Distamycin A Inhibits HMGA1-Binding to the P-Selectin Promoter and Attenuates Lung and Liver Inflammation during Murine Endotoxemia

Abstract

BackgroundThe architectural transcription factor High Mobility Group-A1 (HMGA1) binds to the minor groove of AT-rich DNA and forms transcription factor complexes (“enhanceosomes”) that upregulate expression of select genes within the inflammatory cascade during critical illness syndromes such as acute lung injury (ALI). AT-rich regions of DNA surround transcription factor binding sites in genes critical for the inflammatory response. Minor groove binding drugs (MGBs), such as Distamycin A (Dist A), interfere with AT-rich region DNA binding in a sequence and conformation-specific manner, and HMGA1 is one of the few transcription factors whose binding is inhibited by MGBs.ObjectivesTo determine whether MGBs exert beneficial effects during endotoxemia through attenuating tissue inflammation via interfering with HMGA1-DNA binding and modulating expression of adhesion molecules.Methodology/Principal FindingsAdministration of Dist A significantly decreased lung and liver inflammation during murine endotoxemia. In intravital microscopy studies, Dist A attenuated neutrophil-endothelial interactions in vivo following an inflammatory stimulus. Endotoxin induction of P-selectin expression in lung and liver tissue and promoter activity in endothelial cells was significantly reduced by Dist A, while E-selectin induction was not significantly affected. Moreover, Dist A disrupted formation of an inducible complex containing NF-κB that binds an AT-rich region of the P-selectin promoter. Transfection studies demonstrated a critical role for HMGA1 in facilitating cytokine and NF-κB induction of P-selectin promoter activity, and Dist A inhibited binding of HMGA1 to this AT-rich region of the P-selectin promoter in vivo.Conclusions/SignificanceWe describe a novel targeted approach in modulating lung and liver inflammation in vivo during murine endotoxemia through decreasing binding of HMGA1 to a distinct AT-rich region of the P-selectin promoter. These studies highlight the ability of MGBs to function as molecular tools for dissecting transcriptional mechanisms in vivo and suggest alternative treatment approaches for critical illness.

The High Mobility Group A1 (HMGA1) Transcriptome in Cancer and Development

“…While many studies cited here underscore the fundamental role of HMGA1 in tumor progression, there has been relatively little work focused on targeting HMGA1 in cancer [176]. To date, disrupting the function of oncogenic transcription factors has been challenging given the hurdles of delivery and specificity.…”

“…HMGA1 also induces expression of PSEL , another CAM gene that is expressed in p latelets (thus designated PSEL ) as well as in endothelial cells [176]. HMGA1 binds to the PSEL promoter, as demonstrated in vitro by gel shift experiments and in vivo by chromatin immunoprecipitation in bovine aortic endothelial cells (BAECs) at an AT-rich site in a complex that includes the p50/p65 members of the NF-κB family.…”

“…Distamycin, a drug that binds to the minor groove, blocks HMGA1 binding to the PSEL promoter in gel shift experiments and decreases PSEL expression in transfection experiments without affecting ESEL expression. Distamycin also blocks PSEL expression in a murine model for inflammation during endotoxemia, with no decrease in ESEL expression [176]. The basis for the differential effects on P- and ESEL are not clear and further studies are needed to determine under what cellular contexts HMGA1 regulates P - and ESEL .…”

Isoflurane Ameliorates Acute Lung Injury by Preserving Epithelial Tight Junction Integrity

“…Gr-1 (neutrophil) staining was performed and quantitated as described previously. 28 Briefly, 3 random 400X images were acquired using an Olympus microscope (Olympus, Center Valley, PA). Images were converted to 8-bit (grayscale) and analyzed using NIH Image J software.…”

Antineoplastic DNA-Binding Compounds: Intercalating and Minor Groove Binding Drugs

“…The tripyrrole peptide distamycin A is a naturally occurring antibiotic agent obtained from the cultures of Streptomyces distallicus (62). It binds exclusively to the minor groove of DNA with high selectivity for the AT rich region (65). Distamycin A (Figure 8) is a potent inhibitor of Werner and Bloom syndrome helicases and a dual inhibitor of topo I and II.…”