We performed a biochemical study on the patient with mucolipidosis III (ML-III, pseudo-Hurler polydystrophy) in Korea. Confluent fibroblasts from the patient and from normal controls were cultured for 4, 12, 24, 48, and 72 hr, respectively. Lysosomal enzyme activities in culture media after different incubation times and in plasma, leukocytes, and fibroblasts were determined. Most of the leukocyte lysosomal enzymes were within normal limits or slightly lowered; however, plasma lysosomal enzyme activities such as those of hexosaminidase and arylsulfatase A were markedly increased. Numerous phase-dense inclusions were present in the cytoplasm of cultured fibroblasts. Lysosomal enzyme activities of fibroblasts were markedly decreased except for beta-glucosidase. The rates of increase of the lysosomal enzyme activities with incubation time were greater in the culture medium of the patient than in normal control, whereas no difference in the beta-glucosidase activity of the culture media of the patient and the control was found. This study describes the first case of ML-III in Korea, with its typical biochemical characteristics, i.e., a problem with targeting and transporting of lysosomal enzymes which results in a marked increase in plasma lysosomal enzyme activities and a high ratio of extracellular to intracellular lysosomal enzyme activities in cultured fibroblasts.
Cerebroside-Sulfatase/blood ; Child, Preschool ; Culture Media/metabolism ; Cytoplasm/metabolism ; Female ; Fibroblasts/metabolism ; Human ; Korea ; Lysosomes/metabolism ; Microscopy, Phase-Contrast ; Mucolipidoses/*metabolism ; Support, Non-U.S. Gov't ; Time Factors ; beta-Glucosidase/metabolism ; beta-N-Acetylhexosaminidase/blood

TRPML1 channel is a non-selective group-2 transient receptor potential (TRP) channel with Ca permeability. Located mainly in late endosome and lysosome of all mammalian cell types, TRPML1 is indispensable in the processes of endocytosis, membrane trafficking, and lysosome biogenesis. Mutations of TRPML1 cause a severe lysosomal storage disorder called mucolipidosis type IV (MLIV). In the present study, we determined the cryo-electron microscopy (cryo-EM) structures of Mus musculus TRPML1 (mTRPML1) in lipid nanodiscs and Amphipols. Two distinct states of mTRPML1 in Amphipols are added to the closed state, on which could represent two different confirmations upon activation and regulation. The polycystin-mucolipin domain (PMD) may sense the luminal/extracellular stimuli and undergo a "move upward" motion during endocytosis, thus triggering the overall conformational change in TRPML1. Based on the structural comparisons, we propose TRPML1 is regulated by pH, Ca, and phosphoinositides in a combined manner so as to accommodate the dynamic endocytosis process.
Animals ; Calcium ; metabolism ; Cryoelectron Microscopy ; Endocytosis ; Endosomes ; metabolism ; Gene Expression ; HEK293 Cells ; Humans ; Hydrogen-Ion Concentration ; Lysosomes ; metabolism ; Mice ; Models, Biological ; Mucolipidoses ; genetics ; metabolism ; pathology ; Nanostructures ; chemistry ; ultrastructure ; Phosphatidylinositols ; metabolism ; Transgenes ; Transient Receptor Potential Channels ; chemistry ; genetics ; metabolism

Diseases of inborn errors of metabolism (IEMs) are very rare but the overall prevalence of IEMs is not low, and in the United States, about 5~10% of admitted patients have some genetic predispositions. Clinical manifestations of IEMs are very diverse, but most frequent manifestations are neurological symptoms and signs. IEMs in Korea have been underestimated because of prejudice, underdevelopment of diagnostic tools and ignorance. The Korean Pediatric Society has done a retrospective study in order to know the relative incidence of IEMs in 2001. All hospitals with over 100 beds participated in the study. The most frequent disease was Wilson disease (201 cases for 10 years) followed by phenylketonuria (98 cases for 10 years) and Hunters disease (69 cases for 10 years). Disorders of mineral metabolism were the most frequently diagnosed disease groups (252 cases for 10 years) followed by organic acidopathies (220 cases), aminoacidopathies (139 cases), mucopolysaccharidosis (131 cases), disorders of carbohydrate metabolism (84 cases), sphingolipidosis (69 cases), urea cycle disorders (39 cases), peroxisomal disorders (27 cases), porphyrias (16 cases), disorders of purine and pyrimidine metabolism (14 cases), disorders of membrane transport (13 cases), fatty acid oxidation disorders (9 cases), oligosaccharidosis (2 cases), and mucolipidosis (1 case). Clearly, Koreans are not protected from IEMs and a systematic approach is needed to make diagnosis more easy and accurate.
Brain Diseases, Metabolic, Inborn ; Carbohydrate Metabolism ; Diagnosis ; Genetic Predisposition to Disease ; Hepatolenticular Degeneration ; Humans ; Incidence ; Korea* ; Membranes ; Metabolism ; Metabolism, Inborn Errors* ; Mucolipidoses ; Mucopolysaccharidoses ; Peroxisomal Disorders ; Phenylketonurias ; Porphyrias ; Prejudice ; Prevalence ; Retrospective Studies ; Sphingolipidoses ; United States ; Urea Cycle Disorders, Inborn