Molecular Physiology of the Cell

Fall 2015 Biopark News

Martin Van Vlasselaer joined the lab

We are pleased to welcome a new pregraduate student, Martin Van Vlasselaer, who will carry out his master thesis in the lab. During his thesis, Martin will use yeast as a model system to address specific questions relevant for the study of cystinosis, a rare genetic disease caused by mutations in the gene encoding the lysosomal cystine exporter.

Practical course on “In vivo analysis of ubiquitylation and sumoylation in yeast”

Elie Saliba attended a practical course organized by Dr. Sébastien Léon and collaborators (Jacques Monod Institute, Paris) on techniques for “In vivo analysis of ubiquitylation and sumoylation in yeast” (7-11 Sept.). Elie was supported by a grant of the PROTEOSTASIS Cost Action network.

“Membrane Compartmentalization” meeting in Münster

Christos Gournas attended a top-level meeting organized in Münster (Germany) by Roland Wedlich-Söldner and Joost Holthuis on “Mechanisms and Functions of Membrane Compartmentalization” (6-10 September). Christos presented a poster reporting his recent data about the regulation of heterogenous distribution of the Can1 permease at the plasma membrane.

“SMYTE” meeting in Lisbon

Florent Corrillon and Bruno André attended the 33rd SMYTE, the annual meeting on yeast membrane transporters, organized this year in Lisbon (Portugal). Florent gave a presentation about the yeast Ssy1 sensor of amino acids (he studied during his master thesis work) and Bruno gave a general talk about the role of arrestins in transporter ubiquitylation.

News about students who joined the lab for internship or master thesis work

Some news about students who joined or will soon join the lab :

Nathan Fraikin (ULB, master in Biochemistry and Molecular and Cellular Biology), who did his master thesis work in the lab, defended his “mémoire” in early April before moving to the group of Pr. Claudio De Virgilio (University of Fribourg, Switzerland) for an internship. During his master thesis work, Nathan studied the role of Gap1 phosphorylation.

Gabriel Rocha is a PhD student working in the group of Sandra Paiva (Braga, Portugal), he recently spent a few weeks in the lab to carry out experiments on proteins playing a key role in endocytosis of the Jen1 lactate permease.

Alyn Alkan is 3rd year student in Molecular Biology and Genetics Department at Izmir Institute of Technology(Turkey). She joined the lab for a summer internship and works in collaboration with Celine Barthelemy on a human amino acid transporter.

We will soon welcome two new pregraduate students, Martin Van Vlasselaer (ULB, master in Biochemistry and Molecular and Cellular Biology, 2nd year) and Stelios Gionis (University of Athens, Greece). The team grows up !

Kassem Ghaddar is a laureate of the “2015 Solvay awards”

The “Solvay Award” is awarded annually by the Solvay group to 2nd and 3rd cycle students who have realized a high-quality work within the Faculty of Science or the Faculty of Applied Sciences of ULB or VUB. This year one of the 3rd cycle awards was attributed to our former PhD student Kassem Ghaddar for his research work on the yeast Can1 and Gap1 transporters of the yeast S. cerevisiae. Kassem is currently postdoc in the group of Decio Laks Eizirik of ULB. Congratulations to Kassem for this award !

Summer 2015 Biopark News

1995 : first report on a role of ubiquitin in permease endocytosis

Time flies… Our very first publication reporting a potential role of ubiquitin in downregulation of plasma membrane transporters was released in 1995, so 20 years ago. Claudine Hein, a PhD student of the lab, constructed a myc-tagged version of the Gap1 permease, allowing her to show that the inhibition of Gap1 activity observed after addition of ammonium coincides with degradation of the protein. This result surprised us as the inhibitory effect of ammonium on Gap1 was thought to be reversible. This regulation of Gap1 by ammonium had been described in 1983 by Marcelle Grenson who also isolated a mutant strain, npi1 (nitrogen permease inactivator 1), in which this regulation is defective (Grenson, 1983). Jean-Yves Springael, another PhD student of the lab, used this mutant to clone the NPI1 gene and realized that it corresponds to the RSP5 gene just shown by Johan Huibregtse and coll. to code for a new type of ubiquitin ligase, but whose molecular function remained unclear (Huibregtse et al. 1995). Finally, the paper reports the data of a collaboration with the group of Rosine Haguenauer-Tsapis (J. Monod Institute, Paris) showing that Npi1/Rsp5 is also required for stress-induced degradation of the uracil permease, a process known to involve prior endocytosis of the protein. Altogether, these observations indicated that the yeast Npi1/Rsp5 ubiquitin ligase plays a central role in endocytosis of several transporters. Furthermore, Npi1/Rsp5 turned out to be conserved in mammals, suggesting that ubiquitin could serve as a signal for protein endocytosis in more complex species as well (what was later confirmed). This article, published in 1995 in the journal Molecular Microbiology, remains one of our best cited papers (306 citations in August 2015). Time flies …

Sunny “PhD student day” at Parentville

Like every year, PhD students being at mid-term presented their research data to their committee and members of the institute. Among them were Elie Saliba and Melody Cools, who successfully passed the test. All institute members then moved to the Parentwille park for a giant barbecue. We had a splendid weather, as you can judge from the pictures. Also nice were the musical quizz organized by several PhD students of the Immunobiology group, as well as the football game in the park.