Objective: Batten disease (BD), the juvenile form of neuronal ceroid lipofuscinosis (NCLs), is pathological characterized by finding lysosomal storage of autofluorescent lipofuscins with unique ultrastructural profiles. The gene underlying BD is designated CLN3 and encodes a protein, Battenin, of unknown function that localizes in lysosomes and/or mitochondria. Previously, we hypothesized that Battenin associates with other membrane protein(s) to form a membrane complex. Dysfunction of this complex could result in the pathological changes of BD, and possibly in other NCLs. Two such membranous proteins, the slow and fast Battenin-interactive proteins (BIPs and BIPf) of unknown functions, have been identified. In this study, we have characterized the functional domains of Battenin that interact with both BIP proteins. Methods: Protein-protein interactions with a yeast two-hybrid system were employed. A "deletion assay" was employed to localize the interactive segment(s). Different lengths of cDNA sequences lacking exon 1-5 were used to express CLN3-encoded proteins lacking N-terminal segments in the yeast two-hybrid system. N-terminal exons of CLN3 were deleted with PCR-cloning strategies.Results: We eliminated the possibility of interacting domains from the exon 7-encoded region because both Battenin and mBattenin interact with the BIP proteins. We have shown that peptide sequences encoded by exons 2 and 4 of CLN3 gene include the functional domains by which Battenin interacts with the BIP proteins. Conclusion: Our studies provide evidence that the N-terminus of Battenin is the functional domain for these protein interactions.

Objective:Genotype-phenotype associations were studied in 517 subjects clinically affected by classical neuronal ceroid lipofuscinosis (NCL). Methods:Genetic loci CLN1-3 were analyzed in regard to age of onset, initial neurological symptoms, and electron microscope (EM) profiles. Results: The most common initial symptom leading to a clinical evaluation was developmental delay (30%) in NCL1, seizures (42.4%) in NCL2, and vision problems (53.5%) in NCL3. Eighty-two percent of NCL1 cases had granular osmiophilic deposits (GRODs) or mixed-GROD-containing EM profiles; 94% of NCL2 cases had curvilinear (CV) or mixed-CV-containing profiles; and 91% of NCL3 had fingerprint (FP) or mixed-FP-containing profiles. The mixed-type EM profile was found in approximately one-third of the NCL cases. DNA mutations within a specific CLN gene were further correlated with NCL phenotypes. Seizures were noticed to associate with common mutations 523G>A and 636C>T of CLN2 in NCL2 but not with common mutations 223G>A and 451C>T of CLN1 in NCL1. Vision loss was the initial symptom in all types of mutations in NCL3. Surprisingly, our data showed that the age of onset was atypical in 51.3% of NCL1 (infantile form) cases, 19.7% of NCL2 (late-infantile form) cases, and 42.8% of NCL3 (juvenile form) cases.Conclusion:Our data provide an overall picture regarding the clinical recognition of classical childhood NCLs. This may assist in the prediction and genetic identification of NCL1-3 via their characteristic clinical features.