Graduate Student Spotlight

Caitlin Zuikoski is a Ph.D. Candidate in the Cell & Molecular Concentration

Caitlin came to Lehigh University after earning a Bachelor of Science in Biochemistry, Cell and Molecular Biology at the University of Scranton. During her undergraduate career, Caitlin performed research in the laboratory of Dr. Kathleen Dwyer where she characterized protein expression patterns of receptor-like kinases in the plant Arabidopsis thaliana. In the fall of 2014, Caitlin entered Lehigh’s doctoral program and joined the lab of Dr. Robert Skibbens.

Within a cell cycle, different DNA tethering reactions are required.  In G1, cis tethering brings an enhancer element (E) in close proximity to a gene promotor (P) in order to stimulate gene expression.  During S phase, trans tethering ensures the two identical DNA copies are held together.  In Mitosis, the DNA condenses through cis tethering so that the DNA is properly inherited during cell division.

The Skibbens lab studies the mechanisms through which different DNA architectures are promoted and maintained. DNA is comprised of nucleotide sequences and contains the genetic code that is passed down from parent to offspring. Beyond the nucleotide sequence, DNA adopts various structures that regulate cell functions. As one example, a single DNA can become looped to bring together two distant DNA sequences to promote gene expression (defining cell identity) and DNA compaction (ensuring high fidelity segregation of DNA during cell division) (figure). Looping of a single DNA molecule is referred to as cis tethering since opposing sequences at the base of the DNA loop become bound together. Alternatively, two independent DNA molecules can become tethered together through trans tethering. Trans tethering of replicated DNA molecules ensures proper chromosome segregation during cell division (figure), which is a fundamental aspect of heredity. Defects in these tethering activities lead to loss (and gain) of DNA, a hallmark of cancer cells, and severe birth defects that include Cornelia de Lange syndrome and Roberts syndrome.

In the Skibbens lab, Caitlin studies the protein complex, termed cohesin, that forms the tether in both cis and trans DNA conformations. Little is known regarding how cohesins promote and differentiate between the two forms of tethering, but what is known is that cohesin must become activated to function in these processes. Eco1 in yeast (Esco2 and Esco1 in humans) activates cohesin, a process that appears coordinated with the process of DNA duplication. Caitlin’s thesis research investigates the connection between these two processes; specifically the mechanisms through which DNA replication proteins promote Eco1-dependent DNA tetherings.

Caitlin was on the administrative board for the Biological Organization of Graduate Students (BOGS) for two years. During her time in BOGS, she helped plan and volunteer at outreach events, such as “The Biology Fair” at Broughal Middle School. Caitlin enjoys attending local events in the Bethlehem area, such as comedy events at SteelStacks, and visiting local restaurants with fellow graduate students.