👤 Dinesh Rakheja

The neuronal ceroid-lipofuscinoses (NCL's, Batten disease) represent a group of severe neurodegenerative diseases, which mostly present in childhood. The phenotypes are similar and include visual loss, seizures, loss of motor and cognitive function, and early death. At autopsy, there is massive neuronal loss with characteristic storage in remaining neurons. Neurons appear to die because of increased rates of apoptosis and altered autophagy. Ten genes have been identified so far that result in an NCL (CLN1-10). The most common forms are CLN1, CLN2, and CLN3, which were previously known as Infantile, Late-Infantile, and Juvenile NCL's, respectively. CLN1 and CLN2 result from mutations in soluble lysosomal enzymes palmitoyl-protein thioesterase (PPT) and tripeptidyl peptidase 1 (TPP1), which can be measured in white blood cells for clinical diagnosis. Molecular diagnostic testing is routinely available for CLN1, CLN2, and CLN3. Sequencing of other NCL genes may be required to establish a diagnosis when the common forms are ruled out. The pathogenesis of NCL neuronal loss resulting from loss of function of any of the NCL gene products remains unknown and no treatment options are presently available. Show less

Juvenile neuronal ceroid-lipofuscinosis (JNCL, Batten disease, Spielmeyer-Vogt-Sjogren disease, CLN3) is the most common inherited, autosomal recessive, neurodegenerative disorder in man. Like the other neuronal ceroid-lipofuscinoses, it is characterized by progressive loss of vision, seizures, and loss of cognitive and motor functions, leading to premature demise. JNCL is caused by mutations of CLN3, a gene that encodes a hydrophobic transmembrane protein, which localizes to membrane lipid rafts in lysosomes, endosomes, synaptosomes, and cell membrane. While the primary function of the CLN3 protein (CLN3P) may be debated, its absence affects numerous cellular functions including pH regulation, arginine transport, membrane trafficking, and apoptosis. We have recently suggested that the unifying primary function of CLN3P may be in a novel palmitoyl-protein Delta-9 desaturase (PPD) activity that in our opinion could explain all of the various functional abnormalities seen in the JNCL cells. Another group of researchers has recently shown a correlation between the CLN3P expression and the synthesis of bis(monoacylglycerol)phosphate (BMP) and suggested that CLN3P may play a role in the biosynthesis of BMP. In this review, following an introduction to the neuronal ceroid-lipofuscinoses, we provide a brief overview and an update of the most recent research in JNCL, specifically that related to the function of CLN3P. Show less

Batten's disease, one of the most common recessively inherited, untreatable, neurodegenerative diseases of humans, is characterized by progressive neuronal loss and intraneuronal proteolipid storage. Although the gene for the disorder was cloned more than a decade ago, the function of the encoded protein, CLN3P, has not been defined thus far. Sequence analysis using the Pfam server identified a low stringency match to a fatty acid desaturase domain in the N-terminal sequence of CLN3P. We developed a fatty acid desaturase assay based on measurement of desaturase products by gas chromatography/mass spectrometry. We show that CLN3P is a novel palmitoyl-protein Delta-9 desaturase, which converts membrane-associated palmitoylated proteins to their respective palmitoleated derivatives. We have further demonstrated that this palmitoyl-protein Delta-9 desaturase activity is deficient in cln3(-/-) mouse pancreas and is completely ablated in neuroblastoma cells by RNA inhibition. We propose that palmitoyl-protein desaturation defines a new mechanism of proteolipid modification, and that deficiency of this process leads to the signs and symptoms of Batten's disease. Show less

Juvenile neuronal ceroid-lipofuscinosis (JNCL) or Batten/Spielmeyer-Vogt-Sjogren disease (OMIM #204200) is one of a group of nine clinically related inherited neurodegenerative disorders (CLN1-9). JNCL results from mutations in CLN3 on chromosome 16p12.1. The neuronal loss in Batten disease has been shown to be due to a combination of apoptosis and autophagy suggesting that CLN3P, the defective protein, may have an anti-neuronal death function. PANDER (PANcreatic-DERived factor) is a novel cytokine that was recently cloned from pancreatic islet cells. PANDER is specifically expressed in the pancreatic islets, small intestine, testis, prostate, and neurons of the central nervous system, and has been demonstrated to induce apoptosis. In this study, we over-expressed CLN3P in SH-SY5Y neuroblastoma cells and monitored the effects on PANDER-induced apoptosis. CLN3P significantly increased the survival rate of the SH-SY5Y cells in this system. This study provides additional evidence that the function of CLN3P is related to preventing neuronal apoptosis. Show less

Juvenile neuronal ceroid lipofuscinosis is an inherited pediatric neurodegenerative disorder, which occurs as a result of mutations in the CLN3 gene that is located on chromosome 16p12.1. The encoded protein, CLN3P, is a putative transmembrane protein with no known function. In this study, we demonstrate that CLN3P resides on membrane lipid raft domains (detergent-resistant membranes) and provide important new data towards possible functions of the protein. Show less