ALL-1 is a member of the human trithorax/Polycomb gene family and is also involved in acute leukemia. ALL-1 is present within a stable, very large multiprotein supercomplex composed of > or =29 proteins. The majority of the latter are components of the human transcription complexes TFIID (including TBP), SWI/SNF, NuRD, hSNF2H, and Sin3A. Other components are involved in RNA processing or in histone methylation. The complex remodels, acetylates, deacetylates, and methylates nucleosomes and/or free histones. The complex's H3-K4 methylation activity is conferred by the ALL-1 SET domain. Chromatin immunoprecipitations show that ALL-1 and other complex components examined are bound at the promoter of an active ALL-1-dependent Hox a9 gene. In parallel, H3-K4 is methylated, and histones H3 and H4 are acetylated at this promoter.

To identify human proteins that bind to the Smac and caspase-9 binding pocket on the baculoviral inhibitor of apoptosis protein (IAP) repeat 3 (BIR3) domain of human XIAP, we used BIR3 as an affinity reagent, followed by elution with the BIR3 binding peptide AVPIA, microsequencing, and mass spectrometry. The mature serine protease Omi (also known as HtrA2) was identified as a mitochondrial direct BIR3-binding protein and a caspase activator. Like mature Smac (also known as Diablo), mature Omi contains a conserved IAP-binding motif (AVPS) at its N terminus, which is exposed after processing of its N-terminal mitochondrial targeting sequence upon import into the mitochondria. Mature Omi is released together with mature Smac from the mitochondria into the cytosol upon disruption of the outer mitochondrial membrane during apoptosis. Finally, mature Omi can induce apoptosis in human cells in a caspase-independent manner through its protease activity and in a caspase-dependent manner via its ability to disrupt caspase-IAP interaction. Our results provide clear evidence for the involvement of a mitochondrial serine protease in the apoptotic pathway, emphasizing the critical role of the mitochondria in cell death.

The capacity ofvarious cell types to infiltrate inflammatory sites suggests the existence of specific chemotactic cytokines for each cell type. Snyderman et al. (1) first described that leukocytes from human peripheral blood when stimulated in vitro with a specific antigen (purified protein derivative [PPD]) or a nonspecific mitogen (PHA) produced a soluble factor that was chemotactic for homologous monocytes (2) . The production of this lymphokine proved to be a sensitive in vitro correlate of delayed hypersensitivity (1) . We have previously reported the identification, purification, and cDNA cloning ofa novel neutrophil chemotactic factor (NCF) produced by LPS-stimulated human monocytes (3-5) . In the course of identifying NCF, we detected in the same LPS-stimulated human monocyte-conditioned media a chemotactic activity for monocytes that was distinct in molecular weight from NCF. Since the level of monocyte chemotactic factor (MCF) in these conditioned media was at least 10 times less than that of NCF, we used conditioned media from a human myelomonocytic cell line (THP-1) as a source of MCF The identical conditioned media were previously used for the purification of human IL-1/3 (6). We now report the purification of human MCF produced by THP-1 cells to homogeneity and describe the potent monocyte activating factor (MAF) activity of this MCE Materials and MethodsChromatography Proceduresfor the Purification ofMCF. (a) For Heparin Sepharose chromatography, the 200-ml DEAE Sephacel breakthrough fraction was applied to 50 ml Heparin Sepharose (Pharmacia Fine Chemicals, Uppsala, Sweden), that had been equilibrated with 0.05 M Tris-HCl, pH 8.0, with 0.2 M NaCl. After washing the column extensively, MCF was eluted with 50 mM Tris HCI, pH 8.0, with 0.75 M NaCI. (b) For gel filtration, the 4-ml concentrate from Heparin Sepharose was loaded onto a 2.6 x 90-cm column of Sephacryl S-200 (Pharmacia Fine Chemicals) equilibrated with D-PBS at 4°C. The flow rate was adjusted to 15 ml/h and 8-ml fractions were collected . (c) For cation HPLC, fractions corresponding 10-25 kD in gel filtration were concentrated and dialyzed against 0.02 MOPS, pH 6.5, and applied to a 7.5 x 150-mm CM-3SW column (Toyo Soda, Tokyo, Japan) equipped to an HPLC system (model 2150; LKB Instruments, Inc., Sweden) that had been equilibrated with the same buffer. The starting buffer was 0.02 M MOPS, pH 6.5, and the limiting buffer

Antisera prepared against BALB/c Meth A sarcoma in syngeneic or compatible F1 mice recognize a protein with an apparent molecular weight of 53,000 in extracts of [35S]methionine-labeled transformed BALB/c cells. This component, designated p53, was not detected in normal adult mouse fibroblasts, lymphoid cells, or hematopoietic cells or in mouse embryo cells or 3T3 cells. An extensive variety of antisera, including alloantisera and heterologous antisera directed against structural antigens of murine leukemia viruses, was tested for reactivity with p53; other than Meth A antisera, only comparably prepared antisera against another BALB/c sarcoma, CMS4, had anti-p53 activity. All transformed mouse cells tested were found to express p53; these tests included chemically induced sarcomas, leukemias, spontaneously transformed fibroblasts, and cells transformed by simian virus 40 and murine sarcoma virus. The presence of p53 in tumors of no known viral etiology indicates coding by resident cellular genes; this does not exclude endogenous viruses as the source of coding sequences or the possibility that transforming viruses code directly for p53.

The APJ receptor is widely expressed in the human central nervous system (CNS). Apelin was recently identified as the endogenous peptidic ligand for human APJ. Studies with animal models suggested that APJ and apelin play an important role in the hypothalamic regulation of water intake and the endocrine axis, in the regulation of blood pressure, and in cardiac contractility. Apelin has been found to block the activity of APJ as a human immunodeficiency virus type I (HIV-1) coreceptor. In this study, we combined chemical synthetic approaches with alanine substitution to evaluate the structural requirements for interactions with the APJ receptor. We demonstrated that apelin peptides in aqueous solution adopt a random conformation, and the positive charge and hydrophobic residues of apelin-13 play important roles in interactions with the APJ receptor. We have observed an important correlation between receptor binding affinity and cell-cell fusion inhibitory activity. The elucidation of structural requirements of apelin-13 in its interaction with the APJ receptor is critical for further investigation of apelin-APJ functions in vivo and in the design of small molecular inhibitors for potential treatment of HIV-1 infection in the CNS.