This review focusses on presentations at the 14th International Conference on Neuronal Ceroid Lipofuscinoses (Batten Disease), recent relevant background work, and previews of work in preparation for publication. Themes include CLN5 and CLN6 neuronal cell culture studies, studies on tissues from affected and control animals and whole animal in vivo studies. Topics include the effect of a CLN6 mutation on endoplasmic reticulum proteins, lysosomal function and the interactions of CLN6 with other lysosomal activities and trafficking, scoping gene-based therapies, a molecular dissection of neuroinflammation, identification of differentially expressed genes in brain tissue, an attempted therapy with an anti-inflammatory drug in vivo and work towards gene therapy in ovine models of the NCLs. This article is part of a Special Issue entitled: "Current Research on the Neuronal Ceroid Lipofuscinoses (Batten Disease)".

The neuronal ceroid lipofuscinoses (NCLs) are a group of devastating neurological disorders that have a global distribution and affect people of all ages. Commonly known as Batten disease, this form of neurodegeneration is linked to mutations in 13 genetically distinct genes. The precise mechanisms underlying the disease are unknown, in large part due to our poor understanding of the functions of NCL proteins. The social amoeba Dictyostelium discoideum has proven to be an exceptional model organism for studying a wide range of neurological disorders, including the NCLs. The Dictyostelium genome contains homologs of 11 of the 13 NCL genes. Its life cycle, comprised of both single-cell and multicellular phases, provides an excellent system for studying the effects of NCL gene deficiency on conserved cellular and developmental processes. In this review, we highlight recent advances in NCL research using Dictyostelium as a biomedical model.

Batten disease (neuronal ceroid lipofuscinoses, NCLs) are a group of inherited childhood diseases that result in severe brain atrophy, blindness and seizures, leading to premature death. To date, eight different genes have been identified, each associated with a different form. Linkage analysis indicated a CLN5 form in a colony of affected New Zealand Borderdale sheep. Sequencing. studies established the disease-causing mutation to be a substitution at a consensus splice site (c.571+1G>A), leading to the excision of exon 3 and a truncated putative protein. A molecular diagnostic test has been developed based on the excision of exon 3. Sequence alignments support the gene product being a soluble lysosomal protein. Western blotting of isolated storage bodies indicates the specific storage of subunit c of mitochondrial ATP synthase. This flock is being expanded as a large animal model for mechanistic studies and trial therapies. (C) 2007 Elsevier Inc. All rights reserved.

The neuronal ceroid lipofuscinoses (NCLs, Batten disease) are recessively inherited neurodegenerative disorders that affect humans and other animals, characterised by brain atrophy and the accumulation of lysosome derived fluorescent storage bodies in neurons and most other cells. Common clinical signs include blindness, ataxia, dementia, seizures and premature death. The associated genes for six different human forms have been identified (CLN1, CLN2, CLN3, CLN5, CLN6 and CLN8), and three other human forms suggested (CLNs 4, 7 and 9). A form of NCL in Australian Devon cattle is caused by a single base duplication (c.662dupG) in bovine CLN5. This mutation causes a frame-shift and premature termination (p.Arg221GlyfsX6) which is predicted to result in a severely truncated protein, analogous to disease causing mutations in human Finnish late infantile variant NCL (CLN5), and a simple genetic diagnostic test has been developed. The symptoms and disease course in cattle also matches CLN5. Only one initiation site was found in the bovine gene, equivalent to the third of four possible initiation sites in the human gene. As cattle are anatomically and physiologically similar to humans with a human-like central nervous system and easy to maintain and breed, they provide a valuable alternative model for CLN5 studies.