scholarly journals A LRRK2/dLRRK-mediated lysosomal pathway that contributes to glial cell death and DA neuron survival

2021 ◽  
Author(s):  
Linfang Wang ◽  
Honglei Wang ◽  
Margaret S Ho
Keyword(s):  
Caspase 3 ◽  
Kinase Activity ◽  
Dependent Manner ◽  
Dopaminergic Neurodegeneration ◽  
Age Dependent ◽  
Sporadic Parkinson’S Disease ◽  
Locomotor Deficits ◽  
And Function ◽  
Reduced Activity

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common cause of familial and sporadic Parkinson's disease (PD). A plethora of evidence has indicated a role for LRRK2 in endolysosomal trafficking in neurons, while LRRK2 function in glia, although highly expressed, remains largely unknown. Here we present evidence that LRRK2/dLRRK mediates a glial lysosomal pathway that contributes to the mechanism of PD. Independent of its kinase activity, glial LRRK2/dLRRK knockdown in the immortalized microglial cells or flies results in enlarged and swelling lysosomes fewer in number. These lysosomes are less mobile, wrongly acidified, and exhibit defective membrane permeability and reduced activity of the lysosome hydrolase cathespin B. In addition, microglial LRRK2 depletion causes increased Caspase 3 levels, leading to glial apoptosis, dopaminergic neurodegeneration, and locomotor deficits in an age-dependent manner. Taken together, these findings demonstrate a functional role of LRRK2/dLRRK in regulating the glial lysosomal pathway; deficits in lysosomal biogenesis and function linking to glial apoptosis potentially underlie the mechanism of DA neurodegeneration, contributing to the progression of PD.

scholarly journals Differential role of SIRT1/MAPK pathway during cerebral ischemia in rats and humans

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sireesh Kumar Teertam ◽  
Phanithi Prakash Babu
Keyword(s):  
Cerebral Ischemia ◽  
Caspase 3 ◽  
Mapk Pathway ◽  
Protective Role ◽  
Akt Signaling ◽  
Sirtuin 1 ◽  
Neurological Dysfunction ◽  
Dependent Manner ◽  
Erk Mapk

AbstractCerebral ischemia (CI) is a severe cause of neurological dysfunction and mortality. Sirtuin-1 (Silent information regulator family protein 1, SIRT1), an oxidized nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase, plays an important role in protection against several neurodegenerative disorders. The present study aims to investigate the protective role of SIRT1 after CI in experimental young and aged rats and humans. Also, the study examines the possible regulatory mechanisms of neuronal death in CI settings. Immunoblotting and immunohistochemistry were used to evaluate changes in the expression of SIRT1, JNK/ERK/MAPK/AKT signaling, and pro-apoptotic caspase-3 in experimental rats and CI patients. The study findings demonstrated that, in aged experimental rats, SIRT1 activation positively influenced JNK and ERK phosphorylation and modulated neuronal survival in AKT-dependent manner. Further, the protection conferred by SIRT1 was effectively reversed by JNK inhibition and increased pro-apoptotic caspase-3 expression. In young experimental rats, SIRT1 activation decreased the phosphorylation of stress-induced JNK, ERK, caspase-3, and increased the phosphorylation of AKT after CI. Inhibition of SIRT1 reversed the protective effect of resveratrol. More importantly, in human patients, SIRT1 expression, phosphorylation of JNK/ERK/MAPK/AKT signaling and caspase-3 were up-regulated. In conclusion, SIRT1 could possibly be involved in the modulation of JNK/ERK/MAPK/AKT signaling pathway in experimental rats and humans after CI.

The transmembrane adaptor protein NTAL limits mast cell chemotaxis toward prostaglandin E2

2018 ◽  
Vol 11 (556) ◽  
pp. eaao4354 ◽  
Author(s):  
Ivana Halova ◽  
Monika Bambouskova ◽  
Lubica Draberova ◽  
Viktor Bugajev ◽  
Petr Draber
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
T Cell Activation ◽  
Cell Activation ◽  
Adaptor Protein ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
And Function ◽  
Cell Chemotaxis

Chemotaxis of mast cells is one of the crucial steps in their development and function. Non–T cell activation linker (NTAL) is a transmembrane adaptor protein that inhibits the activation of mast cells and B cells in a phosphorylation-dependent manner. Here, we studied the role of NTAL in the migration of mouse mast cells stimulated by prostaglandin E2 (PGE2). Although PGE2 does not induce the tyrosine phosphorylation of NTAL, unlike IgE immune complex antigens, we found that loss of NTAL increased the chemotaxis of mast cells toward PGE2. Stimulation of mast cells that lacked NTAL with PGE2 enhanced the phosphorylation of AKT and the production of phosphatidylinositol 3,4,5-trisphosphate. In resting NTAL-deficient mast cells, phosphorylation of an inhibitory threonine in ERM family proteins accompanied increased activation of β1-containing integrins, which are features often associated with increased invasiveness in tumors. Rescue experiments indicated that only full-length, wild-type NTAL restored the chemotaxis of NTAL-deficient cells toward PGE2. Together, these data suggest that NTAL is a key inhibitor of mast cell chemotaxis toward PGE2, which may act through the RHOA/ERM/β1-integrin and PI3K/AKT axes.

scholarly journals LRRK2 mediates tubulation and vesicle sorting from membrane damaged lysosomes

2020 ◽  
Author(s):  
Luis Bonet-Ponce ◽  
Alexandra Beilina ◽  
Chad D. Williamson ◽  
Eric Lindberg ◽  
Jillian H. Kluss ◽  
...  
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Super Resolution ◽  
Adaptor Protein ◽  
Dependent Manner ◽  
Leucine Rich Repeat ◽  
Biological Functions ◽  
New Process ◽  
Sporadic Parkinson’S Disease

ABSTRACTMutations in the leucine rich repeat kinase 2 (LRRK2) gene are a cause of familial and sporadic Parkinson’s disease (PD). Nonetheless, the biological functions of LRRK2 remain incompletely understood. Here, we observed that LRRK2 is recruited to lysosomes that have a ruptured membrane. Using unbiased proteomics, we observed that LRRK2 is able to recruit the motor adaptor protein JIP4 to permeabilized lysosomes in a kinase-dependent manner through the phosphorylation of RAB35 and RAB10. Super-resolution live cell imaging microscopy and FIB-SEM revealed that once at the lysosomal membrane, JIP4 promotes the formation of LAMP1-negative lysosomal tubules that release membranous content from ruptured lysosomes. Released vesicular structures are able to interact with other lysosomes. Thus, we described a new process that uses lysosomal tubulation to release vesicular structures from permeabilized lysosomes. LRRK2 orchestrates this process that we name LYTL (LYsosomal Tubulation/sorting driven by LRRK2) that, given the central role of the lysosome in PD, is likely to be disease relevant.

Abstract 218: Pericytic Laminin Regulates Blood-Brain Barrier Integrity in an Age-Dependent Manner

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Yao Yao ◽  
Jyoti Gautam ◽  
Xuanming Zhang
Keyword(s):  
Endothelial Cells ◽  
Basement Membrane ◽  
Blood Brain Barrier ◽  
Vessel Density ◽  
Brain Barrier ◽  
Dependent Manner ◽  
Vascular Integrity ◽  
Blood Brain ◽  
Age Dependent

Introduction: Laminin, a major component of the basement membrane, plays an important role in blood brain barrier (BBB) regulation. At the neurovascular unit, astrocytes, brain endothelial cells, and pericytes synthesize and deposit different laminin isoforms into the basement membrane. Previous studies from our laboratory showed that loss of astrocytic laminin induces age-dependent and region-specific BBB breakdown and intracerebral hemorrhage, suggesting a critical role of astrocytic laminin in vascular integrity maintenance. Laminin α4 (predominantly generated by endothelial cells) has been shown to regulate vascular integrity at embryonic/neonatal stage. The role of pericytic laminin in vascular integrity, however, remains elusive. Methods: We investigated the function of pericyte-derived laminin in vascular integrity using laminin conditional knockout mice. Specifically, laminin floxed mice were crossed with PDGFRβ-Cre line to generate mutants (PKO) with laminin deficiency in PDGFRβ + cells, which include both pericytes and vascular smooth muscle cells (vSMCs). To distinguish the contribution of pericyte- and vSMC-derived laminin, we also generated a vSMC-specific condition knockout line (TKO) by crossing the laminin floxed mice with Transgelin-Cre mice. In this study, mice of both genders on a C57Bl6 background were used. At least 5-6 animals were used in biochemical and histological analyses in this study. Results: Pericyte-derived laminin was abrogated in all PKO mice. However, only old but not young PKO mice showed signs of BBB breakdown and reduced vessel density, suggesting age-dependent changes. Consistent with these data, further mechanistic studies revealed reduced tight junction proteins, diminished AQP4 expression, and deceased pericyte coverage in old but not young PKO mice. In addition, neither BBB disruption nor decreased vessel density was observed in TKO mice, suggesting that these vascular defects are due to loss of pericyte- rather than vSMC-derived laminin. Conclusions: These results strongly suggest that pericyte-derived laminin active regulates BBB integrity and vessel density in an age-dependent manner. I would like this abstract to be considered for the Stroke Basic Science Award.

Tolbutamide inhibits glucagon-induced phosphorylation of 6PF-2-K/Fru-2,6-P2ase in rat hepatocytes

1995 ◽  
Vol 268 (3) ◽  
pp. E391-E396
Author(s):  
H. Ayame ◽  
A. Matsutani ◽  
H. Inoue ◽  
T. Kaneko ◽  
K. Kaku
Keyword(s):  
Rat Hepatocytes ◽  
Bifunctional Enzyme ◽  
Dependent Manner ◽  
Enzyme Protein ◽  
Dependent Protein ◽  
Sulfonylurea Drugs ◽  
Dose Dependent ◽  
Increased Activity ◽  
Reduced Activity

In previous studies, we demonstrated that tolbutamide inhibits a phosphorylation of hepatic 6-phosphofructo-2-kinase (6PF-2-K)/fructose-2,6-bisphosphatase (Fru-2,6-P2ase) catalyzed by the adenosine 3',5'-cyclic monophosphate-dependent protein kinase in a reconstruction system using the purified enzyme from the rat liver. In the current study, to assess a role of tolbutamide on hepatic 6PF-2-K/Fru-2,6-P2ase physiologically, we used intact rat hepatocytes and examined effects of tolbutamide on a phosphorylation of the bifunctional enzyme in the presence of glucagon. Glucagon induced a rapid phosphorylation of hepatic 6PF-2-K/Fru-2,6-P2ase accompanied by an inhibition of 6PF-2-K activity and a stimulation of Fru-2,6-P2ase activity in a dose-dependent manner. Tolbutamide inhibited glucagon-induced phosphorylation of the bifunctional enzyme protein in a dose-dependent manner. By adding 2 mM tolbutamide, reduced activity of 6PF-2-K and increased activity of Fru-2,6-P2ase in the presence of 10(-9) M glucagon were partially restored. The present results suggest the possibility that tolbutamide modulates the activity of hepatic 6PF-2-K/Fru-2,6-P2ase through inhibiting a phosphorylation of the enzyme protein. The counterregulatory influence of tolbutamide on the effect of glucagon suggests a possible mechanism for the extrapancreatic effect of sulfonylurea drugs.

scholarly journals microRNAs Biogenesis, Functions and Role in Tumor Angiogenesis

2020 ◽  
Vol 10 ◽  
Author(s):  
Tiziana Annese ◽  
Roberto Tamma ◽  
Michelina De Giorgis ◽  
Domenico Ribatti
Keyword(s):  
Tumor Angiogenesis ◽  
Vasculogenic Mimicry ◽  
Mirna Biogenesis ◽  
Dependent Manner ◽  
Tumor Initiation ◽  
Rna Molecules ◽  
Angiogenic Switch ◽  
Sprouting Angiogenesis ◽  
And Function

microRNAs (miRNAs) are small non-coding RNA molecules, evolutionary conserved. They target more than one mRNAs, thus influencing multiple molecular pathways, but also mRNAs may bind to a variety of miRNAs, either simultaneously or in a context-dependent manner. miRNAs biogenesis, including miRNA transcription, processing by Drosha and Dicer, transportation, RISC biding, and miRNA decay, are finely controlled in space and time.miRNAs are critical regulators in various biological processes, such as differentiation, proliferation, apoptosis, and development in both health and disease. Their dysregulation is involved in tumor initiation and progression. In tumors, they can act as onco-miRNAs or oncosuppressor-miRNA participating in distinct cellular pathways, and the same miRNA can perform both activities depending on the context.In tumor progression, the angiogenic switch is fundamental. miRNAs derived from tumor cells, endothelial cells, and cells of the surrounding microenvironment regulate tumor angiogenesis, acting as pro-angiomiR or anti-angiomiR.In this review, we described miRNA biogenesis and function, and we update the non-classical aspects of them. The most recent role in the nucleus, as transcriptional gene regulators and the different mechanisms by which they could be dysregulated, in tumor initiation and progression, are treated. In particular, we describe the role of miRNAs in sprouting angiogenesis, vessel co-option, and vasculogenic mimicry. The role of miRNAs in lymphoma angiogenesis is also discussed despite the scarcity of data.The information presented in this review reveals the need to do much more to discover the complete miRNA network regulating angiogenesis, not only using high-throughput computational analysis approaches but also morphological ones.

scholarly journals OsJAZ13 Negatively Regulates Jasmonate Signaling and Activates Hypersensitive Cell Death Response in Rice

2020 ◽  
Vol 21 (12) ◽  
pp. 4379
Author(s):  
Xiujing Feng ◽  
Lei Zhang ◽  
Xiaoli Wei ◽  
Yun Zhou ◽  
Yan Dai ◽  
...  
Keyword(s):  
Cell Death ◽  
Splice Variants ◽  
Adaptor Protein ◽  
Dependent Manner ◽  
Hypersensitive Cell Death ◽  
Cell Death Response ◽  
Jaz Proteins ◽  
Localization Analysis ◽  
And Function

Jasmonate ZIM-domain (JAZ) proteins belong to the subgroup of TIFY family and act as key regulators of jasmonate (JA) responses in plants. To date, only a few JAZ proteins have been characterized in rice. Here, we report the identification and function of rice OsJAZ13 gene. The gene encodes three different splice variants: OsJAZ13a, OsJAZ13b, and OsJAZ13c. The expression of OsJAZ13 was mainly activated in vegetative tissues and transiently responded to JA and ethylene. Subcellular localization analysis indicated OsJAZ13a is a nuclear protein. Yeast two-hybrid assays revealed OsJAZ13a directly interacts with OsMYC2, and also with OsCOI1, in a COR-dependent manner. Furthermore, OsJAZ13a recruited a general co-repressor OsTPL via an adaptor protein OsNINJA. Remarkably, overexpression of OsJAZ13a resulted in the attenuation of root by methyl JA. Furthermore, OsJAZ13a-overexpressing plants developed lesion mimics in the sheath after approximately 30–45 days of growth. Tillers with necrosis died a few days later. Gene-expression analysis suggested the role of OsJAZ13 in modulating the expression of JA/ethylene response-related genes to regulate growth and activate hypersensitive cell death. Taken together, these observations describe a novel regulatory mechanism in rice and provide the basis for elucidating the function of OsJAZ13 in signal transduction and cell death in plants.

PKCϵ has an alcohol-binding site in its second cysteine-rich regulatory domain

2009 ◽  
Vol 421 (3) ◽  
pp. 405-413 ◽  
Author(s):  
Joydip Das ◽  
Satyabrata Pany ◽  
Ghazi M. Rahman ◽  
Simon J. Slater
Keyword(s):  
Protein Kinase ◽  
Binding Site ◽  
Maximum Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Kinase C ◽  
C1 Domain ◽  
Pkc Protein Kinase C ◽  
And Function

Alcohols regulate the expression and function of PKC (protein kinase C), and it has been proposed that an alcohol-binding site is present in PKCα in its C1 domain, which consists of two cysteine-rich subdomains, C1A and C1B. A PKCϵ-knockout mouse showed a significant decrease in alcohol consumption compared with the wild-type. The aim of the present study was to investigate whether an alcohol-binding site could be present in PKCϵ. Here we show that ethanol inhibited PKCϵ activity in a concentration-dependent manner with an EC50 (equilibrium ligand concentration at half-maximum effect) of 43 mM. Ethanol, butanol and octanol increased the binding affinity of a fluorescent phorbol ester SAPD (sapintoxin-D) to PKCϵC1B in a concentration-dependent manner with EC50 values of 78 mM, 8 mM and 340 μM respectively, suggesting the presence of an allosteric alcohol-binding site in this subdomain. To identify this site, PKCϵC1B was photolabelled with 3-azibutanol and 3-azioctanol and analysed by MS. Whereas azibutanol preferentially labelled His236, Tyr238 was the preferred site for azioctanol. Inspection of the model structure of PKCϵC1B reveals that these residues are 3.46 Å (1 Å=0.1 nm) apart from each other and form a groove where His236 is surface-exposed and Tyr238 is buried inside. When these residues were replaced by alanine, it significantly decreased alcohol binding in terms of both photolabelling and alcohol-induced SAPD binding in the mutant H236A/Y238A. Whereas Tyr238 was labelled in mutant H236A, His236 was labelled in mutant Y238A. The present results provide direct evidence for the presence of an allosteric alcohol-binding site on protein kinase Cϵ and underscore the role of His236 and Tyr238 residues in alcohol binding.

HSP27 Protects Malignant Hematopoietic Cells Against VP-16-Induced Apoptosis through Modulation of P38 and C-JUN.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1276-1276
Author(s):  
Hein Schepers ◽  
Marjan Geugien ◽  
Marco van der Toorn ◽  
Anton L. Bryantsev ◽  
Harm H. Kampinga ◽  
...  
Keyword(s):  
Hematopoietic Cells ◽  
Leukemic Cells ◽  
Dependent Manner ◽  
Apoptosis Pathway ◽  
Hsp27 Expression ◽  
Cd34 Cells ◽  
Induced Apoptosis ◽  
And Function ◽  
Jnk Activation

Abstract In the present study, expression and function of Heat Shock Protein 27 (HSP27) was analyzed in acute myeloid leukemia (AML), since HSP27 expression is linked to unfavourable prognosis. HSP27 protein was predominantly expressed in monocytic blasts (M4-M5, 91%, N = 11) and absent in myeloid leukemic blasts (M1-M2, N = 5). A similar lineage restricted expression was observed in normal hematopoietic cells: high expression in normal CD34+ cells and monocytes, and absent in granulocytes. To study the functional role of HSP27, RNA interference (RNAi) studies were performed in the leukemic TF-1 cell line. These experiments demonstrated a twofold increase in VP-16-induced apoptosis after HSP27 siRNA. In contrast, CD95 Fas-induced apoptosis remained the same, as a result of CD95 Fas-mediated upregulation of HSP27. Additional investigations demonstrated that the increased VP-16-induced apoptosis after HSP27 RNAi, was associated with an enhanced phosphorylation of p38 and c-Jun. This VP-16-induced phosphorylation was subsequently followed by the release of cytochrome c into the cytoplasm, which increased twofold after siRNA treatment. These results indicate that HSP27 plays an important role in the protection against VP-16-induced apoptosis through the modulation of p38 and JNK activation, probably through interference with DAXX-mediated ASK1 activation. This was further underscored by co-immunoprecipitation studies, demonstrating complex formation of DAXX and HSP27 in an ASK1-dependent manner. However, in the investigated AML samples, VP-16-mediated apoptosis correlated moderately with HSP27 expression, although HSP27 was highly expressed and phosphorylated and activated in primitive monocytic AML blasts. This is likely due to the co-expression of p21Waf1/Cip1, which is in the majority of the monocytic AML M4-M5 blasts constitutively localised in the cytoplasm and interferes with apoptosis via the DAXX-ASK1-dependent pathway. Preliminary data indicate that overexpression of a cytoplasmic form of p21 is able to reduce the VP-16-induced apoptosis after RNAi for HSP27 as compared to controls, suggesting a predominant anti-apoptotic role of p21 over HSP27. In summary, we demonstrate a role for HSP27 in the survival of leukemic cells by modulation of the DAXX/p38/JNK apoptosis pathway. This survival advantage can further be promoted by the co-expression of cytoplasmic localised p21Waf1/Cip1 protein, indicating that strategies in AML treatment should be focused on targeting multiple signal transduction pathways.

scholarly journals Loss of Endothelial HIF-Prolyl hydroxylase 2 (PHD2) Induces Cardiac Hypertrophy and Fibrosis

2021 ◽  
Author(s):  
Zhiyu Dai ◽  
Jianding Cheng ◽  
Bin Liu ◽  
Dan Yi ◽  
Anlin Feng ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Hypertrophy ◽  
Cardiac Fibrosis ◽  
Left Ventricular ◽  
Dependent Manner ◽  
Adaptive Responses ◽  
Genetic Ablation ◽  
Pathological Cardiac Hypertrophy ◽  
And Function

Cardiac hypertrophy and fibrosis are common adaptive responses to injury and stress, eventually leading to heart failure. Hypoxia signaling is important to the (patho)physiological process of cardiac remodeling. However, the role of endothelial Prolyl-4 hydroxylase 2 (PHD2)/hypoxia inducible factors (HIFs) signaling in the pathogenesis of heart failure remains elusive. We observed a marked decrease of PHD2 expression in heart tissues and cardiovascular endothelial cells from patients with cardiomyopathy. Mice with Tie2-Cre-mediated deletion of Egln1 (encoding PHD2) or tamoxifen-induced endothelial Egln1 deletion exhibited left ventricular hypertrophy and cardiac fibrosis. Genetic ablation and pharmacological inhibition of Hif2a but not Hif1a in endothelial Egln1 deficient mice normalized cardiac size and function. The present studies define for the first time an unexpected role of endothelial PHD2 deficiency in inducing cardiac hypertrophy and fibrosis in a HIF-2α dependent manner. Targeting PHD2/HIF-2α signaling may represent a novel therapeutic approach for the treatment of pathological cardiac hypertrophy and failure.

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