Sequence of a cDNA encoding turtle high mobility group 1 protein

In order to understand sequence information about turtle HMG1 gene, a cDNA encoding HMG1 protein of the Chinese soft-shell turtle (Pelodiscus sinensis) was amplified by RT-PCR from kidney total RNA, and was cloned, sequenced and analyzed. The results revealed that the open reading frame (ORF) of turtle HMG1 cDNA is 606 bp long. The ORF codifies 202 amino acid residues, from which two DNA-binding domains and one polyacidic region are derived. The DNA-binding domains share higher amino acid identity with homologues sequences of chicken (96.5%) and mammalian (74%) than homologues sequence of rainbow trout (67%). The polyacidic region shows 84.6% amino acid homology with the equivalent region of chicken HMG1 cDNA. Turtle HMG1 protein contains 3 Cys residues located at completely conserved positions. Conservation in sequence and structure suggests that the functions of turtle HMG1 cDNA may be highly conserved during evolution. To our knowledge, this is the first report of HMG1 cDNA sequence in any reptilian.     

Monoclonal antibody against non-histone chromosomal protein high mobility group 1 Co-migrates with high mobility group 1 into the nucleus

Non-histone chromosomal protein high mobility group 1 (HMG-1) rapidly migrates into the nucleus when injected into the cytoplasm of bovine fibroblasts and HeLa cells by red cell-mediated microinjection (Rechsteiner, M., and Kuehl, L. (1979) Cell 16, 901-908). We isolated hybridomas secreting monoclonal antibodies against HMG-1. One of these monoclonal antibodies, FR-1, inhibited in vitro binding of 125I-HMG-1 to chromatin isolated from FL cells. When 125I-HMG-1 was co-introduced with antibody FR-1 by red cell-mediated microinjection, antibody FR-1 did not prevent the accumulation of 125I-HMG-1 in the nucleus. When 125I-antibody FR-1 or fluorescein isothiocyanate antibody FR-1 was introduced into the cytoplasm of FL cells, most of the antibody did not accumulate in the nucleus. But when 125I- or fluorescein isothiocyanate antibody FR-1 was co-introduced with HMG-1 into the cytoplasm of FL cells, it did migrate into the nucleus.     

The high mobility group proteins and transcribed nucleosomes

Monomer nucleosomes released from nuclei during brief micrococcal nuclease digestions are enriched in transcribed sequences (Bloom and Anderson, 1978). These nucleosomes are depleted in H1 and enriched in three high mobility group proteins HMG14, HMG17 and another HMG-like protein. Analysis of such nucleosomes by polyacrylamide gel electrophoresis reveal that they are heterogenous. Similarly, monomer nucleosomes soluble in 0.1 M NaCl separate on polyacrylamide gels into mainly two types of particle, one of which has HMG14 and HMG17 bound. However, the DNA of the HMG-nucleosomes from chick erythrocytes is not enriched in globin sequences, suggesting that protein rearrangement may have occurred.     

Evidence for a quantitative tissue-specific distribution of high mobility group chromosomal proteins

The quantitative tissue specificity of the high mobility group (HMG) chromosomal proteins was investigated. Perchloric acid (PCA) extracts of four different chicken tissues and erythrocytes contained three proteins which comigrated on NaDodSO4-polyacrylamide gels with the HMG's 1,2, and E from erythrocyte nuclei. These three HMG's from embryonic skeletal muscle and erythrocytes also comigrated on two-dimensional gels, employing an acid-urea system in the first dimension and an NaDodSO4 system in the second. Interpretation of the two-dimensional gels suggested that the two low molecular weight proteins of this triplet arose from the HMG 2 band of the acid-urea gels. These have been designated HMG 2A and HMG 2B. Three proteins of similar molecular weights were also found in the PCA extracts of calf thymus. They were arranged in a similar but not identical pattern on two-dimensional gels. Thus, these three HMG's appear to be neither tissue nor species specific. In addition, the 2.0% PCA extracts of all chicken tissues examined contain a 38 000-dalton (38K) nuclear protein which coisolates with the HMG's. These four proteins are found in different relative amounts in each of the four chicken tissues and erythrocytes. They are found in the same relative amounts, however, in embryonic skeletal muscles from different chicken strains with widely different highly repetitive sequence content, suggesting that none of these individual proteins is selectively localized to constitutive heterochromatin. The quantitative tissue specificity of the HMG's and the 38K protein, however, suggests that they may participate in regulating cell-specific gene expression.     

高速泳动族蛋白1的致炎症作用机制

高速泳动族蛋白1(high-mobility group box 1,HMGB1)是一种高度保守的DNA结合蛋白,具有维持核小体结构和调节基因转录的功能,近来发现它是炎性反应强有力的促炎因子。在大多炎性疾病,特别是脓毒症病例中,HMGB1的血清和组织水平均显著升高,而且它与其受体如糖基化终末产物受体(receptor for advanced glycation end products,RAGE)、Toll样受体4(toll-like receptor,TLR4)、Toll样受体2(TLR2)等相互作用促进炎性疾病的发展。为了进一步了解HMGB1,本文就HMGB1的结构、生物学活性、与免疫细胞相互作用、细胞表面受体、以及拮抗HMGB1的药物等进行综述。     

Discrete proteolytic cleavage of high mobility group proteins.

Chromatographic fractionation on CM-Sephadex of a 0.35 M NaCl extract from calf thymus chromatin reveals the presence of a High Mobility Group (HMG) protein which comigrates electrophoretically with HMG-17. Further amino acid analysis and partial sequence determination suggest that this protein is a proteolytic degradation product of either HMG-1 or HMG-2 from which the acidic C-terminal region has been removed.     

晚期炎症介质-高迁移率族蛋白B-1

高迁移率族蛋白-1(HMGB-1)是一类广泛存在于真核细胞内的非组核蛋白,是由肿瘤坏死因子(TNF-a)刺激巨噬细胞分泌。HMGB-1全身性炎症反应失控性发展是致使组织损伤和器官衰竭的根本原因,在脓毒症HMGB-1升高程度与感染严重性呈正相关。HMGB-1是炎症晚期重要介质,抑制HMGB-1能够预防内毒素和细菌攻击所致MODS,改善严重脓毒症的预后。尽管对HMGB-1防治作用的确切机制与应用效果尚待深入探讨,但HMGB-1为临床干预脓毒症提供了较宽的时间窗。     

Heterogeneous binding of high mobility group chromosomal proteins to nuclei

A dramatic difference is observed in the intracellular distribution of the high mobility group (HMG) proteins when chicken embryo fibroblasts are fractionated into nucleus and cytoplasm by either mass enucleation of cytochalasin-B-treated cells or by differential centrifugation of mechanically disrupted cells. Nuclei (karyoplasts) obtained by cytochalasin B treatment of cells contain more than 90 percent of the HMG 1, while enucleated cytoplasts contain the remainder. A similar distribution between karyoplasts and cytoplasts is observed for the H1 histones and the nucleosomal core histones as anticipated. The presence of these proteins, in low amounts, in the cytoplast preparation can be accounted for by the small percentage of unenucleated cells present. In contrast, the nuclei isolated from mechanically disrupted cells contain only 30-40 percent of the total HMGs 1 and 2, the remainder being recovered in the cytosol fraction. No histone is observed in the cytosol fraction. Unike the higher molecular weight HMGs, most of the HMGs 14 and 17 sediment with the nuclei after cell lysis by mechanical disruption. The distribution of HMGs is unaffected by incubating cells with cytochalasin B and mechanically fractionating rather than enucleating them. Therefore, the dramatic difference in HMG 1 distribution observed using the two fractionation techniques cannot be explained by a cytochalasin-B-induced redistribution. On reextraction and sedimentation of isolated nuclei obtained by mechanical cell disruption, only 8 percent of the HMG 1 is released to the supernate. Thus, the majority of the HMG 1 originally isolated with these nuclei, representing 35 percent of the total HMG 1, is stably bound, as is all the HMGs 14 and 17. The remaining 65 percent of the HMGs 1 and 2 is unstably bound and leaks to the cytosol fraction under the conditions of mechanical disruption. It is suggested that the unstably bound HMGs form a protein pool capable of equilibrating between cytoplasm and stably bound HMGs.     

ADP-ribosylation of nonhistone high mobility group proteins in intact cells

The ADP-ribosylation of nonhistone, high mobility group (HMG) proteins in intact cultured cells was investigated. Radioactively labeled adenosine was used as a precursor to detect (ADP-ribose)n on protein. A protein fraction enriched in HMG proteins and histone H1 was separated from RNA and DNA by CsCl density gradient centrifugation, 5% perchloric acid extraction, and CM-Sephadex C-50 column chromatography. Poly- and mono(ADP-ribose) were recovered following alkaline hydrolysis, and 5'-AMP and (2'-(5"-phosphoribosyl)-5'-AMP) were produced by phosphodiesterase treatment, indicating that the protein-bound radioactive material was (ADP-ribose)n. An average chain length of 1.5 to 1.8 was determined. Analysis of proteins by sodium dodecyl sulfate and acetic acid/urea polyacrylamide gel electrophoresis demonstrated that HMG 1, 2, 14, and 17 as well as histone H1 contained (ADP-ribose)n. Treatment of cells with 3-aminobenzamide, an inhibitor of (ADP-ribose)n synthetase, decreased endogenous ADP-ribosylation in both types of chromosomal proteins but that of HMG 14 and 17 was affected more.