Biological Significance of Isoaspartate and Its Repair System

Shimizu, Takahiko; Matsuoka, Yasuji; Shirasawa, Takuji

doi:10.1248/bpb.28.1590

Cited by 168 publications

(171 citation statements)

References 80 publications

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“…This enzyme does not catalyze this transfer to normal L-aspartyl residues contained in peptides or proteins [6,7] . The functional role of PIMT in cancer cell migration has not been clearly elucidated.…”

Section: Introductionmentioning

confidence: 96%

Cross-regulation between protein L-isoaspartyl O-methyltransferase and ERK in epithelial mesenchymal transition of MDA-MB-231 cells

et al. 2011

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Aim: Protein L-isoaspartyl O-methyltransferase (PIMT) regulates cell adhesion in various cancer cell lines through activation of integrin αv and the PI3K pathway. The epithelial mesenchymal transition (EMT) enables epithelial cells to acquire the characteristics of mesenchymal cells, and to allow them to migrate for metastasis. Here, we examined the relationship between PIMT and EMT with attached or detached MDA-MB 231 cells. Methods: Human breast cancer cell line MDA-MB-231 cells were maintained in a suspension on poly-HEMA in the presence or absence of PIMT siRNA or ERK inhibitor PD98059. The mRNAs and proteins were analyzed using RT-PCR and immunoblotting, respectively. Results: During cellular incubation under detached conditions, PIMT, integrin αv and EMT proteins, such as Snail, Slug and matrix metalloproteinase 2 (MMP-2), were significantly increased in correlation with the phosphorylation of ERK1/2. The ERK inhibitor PD98059 (25 µmol/L) strongly suppressed the expression of the proteins and PIMT. Interestingly, PIMT siRNA blocked the phosphorylation of ERK and the expression of the EMT proteins. Additionally, PIMT and ERK phosphorylation were both co-activated by treatment with TGF-β (10 ng/mL) and TNF-α (10 ng/mL). Conclusion: A tight cross-regulation exists between ERK and PIMT in regards to their activation and expression during the EMT. Because the role of PIMT in the EMT and metastatic processes remains unclear, in this study, we explored the involvement of PIMT in the regulation of the detachment and attachment of the anoikis-resistant cell line MDA-MB-231, an aggressive breast cancer cell line with a highly invasive, migrative, and metastatic characters [10] , by culturing the cells in poly-HEMA (2-hydroxyethylmethacrylate)-coated dishes and introducing siRNA specific for PIMT. Materials and methods MaterialsLiCl and poly-HEMA were purchased from Sigma-Aldrich (St Louis, MO, USA). Dulbecco's modified Eagle's medium (DMEM), penicillin/streptomycin solution (10 000 unit/mL and 10 mg/mL, respectively), fetal bovine serum (FBS) and Dulbecco's phosphate-buffered saline (DPBS) were purchased from Gibco BRL (Gaithersburg, MD, USA). MDA-MB 231 cells were obtained from American Type Culture Collection (Manassas, VA, USA). Moloney murine leukemia virus (M-MLV) reverse transcriptase, polymerase chain reaction (PCR) premix, and Sapphire Super Taq were purchased from Rexgene Biotech Co, Ltd (Ochang, Korea). All primers used for PCR were purchased from Bioneer (Taejeon, Korea). A mixture of Stealth TM /siRNA duplex oligoribonucleotides against PIMT and Lipofectamine TM RNAiMAX was purchased from Invitrogen (Carlsbad, CA, USA). Rabbit anti-PIMT antiserum was produced against recombinant PIMT proteins of porcine brain as previously described (Koh and Hong, unpublished data). Antibodies against MAPK, MMP-2, MMP-9, N-cadherin, integrin αv, phospho-GSK3 (Tyr 279/216 ), phospho-ERK1/2 (Thr 202 /Tyr 204 ), phospho-MEK1 (Ser 218/222 )/MEK2 (Ser 222/226 ), phospho-Akt1/PkBα (Ser 473 ) and phospho-p90RSK (Ser 380 ) were...

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Section: Introductionmentioning

confidence: 96%

Cross-regulation between protein L-isoaspartyl O-methyltransferase and ERK in epithelial mesenchymal transition of MDA-MB-231 cells

et al. 2011

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“…A␤ isomerized at the seventh amino acid was suggested to compose a major fraction of A␤ in neuritic plaques (20). Both modifications have been shown to accelerate peptide aggregation and fibril formation (18,21,22). Other modifications include metal-induced oxidation (23) or phosphorylation (24,25).…”

mentioning

confidence: 99%

Pyroglutamate Amyloid-β (Aβ): A Hatchet Man in Alzheimer Disease

Jawhar

Wirths

Bayer

2011

Journal of Biological Chemistry

197

225

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Pyroglutamate-modified amyloid-␤ (A␤ pE3 ) peptides are gaining considerable attention as potential key participants in the pathology of Alzheimer disease (AD) due to their abundance in AD brain, high aggregation propensity, stability, and cellular toxicity. Transgenic mice that produce high levels of A␤ pE3-42 show severe neuron loss. Recent in vitro and in vivo experiments have proven that the enzyme glutaminyl cyclase catalyzes the formation of A␤ pE3 . In this minireview, we summarize the current knowledge on A␤ pE3 , discussing its discovery, biochemical properties, molecular events determining formation, prevalence in the brains of AD patients, Alzheimer mouse models, and potential as a target for therapy and as a diagnostic marker.When Alois Alzheimer presented the case of his patient Auguste Deter at the Tübingen meeting of the Southwest German Psychiatrists in 1906, he did not attract much attention or stimulate any discussion in the audience. The young doctor likely would not have believed that, 100 years later, the disease that now holds his name would be the most common cause of dementia and a source of a critical medical and economical problem. At this meeting, Alzheimer presented Auguste Deter's symptoms and reported the histopathological features that are now associated with Alzheimer disease (AD) 2 : neuron loss, extracellular amyloid plaques, and intracellular neurofibrillary tangles. For more than 2 decades, the amyloid hypothesis has been the cardinal hypothesis in describing the sequence of AD etiology. The amyloid hypothesis considers amyloid-␤ (A␤) deposition to be the causative event of AD pathology and that neurofibrillary tangles, cell loss, vascular damage, and dementia occur as a consequence of it (1). However, it has been recently suggested that the extracellular formation of A␤ plaques and other AD pathological events are preceded by intraneuronal A␤ accumulation, giving rise to a modified amyloid hypothesis (2).The story of successful discoveries in modern AD research using novel molecular biological tools started with the biochemical analysis of ␤-amyloid-containing blood vessels (congophilic amyloid angiopathy) (3) and amyloid plaques consisting of A␤ (4), which led to the isolation and sequencing of the gene encoding the larger amyloid precursor protein (APP) (5, 6).In vitro and in vivo analyses of amyloid deposits in AD revealed various N-and C-terminal variants (4, 7, 8). Increased C-terminal length of A␤ (from A␤ x-40 to A␤ x-42 ) in AD enhanced aggregation and early deposition and promoted the toxicity of A␤ (9 -11). Recently, A␤ 1-43 has been discussed as a novel toxic peptide in AD (12).Beside A␤ peptides, starting with aspartate as the first amino acid (A␤ 1-x ), several N-terminally truncated and modified A␤ species have been described (4, 13-15). Among A␤ species present in AD plaques, Lewis et al. (16) reported that A␤ 4 -42 is a relatively abundant species in AD, aged control, and vascular dementia patients. Using immunoprecipitation in combination with mass spectrome...

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“…This can arise for a number of reasons that reflect both biological and nonbiological processes [3][4][5][6]. In both cases, characterization of the heterogeneity is crucial.…”

Section: Discussionmentioning

confidence: 99%

“…Whilst this is often the case, biological and artefactual circumstances can give rise to protein populations showing low mass heterogeneity (LMH), here defined as distinct molecular species differing in mass by 2 Da or less. Deamidation of glutamine and asparagine residues (ϩ1 Da) and reduction of the disulfide bridge (ϩ2 Da) are examples of biological LMH, both of which are associated with regulation of protein activity [3,4]. Partial modification in these instances will result in a heterogeneous protein population comprising constituents with overlapping natural isotope distributions.…”

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confidence: 99%

Observation of heterogeneous gene products by FT-ICR MS

Robertson

Wong

Beynon

et al. 2008

J. Am. Soc. Mass Spectrom.

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The ability of FT-ICR MS to resolve isotopic variants of intact proteins for each of the charge states formed by electrospray ionization offers a sensitive, rapid method for detecting "low mass" heterogeneity, where this is defined as the presence of structural variants differing in mass by 2 Da or less. Such heterogeneity may reflect biological or chemical modifications of structure or may result from the coexpression of related proteins from a multi-gene family. In the analytical approach described here, comparisons are made between observed isotopic distributions and those expected for predicted protein sequences. Close agreement is demonstrated for a homogeneous model protein, and the utility of the method has been evaluated in the study of mouse major urinary proteins (MUPs), a group of closely related sequences. Divergence of the experimental isotopic distribution from distributions predicted for known MUP sequences can be explained, in quantitative terms, by the coexpression of closely related sequences. This approach provides a facile method for the assessment of protein homogeneity and for the detection of structural variants, without recourse to proteolytic digestion and analysis of the resulting products. (J

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Biological Significance of Isoaspartate and Its Repair System

Cited by 168 publications

References 80 publications

Cross-regulation between protein L-isoaspartyl O-methyltransferase and ERK in epithelial mesenchymal transition of MDA-MB-231 cells

Cross-regulation between protein L-isoaspartyl O-methyltransferase and ERK in epithelial mesenchymal transition of MDA-MB-231 cells

Pyroglutamate Amyloid-β (Aβ): A Hatchet Man in Alzheimer Disease

Observation of heterogeneous gene products by FT-ICR MS

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