Rhodium-diene complexes with the Tp iPr ligand, Tp iPr Rh(diene) (Tp iPr ) hydridotris(3,5-diisopropylpyrazolyl)borate; diene ) 1,5-cyclooctadiene (cod) (1), norbornadiene (nbd) (2)), are prepared by treatment of [Rh(µ-Cl)(diene)] 2 with KTp iPr or TlTp iPr . The structure of 1, characterized by X-ray crystallography, contains the κ 2 -coordinated Tp iPr ligand, and its central Rh atom adopts a square-planar geometry, whereas the unit cell of 2 contains two independent molecules: a square-planar structure with a κ 2 -coordinated Tp iPr ligand similar to 1 and a trigonal-bipyramidal one with a κ 3 -coordinated Tp iPr ligand. Although 1 H and 13 C NMR spectroscopy does not provide any information concerning the coordination geometry due to the interconversion between the square-planar and trigonal-bipyramidal structures, which occurs at a rate much faster than the NMR time scale, IR analysis reveals that the bands observed around 2470 and 2540 cm -1 are assigned to the B-H stretching vibrations of the square-planar and trigonal-bipyramidal structures, respectively. Thus, the ν(B-H) value can be used as an indicator of the hapticity of a Tp iPr ligand (κ 2 (∼2470 cm -1 ) vs κ 3 (>2530 cm -1 )) as compared with related Tp iPr ML n -type complexes.

Peptide-based specific immunotherapy has resulted in tumor regression in some melanoma patients. However, tumor Ags and peptides for specific immunotherapy, except for treatment of melanomas, have not yet been well identified. In this study, we report a gene encoding a new squamous cell carcinoma (SCC) Ag recognized by cells of the HLA-A24-restricted and tumor-specific CTL line. This gene with 3958-bp length was transcribed from the chromosome 6q22 with six exons, and its mRNA was ubiquitously expressed in both SCCs and normal tissues, and partly expressed in adenocarcinomas. The deduced 958-aa sequence encoded by this gene showed no similarity to any known amino acid sequences. This gene product had a characteristic of an endoplasmic reticulum-resident protein. A 100-kDa protein was detected in the vast majority of SCCs from various tissues, in majority of renal cell carcinomas and brain tumors, and in about one-third of melanomas and adenocarcinomas from various organs other than the breast. In contrast, it was not expressed at all in any of the normal cells or tissues tested, including the testis and fetal liver. Three different peptides at positions 93–101, 161–169, and 899–907 of this Ag were recognized by this CTL line, and all of them induced HLA-A24-restricted and tumor-specific CTLs from PBMCs of SCC patients. Therefore, these peptides may be useful for peptide-based specific immunotherapy of HLA-A24+ patients with SCC in various organs, as well as for treatment of other cancer.

Unstable lipid-rich plaques in atherosclerosis are characterized by the accumulation of macrophage foam cells loaded with cholesterol ester (CE). Although hormone-sensitive lipase and cholesteryl ester hydrolase (CEH) have been proposed to mediate the hydrolysis of CE in macrophages, circumstantial evidence suggests the presence of other enzymes with neutral cholesterol ester hydrolase (nCEH) activity. Here we show that the murine orthologue of KIAA1363, designated as neutral cholesterol ester hydrolase (NCEH), is a microsomal nCEH with high expression in murine and human macrophages. The effect of various concentrations of NaCl on its nCEH activity resembles that on endogenous nCEH activity of macrophages. RNA silencing of NCEH decreases nCEH activity at least by 50%; conversely, its overexpression inhibits the CE formation in macrophages. Immunohistochemistry reveals that NCEH is expressed in macrophage foam cells in atherosclerotic lesions. These data indicate that NCEH is responsible for a major part of nCEH activity in macrophages and may be a potential therapeutic target for the prevention of atherosclerosis.Atherosclerotic cardiovascular diseases are the leading causes of mortality in industrialized countries, despite advances in the management of coronary risk factors. Heart attacks arise from thrombotic occlusion of coronary arteries following the rupture of plaques. Lipid-rich plaques, which are characterized by a plethora of CE 3 -laden macrophage foam cells, are prone to rupture (1). Thus, it is important to clarify the mechanism that eliminates CE from macrophage-derived foam cells. Foam cells are generated by the unlimited uptake of modified lipoproteins through scavenger receptors (2). Cholesterol in the lipoproteins is stored in lipid droplets as CE after re-esterification by acyl-CoA:cholesterol acyltransferase 1 (ACAT1) (3). Hydrolysis of CE is the initial step toward elimination of cholesterol from foam cells (4). Free cholesterol thus generated is re-esterified or is released from the cells primarily through ATP-binding cassette transporters (5). Thus, the balance between synthesis and hydrolysis of CE conceivably governs the level of CE in macrophages.Hydrolysis of CE in macrophages has been known for over 40 years (6). However, its molecular mechanism has yet to be fully understood. Circumstantial evidence suggests that the hydrolysis of CE in foam cell macrophages is mediated by hormonesensitive lipase (HSL), a multifunctional enzyme that catalyzes the hydrolysis of triacylglyerol (TG), diacylglycerol, CE, and retinyl ester in various organs such as adipose tissue, muscle, and testis (7,8). This belief is supported by the following facts. First, it has been demonstrated that various lines of macrophages express HSL (9 -12). Second, HSL expression is regulated coordinately with nCEH activity in murine macrophages (13). Third, we (14) and others (15) demonstrated that overexpression of HSL is associated with increased hydrolysis of CE stores in THP-1 and RAW264.7 macrophages.However, recent ...

Cholesterol ester (CE)-laden macrophage foam cells are the hallmark of atherosclerosis, and the hydrolysis of intracellular CE is one of the key steps in foam cell formation. Although hormone-sensitive lipase (LIPE) and cholesterol ester hydrolase (CEH), which is identical to carboxylsterase 1 (CES1, hCE1), were proposed to mediate the neutral CE hydrolase (nCEH) activity in macrophages, recent evidences have suggested the involvement of other enzymes. We have recently reported the identification of a candidate, neutral cholesterol ester hydrolase 1(Nceh1). Here we demonstrate that genetic ablation of Nceh1 promotes foam cell formation and the development of atherosclerosis in mice. We further demonstrate that Nceh1 and Lipe mediate a comparable degree of nCEH activity in macrophages and together account for most of the activity. Mice lacking both Nceh1 and Lipe aggravated atherosclerosis in an additive manner. Thus, Nceh1 is a promising target for the treatment of atherosclerosis.

Loss of mitochondrial membrane potential (ΔΨm) triggers dramatic structural changes in mitochondria from a tubular to globular shape, referred to as mitochondrial fragmentation; the resulting globular mitochondria are called swelled or ring/doughnut mitochondria. We evaluated the early period of structural changes during the ΔΨm loss-induced transformation after carbonyl cyanide m-chlorophenyl hydrazine (CCCP) administration using a newly developed correlative microscopic method combined with fluorescence microscopic live imaging and volume electron microscopy. We found that most mitochondria changed from a tubular shape to a globular shape without fusion or fission and typically showed ring shapes within 10 min after CCCP exposure. In contrast, most ring mitochondria did not have a true through hole; rather, they had various indents, and 47% showed stomatocyte shapes with vase-shaped cavities, which is the most stable physical structure without any structural support if the long tubular shape shortens into a sphere. Our results suggested that loss of ΔΨm triggered collapse of mitochondrial structural support mechanisms.

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Endosome maturation depends on membrane contact sites (MCSs) formed between endoplasmic reticulum (ER) and endolysosomes (LyLEs). The mechanism underlying lipid supply for this process and its pathophysiological relevance remains unclear, however. Here, we identify PDZD8—the mammalian ortholog of a yeast ERMES subunit—as a protein that interacts with protrudin, which is located at ER-LyLE MCSs. Protrudin and PDZD8 promote the formation of ER-LyLE MCSs, and PDZD8 shows the ability to extract various lipids from the ER. Overexpression of both protrudin and PDZD8 in HeLa cells, as well as their depletion in mouse primary neurons, impairs endosomal homeostasis by inducing the formation of abnormal large vacuoles reminiscent of those apparent in spastin- or REEP1-deficient neurons. The protrudin-PDZD8 system is also essential for the establishment of neuronal polarity. Our results suggest that protrudin and PDZD8 cooperatively promote endosome maturation by mediating ER-LyLE tethering and lipid extraction at MCSs, thereby maintaining neuronal polarity and integrity.

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