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The High Mobility Group (HMG) Proteins
Published in Lubomir S. Hnilica, Chromosomal Nonhistone Proteins, 2018
The nuclei of a wide variety of mammalian, avian, and fish tissues contain a series of proteins of about 29,000 mol wt which have high contents of acidic and basic amino acids. Originally two such proteins, HMG1 and 2, were isolated by salt or PCA extractions of calf thymus chromatin,1,3,10 but later it was shown that HMG2 was composed of a family of at least four subfractions which differed in their isoelectric points.14Figure 2 is an example of a more recent analysis and shows that HMG2 is composed of five subfractions, A to E.15 (HMG1 does not focus as a discrete band in the isoelectric focusing dimension of Figure 2, probably because of aggregation.) These six proteins (HMG1, 2A, 2B, 2C, 2D, 2E) are apparently present in all calf tissues15,16 and very similar proteins have been found in other mammalian tissues.5,8 The amino acid compositions of calf thymus HMG1 and four of the five HMG2 subfractions are given in Table 2. These analyses demonstrate the highly charged nature of the proteins and the close similarities of the members of the group of proteins within a species.
Cisplatin and Related Anticancer Drugs: Recent Advances and Insights
Published in Astrid Sigel, Helmut Sigel, Metal Ions in Biological Systems, 2004
Katie R. Barnes, Stephen J. Lippard
Although many studies have demonstrated that HMG-domain proteins potentiate cisplatin cytotoxicity, others reveal that HMG-domain proteins either have no effect or actually protect the cell from cisplatin damage. The cytotoxicity of cisplatin was investigated in two mouse embryonic fibroblast cell lines, Hmgbl+/+ and Hmgb1−/− [83]. Unexpectedly, the sensitivity of the two cell lines to cisplatin was equivalent. In addition, the levels of cisplatin-induced apoptosis were similar, suggesting that HMGB1 levels do not effect cisplatin cytotoxicity in mouse embryonic cells [83]. It is possible that HMGB1 is engaged in protein complexes and unavailable for repair shielding of cisplatin-DNA adducts. Alternatively, in the HMGB1 deficient Hmgb1−/− cells, other proteins such as HMGB2 may play a role in modulating cisplatin sensitivity [83]. Other work has indicated that HMGB1 is overexpressed in cisplatin-resistant cell lines and several yeast cell lines deficient in HMG-domain proteins are hypersensitive to cisplatin [84,85]. Clearly the effect of HMG-domain proteins in modulating the activity of cisplatin depends upon the cell type and/or context.
MicroRNAs in IgA nephropathy
Published in Renal Failure, 2021
Xingchen Yao, Yaling Zhai, Huanping An, Jingge Gao, Yazhuo Chen, Wenhui Zhang, Zhanzheng Zhao
HMGB2 participates in four IgAN-related pathways, namely, the inflammatory response, defense response to bacteria, diversification of immune receptors, and cell surface receptor signaling pathways [17,18]. Zhai et al. used three gene expression profile datasets (GSE14795, GSE73953, and GSE25590), and the differentially expressed genes (DEGs) and miRNA network associated with IgAN constructed by Cytoscape, to screen out the associations of HMGB2 and hsa‐miR‐590‐3p with IgAN [19]. The dual‐luciferase reporter system indicated that hsa‐miR‐590‐3p bound to the 3′-UTR of HMGB2 and inhibited its expression. They found that hsa‐miR‐590‐3p increased, while HMGB2 decreased in PBMCs of IgAN patients, indicating a significant negative correlation between the expression of HMGB2 and hsa-miR-590-3p. However, the mechanism by which HMGB2 affects the production of gd-IgA1 is still unclear and needs further research.
Ginsenoside Rb1 inhibits proliferation and promotes apoptosis by regulating HMGB1 in uterine fibroid cells
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Jianqiang Zhang, Jing Wang, Xinan Wu, Yuhui Wei
High-mobility protein (HMG) consists of three members: HMGA, HMGB and HMGN, of which HMGB includes HMGB1, HMGB2 and HMGB3 [17]. HMGB1 is a ubiquitous and highly conserved nuclear protein involved in nucleosome maintenance and gene transcription. In addition, HMGB1 is involved in DNA recombination, repair and replication [18]. As early as the end of the twentieth century, a large number of studies reported that HMGB1 played an important role in uterine fibroids [19,20]. As early as 1999, German research team by Michael et al. [21] found that HMGI is highly expressed in uterine leiomyoma, and immunohistochemistry is used to verify that HMGI-C is only expressed in leiomyoma smooth muscle cells. These findings suggest that overexpression of HMGI protein is critical for the pathogenesis of uterine leiomyoma. A year later, American team by Tallini et al. [22] used probes for in-situ-hybridization analysis in benign tumors (uterine leiomyoma, lipoma, endometrial polyps) which found that HMGI-C or HMGI(Y) was highly expressed, and associated with 12q15 and 6p21 chromosomal mutations, revealing that in a biphasic lesion composed of a mixture of stromal cells and epithelial cells, the mesenchymal component is the site of HMGI gene variation. In this study, gene intervention (knockdown HMGB1 and overexpressing HMGB1) was used to detect the proliferation and apoptosis abilities of uterine fibroid cells. Knockdown of HMGB1 inhibited proliferation and promoted apoptosis of uterine fibroid cells. Overexpression of HMGB1 rescued the effects of ginsenoside Rb1 inhibition on proliferation and apoptosis of uterine fibroid cells.
Extracellular vesicles derived from natural killer cells use multiple cytotoxic proteins and killing mechanisms to target cancer cells
Published in Journal of Extracellular Vesicles, 2019
Chun-Hua Wu, Jingbo Li, Li Li, Jianping Sun, Muller Fabbri, Alan S. Wayne, Robert C. Seeger, Ambrose Y. Jong
The SET and HMG2 proteins are GzmA substrates during programmed cell death [27]. To test the role of GzmA contained in isolated NK-EVs, we used Western blots to detect these proteins (HMG2 and SET) in target cells (Figure 5). The immunoblots were probed with an antibody to HMG2 first, and the same blots were stripped and re-probed with an antibody to SET (also known as 12PP2A). In CHLA255 cell lysates (Figure 5(a)), SET (~45 KDa) decreased during incubation with increasing amounts of NK-EVs (upper panel), an effect that was time-dependent (lower panel). A similar effect was observed in SupB15 cell lysates, except that the protein level of HMG2B in SupB15 was less abundant than that in CHLA255, and the time course of HMG2B degradation in the presence of NK-EVs was more rapid (Figure 5(b)). The Western-blot signals were quantified by the ImageJ program (Supplement Figure S5). Thus, titration and time-point studies showed that in the presence of NK-EVs, the degradation of SET and HMG2B can be observed in both CHLA255 and SupB15 cells. These results indicate that NK-EVs, most likely via GzmA, can cleave SET and HMG2 to promote cell death in a caspase-independent death pathway.