Molecular Biology and Genetics / Moleküler Biyoloji ve Genetik
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Review Citation - WoS: 6Citation - Scopus: 8Molecular Trojan Horses for Treating Lysosomal Storage Diseases(Academic Press, 2023) Leal, Andres Felipe; Rintz, Estera; Çelik, Betül; Ago, Yasuhiko; León, Daniel; İnci, Orhan Kerim; Seyrantepe, VolkanLysosomal storage diseases (LSDs) are caused by monogenic mutations in genes encoding for proteins related to the lysosomal function. Lysosome plays critical roles in molecule degradation and cell signaling through interplay with many other cell organelles, such as mitochondria, endoplasmic reticulum, and peroxisomes. Even though several strategies (i.e., protein replacement and gene therapy) have been attempted for LSDs with promising results, there are still some challenges when hard-to-treat tissues such as bone (i.e., cartilages, ligaments, meniscus, etc.), the central nervous system (mostly neurons), and the eye (i.e., cornea, retina) are affected. Consistently, searching for novel strategies to reach those tissues remains a priority. Molecular Trojan Horses have been well-recognized as a potential alternative in several pathological scenarios for drug delivery, including LSDs. Even though molecular Trojan Horses refer to genetically engineered proteins to overcome the blood-brain barrier, such strategy can be extended to strategies able to transport and deliver drugs to specific tissues or cells using cell-penetrating peptides, monoclonal antibodies, vesicles, extracellular vesicles, and patient-derived cells. Only some of those platforms have been attempted in LSDs. In this paper, we review the most recent efforts to develop molecular Trojan Horses and discuss how this strategy could be implemented to enhance the current efficacy of strategies such as protein replacement and gene therapy in the context of LSDs. © 2023Conference Object Elimination of the B4galnt1 Gene Normalizes Lifespan and Prevents Pathology in Tay-Sachs Disease Mice(Elsevier, 2023) Seyrantepe, VolkanTay-Sachs disease is a neurodegenerative lysosomal storage disorder caused by mutations in the Hexa gene, which encodes the alpha subunit of lysosomal ß-hexaminidase A (HEXA). HEXA is responsible for the conversion of GM2 to GM3, therefore the deficiency leads to the accumulation of GM2 in the lysosomes, neurodegeneration, and eventual death. Currently, there is no efficient therapy for the disease yet.Article Citation - WoS: 5Citation - Scopus: 5Sialidase Neu4 Deficiency Is Associated With Neuroinflammation in Mice(Springer, 2021) Timur, Zehra Kevser; İnci, Orhan Kerim; Akyıldız Demir, Seçil; Seyrantepe, VolkanSialidases catalyze the removal of sialic acid residues from glycoproteins, oligosaccharides, and sialylated glycolipids. Sialidase Neu4 is in the lysosome and has broad substrate specificity. Previously generated Neu4-/- mice were viable, fertile and lacked gross morphological abnormalities, but displayed a marked vacuolization and lysosomal storage in lung and spleen cells. In addition, we showed that there is an increased level of GD1a ganglioside and a markedly decreased level of GM1 ganglioside in the brain of Neu4-/- mice. In this study, we further explored whether sialidase Neu4 deficiency causes neuroinflammation. We demostrated that elevated level of GD1a and GT1b is associated with an increased level of LAMP1-positive lysosomal vesicles and Tunel-positive neurons correlated with alterations in the expression of cytokines and chemokines in adult Neu4-/- mice. Astrogliosis and microgliosis were also significantly enhanced in the hippocampus, and cerebellum. These changes in brain immunity were accompanied by motor impairment in these mice. Our results indicate that sialidase Neu4 is a novel mediator of an inflammatory response in the mouse brain due to the altered catabolism of gangliosides.Conference Object Deletion of Sialidase Neu3 Causes Progressive Neurodegeneration in Tay-Sachs Mice(Academic Press, 2016) Seyrantepe, VolkanTay-Sachs disease is a severe lysosomal disorder caused by mutations in the HEXA gene coding for α subunit of lysosomal βhexosaminidase A which converts GM2 to GM3 ganglioside. HexA-/-mice, depleted of β-hexosaminidase A gene, remains asymptomatic to 1 year of age, owing to the ability of these mice to catabolise stored GM2 ganglioside via sialidase(s) removing sialic acid into glycolipid GA2 which further processed by β-Hexosaminidase B, thereby bypassing the HexA defect.Conference Object Abnormal Gm2 Accumulation Alters the Function of the Autophagic Pathway in Early-Onset Tay-Sachs Disease Mouse Model(Academic Press, 2018) Seyrantepe, Volkan; Ateş, Nurselin; Can, Melike; Şengül, Tuğçe; Akyıldız Demir, SeçilTay-Sachs disease (TSD) is an inborn error of metabolism, a prototypical lysosomal disease of the nervous system. In humans, the fatal infantile acute form is the most common, and with no current treatment, prevention and palliative care the only options. TSD mice did not mimic human infantile TSD, and although mice showed some early pathology and storage of GM2 ganglioside, clinical disease would take many months to develop. The extremely mild disease in the TSD mice was likely due to a biochemical bypass, a neuraminidase. We recently demostrated that at least one of the principal murine neuraminidase, Neu3, responsible for the biochemical bypass in the catabolism of the GM2 ganglioside.Conference Object Alteration in Redox Homeostasis in Early-Onset Tay-Sachs Disease Mouse Model(Academic Press, 2020) Seyrantepe, Volkan; Ateş, Nurselin; Başırlı, Hatice Hande; Demir, Seçil Akyıldız; Dağalp, Berkay; Nalbant, Ayten; Çalışkan, Tufan UtkuTay-Sachs disease is an autosomal recessively inherited lysosomal disorder. It is caused by mutations on the HEXA gene encoding α-subunit of β-Hexosaminidase A enzyme. The enzyme normally catalyzes GM2 to GM3 conversion but when it is absent or dysfunctional the GM2 degradation is interrupted. The undegraded GM2 ganglioside is progressively accumulated especially in neurons and causes neurodegenaration at the end. The Hexa−/− mice generated as Tay-Sachs model was nearly normal and a bypass mechanism mediated by a sialidase was suggested. Recently we determined that Neu3 sialidase involves in ganglioside degradation in the Tay-Sachs disease pathology and the Hexa−/-Neu3−/− mice mimic the neuropathologic and clinical phenotype of the disease. It was reported that oxidative stress is triggered in neurodegenerative diseases and several lysosomal disorders. It is caused by the imbalance between antioxidant defence mechanism and production of reactive oxygen species (ROS). ROS have high chemical reactivity which react and damage DNA, protein, carbohydrates and lipids.Article Citation - WoS: 18Citation - Scopus: 20Serine Carboxypeptidase Scpep1 and Cathepsin a Play Complementary Roles in Regulation of Vasoconstriction Via Inactivation of Endothelin-1(Public Library of Science, 2014) Pan, Xuefang; Grigoryeva, Lubov; Seyrantepe, Volkan; Peng, Junzheng; Kollmann, Katrin; Tremblay, Johanne; Lavoie, Julie L.; Hinek, Aleksander; Lübke, Torben; Pshezhetsky, Alexey V.The potent vasoconstrictor peptides, endothelin 1 (ET-1) and angiotensin II control adaptation of blood vessels to fluctuations of blood pressure. Previously we have shown that the circulating level of ET-1 is regulated through its proteolytic cleavage by secreted serine carboxypeptidase, cathepsin A (CathA). However, genetically-modified mouse expressing catalytically inactive CathA S190A mutant retained about 10-15% of the carboxypeptidase activity against ET-1 in its tissues suggesting a presence of parallel/redundant catabolic pathway(s). In the current work we provide direct evidence that the enzyme, which complements CathA action towards ET-1 is a retinoid-inducible lysosomal serine carboxypeptidase 1 (Scpep1), a CathA homolog with previously unknown biological function. We generated a mouse strain devoid of both CathA and Scpep1 activities (DD mice) and found that in response to high-salt diet and systemic injections of ET-1 these animals showed significantly increased blood pressure as compared to wild type mice or those with single deficiencies of CathA or Scpep1. We also found that the reactivity of mesenteric arteries from DD mice towards ET-1 was significantly higher than that for all other groups of mice. The DD mice had a reduced degradation rate of ET-1 in the blood whereas their cultured arterial vascular smooth muscle cells showed increased ET-1-dependent phosphorylation of myosin light chain 2. Together, our results define the biological role of mammalian serine carboxypeptidase Scpep1 and suggest that Scpep1 and CathA together participate in the control of ET-1 regulation of vascular tone and hemodynamics.Article Citation - WoS: 40Citation - Scopus: 50Hyaluronidase 1 and Ss-Hexosaminidase Have Redundant Functions in Hyaluronan and Chondroitin Sulfate Degradation(American Society for Biochemistry and Molecular Biology, 2012) Gushulak, Lara; Hemming, Richard; Martin, Dianna; Seyrantepe, Volkan; Pshezhetsky, Alexey; Triggs-Raine, BarbaraHyaluronan (HA), a member of the glycosaminoglycan (GAG) family, is a critical component of the extracellular matrix. A model for HA degradation that invokes the activity of both hyaluronidases and exoglycosidases has been advanced. However, no in vivo studies have been done to determine the extent to which these enzymes contribute to HA breakdown. Herein, we used mouse models to investigate the contributions of the endoglycosidase HYAL1 and the exoglycosidase β-hexosaminidase to the lysosomal degradation of HA. We employed histochemistry and fluorophore-assisted carbohydrate electrophoresis to determine the degree of HA accumulation in mice deficient in one or both enzyme activities. Global HA accumulation was present in mice deficient in both enzymes, with the highest levels found in the lymph node and liver. Chondroitin, a GAG similar in structure to HA, also broadly accumulated in mice deficient in both enzymes. Accumulation of chondroitin sulfate derivatives was detected in mice deficient in both enzymes, as well as in β-hexosaminidase-deficient mice, indicating that both enzymes play a significant role in chondroitin sulfate breakdown. Extensive accumulation of HA and chondroitin when both enzymes are lacking was not observed in mice deficient in only one of these enzymes, suggesting that HYAL1 and β-hexosaminidase are functionally redundant in HA and chondroitin breakdown. Furthermore, accumulation of sulfated chondroitin in tissues provides in vivo evidence that both HYAL1 and β-hexosaminidase cleave chondroitin sulfate, but it is a preferred substrate for β-hexosaminidase. These studies provide in vivo evidence to support and extend existing knowledge of GAG breakdown.Article Citation - WoS: 24Citation - Scopus: 24Mice Doubly-Deficient in Lysosomal Hexosaminidase a and Neuraminidase 4 Show Epileptic Crises and Rapid Neuronal Loss(Public Library of Science, 2010) Seyrantepe, Volkan; Lema, Pablo; Caqueret, Aurore; Dridi, Larbi; Hadj, Samar Bel; Carpentier, Stephane; Boucher, Francine; Levade, Thierry; Carmant, Lionel; Gravel, Roy A.; Hamel, Edith; Vachon, Pascal; Di Cristo, Graziella; Michaud, Jacques L.; Morales, Carlos R.; Pshezhetsky, Alexey V.Tay-Sachs disease is a severe lysosomal disorder caused by mutations in the HexA gene coding for the a-subunit of lysosomal β-hexosaminidase A, which converts GM2 to GM3 ganglioside. Hexa-/- mice, depleted of b-hexosaminidase A, remain asymptomatic to 1 year of age, because they catabolise GM2 ganglioside via a lysosomal sialidase into glycolipid GA2, which is further processed by β-hexosaminidase B to lactosyl-ceramide, thereby bypassing the β-hexosaminidase A defect. Since this bypass is not effective in humans, infantile Tay-Sachs disease is fatal in the first years of life. Previously, we identified a novel ganglioside metabolizing sialidase, Neu4, abundantly expressed in mouse brain neurons. Now we demonstrate that mice with targeted disruption of both Neu4 and Hexa genes (Neu4-/-;Hexa-/-) show epileptic seizures with 40% penetrance correlating with polyspike discharges on the cortical electrodes of the electroencephalogram. Single knockout Hexa-/- or Neu4-/- siblings do not show such symptoms. Further, double-knockout but not single-knockout mice have multiple degenerating neurons in the cortex and hippocampus and multiple layers of cortical neurons accumulating GM2 ganglioside. Together, our data suggest that the Neu4 block exacerbates the disease in Hexa-/- mice, indicating that Neu4 is a modifier gene in the mouse model of Tay-Sachs disease, reducing the disease severity through the metabolic bypass. However, while disease severity in the double mutant is increased, it is not profound suggesting that Neu4 is not the only sialidase contributing to the metabolic bypass in Hexa-/- mice.