Cellular retinoic acid binding protein: cloning and expression of the gene

The work described in this thesis aims at the elucidation of mechanisms that govern cellular differentiation. To gain insight in these processes, molecular changes associated with differentiation of embryonal carcinoma cells were investigated. As similar differentiation events are assumed to occur during normal embryogenesis, this may contribute to the understanding of early embryonic development. Chapter II describes the isolation and preliminary characterization of a number of CDNA clones corresponding to gene sequences that are induced upon differentiation of a mouse embryonal carcinoma cell line. After determination of the nucleotide sequences, we were able to establish the identity of four of the selected eDNA clones. One of these was found to encode the cellular retinoic acid binding protein CRABP. In view of the known involvement of RA in cellular differentiation and embryonic pattern formation, we decided to focus our attention on analysis of the CRAB!' gene. The chapters III and W deal with the expression of CRABP during embryoni7d'~velopment. Our data show that the CRABP gene exhibits a spatia-temporally speCified expression pattern in both mouse and chick embryos. A striking correlation is observed between CRABP expression and susceptibility to RA-induced malformations. In chapter V, tissue culture experiments will be described that provide a better understanding of the role of CRABP in RA-mediated signal transduction. Finally, we have started to study the regulation of CRABP gene expression. These experiments, which include a detailed analysis of the CRABP promoter region, will be presented in chapter VI. The results presented in this thesis show that a gene that is induced upon differentiation of an EC cell line is also differentially expressed during embryogenesis. Our in vivo expression data point to an important role for CRABP in the regulation of RA mediated morphogenetic event

ベルト・モリゾと日本美術(1) : 扇・団扇のジャポニスムから1890年ビングの「日本版画展」まで

textabstractA human genomic fragment comprising the cellular retinoic acid binding protein (CRABP) gene was isolated. By using a panel of somatic cell hybrids, this gene could be assigned to human chromosome 15. Subsequently, a possible involvement of the CRABP gene in translocation (15;17) (q22;q11) positive acute promyelocytic leukemia (APL) was investigated. Although transposition of the CRABP gene could be demonstrated, we did not observe any gross CRABP rearrangement in a series of primary APL patients, nor in the acute myeloblastic leukemia cell line HL-60. Thus, the observed lack of CRABP expression in these leukemic cells may not be caused by disruption of its gene. CRABP maps to the region 15q22-qter

Regulation of the CRABP-1 gene during mouse embryogenesis.

The cellular retinoic acid binding protein type I (CRABP-I) shows a highly specific expression pattern during mouse embryonic development. The tissues that express CRABP-I, i.e. the central nervous system (CNS), neural crest, branchial arches, limb bud and frontonasal mass, coincide with those that are most sensitive to unphysiological retinoic acid (RA) concentrations. We have investigated the transcriptional elements that are responsible for the spatiotemporal regulation of CRABP-I expression in the mouse embryo. We show here that a 16 kb fragment harbours all the elements needed for the correct spatiotemporal expression pattern. Upon further dissection of this fragment we have found that expression in the CNS is driven by elements in the upstream region of the gene, while expression in mesenchymal and neural crest tissue is regulated via element(s) located downstream of exon II of the gene. Two distinct fragments in the upstream region are required for expression in the CNS, as neither of these fragments alone is able to drive correct expression of a reporter gene in transgenic mice. DNAseI footprinting analysis of the two upstream fragments revealed the presence of a number of protected elements. One of these regulatory elements has the hallmarks of an RA response element, suggesting that CRABP-I expression in neural tissue can be directly modulated by RA via the RARs/RXRs