Nan-Chi A. Chang

Transient expression of Ym1, a heparin-binding lectin, during developmental hematopoiesis and inflammation.

Ym1, a secretory protein transiently produced by activated peritoneal macrophages elicited by parasitic infections, has been identified as a novel heparin‐binding lectin. X‐ray crystallography study revealed that Ym1 has a β/α barrel structure with a carbohydrate‐binding cleft similar to that of triose‐phosphate isomerases. To further delineate the physiological significance of Ym1, we examined its expression patterns during mouse embryonic development and inflammation states elicited by agents other than parasitic infections in the peritoneal cavity and brain. This is the first report revealing prominent expression of Ym1 in early myeloid precursor cells of hematopoietic tissues—initially in the yolk sac and subsequently in fetal liver, spleen, and bone marrow. In nonhematopoietic systems, Ym1 was not detected in most of the tissues examined, with the exception of lung. Although no expression was detected up to gestation day 16.5 (E16.5), an increasing level of Ym1 expression in lung was detected from E18.5 on and persisted through adulthood. While most resident macrophages in various tissues examined are Ym1‐negative, transient expression of Ym1 may be induced in their activated counterparts during inflammation in response to different stimuli in vivo, ranging from various chemical agents to brain injuries. The temporal and spatial expression in myeloid precursors and its transient induction in activated macrophages support the notion that Ym1 may be involved in hematopoiesis and inflammation. In addition, its putative functional association with heparin/heparan sulfate is discussed.

Restricted expression of LUZP in neural lineage cells: a study in embryonic stem cells.

A novel protein LUZP with 3 leucine zipper motifs at its amino terminus is predominantly expressed in the adult brain. A modified gene targeting approach was employed in an attempt to establish in vitro and in vivo models in which Luzp is knock-out (KO) for phenotype assessment and a reporter gene lacZ is knock-in (KI) for tracing its expression. We report in this study the molecular cloning of the Luzp gene, its targeting vector construction and Luzp-KO/lacZ-KI embryonic stem (ES) clone selection. Since LUZP is also expressed in ES cells, the possibility of embryonic lethality cannot be excluded when attempting to establish Luzp-null mutant mice. We have therefore examined the development of homozygous Luzp-KO/lacZ-KI clones in nude mice. Tissue types derived from all three embryonic germ layers were observed in teratomas developed in nude mice. In situ X-gal staining further revealed restricted expression of LUZP in neural lineage cells.

Characterization of the regulatory region ofAdra2c, the gene encoding the murine a2C adrenoceptor subtype

The 5′ flanking sequence (3,227 base pairs, bp) of the mouseAdra2c subtype gene was determined and characterized. The transcription start site was mapped to nucleotide ‘A’ of two initiator motifs in tandem array, i.e. 1,159 and 1,153 bp upstream from the initiation codon of the open reading frame (ORF) ofAdra2c, respectively. One structural feature salient to the 5′ regulatory region ofAdra2c is present in the sequence 1 kb immediately upstream from the receptor ORF, which is highly enriched in GC content (76%) and CpG island counts (i.e. CpG/GpC, 146:177), and thus rich in Sp1-binding motifs. At the 3′ flanking region, the polyadenylation signal was mapped to 481 bp downstream from the termination codon. The transcript defined by sequence data thereby is consistent with a size of 3 kb (brain form) determined by Northern blot analysis. The transgene,Adra2c-NN-lacZ, which links the promoter region ofAdra2c to thelacZ reporter gene, was constructed in order to evaluate the functional capacity of the promoter and the putative motifs residing within the defined regulatory region (1.9 kb upstream from the ORF) in directing the reporter gene expression in vitro in transiently transfected cells and in vivo in transgenic (Tg) mice. Permissive cell types toAdra2c-NN include those derived from neural and kidney lineages. SignificantAdra2c-NN-driven reporter expression in Tg mice established suggests that α2C adrenoceptor expression is permissive underAdra2c-NN in central (cerebral cortex, hippocampus, subthalamus, hypothalamus, superior colliculus, cerebellum, and brain stem) and peripheral (pancreatic β-islets) tissues.

Characterization of the Regulatory Region of Adra2c, the Gene Encoding the Murine α2C Adrenoceptor Subtype

The 5′ flanking sequence (3,227 base pairs, bp) of the mouse Adra2c subtype gene was determined and characterized. The transcription start site was mapped to nucleotide ‘A’ of two initiator motifs in tandem array, i.e. 1,159 and 1,153 bp upstream from the initiation codon of the open reading frame (ORF) of Adra2c, respectively. One structural feature salient to the 5′ regulatory region of Adra2c is present in the sequence 1 kb immediately upstream from the receptor ORF, which is highly enriched in GC content (76%) and CpG island counts (i.e. CpG/GpC, 146:177), and thus rich in Sp1-binding motifs. At the 3′ flanking region, the polyadenylation signal was mapped to 481 bp downstream from the termination codon. The transcript defined by sequence data thereby is consistent with a size of 3 kb (brain form) determined by Northern blot analysis. The transgene, Adra2c-NN- lacZ, which links the promoter region of Adra2c to the lacZ reporter gene, was constructed in order to evaluate the functional capacity of the promoter and the putative motifs residing within the defined regulatory region (1.9 kb upstream from the ORF) in directing the reporter gene expression in vitro in transiently transfected cells and in vivo in transgenic (Tg) mice. Permissive cell types to Adra2c-NN include those derived from neural and kidney lineages. Significant Adra2c-NN-driven reporter expression in Tg mice established suggests that α2C adrenoceptor expression is permissive under Adra2c-NN in central (cerebral cortex, hippocampus, subthalamus, hypothalamus, superior colliculus, cerebellum, and brain stem) and peripheral (pancreatic β-islets) tissues.