Alternative initiations of translation of the human fibroblast growth factor 2 (FGF-2) mRNA, at three CUG start codons and one AUG start codon, result in the synthesis of four isoforms of FGF-2. This process has important consequences on the fate of FGF-2: the CUG-initiated products are nuclear and their constitutive expression is able to induce cell immortalization, whereas the AUG-initiated product, mostly cytoplasmic, can generate cell transformation. Thus, the different isoforms probably have distinct targets in the cell. We show here that translation initiation of the FGF-2 mRNA breaks the rule of the cap-dependent ribosome scanning mechanism. First, translation of the FGF-2 mRNA was shown to be cap independent in vitro. This cap-independent translation required a sequence located between nucleotides (nt) 192 and 256 from the 5' end of the 318-nt-long 5' untranslated region. Second, expression of bicistronic vectors in COS-7 cells indicated that the FGF-2 mRNA is translated through a process of internal ribosome entry mediated by the mRNA leader sequence. By introducing additional AUG codons into the RNA leader sequence, we localized an internal ribosome entry site to between nt 154 and 318 of the 5' untranslated region, just upstream of the first CUG. The presence of an internal ribosome entry site in the FGF-2 mRNA suggests that the process of internal translation initiation, by controlling the expression of a growth factor, could have a crucial role in the control of cell proliferation and differentiation.

It is widely accepted that females have superior immune responses than males, but the ways by which sex hormones may enhance T cell responses are still poorly understood. In the present study, we analyzed the effect of estrogens on CD4 T cell activation and differentiation after immunization with exogenous antigens. We show that administration of low doses of 17ß-estradiol (E2) to castrated female mice results in a striking increase of antigen-specific CD4 T cell responses and in the selective development of IFN-+ -producing cells. Quantitative assessment of the frequency of T cells bearing a public TCR ß chain CDR3 motif demonstrated that the clonal size of primary antigen-specific CD4 T cells was dramatically increased in immune lymph nodes from E2-treated mice. By using mice with disrupted estrogen receptor (ER) § or ß genes, we show that ER § , but not ER g , was necessary for the enhanced E2-driven Th1 cell responsiveness. Furthermore, ER § expression in hematopoietic cells was essential, since E2 effects on Th1 responses were only observed in mice reconstituted with bone marrow cells from ER § +/+ , but not ER § -deficient mice. These results demonstrate that estrogen administration promotes strong antigen-specific Th1 cell responses in a mechanism that requires functional expression of ER § in hematopoietic cells.

Background-The cytokines interleukin 1 (IL-1) and tumor necrosis factor (TNF) are secreted by the different cell populations of the vascular wall and have been suggested to promote atherosclerosis. Methods and Results-Their respective roles in fatty-streak formation in apolipoprotein E-deficient mice were investigated by use of IL-1 receptor antagonist and TNF binding protein. Estradiol-17␤ was used as a positive control. Blocking TNF seemed to be active in female animals but not in males. IL-1 receptor antagonist was as effective as or more effective than estradiol in both sexes. Conclusions-IL-1 plays a crucial role in the initial step of the atherosclerotic process in this animal model, and blocking the activity of this cytokine should be considered as a therapeutic possibility. (Circulation. 1998;97:242-244.)Key Words: atherosclerosis Ⅲ apolipoproteins Ⅲ interleukins Ⅲ tumor necrosis factor I t is known that IL-1␣ and -1␤ and TNF-␣ and -␤ are secreted in the vascular wall by endothelial and smooth muscle cells as well as by monocytes/macrophages. 1,2 These cytokines have been shown to increase permeability of the endothelial cell barrier, 3 induce the expression of surface leukocyte adhesion molecules, 1,4,5 and enhance the production of other cytokines and growth factors, such as IL-6 6 and macrophage colony-stimulating factor, 7-9 all such activities being considered to promote atherosclerosis. The objective of the present study was therefore to clarify the role of IL-1 and TNF in the initial steps of the atherosclerotic process, ie, fatty-streak formation, using apo E KO mice as an animal model of atherosclerosis 10,11 and human IL-1ra and TNFbp as the specific cytokine antagonists. IL-1ra is a recombinant 17-kD protein, which binds to IL-1 receptors and competes with both IL-1␣ and IL-1␤ without detectable IL-1 agonistic effects. 12,13 TNFbp is a specific TNF inhibitor consisting of two molecules of the extracellular domain of the human type 1 TNF receptor added to both ends of a molecule of polyethylene glycol. TNFbp binds with equal affinity to TNF-␣ and TNF-␤.14 -16 E 2 treatment was used as a positive control, because we and others have shown that this hormone prevents fatty-streak formation in the apo E KO mouse animal model. 17,18 The data obtained showed that TNFbp was active in female animals but not in males. Like E 2 , IL-1ra was active in both sexes, suggesting that IL-1 plays a crucial role in the initial step of the atherosclerotic process in this animal model. Methods Study ProtocolApo E KO mice, originally obtained from the Jackson Laboratory, Bar Harbor, Me (sixth generation of backcross from 129/B6 F1 heterozygous to C57BL/6), were housed as previously described 18 and fed normal laboratory mouse chow containing 4.3% fat and 0.02% cholesterol. Four-week-old animals were gonadectomized under general anesthesia. At 2 months of age, these animals were given 0.2 mg 60-day time-release E 2 pellets (Innovative Research of America), a dose that was found to exert a maximal effect on fatty-strea...

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Epstein-Barr virus (EBV) transformed lymphoid cell lines (LCL) were established from blood lymphocytes of a patient affected with Wolman's disease (WD) and from her parents. These LCL showed a severe deficiency in acid lipase activity using every substrate in comparison to LCL from normal subjects, in which acid lipase activity was similar to that in blood lymphocytes. In the LCL from Wolman's disease a major accumulation of neutral lipids was observed, mainly cholesteryl esters, CE (amount around 7 times higher than in normal cells and ratio of esterified/free cholesterol increased by 10 times) and to a lesser extent triglycerides, TG (amount increased by 1.5 times). Electron microscopy showed the storage vacuoles of neutral lipids quite characteristic of this lysosomal disease. The reported data demonstrated the validity of transformed LCL as a cellular model system in culture for experimental studies of Wolman's disease and for investigating the lysosomal metabolism of neutral lipids.

The radiation inactivation method has been used to determine the molecular mass of membrane‐bound acid β‐glucosidase (EC 3.2.1.21) in situ, in normal human spleen and in that of two patients with type I Gaucher disease: the molecular mass in Gaucher spleen is about double (125 000 ± 8900) of that found in the normal spleen (67 000 ± 7700) which is compatible with the existence of subunit coupling in the muted acid β‐glucosidase. From the results, we conclude that subunit interaction is altered in mutant acid β‐glucosidase and that this may be due to a direct effect of the mutation.