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1、异质性细胞器第1页，本讲稿共10页Characteristics of LysosomesLysosome is a Lysosome is a heterogenous heterogenous organelleorganelle（异质性细（异质性细（异质性细（异质性细胞器）胞器）胞器）胞器）:l lPrimary Primary lysosomelysosome（初级溶（初级溶（初级溶（初级溶酶体）酶体）酶体）酶体）l lSecond Second lysosomeslysosomes（次级（次级（次级（次级溶酶体）溶酶体）溶酶体）溶酶体）l l heterophagicheteroph
2、agic（异噬溶酶体）（异噬溶酶体）（异噬溶酶体）（异噬溶酶体）l l autophagicautophagic（自噬溶酶体）（自噬溶酶体）（自噬溶酶体）（自噬溶酶体）l lResidual bodyResidual body（残余小体）（残余小体）（残余小体）（残余小体）Primary LysSecond Lys第2页，本讲稿共10页The Functions of LysosomesvvLysosomes are involved in Lysosomes are involved in three major cell functions:three major cell functio
3、ns:phagocytosis phagocytosis（吞噬）（吞噬）（吞噬）（吞噬）A summary of the phagocytic pathway第3页，本讲稿共10页 autophagy（自吞）（自吞）Electron micrograph of a mitochondrion and peroxisome(过氧化物酶体)enclosed in a double membrane wrapper derived from the ER.This autophagic vacuole would have fused with a lysosome and its contents
4、 digested.第4页，本讲稿共10页 endocytosis（内吞（内吞作用）作用）第5页，本讲稿共10页Disorders Resulting from Defects in lysosomal FunctionDisorders Resulting from Defects in lysosomal Function I-cell disease:Many cells in these patients contain lysosomes that are bloated with undergraded materials.When fibroblasts from these p
5、atients were studied in culture,it was found that lysosomal enzymes are synthesized at normal levels but are secreted into the medium and not targeted to lysosomes.第6页，本讲稿共10页The I-cell defect was soon traced to the deficiency of an enzyme(N-acetyglucosamine phosphotransferase)required for mannose p
6、hosphorylation.The secreted enzymes lacked the mannose phosphate residue that are present on the corresponding enzymes of cells from normal individuals.第7页，本讲稿共10页Pompe disease:a fatal inherited conditiona fatal inherited condition in the absence of-glucosidase,undigested glycogen in the absence of-
7、glucosidase,undigested glycogen accumulated in lysosomes,causing swelling of the organelles accumulated in lysosomes,causing swelling of the organelles and irreversible damage to the cells and tissuesand irreversible damage to the cells and tissuesDiseases of this type,characterized by the deficienc
8、y of a single Diseases of this type,characterized by the deficiency of a single lysosomal enzyme and the corresponding accumulation of lysosomal enzyme and the corresponding accumulation of undergraded substrate,are called undergraded substrate,are called lysosomal storage lysosomal storage diseases
9、diseases第8页，本讲稿共10页Other lysosomal storage diseasesDiseaseDiseaseEnzyme Enzyme DeficiencyDeficiencyPrinciple Storage Principle Storage substancesubstanceconsequencesconsequencesGGM1M1 Gangliosid-Gangliosid-osisosisGM1-GM1-GalactosidaseGalactosidaseGanglioside GGanglioside GM1M1Mental retardation,liv
10、er Mental retardation,liver enlargement,skeletal enlargement,skeletal involvement,death by age 2 involvement,death by age 2 Tay-Sachs Tay-Sachs dieasedieaseHexosaminidasHexosaminidase Ae AGanglioside GGanglioside GM2M2Mental retardation,blindness,death Mental retardation,blindness,death by age 3by a
11、ge 3Fabrys Fabrys diseasedisease-Galactosidase-Galactosidase A ATrihexosylceramidTrihexosylceramide eSkin rash,kidney failure,pain in Skin rash,kidney failure,pain in lower extremitieslower extremitiesSandhoffsdisSandhoffsdiseaseeaseHexosaminidasHexosaminidase A and Be A and BGanglioside GGangliosid
12、e GM2 M2 and globosideand globosideSimilar to Tay-Sachs diease but Similar to Tay-Sachs diease but more rapidly progressingmore rapidly progressingGauchers Gauchers diseasediseaseGlucocerebrosiGlucocerebrosidasedaseGlucocerebrosideGlucocerebrosideLiver and spleen Liver and spleen enlargement,erosion
13、 of long enlargement,erosion of long bones,mental retardation in infantile bones,mental retardation in infantile form onlyform only第9页，本讲稿共10页Tay-Sachs disease:the best studied lysosomal storage the best studied lysosomal storage diseasesdiseases It results from a deficiency of the enzyme-N-hexosami
14、nidase A,an It results from a deficiency of the enzyme-N-hexosaminidase A,an enzyme that degrades the ganglioside Genzyme that degrades the ganglioside GM2M2 G GM2M2 is a major component of the membranes of brain cells,and in is a major component of the membranes of brain cells,and in the absence of
15、 the hydrolytic enzyme,the ganglioside accumulates in the absence of the hydrolytic enzyme,the ganglioside accumulates in the bloated lysosomes of brain cells,causing dysfunctionthe bloated lysosomes of brain cells,causing dysfunction In its severe form,which strikes during infancy,the disease is In its severe form,which strikes during infancy,the disease is chacterized by progressive mental and motor retardation,as well chacterized by progressive mental and motor retardation,as well as skeletal,cardiac,and resiratory abnormalitiesas skeletal,cardiac,and resiratory abnormalities 第10页，本讲稿共10页