Post Doc Fellowships
Romanian Society of Biochemistry
Romanian Journal of Biochemistry

      IB_Molecular Glycobiology
Department of Molecular Cell Biology

  Protein Processing and Transport in the Cell

Current Work, Future Projects, Selected Publications, Lectures

Stefana M. Petrescu, PhD - Head of Department
Gabriela Negroiu, PhD
Simona Ghenea, PhD
Florentina Pena, PhD
Livia Zdrentu, PhD
Mari Marin, PhD Student
Gabi Chiritoiu, PhD Student
Petruta Alexandru, PhD Student
Anca Filimon, PhD Student
Emilia Ardelean-technician

Current Work
Glycoprotein folding is regulated in the ER by multiple mechanisms destined to enable the polypeptide chain to acquire the correct 3D structure of the native glycoprotein. Folding efficiency depends on the interaction of the folding polypeptide with ER resident molecular chaperones.
We have recently found that tyrosinase, the key enzyme of melanin synthesis, is a good model to study the dependency of the glycoprotein function on the interaction with the ER resident molecular chaperones.
Inhibition of the N-glycan processing in melanoma cells with glucosidases inhibitors results in the synthesis of catalytically inactive tyrosinase unable to initiate melanin biosynthesis. Further studies destined to reveal the underlying mechanisms of tyrosinase inactivation showed that tyrosinase optimal folding is dependent on its association with the chaperones calnexin/calreticulin. These ER chaperones recognize tyrosinase N-glycans and drive the protein into an on and off cycle in which -glucosidase II and GT play important roles. Our data show that in the case of tyrosinase, the quality control acts by selecting a conformation of the polypeptide chain able to acquire copper in its active site. Based on mutation experiments we have also showed that individual N-glycans play distinctive roles in tyrosinase folding depending on their location on the polypeptide chain. From these new perspectives on protein folding arising from the work on tyrosinase, it seems likely that the presence of glycans in regions of the protein structure that spontaneously fold less efficiently, may be necessary for the correct function of the quality control system.
We are now extending these investigations to human tyrosinase and to the other tyrosinase related proteins, TRP-1 and TRP-2.
Other projects of the lab deal with the targeted delivery using encapsulation in liposomes and dendrimers. For example liposome encapsulation of N-glycosylation inhibitors proved to be highly effective in modulating glycan processing in the ER.
More recently due to a significant upgrade of the facilities core of IBAR, made possible by the PROCERA Project, the Department of Molecular Cell Biology was able to extend research in various areas of intracellular trafficking and interactomics along the secretory pathway by using cutting edge techniques such as - Mass Spectrometry, Surface Plasmon Resonance, Confocal Immuno-Fluorescence Microscopy, FRET etc.

Future Projects
In the next years our research will focus on the molecular mechanisms of the folding and intracellular transport of soluble and membrane bound glycoproteins. In particular, melanoma proteins will be investigated in terms of  maturation, degradation and antigen presentation.

Selected Publications

"Combination of bortezomib and mitotic inhibitors down-modulate Bcr-Abl and efficiently eliminates tyrosine-kinase inhibitor sensitive and resistant Bcr-Abl-positive leukemic cells.", PLoS One; 8(10), e77390, (2013)
Bucur O, Stancu AL, Goganau I, Petrescu SM, Pennarun B, Bertomeu T, Dewar R, Khosravi-Far R

"Tyrosinase degradation is prevented when EDEM1 lacks the intrinsically disordered region", PLoS One; 7(8), e42998, (2012)
Marin MB, Ghenea S, Spiridon LN, Chiritoiu GN, Petrescu AJ, Petrescu SM

"AP-3 and Rabip4' Coordinately Regulate Spatial Distribution of Lysosomes", PLoS One; 7(10), e48142, (2012)
Ivan V, Martinez-Sanchez E, Sima LE, Ooschot V, Klumperman J, Petrescu SM, Van der Sluj P

"Internalization and Intracellular Trafficking of Poly(propylene imine) Glycodendrimers with Maltose Shell in Melanoma Cells", Cur.Med.Chem; 19(29), 4955-68, (2012)
Filimon A, Sima LE, Appelhans D, Voit B, Negroiu G.

"C-terminus glycans with critical functional role in the maturation of secretory glycoproteins", PLoS One; 6(5), e19979, (2011)
Cioaca D, Ghenea S, Spiridon LN, Marin M, Petrescu AJ, Petrescu SM

"Encapsulated cargo internalized by fusogenic liposomes partially overlaps the endoplasmic reticulum", J.Cell.Mol.Med; 13, 3110-3121, (2009)
Mustata RC, Grigorescu A, Petrescu SM

"Ovarian Cancer is Associated With Changes in Glycosylation in Both Acute-Phase Proteins and IgG.", Glycobiology; 17, 1344-1356, (2007)
Saldova R, Royle L, Petrescu SM, Dwek RA, Rudd PM

"Productive folding of tyrosinase ectodomain is controlled by the TM anchor.", J.Biol.Chem.; 281, 21682-21689, (2006)
Popescu CI, Mares A, Zdrentu L, Zitzmann N, Dwek RA, Petrescu SM

"Soluble tyrosinase is an ER-associated degradation substrate retained in the ER by calreticulin and not calnexin.", J.Biol.Chem.; 280, 13833-13840, (2005)
Popescu CI, Mares A, Zdrentu L, Zitzmann N, Dwek RA, Petrescu SM

"Do calnexin have a role in melanin formation?", IUBMB Life; 57, 455-457, (2005)
Petrescu SM

"Tyrosinase-related proteins are trafficked on distinct routes in B16 melanoma cells", BBRC; 328, 914-921, (2005)
Negroiu G, Dwek RA, Petrescu SM

"The glycosylation of tyrosinase in melanoma cells and the effect on antigen presentation.", Glycobiology and medicine, ed. J.Axford, 286 pp, in the series Adv.Exp.Med.Biol.; 535, 257-269, chapter 17,  (2003)
Petrescu SM, Popescu CI, Petrescu AJ, Dwek RA.

"The inhibition of early N-glycan processing targets TRP-2 to degradation in B16 melanoma cells." J.Biol.Chem. 278: 27035- 27042 (2003)
Negroiu G, Dwek RA, Petrescu SM.

"pH-sensitive liposomes are efficient carriers for endoplasmic reticulum-targed drugs in mouse melanoma cells", Biochem.Biophys.Res. Commun., 293: 918-923 (2002)
Costin GE, Trif M, Branza-Nichita N, Dwek RA, Petrescu SM

"Mutations at critical N-glycosylation sites reduce tyrosinase activity by altering folding and quality control", J.Biol.Chem., 275, 8169-8175 (2000).
Branza-Nichita N, Negroiu G, Petrescu AJ, Garman EF, Platt FM, Wormald M, Dwek RA, Petrescu SM.

"N-glycosylation processing and glycoprotein folding-lessons from the tyrosinase-related proteins", Chem.Rev. 100, 4697-712 (2000).
Branza-Nichita N, Petrescu AJ, Negroiu G, Dwek RA, Petrescu SM.

"Folding and maturation of tyrosinase-related protein-1 are regulated by the post-translational formation of disulfide bonds and by N-glycan processing", J.Biol.Chem. 275, 32200-7 (2000).
Negroiu G, Dwek RA, Petrescu SM.

"Investigation of the intracellular transport of tyrosinase and TRP-1. The effect of ER glucosidases inhibition", Cell.Mol.Biol., 45, 1001-1010 (1999)
Negroiu G, Branza-Nichita N., Costin GE, Titu H, Petrescu AJ, Dwek RA , Petrescu SM

"Protein specific N-glycosylation of tyrosinase and tyrosinase-related protein-1 in B16 mouse melanoma cells", Biochem J., 344, 659-665 (1999)
Negroiu G, Branza-Nichita N, Petrescu AJ, Dwek RA, Petrescu SM,

"Tyrosinase folding and copper loading in vivo: a crucial role for calnexin and a-glucosidase II.", Biochem.Biophys.Res Commun., 261, 720-725 (1999).
Branza-Nichita N, Petrescu AJ, Dwek RA, Wormald MR, Platt FM, Petrescu SM

"Conformation - independent binding of monoglucosylated ribonuclease B to calnexin", Cell, 88, 29-38 (1997).
Zapun A, Petrescu SM, Rudd PM, Dwek RA., Thomas DY., Bergeron JJM

"Inhibition of N-glycan processing in B16 melanoma cells results in inactivation of tyrosinase but does not prevent its transport to the melanosome", J.Biol.Chem., 272, 15796-15803 (1997).
Petrescu SM, Petrescu AJ, Dwek RA,Platt FM

Curs de Biologie Moleculara si Celulara 2006 - 2007

Curs de Biologie Moleculara si Celulara 2007 - 2008