Browsing by Subject "Lysosome"
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- PublicationEmbargoGuidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)(Taylor and Francis, 2016-01-21) Klionsky, Daniel J.; Abdelmohsen, Kotb ; et al.; Valdor Alonso, Rut; Bioquímica y Biología Molecular B e Inmunología
PublicationRestrictedGuidelines for the use and interpretation of assays for monitoring autophagy (4th edition)(Taylor and Francis Group, Taylor and Francis, 2016-01-21) Klionsky, Daniel J. "et.al."; Valdor Alonso, Rut; Bioquímica y Biología Molecular B e Inmunología- PublicationOpen AccessHeterogeneous ulmtrastrucmtuorf em elanosome formation in the goldfish induced by osmotic stress(Murcia : F. Hernández, 1996) Schraerrneyer, U.; Dohms, M.; Rack, M.In this study, melanophore cytodifferentiation in the fins of xanthic goldfish that had been exposed to osmotic stress for 18 days was investigated. It was found that multi-vesicular bodies (MVB) are not the only type of premelanosome. Granules having a homogeneous matrix also function as premelanosomes. The presence of acid phosphatase reaction product inside the melanin granules indicated that these organelles in this animal were also related to lysosomes. DOPA-oxidase of tyrosinase, the key enzyme in melanogenesis, was surprisingly not only detected in melanocytes but also in the Golgi stacks of dermal cells. Due to the mechanisms of premelanosome formation it is evident that cytoplasmic material also serves as substrate for melanogenesis. EDX microanalysis was performed to measure the ionic composition of the melanin granules. After aldehyde fixation the newly-formed melanin granules did not contain Na, but had accumulated Ca.
- PublicationOpen AccessHGSNAT enzyme deficiency results in accumulation of heparan sulfate in podocytes and basement membranes(Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2019) Nagel, Lauren; Oliveira, Regiana; Pshezhetsky, Alexey V.; Morales, Carlos R.ucopolysaccharidosis III type C is a lysosomal storage disorder caused by the accumulation of heparan sulfate in lysosomes. The disorder occurs due to Heparan Acetyl-CoA: α-glucosaminide N- acetyltransferase (HGSNAT) deficiency, an enzyme which typically catalyzes the transmembrane acetylation of heparan sulfate, a basement membrane component. When the gene encoding this enzyme is mutated, it cannot perform the processing of heparan sulfate, leading to un-acetylated heparan sulfate build-up in the lysosomes of cells, causing a storage disorder. This defect has been studied primarily in brain and liver cells, but its effect on the structural integrity of the glomerulus is poorly known. The present study focuses on the effect of Hgsnat gene inactivation and heparan sulfate toxicity on the integrity of the renal corpuscle. This cortical structure was chosen because of its abundance of basement membranes and heparan sulfate as well as the renal corpuscle’s physiological importance in glomerular filtration. Light microscopy, electron microscopy, and immunocytochemistry of genetically modified mice revealed a buildup of lysosomes in the podocytes, suggesting that these cells are responsible for the processing of glomerular basement membranes
- PublicationOpen AccessIntermittent fasting-induced autophagy normalization confers hepatic protection in metabolic dysfunction-associated fatty liver disease: Mechanistic insights and implications(2026) Gehan El-Akabawy; MoezAlIslam E. Faris; Manoj B. Menon; Mohamed Abdel Wahab; Farida Hussan; Mohd Hazim Bin Zulkaflee; Nabil Eid; Payal Bhatnagar; Biología Celular e Histología; Universidad de Murcia, Departamento de Biologia Celular e HistiologiaMetabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic liver condition that can progress to steatohepatitis, cirrhosis, and even liver cancer. Macroautophagy (hereinafter referred to as autophagy) is a pro-survival mechanism that facilitates the lysosomal clearance of damaged organelles, abnormal proteins, and excess lipids. A growing body of evidence indicates that autophagy dysfunction and reduced autophagic flux play critical roles in the pathogenesis of MAFLD. Therefore, restoring autophagy in MAFLD may help reduce steatosis and prevent disease progression. Intermittent fasting (IF), involving periods of restricted to no food intake alternating with periods of regulated/free eating, has been demonstrated to have beneficial effects on body composition, glucose regulation, lipid profiles, and liver function in studies involving both animal models of MAFLD and human subjects. Studies involving individuals with obesity and MAFLD have shown that Ramadan intermittent fasting (RIF), an Islamic religious practice that involves abstaining from food and water intake from sunrise to sunset over approximately 30 consecutive days, significantly reduces body weight, BMI, fat mass, and inflammatory markers while improving liver function and steatosis. The hepatoprotective effects of RIF are associated with the enhanced expression of autophagy-related genes and the restoration of autophagic flux. This upregulation of autophagy as a result of RIF makes it a potentially promising therapeutic strategy for MAFLD. This review summarizes various forms of IF, the mechanisms of autophagy, and evidence of autophagy dysfunction in MAFLD. It also explores how IF, specifically RIF, may normalize autophagy, reduce hepatic steatosis, and improve liver function in human subjects.
- PublicationOpen AccessLysosomal glycolipid storage in the renal tubular epithelium in mastomys (Praomys coucha)(Murcia : F. Hernández, 1996) Fujimura, H.; Ogura, A.; Asano, T.; Noguchi, Y.; Mochida, K.; Takimoto, K.The renal proximal tubular epithelium of MCC strain of mastomys (Praomys coucha) exhibited a number of cytoplasmic vacuoles after conventional paraffin-embedding procedures. These vacuoles were strongly PAS-positive in cryostat sections. Ultrastructurally, they were double membrane-bound structures filled with myelin figures and acid phosphatase-positive electron-dense matrix. Immunofluorescent microscopy revealed that these structures contained GM2 ganglioside. Other tissues or organs were histologically normal. Mating experiments indicated that the ganglioside storage in MCC mastomys is inherited as an autosomal recessive trait.
- PublicationOpen AccessProsaposin: a protein with differential sorting and multiple functions(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2015) Carvelli, L.; Libin, Yuan; Morales, C.R.In eukaryotes the delivery of newly synthesized proteins to their final destination is dependent on a series of functionally distinct compartments, including the endoplasmic reticulum and the Golgi apparatus, which plays a role in posttranslational modification, sorting and distribution of proteins. Most cargo is sorted within, and exits from, the trans-Golgi network (TGN). Proteins delivered to lysosomes include hydrolytic enzymes and nonenzymic activator proteins. They are directed away from the cell surface by their binding to mannose-6-phosphate receptors (MPR). However, in I-cell disease, in which the MPR pathway is disrupted, the nonenzymic sphingolipid activator protein, prosaposin, continue to traffic to lysosomes. This observation led to discovery of a new lysosomal sorting receptor, sortilin. The targeting prosaposin to the lysosomes results from the interaction of its C-terminus with sortilin. Deletion of the Cterminus did not interfere with its secretion, but abolished its transport to the lysosomes. Mutational analysis revealed that the first half of the prosaposin Cterminus contains a motif required for its binding to sortilin and its transport to the lysosomes. Prosaposin can be also secreted to the extracellular space as oligomers. Extracellular prosaposin showed to exert a variety of responses in nervous tissues including the activation of G protein-coupled receptors and ERK phosphorylation. Lastly, prosaposin has been found to be expressed in other fluids of the body such as pancreaticjuice, bile, cerebrospinal fluid, milk and seminal fluid, indicating that prosaposin is not only a house keeping lysosomal protein but an essential factor in the development and maintenance of the nervous systems and other systems of the body.
- PublicationOpen AccessSex- and strain-dependent histological features of the proximal convoluted tubular epithelium of mouse kidney: association with lysosomes containing apolipoprotein B(Murcia : F. Hernández, 2002) Yabuki, A.; Suzuki, S.; Matsumoto, M.; Nishinakagawa, H.In the present study, we performed comparative histological observations of ICR, BALB/c, C57BL/6, C3H/HeN and DBA/2 mice kidneys. Sex and strain differences were observed in the appearance of vacuolar structures of the proximal convoluted tubules (toluidine blue-positive granules in osmium-postfixed epoxy-resin sections). These features were especially remarkable in male DBA/2 mice. The vacuolar structures in male DBA/2 mice showed heterogeneous staining with Sudan B in frozen sections and appeared under an electron microscope as multilammelar giant dense bodies. In addition, these dense bodies showed heterogeneous acid phosphatase reactions. Immunohistochemical analyses of these structures for apolipoprotein B showed strong positive reactions. These results suggested that vacuolar structures in the proximal convoluted tubules, which were remarkable in male DBA/2 mice, were giant lysosomes containing apolipoprotein B.
- PublicationOpen AccessThe intracellular origin of the melanosome in pigment cells. A review of ultrastructural data(Murcia : F. Hernández, 1996) Schraerrneyer, U.This paper is a review about the ultrastructural data dealing with the origin of the melanin granules in retina1 pigment epithelial cells, in melanocytes, in the ink gland of cuttle fish, in Kupffer cells of the liver, in neurona1 tissues, in cultured pigment cells. The role and structure of lysosomes in melanogenesis are discussed in a separate chapter. The early steps of melanogenesis are ultrastructurally very heterogeneous, even in the same cell types. With respect to this heterogeneity and the considerably different views on melanosome origin in the literature, the author hypothesizes that pigment cells may use protein matrices originated from different cellular pathways. 1) They may either produce a specific protein matrix and be converted into melanin in the classical way, or 2) altematively, a matrix resulting from lysosomal protein degradation or endocytotic pathways may be used and converted into melanin, as found in fibroblasts transfected with the tyrosinase gen or in Kupffer cells. The very heterogeneous ultrastructure of the polymerizing melanin may be influenced by the amount and sterical availability of tyrosine residues in the protein moieties and the activity of tyrosinase.