Epigenetic Regulation Of The HIF Pathway And Novel Therapeutic Opportunities

The research presented in this dissertation is aimed at understanding the epigenetic regulation of the HIF pathway and the efficacy of treatment for retinal diseases and hemangioblastomas using HIF pathway inhibitors. Jumonji domain containing proteins demethylate tri- and dimethylated histone lysines and regulate chromatin structure. Substrate specificity of Jumonji domain-2 family histone demethylases (JMJD2A-C) was evaluated. A candidate substrate-based approach demonstrated that JMJD2A-C demethylate trimethylated lysine containing peptides from WIZ, CDYL1, CSB and G9a proteins, all constituents of transcription repression complexes. Also preference of Arg at –1 position and a smaller amino acid at –2 position was identified. The results obtained are consistent with lax substrate specificities observed for the iron (II), 2- oxoglutarate-dependent dioxygenases, and shed new light on the role of JMJD2 family of KDMs during epigenetic transcriptional regulation. Hypoxia inducible factor (HIF) plays a critical role in cellular adaptation to hypoxia. Little is known about the epigenetic regulations during HIF-mediated transcription of pro-angiogenic genes in oxygen-dependent retinal diseases and hemangioblastomas. Hypoxic induction of a number of histone lysine demethylases (KDMs) and stem cell markers in retinal pigment epithelial cells and VHL‒/‒ renal cell carcinoma cells was evaluated. Also, expression of pro-angiogenic genes (ADM, GDF15, HMOX1, SERPE1 and SERPB8) was determined to be dependent on KDMs under hypoxia. Further, treating cells with a general KDM inhibitor blocked the induction of these pro-angiogenic genes. Expression of stem cell markers in hemangioblastomas was determined to be due to activation of the HIF pathway. Further, honokiol, digoxin, and doxorubicin, three recently identified HIF inhibitors from natural sources effectively blocked the expression of stem cell markers. These results present the possible cytological origin of neoplastic stromal cells in hemangioblastomas. Based on our results we believe that inhibition of the HIF pathway is an attractive strategy for the treatment of hemangioblastomas and retinal diseases. Also, blocking of KDMs using specific inhibitors can inhibit the amplification of the HIF pathway. TET2 is a Fe(II), 2OG dependent dioxygenase which can demethylate 5mC in a CpG context, a key epigenetic modification. In this study we developed a HPLC based analytical method for evaluating the catalysis by recombinant TET2 protein

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Pharmaceutical Sciences (UMKC)

Grantor

University of Missouri--Kansas City

Year dc:date.issued

2014

Author dc:creator

• Ponnaluri, Venkata Krishna Chaithanya

Advisor dc:contributor.advisor

• Mukherji, Mridul

Handle dc:identifier.uri

http://hdl.handle.net/10355/43711

OAI identifier oai:identifier

oai:mospace.umsystem.edu:10355/43711