Classical late infantile neuronal ceroid lipofuscinosis fibroblasts are deficient in lysosomal tripeptidyl peptidase I¹

Abstract

Tripeptidyl peptidase I (TPP-I) is a lysosomal enzyme that cleaves tripeptides from the N-terminus of polypeptides. A comparison of TPP-I amino acid sequences with sequences derived from an EST database suggested that TPP-I is identical to a pepstatin-insensitive carboxyl proteinase of unknown specificity which is mutated in classical late infantile neuronal ceroid lipofuscinosis (LINCL), a lysosomal storage disease. Both TPP-I and the carboxyl proteinase have an M r of about 46 kDa and are, or are predicted to be, resistant to inhibitors of the four major classes of proteinases. Fibroblasts from LINCL patients have less than 5% of the normal TPP-I activity. The activities of other lysosomal enzymes, including proteinases, are in the normal range. LINCL fibroblasts are also defective at degrading short polypeptides and this defect can be induced in normal fibroblasts by treatment with a specific inhibitor or TPP-I. These results suggest that the cell damage, especially neuronal, observed in LINCL results from the defective degradation and consequent lysosomal storage of small peptides.z 1999 Federation of European Biochemical Societies.

Gemfibrozil and Fenofibrate, Food and Drug Administration-approved Lipid-lowering Drugs, Up-regulate Tripeptidyl-peptidase 1 in Brain Cells via Peroxisome Proliferator-activated Receptor α

“…TPP1 Activity Assay-TPP-I activity was assayed in 96-well format plates using the following modification of the method described by Vines and Warburton (6). Briefly, samples and substrate (40 l) were mixed in individual wells of a polystyrene 96-well plate (Nalge Nunc International).…”

“…TPP1 Proteins Up-regulated by the Fibrate Drugs Are Functionally Active-Because the functional activity of the TPP1 protein is of critical importance in the clinical setting for LINCL (6), activity of the enzyme was measured. The cells were homogenized, and the cell extracts were subjected to TPP1 activity assay.…”

Neuronal loss and brain atrophy in mice lacking cathepsins B and L

“…Palmitoyl-protein-thioesterase-and tripeptidylpeptidase-I enzyme activities were determined by using the f luorogenic substrates MU-6S-palm-␤Glc (4-methylumbelliferyl-6-thiopalmitoyl ␤-D-galactopyranoside) (Moscerdam, Rotterdam, The Netherlands) and AAF-AMC (Ala-Ala-Phe-7-amido-4-methylcoumarin) (Sigma), respectively, and the assays were performed twice in triplicate as described (20)(21)(22).…”

The crystal structure of palmitoyl protein thioesterase 1 and the molecular basis of infantile neuronal ceroid lipofuscinosis

“…CLN2 codes for a lysosomal pepstatin-insensitive acid protease that is deficient in LINCL patients (38); the gene product of CLN3 is a lysosomal membrane protein of unknown function (39)(40)(41). LINCL and JNCL differ from INCL in the age of onset and severity of symptoms, and by differences in morphology of the lysosomal storage material (granular osmiophilic deposits in INCL, curvilinear inclusions in LINCL, and fingerprint inclusions in JNCL).…”