scholarly journals Cathepsin D Variants Associated With Neurodegenerative Diseases Show Dysregulated Functionality and Modified α-Synuclein Degradation Properties

2021 ◽  
Vol 9 ◽  
Author(s):  
Josina Bunk ◽  
Susy Prieto Huarcaya ◽  
Alice Drobny ◽  
Jan Philipp Dobert ◽  
Lina Walther ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Neurodegenerative Diseases ◽  
Cathepsin D ◽  
Cellular Localization ◽  
Neuronal Ceroid Lipofuscinosis ◽  
Dynamics Simulation ◽  
Disease Development ◽  
Lysosomal Protease ◽  
Enzymatic Function

Cathepsin D (CTSD) is a lysosomal protease important for the degradation of various substrates, including disease-associated proteins like α-synuclein (a-syn), amyloid precursor protein (APP) and tau, all of which tend to aggregate if not efficiently degraded. Hence, it is not surprising that genetic variants within the CTSD gene have been linked to neurodegenerative diseases, like Parkinson’s and Alzheimer’s disease (PD, AD), as well as the lysosomal storage disorder neuronal ceroid lipofuscinosis type-10 (NCL10). Although recent studies have shown the molecular dependence of substrate degradation via CTSD within autophagic pathways, only little is known about the precise role of lysosomal CTSD function in disease development. We here performed biochemical, cellular and structural analyses of eleven disease-causing CTSD point mutations found in genomic sequencing data of patients to understand their role in neurodegeneration. These CTSD variants were analyzed for cellular localization, maturation and enzymatic activity in overexpression analyses. Moreover, for PD-associated mutants, intracellular degradation of a-syn was monitored. In summary, our results suggest that NCL10-associated CTSD variants are significantly impaired in lysosomal maturation and enzymatic activity, whereas the AD- and PD-associated variants seemed rather unaffected, indicating normal maturation, and lysosomal presence. Interestingly, a PD-associated CTSD variant (A239V) exhibited increased enzymatic activity accompanied by enhanced a-syn degradation. By structural analyses of this mutant utilizing molecular dynamics simulation (MDS), we identified a structural change within a loop adjacent to the catalytic center leading to a higher flexibility and potentially accelerated substrate exchange rates. Our data sheds light onto the role of CTSD in disease development and helps to understand the structural regulation of enzymatic function, which could be utilized for targeted CTSD activation. Because of the degradative function of CTSD, this enzyme is especially interesting for therapeutic strategies tackling protein aggregates in neurodegenerative disorders.

scholarly journals A replacement of the active-site aspartic acid residue 293 in mouse cathepsin D affects its intracellular stability, processing and transport in HEK-293 cells

2003 ◽  
Vol 369 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Sanna PARTANEN ◽  
Stephan STORCH ◽  
Hans-Gerhard LÖFFLER ◽  
Andrej HASILIK ◽  
Jaana TYYNELÄ ◽  
...  
Keyword(s):  
Aspartic Acid ◽  
Active Site ◽  
Cathepsin D ◽  
Secretory Pathway ◽  
Neuronal Ceroid Lipofuscinosis ◽  
Aspartic Acid Residue ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
Lysosomal Protease ◽  
293 Cells

The substitution of an active-site aspartic acid residue by asparagine in the lysosomal protease cathepsin D (CTSD) results in a loss of enzyme activity and severe cerebrocortical atrophy in a novel form of neuronal ceroid lipofuscinosis in sheep [Tyynelä, Sohar, Sleat, Gin, Donnelly, Baumann, Haltia and Lobel (2000) EMBO J. 19, 2786—2792]. In the present study we have introduced the corresponding mutation by replacing aspartic acid residue 293 with asparagine (D293N) into the mouse CTSD cDNA to analyse its effect on synthesis, transport and stability in transfected HEK-293 cells. The complete inactivation of mutant D293N mouse CTSD was confirmed by a newly developed fluorimetric quantification system. Moreover, in the heterologous overexpression systems used, mutant D293N mouse CTSD was apparently unstable and proteolytically modified during early steps of the secretory pathway, resulting in a loss of mass by about 1kDa. In the affected sheep, the endogenous mutant enzyme was stable but also showed the shift in its molecular mass. In HEK-293 cells, the transport of the mutant D293N mouse CTSD to the lysosome was delayed and associated with a low secretion rate compared with wild-type CTSD. These data suggest that the mutation may result in a conformational change which affects stability, processing and transport of the enzyme.

scholarly journals The noncanonical role of the protease cathepsin D as a cofilin phosphatase

Cell Research ◽  
2021 ◽  
Author(s):  
Yi-Jun Liu ◽  
Ting Zhang ◽  
Sicong Chen ◽  
Daxiao Cheng ◽  
Cunjin Wu ◽  
...  
Keyword(s):  
Cathepsin D ◽  
Dual Function ◽  
Actin Remodeling ◽  
Actin Organization ◽  
Cellular Processes ◽  
Lysosomal Protease ◽  
Ph Conditions ◽  
Maturation State ◽  
Acidic Compartments

AbstractCathepsin D (cathD) is traditionally regarded as a lysosomal protease that degrades substrates in acidic compartments. Here we report cathD plays an unconventional role as a cofilin phosphatase orchestrating actin remodeling. In neutral pH environments, the cathD precursor directly dephosphorylates and activates the actin-severing protein cofilin independent of its proteolytic activity, whereas mature cathD degrades cofilin in acidic pH conditions. During development, cathD complements the canonical cofilin phosphatase slingshot and regulates the morphogenesis of actin-based structures. Moreover, suppression of cathD phosphatase activity leads to defective actin organization and cytokinesis failure. Our findings identify cathD as a dual-function molecule, whose functional switch is regulated by environmental pH and its maturation state, and reveal a novel regulatory role of cathD in actin-based cellular processes.

scholarly journals A role of the frontotemporal lobar degeneration risk factor TMEM106B in myelination

Brain ◽  
2020 ◽  
Vol 143 (7) ◽  
pp. 2255-2271 ◽  
Author(s):  
Tuancheng Feng ◽  
Rory R Sheng ◽  
Santiago Solé-Domènech ◽  
Mohammed Ullah ◽  
Xiaolai Zhou ◽  
...  
Keyword(s):  
Risk Factor ◽  
Frontotemporal Lobar Degeneration ◽  
Cathepsin D ◽  
Proteolipid Protein ◽  
Wild Type ◽  
Protein Levels ◽  
Lysosomal Protease ◽  
Precursor Cell Line ◽  
Lysosomal Membrane Protein

Abstract TMEM106B encodes a lysosomal membrane protein and was initially identified as a risk factor for frontotemporal lobar degeneration. Recently, a dominant D252N mutation in TMEM106B was shown to cause hypomyelinating leukodystrophy. However, how TMEM106B regulates myelination is still unclear. Here we show that TMEM106B is expressed and localized to the lysosome compartment in oligodendrocytes. TMEM106B deficiency in mice results in myelination defects with a significant reduction of protein levels of proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG), the membrane proteins found in the myelin sheath. The levels of many lysosome proteins are significantly decreased in the TMEM106B-deficient Oli-neu oligodendroglial precursor cell line. TMEM106B physically interacts with the lysosomal protease cathepsin D and is required to maintain proper cathepsin D levels in oligodendrocytes. Furthermore, we found that TMEM106B deficiency results in lysosome clustering in the perinuclear region and a decrease in lysosome exocytosis and cell surface PLP levels. Moreover, we found that the D252N mutation abolished lysosome enlargement and lysosome acidification induced by wild-type TMEM106B overexpression. Instead, it stimulates lysosome clustering near the nucleus as seen in TMEM106B-deficient cells. Our results support that TMEM106B regulates myelination through modulation of lysosome function in oligodendrocytes.

scholarly journals Ca2+ administration prevents α-synuclein proteotoxicity by stimulating calcineurin-dependent lysosomal proteolysis

PLoS Genetics ◽  
2021 ◽  
Vol 17 (11) ◽  
pp. e1009911
Author(s):  
Lukas Habernig ◽  
Filomena Broeskamp ◽  
Andreas Aufschnaiter ◽  
Jutta Diessl ◽  
Carlotta Peselj ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Cathepsin D ◽  
Lysosomal Protease ◽  
Lysosomal Proteolysis ◽  
Intracellular Ca ◽  
A Cell ◽  
Cellular Ca ◽  
Drosophila Models

The capacity of a cell to maintain proteostasis progressively declines during aging. Virtually all age-associated neurodegenerative disorders associated with aggregation of neurotoxic proteins are linked to defects in the cellular proteostasis network, including insufficient lysosomal hydrolysis. Here, we report that proteotoxicity in yeast and Drosophila models for Parkinson’s disease can be prevented by increasing the bioavailability of Ca2+, which adjusts intracellular Ca2+ handling and boosts lysosomal proteolysis. Heterologous expression of human α-synuclein (αSyn), a protein critically linked to Parkinson’s disease, selectively increases total cellular Ca2+ content, while the levels of manganese and iron remain unchanged. Disrupted Ca2+ homeostasis results in inhibition of the lysosomal protease cathepsin D and triggers premature cellular and organismal death. External administration of Ca2+ reduces αSyn oligomerization, stimulates cathepsin D activity and in consequence restores survival, which critically depends on the Ca2+/calmodulin-dependent phosphatase calcineurin. In flies, increasing the availability of Ca2+ discloses a neuroprotective role of αSyn upon manganese overload. In sum, we establish a molecular interplay between cathepsin D and calcineurin that can be activated by Ca2+ administration to counteract αSyn proteotoxicity.

scholarly journals Characterization of essential domains in HSD17B13 for cellular localization and enzymatic activity

2020 ◽  
Vol 61 (11) ◽  
pp. 1400-1409 ◽  
Author(s):  
Yanling Ma ◽  
Suman Karki ◽  
Philip M. Brown ◽  
Dennis D. Lin ◽  
Maren C. Podszun ◽  
...  
Keyword(s):  
Amino Acid ◽  
Enzymatic Activity ◽  
Cellular Localization ◽  
Acid Sites ◽  
Hydrophobic Domain ◽  
Nonalcoholic Fatty Liver ◽  
Interaction Sites ◽  
Enzymatic Function ◽  
Α Helix

Human genetic studies recently identified an association of SNPs in the 17-β hydroxysteroid dehydrogenase 13 (HSD17B13) gene with alcoholic and nonalcoholic fatty liver disease development. Mutant HSD17B13 variants devoid of enzymatic function have been demonstrated to be protective from cirrhosis and liver cancer, supporting the development of HSD17B13 as a promising therapeutic target. Previous studies have demonstrated that HSD17B13 is a lipid droplet (LD)-associated protein. However, the critical domains that drive LD targeting or determine the enzymatic activity have yet to be defined. Here we used mutagenesis to generate multiple truncated and point-mutated proteins and were able to demonstrate in vitro that the N-terminal hydrophobic domain, PAT-like domain, and a putative α-helix/β-sheet/α-helix domain in HSD17B13 are all critical for LD targeting. Similarly, we characterized the predicted catalytic, substrate-binding, and homodimer interaction sites and found them to be essential for the enzymatic activity of HSD17B13, in addition to our previous identification of amino acid P260 and cofactor binding site. In conclusion, we identified critical domains and amino acid sites that are essential for the LD localization and protein function of HSD17B13, which may facilitate understanding of its function and targeting of this protein to treat chronic liver diseases.

Role of the Structural Characteristics of Dendrimers in the Manifestation of the Antiamyloid Properties

INEOS OPEN ◽  
2020 ◽  
Vol 3 ◽  
Author(s):  
S. A. Sorokina ◽  
◽  
Yu. Yu. Stroilova ◽  
V. I. Muronets ◽  
Z. B. Shifrina ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Structural Characteristics ◽  
Short Review ◽  
External Factors ◽  
Amyloid Aggregation ◽  
Amyloid Proteins ◽  
Molecular Parameters ◽  
Amyloid Aggregates ◽  
Aggregation Processes

Among the compounds able to efficiently inhibit the amyloid aggregation of proteins and decompose the amyloid aggregates that cause neurodegenerative diseases, of particular interest are dendrimers, which represent individual macromolecules with the hypercrosslinked architectures and given molecular parameters. This short review outlines the peculiarities of the antiamyloid activity of dendrimers and discusses the effect of dendrimer structures and external factors on their antiamyloid properties. The potential of application of dendrimers in further investigations on the aggregation processes of amyloid proteins as the compounds that exhibit the remarkable antiamyloid activity is evaluated.

Involvement of Heme Oxygenase-1 in Neuropsychiatric and Neurodegenerative Diseases

2018 ◽  
Vol 24 (20) ◽  
pp. 2283-2302 ◽  
Author(s):  
Vivian B. Neis ◽  
Priscila B. Rosa ◽  
Morgana Moretti ◽  
Ana Lucia S. Rodrigues
Keyword(s):  
Neurodegenerative Diseases ◽  
Heme Oxygenase ◽  
Therapeutic Potential ◽  
Redox Homeostasis ◽  
Antioxidant Defenses ◽  
Heme Oxygenase 1 ◽  
Physiological Conditions ◽  
And Oxidative Stress ◽  
Defensive Mechanism

Heme oxygenase (HO) family catalyzes the conversion of heme into free iron, carbon monoxide and biliverdin. It possesses two well-characterized isoforms: HO-1 and HO-2. Under brain physiological conditions, the expression of HO-2 is constitutive, abundant and ubiquitous, whereas HO-1 mRNA and protein are restricted to small populations of neurons and neuroglia. HO-1 is an inducible enzyme that has been shown to participate as an essential defensive mechanism for neurons exposed to oxidant challenges, being related to antioxidant defenses in certain neuropathological conditions. Considering that neurodegenerative diseases (Alzheimer’s Disease (AD), Parkinson’s Disease (PD) and Multiple Sclerosis (MS)) and neuropsychiatric disorders (depression, anxiety, Bipolar Disorder (BD) and schizophrenia) are associated with increased inflammatory markers, impaired redox homeostasis and oxidative stress, conditions that may be associated with alterations in HO-levels/activity, the purpose of this review is to present evidence on the possible role of HO-1 in these Central Nervous System (CNS) diseases. In addition, the possible therapeutic potential of targeting brain HO-1 is explored in this review.

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