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1.
Sci Rep ; 13(1): 6316, 2023 04 18.
Article in English | MEDLINE | ID: mdl-37072456

ABSTRACT

All current categorizations of human population, such as ethnicity, ancestry and race, are based on various selections and combinations of complex and dynamic common characteristics, that are mostly societal and cultural in nature, perceived by the members within or from outside of the categorized group. During the last decade, a massive amount of a new type of characteristics, that are exclusively genomic in nature, became available that allows us to analyze the inherited whole-genome demographics of extant human, especially in the fields such as human genetics, health sciences and medical practices (e.g., 1,2,3), where such health-related characteristics can be related to whole-genome-based categorization. Here we show the feasibility of deriving such whole-genome-based categorization. We observe that, within the available genomic data at present, (a) the study populations form about 14 genomic groups, each consisting of multiple ethnic groups; and (b), at an individual level, approximately 99.8%, on average, of the whole autosomal-genome contents are identical between any two individuals regardless of their genomic or ethnic groups.


Subject(s)
Ethnicity , Genomics , Humans , Ethnicity/genetics , Genome, Human
2.
Exp Mol Med ; 55(2): 283-289, 2023 02.
Article in English | MEDLINE | ID: mdl-36720916

ABSTRACT

Translation is mediated by precisely orchestrated sequential interactions among translation initiation components, mRNA, and ribosomes. Biochemical, structural, and genetic techniques have revealed the fundamental mechanism that determines what occurs and when, where and in what order. Most mRNAs are circularized via the eIF4E-eIF4G-PABP interaction, which stabilizes mRNAs and enhances translation by recycling ribosomes. However, studies using single-molecule fluorescence imaging have allowed for the visualization of complex data that opposes the traditional "functional circularization" theory. Here, we briefly introduce single-molecule techniques applied to studies on mRNA circularization and describe the results of in vitro and live-cell imaging. Finally, we discuss relevant insights and questions gained from single-molecule research related to translation.


Subject(s)
Poly(A)-Binding Proteins , Protein Biosynthesis , RNA, Messenger/metabolism , Poly(A)-Binding Proteins/chemistry , Poly(A)-Binding Proteins/genetics , Poly(A)-Binding Proteins/metabolism , Protein Binding , Eukaryotic Initiation Factor-4G/chemistry , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism
3.
Biomolecules ; 14(1)2023 Dec 22.
Article in English | MEDLINE | ID: mdl-38254619

ABSTRACT

Honey bees play a significant role in ecology, producing biologically active substances used to promote human health. However, unlike humans, the molecular markers indicating honey bee health remain unknown. Unfortunately, numerous reports of honey bee collapse have been documented. To identify health markers, we analyzed ten defense system genes in Apis mellifera ligustica honey bees from winter (Owb) and spring (Fb for foragers and Nb for newly emerged) populations sampled in February and late April 2023, respectively. We focused on colonies free from SBV and DWV viruses. Molecular profiling revealed five molecular markers of honey bee health. Of these, two seasonal molecular markers-domeless and spz genes-were significantly downregulated in Owb compared to Nb and Fb honey bees. One task-related marker gene, apid-1, was identified as being downregulated in Owb and Nb compared to Fb honey bees. Two recommended general health markers, SOD and defensin-2, were upregulated in honey bees. These markers require further testing across various honey bee subspecies in different climatic regions. They can diagnose bee health without colony intervention, especially during low-temperature months like winter. Beekeepers can use this information to make timely adjustments to nutrients or heating to prevent seasonal losses.


Subject(s)
Cold Temperature , Ecology , Humans , Bees/genetics , Animals , Seasons , Heating , Nutrients
4.
Biochem Biophys Res Commun ; 618: 73-78, 2022 08 27.
Article in English | MEDLINE | ID: mdl-35716598

ABSTRACT

Eukaryotic translation is a complex process that involves the interplay of various translation factors to convert genetic information into a specific amino acid chain. According to an elegant model of eukaryotic translation initiation, the 3' poly(A) tail of an mRNA, which is occupied by poly(A)-binding proteins (PABPs), communicates with the 5'-cap bound by eIF4E to enhance translation. Although the circularization of mRNA resulting from the communication is widely understood, it has yet to be directly observed. To explore mRNA circularization in translation, we analyzed the level of colocalization of eIF4E, eIF4G, and PABP on individual mRNAs in polysomal and subpolysomal fractions using single polysome analysis. Our results show that the three tested proteins barely coexist in mRNA in either polysomal or subpolysomal fractions, implying that the closed-loop structure generated by the communication between eIF4E, eIF4G, and PAPB may be transient during translation.


Subject(s)
Eukaryotic Initiation Factor-4E , Eukaryotic Initiation Factor-4G , Eukaryotic Initiation Factor-4E/genetics , Eukaryotic Initiation Factor-4E/metabolism , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism , Poly(A)-Binding Proteins/genetics , Polyribosomes/metabolism , Protein Binding , Protein Biosynthesis , RNA, Messenger/metabolism , Ribonucleoproteins
5.
Autophagy ; 17(12): 4231-4248, 2021 12.
Article in English | MEDLINE | ID: mdl-33783327

ABSTRACT

Selective recognition and elimination of misfolded polypeptides are crucial for protein homeostasis. When the ubiquitin-proteasome system is impaired, misfolded polypeptides tend to form small cytosolic aggregates and are transported to the aggresome and eventually eliminated by the autophagy pathway. Despite the importance of this process, the regulation of aggresome formation remains poorly understood. Here, we identify TRIM28/TIF1ß/KAP1 (tripartite motif containing 28) as a negative regulator of aggresome formation. Direct interaction between TRIM28 and CTIF (cap binding complex dependent translation initiation factor) leads to inefficient aggresomal targeting of misfolded polypeptides. We also find that either treatment of cells with poly I:C or infection of the cells by influenza A viruses triggers the phosphorylation of TRIM28 at S473 in a way that depends on double-stranded RNA-activated protein kinase. The phosphorylation promotes association of TRIM28 with CTIF, inhibits aggresome formation, and consequently suppresses viral proliferation. Collectively, our data provide compelling evidence that TRIM28 is a negative regulator of aggresome formation.Abbreviations: BAG3: BCL2-associated athanogene 3; CTIF: CBC-dependent translation initiation factor; CED: CTIF-EEF1A1-DCTN1; DCTN1: dynactin subunit 1; EEF1A1: eukaryotic translation elongation factor 1 alpha 1; EIF2AK2: eukaryotic translation initiation factor 2 alpha kinase 2; HDAC6: histone deacetylase 6; IAV: influenza A virus; IP: immunoprecipitation; PLA: proximity ligation assay; polypeptidyl-puro: polypeptidyl-puromycin; qRT-PCR: quantitative reverse-transcription PCR; siRNA: small interfering RNA.


Subject(s)
Autophagy , Influenza A virus , Inclusion Bodies/metabolism , Influenza A virus/metabolism , Proteasome Endopeptidase Complex/metabolism , Ubiquitin/metabolism
6.
Nat Commun ; 11(1): 3106, 2020 06 19.
Article in English | MEDLINE | ID: mdl-32561765

ABSTRACT

Nonsense-mediated mRNA decay (NMD) typifies an mRNA surveillance pathway. Because NMD necessitates a translation event to recognize a premature termination codon on mRNAs, truncated misfolded polypeptides (NMD-polypeptides) could potentially be generated from NMD substrates as byproducts. Here, we show that when the ubiquitin-proteasome system is overwhelmed, various misfolded polypeptides including NMD-polypeptides accumulate in the aggresome: a perinuclear nonmembranous compartment eventually cleared by autophagy. Hyperphosphorylation of the key NMD factor UPF1 is required for selective targeting of the misfolded polypeptide aggregates toward the aggresome via the CTIF-eEF1A1-DCTN1 complex: the aggresome-targeting cellular machinery. Visualization at a single-particle level reveals that UPF1 increases the frequency and fidelity of movement of CTIF aggregates toward the aggresome. Furthermore, the apoptosis induced by proteotoxic stresses is suppressed by UPF1 hyperphosphorylation. Altogether, our data provide evidence that UPF1 functions in the regulation of a protein surveillance as well as an mRNA quality control.


Subject(s)
Nonsense Mediated mRNA Decay , Proteasome Endopeptidase Complex/metabolism , RNA Helicases/metabolism , RNA, Messenger/metabolism , Trans-Activators/metabolism , Unfolded Protein Response/genetics , Autophagy , Codon, Nonsense , Dynactin Complex/metabolism , Eukaryotic Initiation Factors/metabolism , HEK293 Cells , HeLa Cells , Humans , Molecular Imaging , Peptide Elongation Factor 1/metabolism , Phosphorylation , Protein Aggregates/genetics , Single Molecule Imaging , Ubiquitin/metabolism
7.
Mol Neurobiol ; 56(5): 3819-3832, 2019 May.
Article in English | MEDLINE | ID: mdl-30215158

ABSTRACT

TRPM2 a cation channel is also known to work as an enzyme that hydrolyzes highly reactive, neurotoxic ADP-ribose (ADPR). Although ADPR is hydrolyzed by NUT9 pyrophosphatase in major organs, the enzyme is defective in the brain. The present study questions the role of TRPM2 in the catabolism of ADPR in the brain. Genetic ablation of Trpm2 results in the disruption of ADPR catabolism that leads to the accumulation of ADPR and reduction in AMP. Trpm2-/- mice elicit the reduction in autophagosome formation in the hippocampus. Trpm2-/- mice also show aggregations of proteins in the hippocampus, aberrant structural changes and neuronal connections in synapses, and neuronal degeneration. Trpm2-/- mice exhibit learning and memory impairment, enhanced neuronal intrinsic excitability, and imbalanced synaptic transmission. These results respond to long-unanswered questions regarding the potential role of the enzymatic function of TRPM2 in the brain, whose dysfunction evokes protein aggregation. In addition, the present finding answers to the conflicting reports such as neuroprotective or neurodegenerative phenotypes observed in Trpm2-/- mice.


Subject(s)
Adenosine Diphosphate Ribose/metabolism , Autophagy , Brain/metabolism , Gene Deletion , Protein Aggregates , TRPM Cation Channels/deficiency , Animals , Cognition , Hippocampus/metabolism , Hydrolysis , Memory , Mice, Inbred C57BL , Mice, Knockout , Nerve Degeneration/metabolism , Nerve Degeneration/pathology , Neuronal Plasticity , Neurons/metabolism , Synaptic Transmission , TRPM Cation Channels/metabolism
8.
Proc Natl Acad Sci U S A ; 115(6): 1322-1327, 2018 02 06.
Article in English | MEDLINE | ID: mdl-29358382

ABSTRACT

Prevention and early intervention are the most effective ways of avoiding or minimizing psychological, physical, and financial suffering from cancer. However, such proactive action requires the ability to predict the individual's susceptibility to cancer with a measure of probability. Of the triad of cancer-causing factors (inherited genomic susceptibility, environmental factors, and lifestyle factors), the inherited genomic component may be derivable from the recent public availability of a large body of whole-genome variation data. However, genome-wide association studies have so far showed limited success in predicting the inherited susceptibility to common cancers. We present here a multiple classification approach for predicting individuals' inherited genomic susceptibility to acquire the most likely phenotype among a panel of 20 major common cancer types plus 1 "healthy" type by application of a supervised machine-learning method under competing conditions among the cohorts of the 21 types. This approach suggests that, depending on the phenotypes of 5,919 individuals of "white" ethnic population in this study, (i) the portion of the cohort of a cancer type who acquired the observed type due to mostly inherited genomic susceptibility factors ranges from about 33 to 88% (or its corollary: the portion due to mostly environmental and lifestyle factors ranges from 12 to 67%), and (ii) on an individual level, the method also predicts individuals' inherited genomic susceptibility to acquire the other types ranked with associated probabilities. These probabilities may provide practical information for individuals, heath professionals, and health policymakers related to prevention and/or early intervention of cancer.


Subject(s)
Genetic Predisposition to Disease , Machine Learning , Neoplasms/genetics , Polymorphism, Single Nucleotide , Genome, Human , Humans , Life Style , Probability
9.
J Appl Physiol (1985) ; 124(2): 364-373, 2018 02 01.
Article in English | MEDLINE | ID: mdl-29146687

ABSTRACT

The aim of the present study was to examine whether transient receptor potential melastatin 2 (TRPM2) plays a role in muscle fiber-type transition during exercise. Mice were trained at a speed of 12 m/min at a slope of 0° for 60 min for 5 consecutive days/wk for 4 wk. Exhaustion tests were performed on the treadmill (the speed was set at 6 m/min at a slope of 0° and increased at a rate of 1 m/min every 6 min). Isolated primary skeletal muscle cells from TRPM2-knockout (KO) mice showed lower amplitudes of electrical stimuli (ES)-induced Ca2+ signals when compared with wild-type (WT) mice due to a defect in Ca2+ influx. Moreover, TRPM2-KO mice had a higher proportion of fast-twitch skeletal muscle fibers and a lower proportion of slow-twitch muscle fibers before exercise than WT mice. After exercise, the expression of slow-twitch skeletal muscle fibers was increased only in WT mice but not in TRPM2-KO mice. ES-induced nuclear translocation of the Ca2+-dependent transcription factor NFATc1 was significantly lower in TRPM2-KO mice than in WT mice. TRPM2-KO mice also showed decreased mitochondrial Ca2+ and membrane potential. Lactate levels were higher in the skeletal muscle cells of TRPM2-KO mice before and after ES compared with WT mice. Collectively, these data indicate that TRPM2-mediated Ca2+ signaling plays a critical role in the regulation of fiber-type switching and mitochondrial function in skeletal muscle. NEW & NOTEWORTHY TRPM2 has been shown to play an important role in a variety of cellular functions. However, the role of TRPM2 in skeletal muscle remains poorly understood. Here, we provide evidence that TRPM2-mediated Ca2+ signaling is required for training-induced improvement in skeletal muscle mitochondrial function and fiber type transition.


Subject(s)
Calcium Signaling , Mitochondria, Muscle/metabolism , Muscle, Skeletal/physiology , Physical Conditioning, Animal/physiology , TRPM Cation Channels/metabolism , Animals , Exercise Tolerance , Male , Mice, Knockout , Pyruvate Dehydrogenase (Lipoamide)/metabolism
10.
Chin J Integr Med ; 24(1): 64-71, 2018 Jan.
Article in English | MEDLINE | ID: mdl-28251475

ABSTRACT

Contact dermatitis (CD) is one of the most common skin diseases in industrialized countries. Chinese medicines (CMs) have been investigated worldwide as complementary and alternative medicines for corticosteroids, which are the first choice for treatment of inflflammatory skin diseases owing to their favorable efficacy. This article describes the CMs that have been reported to have anti-dermatitis effects against CD in the last 20 years.


Subject(s)
Dermatitis, Contact/therapy , Medicine, Chinese Traditional , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/therapeutic use , Dermatitis, Contact/pathology , Drugs, Chinese Herbal/therapeutic use , Humans , Meridians , Treatment Outcome
11.
Reproduction ; 154(5): 595-605, 2017 11.
Article in English | MEDLINE | ID: mdl-28780571

ABSTRACT

CD31 has been shown to play a role in endothelial cell migration and angiogenesis, which are critical to the formation and function of the endometrium and myometrium in uterine development during early pregnancy. However, the role of CD31 in uterine receptivity during blastocyst implantation is poorly understood. The pregnancy rate in CD31-/- female mice mated with CD31+/+ male mice was higher than that observed in CD31+/+ female mice mated with CD31+/+ male mice. During the receptive phase of implantation, uterine glands were more developed in CD31-/- mice than in CD31+/+ mice, and the uterine weights of CD31-/- mice were increased. Leukemia inhibitory factor (LIF) was highly expressed in the CD31-/- mice during implantation and the expression of LIF was up-regulated by estradiol-17ß (E2 ) + progesterone (P4 ) in ovariectomized CD31-/- mice, compared with CD31+/+ mice at 8 h after hormone treatment. E2 -induced protein synthesis was inhibited by P4 in the CD31+/+ uterus, but not in the uterus of CD31-/- mice. Also, STAT3, HAND2, LIF, and mTOR signals were enhanced in CD31-/- mice. Stromal DNA replication was highly activated in the uterus of CD31-/- mice, manifested by upregulated cyclin series signaling and PCNA expression after E2 + P4 treatment. Collectively, CD31 inhibits E2 -mediated epithelial proliferation via recruitment and phosphorylation of SHP-2 upon receiving P4 signal in early pregnancy.


Subject(s)
Platelet Endothelial Cell Adhesion Molecule-1/physiology , Progesterone/pharmacology , Uterus/metabolism , Animals , Embryo Implantation/drug effects , Embryo Implantation/genetics , Endometrium/drug effects , Endometrium/metabolism , Estradiol/pharmacology , Female , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Platelet Endothelial Cell Adhesion Molecule-1/genetics , Platelet Endothelial Cell Adhesion Molecule-1/metabolism , Pregnancy , Signal Transduction/drug effects , Uterus/drug effects
12.
PLoS One ; 10(9): e0139110, 2015.
Article in English | MEDLINE | ID: mdl-26407101

ABSTRACT

Human sperm have to undergo a maturational process called capacitation in the female reproductive tract. Capacitation confers upon the sperm an ability to gain hypermotility and undergo acrosome reaction. Previous studies have suggested that seminal plasma proteins induce the capacitation of sperm in the female reproductive tract for the successful fertilization of the oocyte. However, the function of seminal plasma proteins in capacitation remains largely unclear. To the end, we found that soluble CD38 (sCD38) in seminal plasma increases the capacitation of sperm via specific interactions between sCD38 and the CD31 on the sperm. Upon the association of sCD38 with CD31, tyrosine kinase Src phosphorylates CD31, a process blocked by Src inhibitors. Shc, SHP-2, Grb2, and SOS, as well as Src kinase were found to associate with the phosphorylated CD31. The sCD38-induced phosphorylation of CD31 initiates a cascade reaction through the phosphorylation of Erk1/2, which results in the acrosome reaction, and sperm hypermotility. These processes were prevented by Src, Ras and MEK inhibitors. Taken together, these data indicate that the sCD38 present in seminal plasma plays a critical role in the capacitation of sperm.


Subject(s)
ADP-ribosyl Cyclase 1/metabolism , Platelet Endothelial Cell Adhesion Molecule-1/metabolism , Semen/metabolism , Sperm Capacitation , Acrosome Reaction , Humans , MAP Kinase Signaling System , Male , Phosphorylation , Phosphotyrosine/metabolism , Protein Binding , Solubility , Sperm Motility
13.
Proc Natl Acad Sci U S A ; 112(5): 1559-64, 2015 Feb 03.
Article in English | MEDLINE | ID: mdl-25591581

ABSTRACT

A successful pregnancy depends on a complex process that establishes fetomaternal tolerance. Seminal plasma is known to induce maternal immune tolerance to paternal alloantigens, but the seminal factors that regulate maternal immunity have yet to be characterized. Here, we show that a soluble form of CD38 (sCD38) released from seminal vesicles to the seminal plasma plays a crucial role in inducing tolerogenic dendritic cells and CD4(+) forkhead box P3(+) (Foxp3(+)) regulatory T cells (Tregs), thereby enhancing maternal immune tolerance and protecting the semiallogeneic fetus from resorption. The abortion rate in BALB/c females mated with C57BL/6 Cd38(-/-) males was high compared with that in females mated with Cd38(+/+) males, and this was associated with a reduced proportion of Tregs within the CD4(+) T-cell pool. Direct intravaginal injection of sCD38 to CBA/J pregnant mice at preimplantation increased Tregs and pregnancy rates in mice under abortive sonic stress from 48 h after mating until euthanasia. Thus, sCD38 released from seminal vesicles to the seminal plasma acts as an immunoregulatory factor to protect semiallogeneic fetuses from maternal immune responses.


Subject(s)
ADP-ribosyl Cyclase 1/immunology , Immune Tolerance , Maternal-Fetal Exchange , Semen/immunology , ADP-ribosyl Cyclase 1/genetics , Animals , Dendritic Cells/immunology , Female , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Pregnancy
14.
Diabetes ; 64(4): 1224-34, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25409702

ABSTRACT

Muscle contraction and insulin induce glucose uptake in skeletal muscle through GLUT4 membrane translocation. Beneficial effects of exercise on glucose homeostasis in insulin-resistant individuals are known to be due to their distinct mechanism between contraction and insulin action on glucose uptake in skeletal muscle. However, the underlying mechanisms are not clear. Here we show that in skeletal muscle, distinct Ca(2+) second messengers regulate GLUT4 translocation by contraction and insulin treatment; d-myo-inositol 1,4,5-trisphosphate/nicotinic acid adenine dinucleotide phosphate (NAADP) and cyclic ADP-ribose/NAADP are main players for insulin- and contraction-induced glucose uptake, respectively. Different patterns of phosphorylation of AMPK and Ca(2+)/calmodulin-dependent protein kinase II were shown in electrical stimuli (ES)- and insulin-induced glucose uptake pathways. ES-induced Ca(2+) signals and glucose uptake are dependent on glycolysis, which influences formation of NAD(P)-derived signaling messengers, whereas insulin-induced signals are not. High-fat diet (HFD) induced a defect in only insulin-mediated, but not ES-mediated, Ca(2+) signaling for glucose uptake, which is related to a specifically lower NAADP formation. Exercise decreases blood glucose levels in HFD-induced insulin resistance mice via NAADP formation. Thus we conclude that different usage of Ca(2+) signaling in contraction/insulin-stimulated glucose uptake in skeletal muscle may account for the mechanism by which exercise ameliorates glucose homeostasis in individuals with type 2 diabetes.


Subject(s)
Calcium Signaling/physiology , Glucose Transporter Type 4/metabolism , Insulin Resistance/physiology , Insulin/metabolism , Muscle, Skeletal/metabolism , Physical Conditioning, Animal/physiology , Animals , Biological Transport/physiology , Calcium/metabolism , Diabetes Mellitus, Type 2/metabolism , Glucose/metabolism , Male , Mice , Phosphorylation , Signal Transduction/physiology
15.
PLoS One ; 9(5): e96858, 2014.
Article in English | MEDLINE | ID: mdl-24802750

ABSTRACT

H1 linker histone proteins are essential for the structural and functional integrity of chromatin and for the fidelity of additional epigenetic modifications. Deletion of H1c, H1d and H1e in mice leads to embryonic lethality by mid-gestation with a broad spectrum of developmental alterations. To elucidate the cellular and molecular mechanisms underlying H1 linker histone developmental functions, we analyzed embryonic stem cells (ESCs) depleted of H1c, H1d and H1e subtypes (H1-KO ESCs) by utilizing established ESC differentiation paradigms. Our study revealed that although H1-KO ESCs continued to express core pluripotency genes and the embryonic stem cell markers, alkaline phosphatase and SSEA1, they exhibited enhanced cell death during embryoid body formation and during specification of mesendoderm and neuroectoderm. In addition, we demonstrated deregulation in the developmental programs of cardiomyocyte, hepatic and pancreatic lineage elaboration. Moreover, ectopic neurogenesis and cardiomyogenesis occurred during endoderm-derived pancreatic but not hepatic differentiation. Furthermore, neural differentiation paradigms revealed selective impairments in the specification and maturation of glutamatergic and dopaminergic neurons with accelerated maturation of glial lineages. These impairments were associated with deregulation in the expression profiles of pro-neural genes in dorsal and ventral forebrain-derived neural stem cell species. Taken together, these experimental observations suggest that H1 linker histone proteins are critical for the specification, maturation and fidelity of organ-specific cellular lineages derived from the three cardinal germ layers.


Subject(s)
Endoderm/metabolism , Histones/metabolism , Mesoderm/metabolism , Neural Plate/metabolism , Animals , Cell Differentiation , Cell Lineage , Cells, Cultured , Embryoid Bodies/metabolism , Embryonic Development , Embryonic Stem Cells/cytology , Embryonic Stem Cells/metabolism , Endoderm/cytology , Hepatocytes/cytology , Hepatocytes/metabolism , Histones/deficiency , Histones/genetics , Mesoderm/cytology , Mice , Myocytes, Cardiac/cytology , Myocytes, Cardiac/metabolism , Neural Plate/cytology , Neurogenesis , Transcriptome
16.
J Biol Chem ; 289(23): 16362-73, 2014 Jun 06.
Article in English | MEDLINE | ID: mdl-24759100

ABSTRACT

NAD glycohydrolases (NADases) catalyze the hydrolysis of NAD to ADP-ribose and nicotinamide. Although many members of the NADase family, including ADP-ribosyltransferases, have been cloned and characterized, the structure and function of NADases with pure hydrolytic activity remain to be elucidated. Here, we report the structural and functional characterization of a novel NADase from rabbit reticulocytes. The novel NADase is a glycosylated, glycosylphosphatidylinositol-anchored cell surface protein exclusively expressed in reticulocytes. shRNA-mediated knockdown of the NADase in bone marrow cells resulted in a reduction of erythroid colony formation and an increase in NAD level. Furthermore, treatment of bone marrow cells with NAD, nicotinamide, or nicotinamide riboside, which induce an increase in NAD content, resulted in a significant decrease in erythroid progenitors. These results indicate that the novel NADase may play a critical role in regulating erythropoiesis of hematopoietic stem cells by modulating intracellular NAD.


Subject(s)
Erythropoiesis , Hematopoietic Stem Cells/metabolism , NAD+ Nucleosidase/metabolism , NAD/metabolism , Amino Acid Sequence , Animals , Base Sequence , Blotting, Western , DNA, Complementary , Glycosylation , HEK293 Cells , Humans , Microscopy, Confocal , Molecular Sequence Data , Mutagenesis, Site-Directed , NAD+ Nucleosidase/chemistry , NAD+ Nucleosidase/genetics , Rabbits , Reverse Transcriptase Polymerase Chain Reaction , Structure-Activity Relationship
17.
Cell Mol Life Sci ; 71(13): 2561-76, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24270855

ABSTRACT

The gamma (γ)-secretase holoenzyme is composed of four core proteins and cleaves APP to generate amyloid beta (Aß), a key molecule that causes major neurotoxicity during the early stage of Alzheimer's disease (AD). However, despite its important role in Aß production, little is known about the regulation of γ-secretase. OCIAD2, a novel modulator of γ-secretase that stimulates Aß production, and which was isolated from a genome-wide functional screen using cell-based assays and a cDNA library comprising 6,178 genes. Ectopic expression of OCIAD2 enhanced Aß production, while reduction of OCIAD2 expression suppressed it. OCIAD2 expression facilitated the formation of an active γ-secretase complex and enhanced subcellular localization of the enzyme components to lipid rafts. OCIAD2 interacted with nicastrin to stimulate γ-secretase activity. OCIAD2 also increased the interaction of nicastrin with C99 and stimulated APP processing via γ-secretase activation, but did not affect Notch processing. In addition, a cell-permeable Tat-OCIAD2 peptide that interfered with the interaction of OCIAD2 with nicastrin interrupted the γ-secretase-mediated AICD production. Finally, OCIAD2 expression was significantly elevated in the brain of AD patients and PDAPP mice. This study identifies OCIAD2 as a selective activator of γ-secretase to increase Aß generation.


Subject(s)
Alzheimer Disease/genetics , Amyloid Precursor Protein Secretases/metabolism , Membrane Glycoproteins/metabolism , Neoplasm Proteins/metabolism , Alzheimer Disease/etiology , Alzheimer Disease/metabolism , Amyloid Precursor Protein Secretases/chemistry , Amyloid Precursor Protein Secretases/genetics , Amyloid beta-Peptides/biosynthesis , Animals , Fibroblasts/metabolism , Gene Library , Humans , Membrane Glycoproteins/genetics , Membrane Microdomains/metabolism , Mice , Mice, Knockout/metabolism , Neoplasm Proteins/genetics , Receptors, Notch/metabolism
18.
J Biol Chem ; 288(49): 35548-58, 2013 Dec 06.
Article in English | MEDLINE | ID: mdl-24165120

ABSTRACT

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a second messenger for mobilizing Ca(2+) from intracellular stores in various cell types. Extracellular application of NAADP has been shown to elicit intracellular Ca(2+) signals, indicating that it is readily transported into cells. However, little is known about the functional role of this NAADP uptake system. Here, we show that NAADP is effectively transported into selected cell types involved in glucose homeostasis, such as adipocytes and pancreatic ß-cells, but not the acinar cells, in a high glucose-dependent manner. NAADP uptake was inhibitable by Ned-19, a NAADP mimic; dipyridamole, a nucleoside inhibitor; or NaN3, a metabolic inhibitor or under Ca(2+)-free conditions. Furthermore, NAADP was found to be released from pancreatic islets upon stimulation by high glucose. Consistently, administration of NAADP to type 2 diabetic mice improved glucose tolerance. We propose that NAADP is functioning as an autocrine/paracrine hormone important in glucose homeostasis. NAADP is thus a potential antidiabetic agent with therapeutic relevance.


Subject(s)
Adipocytes/metabolism , Glucose/metabolism , Insulin-Secreting Cells/metabolism , NADP/analogs & derivatives , Animals , Autocrine Communication , Biological Transport, Active , Calcium Signaling , Diabetes Mellitus, Type 2/drug therapy , Diabetes Mellitus, Type 2/metabolism , Homeostasis , Insulin/metabolism , Kinetics , Male , Mice , NADP/metabolism , NADP/pharmacology , Paracrine Communication , Second Messenger Systems
19.
J Colloid Interface Sci ; 405: 150-6, 2013 Sep 01.
Article in English | MEDLINE | ID: mdl-23759322

ABSTRACT

Mesoporous carbon (MC) was prepared from mesoporous silica (SBA-15) via a conventional templating method for use as a Pt-Ru catalyst support in fuel cells. The effect of surface modifications of the carbon support at different pH on the electrochemical activities of the Pt-Ru/MC catalysts was investigated. The Pt-Ru nanoparticle size and loading were dependent on the surface characteristics of the MC. Base-modified MC-supported Pt-Ru showed the smallest average nanoparticle size (3.3 nm) and the highest loading (77%) among the chemically modified MC-supported Pt-Ru catalysts. The electrochemical activity of the catalysts was enhanced when the MC supports were treated with basic or neutral agents rather than by acid modification.

20.
Islets ; 4(2): 145-51, 2012.
Article in English | MEDLINE | ID: mdl-22627736

ABSTRACT

Glucose is a metabolic regulator of insulin secretion from pancreatic ß-cells, which is regulated by intracellular Ca(2+) signaling. We and others previously demonstrated that glucose activates CD38/ADP-ribosyl cyclase (ADPR-cyclase) to produce two Ca(2+) second messengers, cyclic ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP). Although F-actin remodeling is known to be an important step in glucose stimulated insulin secretion, the role of actin cytoskeleton in regulating Ca(2+) signaling in pancreatic ß-cells remain to be solved. Here, we show that actin filaments are involved in the activation of CD38/ADPR-cyclase in pancreatic ß-cells. Glucose induces a sequential formation of cADPR and NAADP. Pretreatment with jasplakinolide, an actin polymerizing agent, or a myosin heavy chain IIA (MHCIIA) blocker, blebbistatin, inhibited glucose-induced CD38 internalization, an essential step for cADPR formation. Blocking actin disassembly with jasplakinolide also abrogates glucose-induced cADPR and NAADP formation and sustained Ca(2+) signals. These results indicate that actin filaments along with MHCIIA play an important role in CD38 internalization for the generation of Ca(2+) mobilizing messengers for glucose-induced Ca(2+) signaling in pancreatic ß-cells.


Subject(s)
Actins/metabolism , Calcium Signaling/physiology , Glucose/metabolism , Insulin-Secreting Cells/metabolism , ADP-ribosyl Cyclase/metabolism , Animals , Depsipeptides/pharmacology , Heterocyclic Compounds, 4 or More Rings/pharmacology , Histocytochemistry , Insulin-Secreting Cells/drug effects , Mice , Mice, Inbred C57BL , Mice, Inbred ICR , Mice, Knockout , Microscopy, Confocal , NADP/analogs & derivatives , NADP/metabolism
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