Unraveling mysteries of ABCB5β through international collaboration: two research stays at NIH by Louise Gerard

Louise Gerard holds a master's degree in biomedical sciences from the UNamur. In September 2019, she joined the Laboratory of Molecular Cancer Biology led by Prof. Jean-Pierre Gillet (UNamur, URPhyM) for a PhD thesis focusing on the role of the ABCB5β transporter in melanoma. This protein exists as a half-transporter, meaning that it must either homodimerize or heterodimerize to become functional. The aim of her research was to determine which proteins interact with ABCB5β and to further characterize the discovered dimers.

During the first three years of her thesis, she used three complementary techniques (nanoluciferase-based bioluminescence resonance energy transfer, co-immunoprecipitation, and proximity ligation assay), and identified two novel heterodimers in melanoma: ABCB5β/B6 and ABCB5β/B9.

More recently, Louise wanted to determine whether these heterodimers could hydrolyze ATP, which is required for the transport of substrates across membranes. This study was facilitated thanks to a longstanding collaboration between her thesis promoter, Prof. Jean-Pierre Gillet, and Dr. Suresh Ambudkar from the National Cancer Institute (NCI) at the National Institutes of Health (NIH) in the United States. Suresh Ambudkar masters the pharmacological characterization of ABC transporters since he first published a protocol describing the ATPase assay (Ambudkar, 1998).

End 2022, Louise had the opportunity to spend two months in Ambudkar's lab. During this first research stay, she was able to show that both heterodimers exhibit significant levels of basal ATPase activity, and thus can act as functional transporters. Louise returned to Ambudkar’s lab for another stay of two months late 2023 to test additional recombinant proteins, including chimeric homodimers and a set of additional controls.

Louise Gerard’s brilliant work has just been published in the Journal of Biological Chemistry (Gerard et al., 2023). Her groundbreaking study marks an important step toward elucidating the functional role of ABCB5β in melanocytes and melanoma.

Louise Gerard’s mobility was supported through the NARILIS “Research Stay Grants” programme. These grants exemplify NARILIS's commitment to facilitating international collaborations and promoting research excellence. By providing research stay grants, NARILIS enables its researchers to collaborate with world-renowned institutions such as NIH, to acquire new skills and to carry out experimental work that is not feasible in their home labs.

Contact: jean-pierre.gillet@unamur.be

Picture: Louise (third person from the left) with the team of Suresh Ambudkar