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Paper of the Month

Studying the Role of Hif1 in Human Health, Disease and Therapy

By Connie Jeske Crane


Nora Dannah

According to the World Health Organization, cancer is the second leading cause of death globally, responsible for an estimated 9.6 million deaths in 2018. In the face of such widespread and devastating disease, at Ryerson, researchers like molecular science PhD candidate Nora Dannah are actively engaged in learning more and paving the way for new therapeutic approaches.

In recent years, the Human Genome Project has opened up many hopeful new avenues for researchers. A recent study by Dannah and fellow researchers, under the supervision of Ryerson’s Dr. Jeffrey Fillingham, is one such investigation. As Dannah explains: “The entire human genome is condensed into complex protein structures called chromatin. Research investigators have found that there is a correlation between proper chromatin assembly and cancer. As such, proper chromatin assembly is a crucial part of human development and must be highly regulated. Aberrations in chromatin assembly have been implicated in human diseases, including certain forms of cancer.” She adds, “Recent work has discovered NASP (nuclear autoantigenic sperm protein) as a tumor-associated antigen (TAA) meaning that it has elevated expression levels during tumor progression. The NASP protein is the human version of the yeast protein Hif1.”

Cartoon Representation of Hif1

Sketching out the impetus for the study, Dannah says her interest in battling diseases like cancer is paramount. So where does Hif1 come into play? Dannah says, “Hif1, as well as NASP, have been implicated in an array of chromatin-related processes including histone H3/H4 transport, chromatin assembly and DNA repair. In this study, we elucidate the functional aspects of Hif1.”

Using a variety of methods – including phylogenetic analysis of previously published raw data, gene network analysis, Western blots, indirect immunofluorescence and spot assays – Dannah and fellow researchers Syed Nabeel Shah (University of Toronto), Christoph Kurat (Biomedical Center Munich) and Prof. Sarah Sabatinos (Ryerson University), were ultimately able to produce a number of significant findings.

“The work has demonstrated that the acidic region presents within the TPR2 (sequence) of Hif1 in S. cerevisiae is critical for binding with the Hat1/Hat2-complex, Asf1, as well as histones H3/H4,” says Dannah. Underlining the significance here, she adds, “Hat1, Hat2, Asf1, histones H3/H4 are all proteins that are essential for proper chromatin assembly, and thus proper development.”

Indirect Immunofluorescence and Expression Analysis of Hif

As for the links to disease development, Dannah says, “Malfunctions of some histone transacetylases (HATs) have been associated with cancers and diseases including Rubinstein-Taybi syndrome. Moreover, in human cells, H4K5ac and H4K12ac appear to have some relevance to human disease and development. The gain of H4K5ac and loss of H4K12ac have been found in lung cancer cells. H4K5ac and H4K12ac acetylation levels are also associated with Crohn's disease and ulcerative colitis.”

Altogether, Dannah says the Ryerson work has provided novel insights into Hif1 functioning and establishes Hif1 as an important protein in chromatin-associated processes. “This research also provided evidence for the possible involvement of Hif1 in the regulation of histone dynamics emphasizing the central role of NASP-family proteins in the general maintenance of chromatin.”

As part of her Ryerson experience, Dannah greatly benefited from being able to deeply involve herself in all aspects of the work. She performed all but one of the lab experiments, helped design and coordinate the study, coauthored the subsequent research paper and was also able to hone her presentation skills at several conferences and symposiums. The group’s results were also recently published in the journal, G3: Genes, Genomes, Genetics, in a paper called “Functional Analysis of Hif1 Histone Chaperone in Saccharomyces cerevisiae.”

Beyond professional growth, Dannah, an international student from Saudi Arabia, says her time at Ryerson has also included lots of opportunities for personal growth. “I enjoyed being in a new environment, making new friends, and getting to experience a variety of cultures. I've also gotten to mentor many volunteers at my time here and it is great to be able to inspire them to pursue their research dreams.” The Hif1 study was supported by NSERC and the Saudi Arabia ministry of higher education.