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Zhou Y.,Minerva Foundation Institute for Medical Research | Wohlfahrt G.,Computer Aided Drug Design | Paavola J.,Minerva Foundation Institute for Medical Research | Olkkonen V.M.,Minerva Foundation Institute for Medical Research | Olkkonen V.M.,University of Helsinki
Biochemical and Biophysical Research Communications | Year: 2014

Oxysterol-binding protein (OSBP) and OSBP-related (ORP) or OSBP-like (OSBPL) proteins constitute a family of lipid-binding/transfer proteins (LTPs) present in eukaryotes from yeast to man. The mechanisms of ORP function have remained incompletely understood. However, several ORPs are present at membrane contact sites and act as either lipid transporters or sensors that control lipid metabolism, cell signaling, and vesicle transport. Zebrafish, Danio rerio, has gained increasing popularity as a model organism in developmental biology, human disease, toxicology, and drug discovery. However, LTPs in the fish are thus far unexplored. In this article we report a series of bioinformatic analyses showing that the OSBPL gene family is highly conserved between the fish and human. The OSBPL subfamily structure is markedly similar between the two organisms, and all 12 human genes have orthologs, designated osbpl and located on 11 chromosomes in D. rerio. Interestingly, osbpl2 and osbpl3 are present as two closely related homologs (a and b), due to gene duplication events in the teleost lineage. Moreover, the domain structures of the distinct ORP proteins are almost identical between zebrafish and man, and molecular modeling in the present study suggests that ORD liganding by phosphatidylinositol-4-phosphate (PI4P) is a feature conserved between yeast Osh3p, human ORP3, and zebrafish Osbpl3. The present analysis identifies D. rerio as an attractive model to study the functions of ORPs in vertebrate development and metabolism. © 2013 Elsevier Inc. All rights reserved.

Cortes-Ciriano I.,French National Center for Scientific Research | Ain Q.U.,Unilever | Subramanian V.,University of Helsinki | Lenselink E.B.,Leiden Academic Center for Drug Research | And 7 more authors.
MedChemComm | Year: 2015

Proteochemometric (PCM) modelling is a computational method to model the bioactivity of multiple ligands against multiple related protein targets simultaneously. Hence it has been found to be particularly useful when exploring the selectivity and promiscuity of ligands on different proteins. In this review, we will firstly provide a brief introduction to the main concepts of PCM for readers new to the field. The next part focuses on recent technical advances, including the application of support vector machines (SVMs) using different kernel functions, random forests, Gaussian processes and collaborative filtering. The subsequent section will then describe some novel practical applications of PCM in the medicinal chemistry field, including studies on GPCRs, kinases, viral proteins (e.g. from HIV) and epigenetic targets such as histone deacetylases. Finally, we will conclude by summarizing novel developments in PCM, which we expect to gain further importance in the future. These developments include adding three-dimensional protein target information, application of PCM to the prediction of binding energies, and application of the concept in the fields of pharmacogenomics and toxicogenomics. This review is an update to a related publication in 2011 and it mainly focuses on developments in the field since then. This journal is © The Royal Society of Chemistry 2015.

Tervonen T.A.,University of Helsinki | Partanen J.I.,University of Helsinki | Saarikoski S.T.,University of Helsinki | Myllynen M.,University of Helsinki | And 6 more authors.
Advances in Cancer Research | Year: 2011

Epithelial architecture is formed in tissues and organs when groups of epithelial cells are organized into polarized structures. The epithelial function and integrity as well as signaling across the epithelial layer is orchestrated by apical junctional complexes (AJCs), which are landmarks for PAR/CRUMBS and lateral SCRIB polarity modules and by dynamic interactions of the cells with underlying basement membrane (BM). These highly organized epithelial architectures are demolished in cancer. In all advanced epithelial cancers, malignant cells have lost polarity and connections to the basement membrane and they have become proliferative, motile, and invasive. Clearly, loss of epithelial integrity associates with tumor progression but does it contribute to tumor development? Evidence from studies in Drosophila and recently also in vertebrate models have suggested that even the oncogene-driven enforced cell proliferation can be conditional, dependant on the influence of cell-cell or cell-microenvironment contacts. Therefore, loss of epithelial integrity may not only be an obligate consequence of unscheduled proliferation of malignant cells but instead, malignant epithelial cells may need to acquire capacity to break free from the constraints of integrity to freely and autonomously proliferate. We discuss how epithelial polarity complexes form and regulate epithelial integrity, highlighting the roles of enzymes Rho GTPases, aPKCs, PI3K, and type II transmembrane serine proteases (TTSPs). We also discuss relevance of these pathways to cancer in light of genetic alterations found in human cancers and review molecular pathways and potential pharmacological strategies to revert or selectively eradicate disorganized tumor epithelium. © 2011 Elsevier Inc.

Weber M.,University of Helsinki | Chernov K.,University of Helsinki | Turakainen H.,University of Helsinki | Wohlfahrt G.,Computer Aided Drug Design | And 5 more authors.
Molecular Biology of the Cell | Year: 2010

Sec1p/Munc18 (SM) family proteins regulate SNARE complex function in membrane fusion through their interactions with syntaxins. In addition to syntaxins, only a few SM protein interacting proteins are known and typically, their binding modes with SM proteins are poorly characterized. We previously identified Mso1p as a Sec1p-binding protein and showed that it is involved in membrane fusion regulation. Here we demonstrate that Mso1p and Sec1p interact at sites of exocytosis and that the Mso1p-Sec1p interaction site depends on a functional Rab GTPase Sec4p and its GEF Sec2p. Random and targeted mutagenesis of Sec1p, followed by analysis of protein interactions, indicates that Mso1p interacts with Sec1p domain 1 and that this interaction is important for membrane fusion. In many SM family proteins, domain 1 binds to a N-terminal peptide of a syntaxin family protein. The Sec1p-interacting syntaxins Sso1p and Sso2p lack the N-terminal peptide. We show that the putative N-peptide binding area in Sec1p domain 1 is important for Mso1p binding, and that Mso1p can interact with Sso1p and Sso2p. Our results suggest that Mso1p mimics N-peptide binding to facilitate membrane fusion. © 2010 by The American Society for Cell Biology.

Vihervaara T.,Minerva Foundation Institute for Medical Research | Vihervaara T.,Finnish National Institute for Health and Welfare | Uronen R.-L.,University of Helsinki | Wohlfahrt G.,Computer Aided Drug Design | And 5 more authors.
Cellular and Molecular Life Sciences | Year: 2011

ORP1L is an oxysterol binding homologue that regulates late endosome (LE) positioning. We show that ORP1L binds several oxysterols and cholesterol, and characterize a mutant, ORP1L Δ560-563, defective in oxysterol binding. While wild-type ORP1L clusters LE, ORP1L Δ560-563 induces LE scattering, which is reversed by disruption of the endoplasmic reticulum (ER) targeting FFAT motif, suggesting that it is due to enhanced LE-ER interactions. Endosome motility is reduced upon overexpression of ORP1L. Both wild-type ORP1L and the Δ560-563 mutant induce the recruitment of both dynactin and kinesin-2 on LE. Most of the LE decorated by overexpressed ORP1L fail to accept endocytosed dextran or EGF, and the transfected cells display defective degradation of internalized EGF. ORP1L silencing in macrophage foam cells enhances endosome motility and results in inhibition of [3H]cholesterol efflux to apolipoprotein A-I. These data demonstrate that LE motility and functions in both protein and lipid transport are regulated by ORP1L. © 2010 Springer Basel AG.

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