Batten disease and the ATP synthase subunit c turnover pathway: Raising antibodies to subunit c

Abstract

Analysis of storage bodies in the ceroid-lipofuscinoses (Batten disease) has demonstrated a high protein content suggestive of a proteinosis. Direct N-terminal sequencing has shown that subunit c of mitochondrial ATP synthase is specifically stored in the disease in sheep and cattle, and in the human late infantile and juvenile diseases, as well as in 3 breeds of dogs. No differences have been found between the stored subunit c and that in normal mitochondria. No other mitochondrial components are stored. Different proteins, sphingolipid activator proteins (SAPs or saposins) A and D, are stored in the infantile disease. Linkage studies have shown that different forms of ceroid-lipofuscinosis are coded for on different genes on different chromosomes. The genes for subunit c, its production, its insertion into mitochondria, and mitochondrial function are normal. This suggests that underlying the various forms of the disease is a family of lesions in the normal pathway of subunit c turnover, after its normal insertion into the ATP synthase complex. Antibodies to subunit c offer one way of mapping that pathway and detecting the sites of lesions. Specific antibodies have been raised against stored subunit c, using a liposomal adjuvant system which proved superior to classical adjuvants. These antibodies are also useful diagnostically, both in Western blotting and in immunocytochemistry.

Lysosomal accumulation of SCMAS (subunit c of mitochondrial ATP synthase) in neurons of the mouse model of mucopolysaccharidosis III B

“…Use of antiserum raised against full-length SCMAS [22] yielded similar results (not shown) as the antibody against the amino terminus. It is therefore likely that the edges of arrays were stained preferentially because they provided better accessibility to the antibody.…”

Interaction among Btn1p, Btn2p, and Ist2p Reveals Potential Interplay among the Vacuole, Amino Acid Levels, and Ion Homeostasis in the Yeast Saccharomyces cerevisiae

“…Btn1p is 39% identical and 59% similar to human Cln3 protein, mutations in which result in the lysosomal storage disorder Batten disease (11,22). Batten disease is characterized by accumulation of lipopigments in the lysosome (6,8,14,20,21). In summary, btn1⌬ cells are known to have an altered regulation of vacuolar pH and a decrease in the ability to transport basic amino acids into the vacuole, features which presumably account for the decreased levels of basic amino acids in the vacuole.…”

Interaction with Btn2p Is Required for Localization of Rsg1p: Btn2p-Mediated Changes in Arginine Uptake in Saccharomyces cerevisiae

“…We further demonstrated that yeast strains lacking Btn1p were resistant to D-(Ϫ)-threo-2-amino-1-[p-nitrophenyl]-1,3-propanediol (ANP) and that this phenotype was complemented by expression of the human Cln3 protein, indicating that yeast Btn1p and the human Cln3 protein have some functional overlap (17). Furthermore, the degree of ANP resistance was correlated with point mutations identified in the human CLN3 gene that are associated with less-severe forms of Batten disease, further establishing the functional equivalence of Btn1p and the human Cln3 protein (15). The human Cln3 protein, like Btn1p, has been localized to the lysosome, denoted the vacuole in yeast (3,7,9,10,18).…”

“…A characteristic of Batten disease is the lysosomal storage or accumulation of lipopigments such as lipofuscin in all cell types. A predominant component of this storage material is proteolipid subunit c of mitochondrial ATP synthase (6,12,14,15). However, despite knowledge of the genetic defect and evidence for Batten disease being a lysosomal storage disease, an understanding of the molecular basis for Batten disease remains elusive.…”