High mobility group-1 protein is an abundant component of all mammalian nuclei, and related proteins exist in all eukaryotes. HMG1 binds with high affinity to specific DNA structures such as bent or kinked DNA (Bianchi et al., 1989). It is considered to be a structural protein of chromatin.
NCBI Summary:
This gene encodes a protein that belongs to the High Mobility Group-box superfamily. The encoded non-histone, nuclear DNA-binding protein regulates transcription, and is involved in organization of DNA. This protein plays a role in several cellular processes, including inflammation, cell differentiation and tumor cell migration. Multiple pseudogenes of this gene have been identified. Alternative splicing results in multiple transcript variants that encode the same protein. [provided by RefSeq, Sep 2015]
General function
Cell cycle regulation, DNA binding, Transcription factor
Comment
Cellular localization
Secreted, Nuclear
Comment
HMGB1 is increased in adolescents with polycystic ovary syndrome (PCOS) and decreases after treatment with myo-inositol (MYO) in combination with alpha-lipoic acid (ALA). Cirillo F et al. (2020) PCOS treatment should be based on pathophysiology. High-mobility-group-box-1 (HMGB1) was shown to increase in PCOS patients as a consequence of reduced cystic-fibrosis-transmembrane-conductance-regulator (CFTR) expression in the ovary, and was associated with insulin resistance and inflammation, both features of PCOS. Inositols and ALA derivatives could have positive effects on insulin sensitivity, reduce androgens, and improve ovulation rhythm. The aim of this study was to verify changes in HMGB1, in metabolic and endocrine parameters in adolescents with PCOS compared with controls and after treatment with a combination of MYO + ALA. Twenty-three PCOS adolescents and 21 controls matched for age and BMI were enrolled. In all subjects, metabolic and hormonal parameters were assayed. Homeostatic index (HOMA-IR) and the triglyceride/HDL-cholesterol ratio were calculated. Ovarian volumes were evaluated. Patients were treated with MYO + ALA for 6 months. HMGB1 was measured using a specific ELISA assay. HMGB1 was increased in PCOS compared with controls (19.76 ± 5.99 versus 5.65 ± 1.88 ng/ml; p < .05) and normalized after treatment (2.27 ± 0.36 ng/ml, p < .05). Treatment significantly reduced insulin (24.0 ± 4.11 versus 12.13 ± 2.13 uU/ml), HOMA-IR (3.91 ± 0.41 versus 2.42 ± 0.45), and 17-hydroxyprogesterone (1.20 ± 0.15 versus 0.78 ± 0.11 ng/ml). Cholesterol, luteinizing hormone, 17-β-estradiol, delta 4-androstenedione, and testosterone were unchanged. Circulating HMGB1 was increased in PCOS adolescents, and treatment was effective in normalizing HMGB1.//////////////////
Ovarian function
Follicle atresia
Comment
Cellular hallmarks of aging emerge in the ovary prior to primordial follicle depletion. Ansere VA et al. (2021) Decline in ovarian reserve with advancing age is associated with reduced fertility and the emergence of metabolic disturbances, osteoporosis, and neurodegeneration. Recent studies have provided insight into connections between ovarian insufficiency and systemic aging, although the basic mechanisms that promote ovarian reserve depletion remain unknown. Here, we sought to determine if chronological age is linked to changes in ovarian cellular senescence, transcriptomic, and epigenetic mechanisms in a mouse model. Histological assessments and transcriptional analyses revealed the accumulation of lipofuscin aggresomes and senescence-related transcripts (Cdkn1a, Cdkn2a, Pai-1 and Hmgb1) significantly increased with advancing age. Transcriptomic profiling and pathway analyses following RNA sequencing, revealed an upregulation of genes related to pro-inflammatory stress and cell-cycle inhibition, whereas genes involved in cell-cycle progression were downregulated; which could be indicative of senescent cell accumulation. The emergence of these senescence-related markers preceded the dramatic decline in primordial follicle reserve observed. Whole Genome Oxidative Bisulfite Sequencing (WGoxBS) found no genome-wide or genomic context-specific DNA methylation and hydroxymethylation changes with advancing age. These findings suggest that cellular senescence may contribute to ovarian aging, and thus, declines in ovarian follicular reserve. Cell-type-specific analyses across the reproductive lifespan are needed to fully elucidate the mechanisms that promote ovarian insufficiency.////////////////// HMGB1-induced aberrant autophagy contributes to insulin resistance in granulosa cells in PCOS. Zhang C et al. (2020) Insulin resistance (IR) disrupts ovarian functions in polycystic ovary syndrome (PCOS). The contributing factors remains elusive. High mobility group box 1 (HMGB1), a damage-associated molecular pattern molecule, has been shown to be related to IR and autophagy, respectively, in peripheral tissues. Here, we investigated whether increased HMGB1 contributes to IR in granulosa cells of PCOS patients via induction of aberrant autophagy. Results showed that HMGB1 abundance in the follicular fluid was significantly increased with enhanced autophagy in granulosa cells in PCOS patients with IR. HMGB1 exacerbated autophagy in granulosa cells as evinced by increased LC3B II/I ratio and ATG7 as well as decreased p62, the markers for autophagy. Concurrently, HMGB1 impaired insulin sensitivities by attenuating the abundance of insulin receptor substrate-1, Akt phosphorylation, GLUT4 translocation, and glucose uptake in granulosa cells, which were reversed by blocking autophagy pathways with siRNA-mediated knockdown of ATG7 or with chloroquine and bafilomycin A1, the lysosome inhibitors. In conclusion, our results indicate that increased HMGB1 contributes to IR development in granulosa cells of PCOS patients, which is associated with exacerbation of autophagy by HMGB1. Control of HMGB1 production may be benefical for the improvement of insulin sensitivity in granulosa cells in PCOS.//////////////////High Concentration of Insulin Promotes Apoptosis of Primary Cultured Rat Ovarian Granulosa Cells Via Its Increase in Extracellular HMGB1. Ni XR 2014 et al.
Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting women of reproductive age. Insulin resistance/hyperinsulinemia is a prevalent finding in women with PCOS, which indicates that insulin resistance/hyperinsulinemia may be an important player in the pathogenesis of the PCOS. However, the underlying mechanism of insulin resistance/hyperinsulinemia on the pathogenesis of the PCOS remains elusive. In this study, we found an increased high-mobility group box 1 (HMGB1) in the serum from women with PCOS having insulin resistance/hyperinsulinemia. Furthermore, we discovered that high concentration of insulin, which mimics insulin resistance model, promoted apoptosis in primary cultured rat ovarian granulosa cells (GCs) via its effect on the increase in extracellular HMGB1. Our data presented the first evidence that increased HMGB1 induced by insulin resistance/hyperinsulinemia promoted apoptosis of ovarian GCs, which provided new molecular basis for the PCOS pathogenesis.
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Expression regulated by
FSH, ZFAS1
Comment
Downregulation of lncRNA ZFAS1 and upregulation of microRNA-129 repress endocrine disturbance, increase proliferation and inhibit apoptosis of ovarian granulosa cells in polycystic ovarian syndrome by downregulating HMGB1. Zhu HL et al. (2020) The objective was to find the role of long-non-coding RNA zinc finger antisense 1 (lncRNA ZFAS1)/microRNA (miR)-129/high-mobility group box protein 1 (HMGB1) axis in polycystic ovary syndrome (PCOS). Ovarian granulosa cells from non-PCOS patients and PCOS patients were collected, and HMGB1, miR-129 and lncRNA ZFAS1 expression were detected. Ovarian granulosa cells were transfected with si-ZFAS1 or miR-129 mimics to verify their roles in P4 and E2 secretion, and the biological functions of ovarian granulosa cells. LncRNA ZFAS1 and HMGB1 were elevated, while miR-129 was down-regulated in ovarian granulosa cells of PCOS patients. Down-regulated lncRNA ZFAS1 or overexpressed miR-129 could decrease HMGB1 expression, increase P4 and E2 secretion, promote proliferation activity while inhibit apoptosis of ovarian granulosa cells in PCOS. LncRNA ZFAS1 could bind to miR-129 to promote HMGB1 expression, thereby affecting the endocrine disturbance, proliferation and apoptosis of ovarian granulosa cells in PCOS.//////////////////
Ovarian localization
Primordial Germ Cell, Granulosa, Follicular Fluid
Comment
Toll-like receptors and high mobility group box 1 in granulosa cells during bovine follicle maturation. Xie Y et al. (2019) Toll-like receptors (TLRs) are present in the ovaries and reproductive tract of various mammals. The biological function of TLR during ovulation is one of the main contents in the research of reproductive immunology. In this study, we found that messenger RNA levels of TLR1-TLR10 in granulosa cells were different, and TLRs and high mobility group box 1 (HMGB1) in granulosa cells of large follicles were significantly higher than those of small and middle follicles. Coimmunoprecipitation results showed that HMGB1 interacts with TLR2 in granulosa cells, especially large follicles. The result of immunohistochemistry showed that TLRs and HMGB1 were present in granulosa cell layer of ovarian follicles. We also found 25 mIU/ml follicle-stimulating hormone (FSH) significantly upregulated the expression of TLRs and HMGB1. These results suggest that TLR2/4 and HMGB1 in granulosa cells may be involved in the ovarian innate immune and ovarian follicular maturation, regulated by FSH. However, further research of the function and mechanisms of TLRs and HMGB1 in granulosa cells are needed.//////////////////
Association between follicular fluid levels of HMGB1 protein and outcomes in patients undergoing in vitro fertilization/intracytoplasmic sperm injection cycles. Li S et al. (2015) The aim of the present study was to evaluate the association between follicular fluid (FF) levels of high-mobility group box 1 (HMGB1) protein and the reproductive outcome in patients undergoing in vitro fertilization (IVF) with intracytoplasmic sperm injection (ICSI). FF samples were collected from the ovarian follicles (≥14 mm) of 143 infertile patients that had undergone IVF/ICSI, and the HMGB1 expression levels were determined using ELISA. Spearman's correlation and receiver operating characteristic (ROC) curve analysis were applied to analyze the results. Significantly increased levels of HMGB1 protein (7.38±2.02 vs. 6.14±2.52 ng/ml; P<0.01), endometrial thickness on the day of human chorionic gonadotropin (hCG) administration (10.3±1.3 vs. 9.7±1.7 mm; P<0.01) and retrieved oocyte counts (11.68±6.51 vs. 11.00±6.34; P<0.01) were observed in the pregnant group when compared with the non-pregnant group. Conversely, the level of luteinizing hormone on the day of hCG administration was significantly reduced in the pregnant group compared with the non-pregnant group (0.92±1.78 vs. 1.78±2.03 pmol/l, P<0.01). The ROC curve indicated a significant association between the FF level of HMGB1 protein and the pregnancy rate, with an area under the ROC curve of 0.673 (0.581-0.765; P<0.01). In addition, the HMGB1 protein level was shown to have a significant positive correlation with the endometrial thickness (r=0.170; P<0.05). Therefore, the present study indicated that the FF levels of HMGB1 protein are increased in pregnant patients and are positively correlated with endometrial thickness. Thus, FF levels of HMGB1 may be a useful factor for predicting the outcome of IVF/ICSI treatments.//////////////////
Follicle stages
Primordial
Comment
Arraztoa JA, et al 2005
reported the identification of genes expressed in primate primordial oocytes.