title: Immunochemical localization of the Batten disease (CLN3) protein in retina.
abstract: OBJECTIVE
  Batten disease, also known as juvenile ceroid-lipofuscinosis and CLN3, is an autosomal recessively inherited disorder that results in blindness due to retinal degeneration. The CLN3 gene has been identified, but the function of the protein that this gene encodes is unknown. Experiments were conducted to determine where the CLN3 protein is localized in the mouse retina. Localization should provide a clue in evaluating potential functions of this protein.
  
  
  METHODS
  Using oligonucleotide primers based on the reported human CLN3 cDNA sequence, the mouse cDNA nucleotide sequence was determined from products of the reverse transcriptase-polymerase chain reaction and 3' rapid amplification of cDNA ends. A synthetic 20-amino-acid peptide corresponding to an internal hydrophilic region of the predicted amino acid sequence of the mouse CLN3 protein was used to immunize rabbits. The resulting antiserum was used in immunoblot analysis of mouse retina homogenates and in electron microscopic immunocytochemical labeling of mouse retina sections.
  
  
  RESULTS
  The peptide antibody labeled a single protein band of approximately 50 kDa on immunoblots of mouse retina homogenates. No labeling was detected with homogenates from human retinas. The antibody specifically labeled mitochondria of Müller cells and inner retinal neurons. Little labeling was observed in mitochondria of the photoreceptor cells. Mitochondria of other cell types, including the retinal pigment epithelium and choroidal cells, were not labeled.
  
  
  CONCLUSIONS
  The retinal CLN3 protein appears to be localized almost exclusively in the mitochondria, but was detected only in certain cell types. Batten disease is characterized by massive lysosomal accumulations of a small inner mitochondrial membrane protein (subunit c of ATP synthase). The mitochondrial localization of the CLN3 protein suggests that it may play a role in the normal processing of subunit c.
authors.affiliation: Mason Eye Institute, University of Missouri School of Medicine, Columbia 65212, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Katz
authors.forename: C L
authors.initials: CL
authors.lastname: Gao
authors.forename: M
authors.initials: M
authors.lastname: Prabhakaram
authors.forename: H
authors.initials: H
authors.lastname: Shibuya
authors.forename: P C
authors.initials: PC
authors.lastname: Liu
authors.forename: G S
authors.initials: GS
authors.lastname: Johnson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000032:analysis; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D008562:Membrane Glycoproteins; D051379:Mice; D008810:Mice, Inbred C57BL; D016253:Microscopy, Immunoelectron; D008928:Mitochondria / Q000737:chemistry / Q000648:ultrastructure; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009472:Neuronal Ceroid-Lipofuscinoses / Q000473:pathology; D010446:Peptide Fragments / Q000032:analysis; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000032:analysis* / Q000235:genetics / Q000276:immunology / Q000648:ultrastructure; D011817:Rabbits; D012160:Retina / Q000737:chemistry* / Q000648:ultrastructure; D017386:Sequence Homology, Amino Acid
chemical_list: C105199:CLN3 protein, human; C102229:CLN3 protein, mouse; D017931:DNA Primers; D018076:DNA, Complementary; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; D010446:Peptide Fragments; D011506:Proteins