Increased expression of subunit c of mitochondrial ATP synthase in brain tissue from neuronal ceroid lipofuscinoses and mucopolysaccharidosis cases but not in long-term fibroblast cultures.

Recent data showed storage of subunit c of mitochondrial ATP synthase in late infantile, juvenile, and adult forms of neuronal ceroid lipofuscinosis (NCL). The present study demonstrates that the expression of subunit c in NCL fibroblasts in long-term cultures, both grown in standard conditions and after leupeptin and ammonium chloride treatment, is not greater than in controls. It indicates that as a result of yet undefined factors, NCL fibroblasts in long-term cultures, lose their ability to accumulate subunit c. Moreover, both Western blot analysis of brain tissue homogenates and immunohistochemistry showed increased immunoreactivity to subunit c in mucopolysaccharidosis type I and III. This increased subunit c expression in a disorder with impaired lysosomal function other than the NCL supports the hypothesis that accumulation of this proteolipid might be related to its defective degradation.