A study of the mammalian high mobility group protein AT-hook 2 (HMGA2) and its interactions with DNA

Authors

Linjia Su, Florida International UniversityFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Chemistry

First Advisor's Name

Fenfei Leng

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Yuk-Ching Tse-Dinh

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Jeremy Wayne Chambers

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Francisco Alberto Fernandez-Lima

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Kevin O'Shea

Fifth Advisor's Committee Title

Committee member

Keywords

HMGA2, AT-hook, HMGA2-DNA interactions, suramin, daunorubicin/doxorubicin derivatives

Date of Defense

10-6-2021

Abstract

The mammalian high-mobility-group protein AT-hook 2 (HMGA2) is a small DNA-binding protein and consists of three positively charged “AT-hooks” and a negatively charged C-terminal motif. It is a multifunctional nuclear protein linked to obesity, human height, stem cell youth, human intelligence, and tumorigenesis. Previous results showed that HMGA2 is a potential therapeutic target of anticancer and anti‐obesity drugs through inhibiting its DNA‐binding activities. Here a miniaturized, automated AlphaScreen ultra‐high‐throughput screening assay is developed to identify inhibitors targeting HMGA2‐DNA interactions. After screening the LOPAC1280 library, several compounds are identified that strongly inhibit HMGA2‐DNA interactions including suramin, a negatively charged antiparasitic drug. The inhibition is likely through the binding of suramin to the “AT‐hooks” and therefore preventing HMGA2 from binding to the minor groove of AT‐rich DNA sequences. Charge‐charge interactions and hydrogen bonding between the suramin sulfonated groups and Arg/Lys residues likely play critical roles in the binding of suramin to the “AT‐hooks”. This study also suggests that HMGA2 may be one of suramin’s cellular targets.

This dissertation also demonstrates that the negatively charged C-terminus greatly affects the DNA-binding properties of HMGA2, as the C-terminal deletion mutant HMGA2∆95-108 binds much more tightly to the AT-rich DNA compared with the wildtype HMGA2. A synthetic peptide derived from the C-terminus of HMGA2 (CTP) strongly inhibits HMGA2 binding to AT-rich DNA through binding to the positively charged “AT-hooks”, suggesting that the CTP may be used as an inhibitor to block HMGA2 binding to AT-rich DNA.

HMGA2 is also linked to human topoisomerase I and II. HMGA2 greatly reduced the chromosomal DNA damage in cancer cells caused by topoisomerase II poisons such as daunorubicin and doxorubicin. Due to the induced multidrug resistance (MDR) of cancer cells and a cumulative, irreversible cardiotoxicity, the therapeutic efficacy of them is compromised and limited. Here, four new daunorubicin and doxorubicin derivatives, daunorubicin-GTP/dGTP, and doxorubicin-GTP/dGTP conjugates, have been synthesized and characterized. These new derivatives rapidly accumulate intracellularly in human cancer cells and are cytotoxic to both doxorubicin-sensitive SKOV3 and doxorubicin-resistant NCI/ADR-RES cells. Western blotting results show that these derivatives change the expression patterns of DNA topoisomerase I and IIa.

Identifier

FIDC010413

ORCID

0000-0001-5227-6605

Previously Published In

Su, L., Z. Deng, and F. Leng, The mammalian high mobility group protein AT- Hook 2 (HMGA2): biochemical and biophysical properties, and its association with adipogenesis. International Journal of Molecular Sciences, 2020. 21(10): p. 3710.

Su, L., et al., Identification of HMGA2 inhibitors by AlphaScreen-based ultra-high- throughput screening assays. Scientific Reports, 2020. 10(1): p. 1-14.

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Recommended Citation

Su, Linjia, "A study of the mammalian high mobility group protein AT-hook 2 (HMGA2) and its interactions with DNA" (2021). FIU Electronic Theses and Dissertations. 4904.
https://digitalcommons.fiu.edu/etd/4904