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Cell Metabolism Apr 2020Activating transcription factor 4 (ATF4) is a master transcriptional regulator of the integrated stress response (ISR) that enables cell survival under nutrient stress....
Activating transcription factor 4 (ATF4) is a master transcriptional regulator of the integrated stress response (ISR) that enables cell survival under nutrient stress. The mechanisms by which ATF4 couples metabolic stresses to specific transcriptional outputs remain unknown. Using functional genomics, we identified transcription factors that regulate the responses to distinct amino acid deprivation conditions. While ATF4 is universally required under amino acid starvation, our screens yielded a transcription factor, Zinc Finger and BTB domain-containing protein 1 (ZBTB1), as uniquely essential under asparagine deprivation. ZBTB1 knockout cells are unable to synthesize asparagine due to reduced expression of asparagine synthetase (ASNS), the enzyme responsible for asparagine synthesis. Mechanistically, ZBTB1 binds to the ASNS promoter and promotes ASNS transcription. Finally, loss of ZBTB1 sensitizes therapy-resistant T cell leukemia cells to L-asparaginase, a chemotherapeutic that depletes serum asparagine. Our work reveals a critical regulator of the nutrient stress response that may be of therapeutic value.
Topics: Animals; Asparagine; Aspartate-Ammonia Ligase; Cell Line, Tumor; Cell Proliferation; Gene Expression Regulation; Humans; Leukemia; Mice, Inbred NOD; Mice, SCID; Repressor Proteins; Transcription, Genetic
PubMed: 32268116
DOI: 10.1016/j.cmet.2020.03.008 -
Cancer Research Jul 2023Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and has a poor prognosis. Pituitary tumor transforming gene 1 (PTTG1) is highly expressed...
UNLABELLED
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and has a poor prognosis. Pituitary tumor transforming gene 1 (PTTG1) is highly expressed in HCC, suggesting it could play an important role in hepatocellular carcinogenesis. Here, we evaluated the impact of PTTG1 deficiency on HCC development using a diethylnitrosamine (DEN)-induced HCC mouse model and a hepatitis B virus (HBV) regulatory X protein (HBx)-induced spontaneous HCC mouse model. PTTG1 deficiency significantly suppressed DEN- and HBx-induced hepatocellular carcinogenesis. Mechanistically, PTTG1 promoted asparagine synthetase (ASNS) transcription by binding to its promoter, and asparagine (Asn) levels were correspondingly increased. The elevated levels of Asn subsequently activated the mTOR pathway to facilitate HCC progression. In addition, asparaginase treatment reversed the proliferation induced by PTTG1 overexpression. Furthermore, HBx promoted ASNS and Asn metabolism by upregulating PTTG1 expression. Overall, PTTG1 is involved in the reprogramming of Asn metabolism to promote HCC progression and may serve as a therapeutic and diagnostic target for HCC.
SIGNIFICANCE
PTTG1 is upregulated in hepatocellular carcinoma and increases asparagine production to stimulate mTOR activity and promote tumor progression.
Topics: Animals; Mice; Asparagine; Carcinoma, Hepatocellular; Gene Expression Regulation, Neoplastic; Hepatitis B virus; Liver Neoplasms; Prognosis; TOR Serine-Threonine Kinases
PubMed: 37159932
DOI: 10.1158/0008-5472.CAN-22-3561 -
Mechanisms of Ageing and Development Apr 2004
Review
Topics: Amides; Animals; Asparagine; Biological Clocks
PubMed: 15063100
DOI: 10.1016/j.mad.2004.03.002 -
Revue Francaise D'etudes Cliniques Et... Mar 1968
Review
Topics: Animals; Anticonvulsants; Asparaginase; Asparagine; Diuretics; Guinea Pigs; Humans; Intestinal Mucosa; Iron; Liver Diseases; Mental Disorders; Nerve Tissue
PubMed: 4878784
DOI: No ID Found -
Annual Review of Pharmacology 1970
Review
Topics: Animals; Asparaginase; Asparagine; Chemical Phenomena; Chemistry; Dogs; Guinea Pigs; Humans; Mice; Neoplasms; Rats
PubMed: 4911021
DOI: 10.1146/annurev.pa.10.040170.002225 -
Biochemistry May 2011Asparagine-linked glycosylation involves the sequential assembly of an oligosaccharide onto a polyisoprenyl donor, followed by the en bloc transfer of the glycan to... (Review)
Review
Asparagine-linked glycosylation involves the sequential assembly of an oligosaccharide onto a polyisoprenyl donor, followed by the en bloc transfer of the glycan to particular asparagine residues within acceptor proteins. These N-linked glycans play a critical role in a wide variety of biological processes, such as protein folding, cellular targeting and motility, and the immune response. In the past decade, research in the field of N-linked glycosylation has achieved major advances, including the discovery of new carbohydrate modifications, the biochemical characterization of the enzymes involved in glycan assembly, and the determination of the biological impact of these glycans on target proteins. It is now firmly established that this enzyme-catalyzed modification occurs in all three domains of life. However, despite similarities in the overall logic of N-linked glycoprotein biosynthesis among the three kingdoms, the structures of the appended glycans are markedly different and thus influence the functions of elaborated proteins in various ways. Though nearly all eukaryotes produce the same nascent tetradecasaccharide (Glc(3)Man(9)GlcNAc(2)), heterogeneity is introduced into this glycan structure after it is transferred to the protein through a complex series of glycosyl trimming and addition steps. In contrast, bacteria and archaea display diversity within their N-linked glycan structures through the use of unique monosaccharide building blocks during the assembly process. In this review, recent progress toward gaining a deeper biochemical understanding of this modification across all three kingdoms will be summarized. In addition, a brief overview of the role of N-linked glycosylation in viruses will also be presented.
Topics: Asparagine; Bacteria; Carbohydrate Sequence; Glycosylation; Models, Molecular; Molecular Sequence Data; Viruses
PubMed: 21506607
DOI: 10.1021/bi200346n -
Glycobiology Apr 2019Asparagine-linked (N-linked) glycosylation is one of the most common protein modification reactions in eukaryotic cells, occurring upon the majority of proteins that... (Review)
Review
Asparagine-linked (N-linked) glycosylation is one of the most common protein modification reactions in eukaryotic cells, occurring upon the majority of proteins that enter the secretory pathway. X-ray crystal structures of the single subunit OSTs from eubacterial and archaebacterial organisms revealed the location of donor and acceptor substrate binding sites and provided the basis for a catalytic mechanism. Cryoelectron microscopy structures of the octameric yeast OST provided substantial insight into the organization and assembly of the multisubunit oligosaccharyltransferases. Furthermore, the cryoelectron microscopy structure of a complex consisting of a mammalian OST complex, the protein translocation channel and a translating ribosome revealed new insight into the mechanism of cotranslational glycosylation.
Topics: Asparagine; Cryoelectron Microscopy; Crystallography, X-Ray; Eukaryotic Cells; Glycosylation; Hexosyltransferases; Humans; Membrane Proteins; Models, Molecular; Prokaryotic Cells; Protein Conformation
PubMed: 30312397
DOI: 10.1093/glycob/cwy093 -
Experimental Gerontology Sep 2001Nonenzymatic deamidation of peptides and proteins represents an important degradation reaction occurring in vitro in the course of isolation or storage and in vivo... (Review)
Review
Nonenzymatic deamidation of peptides and proteins represents an important degradation reaction occurring in vitro in the course of isolation or storage and in vivo during development and/or aging of cells. This review first presents a synopsis of the influence of structure on deamidation reaction proceeding via a five-membered succinimide intermediate, followed by an outline of procedures for separation and detection of deamidated forms. Selected examples for in vitro and in vivo deamidation are reviewed including the possible biological consequences of this protein degradation. Finally, the reaction of protein methyltransferase with L-isoaspartyl- and D-aspartyl residues and its possible role in protein repair is elucidated.
Topics: Aging; Animals; Asparagine; Humans; Proteins
PubMed: 11525877
DOI: 10.1016/s0531-5565(01)00140-1 -
Electrophoresis Jun 2010One of the most frequent modifications in proteins and peptides is the deamidation of asparagine, a spontaneous non-enzymatic reaction leading to a mixture of... (Review)
Review
One of the most frequent modifications in proteins and peptides is the deamidation of asparagine, a spontaneous non-enzymatic reaction leading to a mixture of L,D-succinimidyl, L,D-aspartyl, and L,D-isoaspartyl forms, with L-isoaspartyl dominating. Spontaneous isomerization of L-Asp yields the same products. In vivo, these unusual forms of aspartate are repaired by the protein L-isoaspartyl O-methyltransferase enzyme, with the balance between isomerization and repair affecting the organism physiology. Mass spectrometric analysis of this balance involves isomer separation, iso-Asp/Asp quantification, and iso-Asp site identification. This review highlights the issues associated with these steps and discusses the prospects of high-throughput iso-Asp analysis.
Topics: Amides; Animals; Asparagine; Aspartic Acid; Electrophoresis, Gel, Two-Dimensional; Humans; Isomerism; Mass Spectrometry; Mice; Proteomics
PubMed: 20446295
DOI: 10.1002/elps.201000027 -
European Journal of Pharmacology Dec 2023Asparagine synthetase (ASNS) is a crucial enzyme for the de novo biosynthesis of endogenous asparagine (Asn), and ASNS shows the positive relationship with the growth of...
Asparagine synthetase (ASNS) is a crucial enzyme for the de novo biosynthesis of endogenous asparagine (Asn), and ASNS shows the positive relationship with the growth of several solid tumors. Most of ASNS inhibitors are analogs of transition-state in ASNS reaction, but their low cell permeability hinders their anticancer activity. Therefore, novel ASNS inhibitors with a new pharmacophore urgently need to be developed. In this study, we established and applied a system for in vitro screening of ASNS inhibitors, and found a promising unique bisabolane-type meroterpenoid molecule, bisabosqual A (Bis A), able to covalently modify K556 site of ASNS protein. Bis A targeted ASNS to suppress cell proliferation of human non-small cell lung cancer A549 cells and exhibited a synergistic effect with L-asparaginase (L-ASNase). Mechanistically, Bis A promoted oxidative stress and apoptosis, while inhibiting autophagy, cell migration and epithelial-mesenchymal transition (EMT), impeding cancer cell development. Moreover, Bis A induced negative feedback pathways containing the GCN2-eIF2α-ATF4, PI3K-AKT-mTORC1 and RAF-MEK-ERK axes, but combination treatment of Bis A and rapamycin/torin-1 overcame the potential drug resistance triggered by mTOR pathways. Our study demonstrates that ASNS inhibition is promising for cancer chemotherapy, and Bis A is a potential lead ASNS inhibitor for anticancer development.
Topics: Humans; Asparagine; Carcinoma, Non-Small-Cell Lung; Aspartate-Ammonia Ligase; A549 Cells; Phosphatidylinositol 3-Kinases; Lung Neoplasms; Cell Line, Tumor; Cell Proliferation
PubMed: 38059445
DOI: 10.1016/j.ejphar.2023.176156