Ben Oostra received his Ph.D. in biochemistry from the University of Groningen in 1981, where he studied the regulation of rRNA synthesis in E. coli in the laboratory of M. Gruber. For his postdoctoral training he joined the group of A.E. Smith at the NIMR in Mill Hill, UK to work on tumour forming activities of Polyoma virus. After returning to Holland he joined the group of A.J. van der Eb at the University of Leiden to study adenoviruses. In 1985 he started in the department of Clinical Genetics to identify and characterize genes that are responsible for a number of genetic disorders. His work now concentrates on the study of genes involved in neurogenetic disorders.

Group Members
Address
Genetic basis of neurogenetic disorders
Fragile X syndrome and FMR1
Dementia
Complex Disorders
Facilities and Expertise
Future projects
Goals
Selected publications
Reviews

Group members
Rob Willemsen, staff member
Andre Hoogeveen, staff member
Vincenzo Bonifati, staff member
Femke de Vrij, postdoctoral fellow
Edwin Mientjes, postdoctoral fellow
Violettea Stoyanova postdoctoral fellow
Aida Bertoli Avella, postdoctoral fellow
Judith Brouwer, Ph.D. student
Sandra van 't Padje, Ph.D. student
Josien Lavenga, Ph.D. student
Alessio di Fonzo, Ph.D. student
Maria Luisa Conte, Ph.D. student
Cathy Bakker, technician
Guido Breedveld, technician
Ingeborg van Nieuwenhuizen, technician
Herma Zondervan, technician
Christan Rohe, technician

Address
Erasmus MC Rotterdam
Department of Clinical Genetics
Dr. Molewaterplein 50
Postbus 1738
3000 DR Rotterdam
Tel: +31-10-4087198
Fax: +31-10-4089489
E-mail: b.oostra@erasmusmc.nl
Homepage: http://www2.eur.nl/fgg/kgen/

Genetic basis of neurogenetic disorders
In the past decade considerable progress has been made in unravelling the etiology of important single gene disorders. In the field of neurological and neuropsychiatric diseases only little progress has been made. It is becoming clear that these disorders are complex and may often result from an interplay of genetic and environmental risk factors. Our group is interested to study the genetic basis for a number of 'brain' disorders, and the (dys)function of the gene(s) involved. We have examined the molecular basis of two monogenetic disorders, fragile X syndrome, causing mental retardation, and FTD, or frontal temporal dementia.

Fragile X syndrome and FMR1
The identification of the FMR1 gene started the era of expanding triplet repeat diseases. In fragile X syndrome patients the repeat has more than 200 CGGs (full mutation) and due to this expansion of the repeat, present in the 5' untranslated region of the FMR1 gene, the promoter region is methylated resulting in silencing of the gene (Fig. 1). The expansion of the CGG repeat to a large repeat only occurs in oocytes and never in sperm, irrespectively of the repeat size in somatic cells. As a result of selection during forming and maturation of primordial germ cells only sperm producing cells with a premutation are present after puberty. The mechanism of the repeat instability occurring during gametogenesis and early embryogenesis is still unclear, mainly due to the lack of a human material. Therefore, we have developed an animal model with an expanded repeat. These mice will enable the study of timing and mechanism of amplification in the mouse germ line. At the same time these mice will be used to study the inclusion bodies seen in the nuclei of neurons in carriers of a premutation.

The identification of normal males with a long unmethylated repeat has learned that it is not the long repeat itself that is causing the disease but the methylation of the promoter of the FMR1 gene during embryogenesis. It has been shown that DNA methylation mediates the forming of a multiprotein repression complex by the interaction of MeCP2 with DNA at methylated cytosine residues and a number of factors including histone deacetylases. This complex formation results in modification of chromatin structure, which might explain the delay in replication of the mutated FMR1 gene. Treatment of cells with demethylating agents results in reactivation of the FMR1 gene. The repression could be alleviated by treatment with deacetylase inhibitors. Further studies will focus on the identification of the factors and enzymes that are involved in the (in)activation of the mutated FMR1 gene. This may eventually lead to strategies to prevent inactivation of the FMR1 gene.

The absence of the FMR1 protein is causing mental retardation, but what is the function of the FMR1 gene. Recent work has indicated that the FMR1 protein might regulate localized protein synthesis. The subcellular behavior of FMRP, including its selective mRNA binding, nucleocyplasmic shuttling, and predominant association with cytoplasmic polyribosomes, has led to the hypothesis that FMRP may play a role in nuclear export of its target mRNAs and further present these mRNAs to the translation machinery (Fig. 1 and 2). The discovery of FMRP-polyribosome association in the neuronal dendritic spine implies the possible involvement of FMRP in modulating localization and/or translation of its target mRNAs in the appropriate compartments. Regulation of localized protein synthesis has been demonstrated to be functionally important in cell growth and polarity development. There is still a lack of knowledge about the specific class of mRNAs whose transport/translation Is affected by the lack of FMRP. We are now examining in more detail the shuttling of FMRP and the identification of the specific mRNAs that can be bound to FMRP. Further studies will be directed towards the detection of differences in (cytoplasmic levels of) these mRNAs in patients and in a developed Fmr1 knockout animal model, using differential DNA chip expression screening. Identification of these mRNAs should help to define the influence of FMRP in mRNA metabolism, and finally to the elucidation of pathogenesis in mental retardation due to the lack of FMRP.

Dementia
Still very little is known about genetic factors involved in most cases of dementia. To unravel the genetics of such complex disorders requires a strategy capable of detecting effects of genetic factors, which may depend strongly on the presence of other genetic and/or environmental factors. In collaboration with van Duijn en Hofman (Dept of Epidemiology, EUR) we plan to identify new genes implicated in (late-onset) Alzheimer's diseases and Parkinson's disease. The rational of the newly developed method that will be applied is that in a genetic isolated population the number of genes implicated in a heterogeneous disorder is strongly reduced because of genetic drift. Chances that patients have inherited a disease gene from a common ancestor are therefore high and patients from recently isolated populations with a common ancestor likely share considerable parts of DNA around a disease gene. If multiple genes play a role they can be localized simultaneously. New genes for Alzheimer's diseases and Parkinson's disease will be identified and molecular and biochemical role of these disease genes will be studied.

Complex Disorders
In 1995 we have started together with Van Duijn (Dept of Epidemiology, Erasmus MC) our research program “Genetic Research in Isolated Populations” (GRIP). This program is conducted in a genetically isolated population in the Southwest of the Netherlands. As part of the GRIP program, we have studied several complex genetic disorders including diabetes mellitus type 1 and 2, Parkinson’s disease, Alzheimer’s disease, ADHD, and Multiple Sclerosis Using municipal records and genealogical data bases of this isolated population of 20,000 residents, we were able to link most of the patients of each disorder to a common ancestor. We have successfully identified various genes that play an important role in the etiology of major diseases. These genes were sometimes identified through searches through the complete genome. These include a new gene involved in Parkinson’s disease (DJ-1: Bonifati et al Science. 2003), a gene involved in hemochromatosis (SLC11A3: Njajou et al, Nature Genetics 2001) and a gene involved in type 2 diabetes and obesity (LIPIN2: Aulchenko, submitted).

Facilities and expertise
EM and fluorescent microscopes
Large population based collection of DNA and RNA samples
ES cell culture facility
Mouse and zebrafish facility

Future projects
Our future work will focus on the cellular processes that are involved in mental ratardation and dementia and the effects on gene expression functional using genetic screens. At the same time we will search for new genes that are involved in Parkinson and Alzheimer and study the contribution of these genes in these heterogeneous disorders.

Goals
The final goal is to identify genes that are involved in common neurogenetic disorders and to study the molecular and biochemical basis of these diseases.

Selected publications
Njajou OT, Vaessen N, Joosse M, Berghuis B, van Dongen JWF, Breuning MH , Snijders PJLM, Rutten WPF, Sandkuijl LA, Oostra BA, van Duijn CM, Heutink P. (2001) A mutation in SLC11A3 is associated with autosomal dominant hemochromatosis. Nature Genet 28:213-214.

Bontekoe CJM, McIlwain KL, Nieuwenhuizen IM, Yuva-Paylor LA, Nellis A, Willemsen R, Fang Z, Kirkpatrick L, Bakker CE, McAninch R, Ching Cheng N, Merriweather M, Hoogeveen AT, Nelson DL, Paylor R , Oostra BA (2002). Knockout mouse model for Fxr2: a model for mental retardation. Hum Mol Genet 11: 487-498.

De Diego Otero Y, Severijnen L, van Cappellen G, Schrier M, Oostra BA, Willemsen R (2002). Transport of FMR1-protein via granules in neurites of PC12 cells. Mol Cell Biol 22: 8332-41.

Vaessen N, Heutink P, Houwing-Duistermaat JJ, Snijders PJLM, Rademaker T, Testers L, Batstra MR, Sandkuijl LA, van Duijn CM, Oostra BA (2002). A genome-wide search for linkage-disequilibrium with type 1 diabetes mellitus in a recent genetically isolated population from the Netherlands. Diabetes 51:856-859.

Aulchenko, Y.S., Vaessen, N., Heutink, P., Pullen, J., Snijders, P.J., Hofman, A., Sandkuijl, L.A., Houwing-Duistermaat, J.J., Edwards, M., Bennett, S., Oostra, B.A. & Van Duijn, C.M. (2003). A Genome-Wide Search for Genes Involved in Type 2 Diabetes in a Recently Genetically Isolated Population From the Netherlands. Diabetes 52: 3001-3004.

Bonifati V, Rizzu P, van Baren MJ, Schaap O, Breedveld GJ, Krieger E, Dekker MCJ, Squitieri F, Ibanez P, Joosse M, van Dongen JWF, Vanacore N, van Swieten JC, Brice A, Meco G, van Duijn CM, Oostra BA, Heutink P. (2003). Mutations in the DJ-1 gene associated with autosomal recessive early onset Parkinson. Science 299: 256-259.

Willemsen, R., Hoogeveen-Westerveld, M., Reis, S., Holstege, J., Severijnen, L., Nieuwenhuizen, I., Schrier, M., VanUnen, L., Tassone, F., Hoogeveen, A., Hagerman, P., Mientjes, E., Oostra, B. (2003). The FMR1 CGG repeat mouse displays ubiquitin-positive intranuclear neuronal inclusions; implications for the cerebellar tremor/ataxia syndrome. Hum Mol Genet 12: 949-959.

Zalfa, F., Giorgi, M., Primerano, B., Moro, A., Di Penta, A., Reis, S., Oostra, B., and Bagni, C. (2003). The Fragile X Syndrome Protein FMRP Associates with BC1 RNA and Regulates the Translation of Specific mRNAs at Synapses. Cell 112: 317-327.

Mientjes EJ, Willemsen R, Kirkpatrick LL, Nieuwenhuizen IM, Hoogeveen-Westerveld M, Verweij M, Reis S, Bardoni B, Hoogeveen AT, Oostra BA, Nelson DL. (2004) Fxr1 knockout mice show a striated muscle phenotype: implications for Fxr1p function in vivo. Hum Mol Genet. 13:1291-1302.

Di Fonzo, A., Rohe, CF., Ferreira, J., Chien, H.F., Vacca, L., Stocchi, F., Guedes, L., Fabrizio, E., Manfredi, M., Vanacore, N. Goldwurm, S., Breedveld, G., Sampaio, C., Meco, G., Barbosa, E., Oostra, B.A., Bonifati, V. (2005). A frequent LRRK2 gene mutation associated with autosomal dominant Parkinson's disease. Lancet, 365: 412-415.

van 't Padje S, Engels B, Blonden L, Severijnen LA, Verheijen F, Oostra BA, Willemsen R (2005). Characterisation of Fmrp in zebrafish: evolutionary dynamics of the fmr1 gene. Dev Genes Evol 215:198-206.

Koekkoek SK, Yamaguchi K, Milojkovic BA, Dortland BR, Ruigrok TJ, Maex R, De Graaf W, Smit AE, Vanderwerf F, Bakker CE, Willemsen R, Ikeda T, Kakizawa S, Onodera K, Nelson DL, Mientjes E, Joosten M, De Schutter E, Oostra BA, Ito M, De Zeeuw CI (2005). Deletion of FMR1 in Purkinje Cells Enhances Parallel Fiber LTD, Enlarges Spines, and Attenuates Cerebellar Eyelid Conditioning in Fragile X Syndrome. Neuron 47:339-352.

Reviews

Heutink P, Oostra BA (2002) Gene finding in genetically isolated populations. Hum Mol Genet 11:2507-2515.

Oostra, B. A., and Willemsen, R. (2003). A fragile balance: FMR1 expression levels. Hum Mol Genet 12: R249-257.

Willemsen R, Oostra BA, Bassell GJ, Dictenberg J. (2004) The fragile X syndrome: From molecular genetics to neurobiology. Ment Retard Dev Disabil Res Rev. 10:60-67.

Willemsen R, Mientjes E, Oostra BA (2005) FXTAS: A Progressive Neurologic Syndrome Associated with Fragile X Premutation. Curr Neurol Neurosci Rep 5:405-410