Primary Structure of the chicken c−mil protein: identification of domains shared with or absent from the retroviral v−mil protein

The complete primary structure of the protein product of the proto−oncogene c−mil was deduced from the nucleotide sequence of chicken c−mil cDNA clones. The c−mil protein contains 647 amino acid residues and has a calculated molecular weight of 73,132. Based on sequence comparisons with proteins of known or presumed biochemical function, two domains were recognized on the c−mil protein. In the carboxyl−terminal half of the protein, a 250−amino acid segment displays significant homology to the protein kinase domains of the src oncogene protein or of protein kinase C. In the amino−terminal half, a cysteine−rich segment (Cys−X2−Cys−X9−Cys−X2−Cys−X7−Cys−X7−Cys) of the c−mil protein shares significant homology with two similar repetitive domains of protein kinase C. Of the two structural and presumably functional domains of the c−mil protein, only the kinase domain is contained within the carboxyl−terminal 379−amino acid polypeptide encoded by the transduced v−mil allele of avian oncogenic retrovirus MH2. Hence, truncation of the 5' coding region in the course of the transduction and the resulting lack of the authentic amino−terminal domain in the protein product of the transduced allele may be a critical event in changing mil function from physiologic to oncogeni

Nuclear Factor I X Deficiency Causes Brain Malformation and Severe Skeletal Defects▿

The transcription factor family of nuclear factor I (NFI) proteins is encoded by four closely related genes: Nfia, Nfib, Nfic, and Nfix. A potential role for NFI proteins in regulating developmental processes has been implicated by their specific expression pattern during embryonic development and by analysis of NFI-deficient mice. It was shown that loss of NFIA results in hydrocephalus and agenesis of the corpus callosum and that NFIB deficiency leads to neurological defects and to severe lung hypoplasia, whereas Nfic knockout mice exhibit specific tooth defects. Here we report the knockout analysis of the fourth and last member of this gene family, Nfix. Loss of NFIX is postnatally lethal and leads to hydrocephalus and to a partial agenesis of the corpus callosum. Furthermore, NFIX-deficient mice develop a deformation of the spine, which is due to a delay in ossification of vertebral bodies and a progressive degeneration of intervertebral disks. Impaired endochondral ossification and decreased mineralization were also observed in femoral sections of Nfix−/− mice. Consistent with the defects in bone ossification we could show that the expression level of tetranectin, a plasminogen-binding protein involved in mineralization, is specifically downregulated in bones of NFIX-deficient mice

Effect of macrophage overexpression of murine liver X receptor-alpha (LXR-alpha) on atherosclerosis in LDL-receptor deficient mice

Background- The nuclear liver X receptor-alpha (LXR-alpha) has been implicated in the regulation of intracellular cholesterol homeostasis, inflammatory response, and atherosclerosis susceptibility. The aim of the present study was to test whether transgenic expression of LXR-alpha might affect these mechanisms and result in a reduction of atherosclerosis. METHODS AND RESULTS: We generated mice with macrophage overexpression of mouse LXR-alpha, evidenced by significantly elevated expression levels of LXR-target genes (ABCA1, ABCG1) in these cells. For atherosclerosis studies, mice were crossed onto the LDL-receptor deficient background. Plasma lipids and lipoproteins as well as liver triglycerides were not significantly different between transgenic animals and nontransgenic controls. However, lesion area at the brachiocephalic artery (BCA) was significantly reduced (-83%, P=0.02) in male LXR-alpha transgenic mice. This was associated with a significantly increased cholesterol efflux to acceptor-free media (+24%, P=0.002) and ApoA1 containing media (+20%, P<0.0001) as well as reduced lipopolysaccharide (LPS)-induced NO-release from macrophages of transgenic animals, providing a potential mechanism for the reduction of atherosclerosis. CONCLUSIONS: Our data show for the first time that transgenic overexpression of LXR-alpha in macrophages has significant antiatherogenic properties. We conclude that overexpression of LXR-alpha in macrophages might be useful as a therapeutic principle for the prevention of atherosclerosis