The Kubiseski Lab

Research Areas: Molecular biology, cell biology, genetics and biochemistry, signaling pathways, oxidative damage, apoptosis, DNA repair.

My work focuses on using genetics to dissect the signaling pathways involved the response of the cell to external stress factors that damage DNA.   Specifically, we are interested in the function and signaling pathways of the Ras/Rho GTPase family of proteins, which play an important part in regulating fundamental a diverse set of cell processes such as oxidative stress response, cell growth and motility.

We use the nematode (aka, the worm) Caenorhabditis elegans as a model for elucidating the signaling pathways.  C.elegans is a small, safe, non-parasitic, simple, and easily maintained organism that has it genome completely sequenced and cell lineage during development completely defined.   C.elegans has proven to be a useful organism for studying the functional mechanisms of the Ras/Rho family of GTPases due to the ease of creating and manipulating genetic mutants of the organism.

We have been studying a putative downstream effector of the Ras GTPase called Brap-2.  Brap-2 was originally discovered as a binding partner to the mammalian tumour suppressor gene Brca1 and our studies have shown that worms containing a mutation in brap-2 show a strong susceptibility to oxidative conditions during development that cause the worms to arrest and stop growing.  The development arrest, we showed, was dependent on the brc-1 (worm homolog of Brca1) gene.   This was the first indication of a functional interaction between brap-2 and brc-1 and further studies involving the signaling function of brap-2 with other tumour suppressor genes in C.elegans (such as p53 and PTEN) is becoming a productive area of research in my research program.

Recently, we have found that the C.elegans brap-2 mutant worms have excessive expression of the class II detoxification enzyme gst-4, (which detoxify reactive oxygen species), but not of other known detoxification systems (class I enzymes, for example).  We have determined that this excessive expression of gst-4 is due to the activation of the transcription factor skn-1 upon mutation in brap-2. Furthermore, we show that activation of skn-1 in brap-2 mutants requires the GATA transcription factor elt-3.  Lifespan of animals require proper detoxification of reactive oxygen species, and we demonstrated that increase lifespan occurs in animals with elevated skn-1 gene expression and that it requires elt-3. This is the first demonstration that brap-2 (i) regulates and activates a major detoxification system through gene regulation, (ii) the GATA transcription factor is essential for the detoxification response in animals, and  (iii) regulates life span in animals. Using C.elegans mutants of brap-2, we have further identified 18 transcription factors responsible for the phase II detoxification response (Hu et al, 2017).

The second research area in my lab deals with studies with C.elegans mutants of the BRCA-1 homolog brc-1, worms that had demonstrated that these worms display increase apoptosis of germline cells upon x-ray irradiation.  My lab has determined that this enhanced apoptosis due to brc-1 mutation requires the presence of a functional BRAP-2 protein.  We have shown that the reduction of apoptosis in brc-1; brap-2 double mutant worms is due to increase in activity of the SKN-1/Nrf2 and AKT-1 pathways. This work has recently been accepted in Cell Death and Differentiation (D’Amora et al, 2018).