Regulation of activity of the transcription factor GATA-1 by acetylation

Modification of histones, DNA-binding proteins found in chromatin, by addition of acetyl groups occurs to a greater degree when the histones are associated with transcriptionally active DNA. A breakthrough in understanding how this acetylation is mediated was the discovery that various transcriptional co-activator proteins have intrinsic histone acetyltransferase activity (for example, Gcn5p, PCAF, TAF(II)250 and p300/CBP. These acetyltransferases also modify certain transcription factors (TFIIEbeta, TFIIF, EKLF and p53). GATA-1 is an important transcription factor in the haematopoietic lineage and is essential for terminal differentiation of erythrocytes and megakaryocytes. It is associated in vivo with the acetyltransferase p300/CBP. Here we report that GATA-1 is acetylated in vitro by p300. This significantly increases the amount of GATA-1 bound to DNA and alters the mobility of GATA-1-DNA complexes, suggestive of a conformational change in GATA-1. GATA-1 is also acetylated in vivo and acetylation directly stimulates GATA-1-dependent transcription. Mutagenesis of important acetylated residues shows that there is a relationship between the acetylation and in vivo function of GATA-1. We propose that acetylation of transcription factors can alter interactions between these factors and DNA and among different transcription factors, and is an integral part of transcription and differentiation processes.

The 400 kDa subunit of the PCAF histone acetylase complex belongs to the ATM superfamily

PCAF histone acetylase is found in a complex with more than 20 associated polypeptides. Here we report cloning and characterization of the 400 kDa PCAF-associated factor referred to as PAF400. PAF400 is almost identical to TRRAP, which binds to c-Myc and E2F, and has significant sequence similarities to the ATM superfamily including FRAP, ATM, ATR, and the catalytic subunit of DNA-PK. Remarkably, PAF400 and FRAP share sequence similarity in broad regions that cover 80% of the entire PAF400 sequence. However, unlike the other members of the ATM superfamily, PAF400 is not a protein kinase as judged from the lack of kinase motif and autophosphorylation activity. We discuss the possibility that PAF400 may play a role in signaling of DNA damage to p53 by stimulation of p53 acetylation.

Effect of troglitazone on microalbuminuria in patients with incipient diabetic nephropathy

OBJECTIVE

Although some studies have suggested a direct action of troglitazone on vascular cells, its effects on diabetic vascular diseases have not been reported. We therefore investigated the effect of troglitazone on microalbuminuria in patients with incipient diabetic nephropathy.

RESEARCH DESIGN AND METHODS

A total of 30 patients with type 2 diabetes associated with microalbuminuria (urinary albumin-to-creatinine ratio [ACR] [milligrams per gram creatinine] ranging from 30 to 300 mg/g creatinine) were studied. They were randomly divided into two groups: patients treated with metformin (500 mg/day, n = 13) or with troglitazone (400 mg/day, n = 17) for 12 weeks. ACR, lipid profile, blood pressure, glycated hemoglobin, and plasma glucose during meal-load tests were measured every 4 weeks.

RESULTS

Anthropometric indices (BMI and percent fat), lipid profile, and blood pressure did not change with either treatment. Fasting and postmeal glucose levels decreased similarly in the two groups. Decrements in glycated hemoglobin were greater in the metformin group at 4 and 8 weeks after the initiation of treatment (P < 0.05). Troglitazone reduced ACR (median [25-75th percentiles]) from 70 (49-195) to 40 (31-90) mg/g creatinine at 4 weeks (P = 0.021) and maintained these reduced levels throughout the treatment period (8 weeks: 35 [26-68], P = 0.007; 12 weeks: 43 [26-103], P = 0.047). Metformin did not change ACR throughout the 12 weeks.

CONCLUSIONS

Troglitazone ameliorated microalbuminuria in diabetic nephropathy. Furthermore, our findings suggest that troglitazone has some effects on vascular cells other than lowering plasma glucose levels. Troglitazone might be useful for diabetic angiopathy, including nephropathy and coronary artery disease.

Effects of aldose reductase inhibitor and vitamin B12 on myocardial uptake of iodine-123 metaiodobenzylguanidine in patients with non-insulin-dependent diabetes mellitus

This study was undertaken to examine the effects of aldose reductase inhibitor (ARI) and vitamin B12 (VB12) on myocardial uptake of iodine-123 metaiodobenzylguanidine (MIBG) in patients with diabetic autonomic disorder. Myocardial scintigraphy using 123I-MIBG was performed on 20 healthy volunteers (controls) and 56 patients with non-insulin-dependent diabetes mellitus (NIDDM), in order to obtain the heart/mediastinum ratio in the initial (HMi) and the delayed images (HMd), and the washout rate (%WR). Thirty-four of the 56 NIDDM patients could be diagnosed as having diabetic autonomic disorder by evaluating their scintigraphic findings in comparison with the controls. Seventeen of these 34 patients received 150 mg/day of doses before meals, and the other 17 received 1.5 mg/day of mecobalamin (VB12 group) in three divided doses after meals, for 3-5 months. According to the presence or absence of clinical symptoms of autonomic or peripheral somatic nerve disorder, the patients were subclassified into four groups. group 1=patients, with autonomic symptoms or somatosensory disorder in the ARI group; group 2=patients without autonomic symptoms or somatosensory disorder in the ARI group; group 3=patients with autonomic symptoms or somatosensory disorder in the VB12 group; and group 4=patients without autonomic symptoms or somatosensory disorder in the VB12 group. After completion of the treatment, myocardial scintigraphy was performed again. Comparing the results obtained before and after the treatment, it was seen that ARI improved only the HMi in group 1 (P=0.046), whereas VB12 significantly improved HMi in the group 3 (P=0.018) and HMi, HMd and %WR in group 4 (P=0.043, P=0.018 and P=0.043, respectively). We conclude that VB12 is more efficacious than ARI in the treatment of diabetic cardiovascular autonomic disorder.

Identification of highly conserved amino-terminal segments of dTAFII230 and yTAFII145 that are functionally interchangeable for inhibiting TBP-DNA interactions in vitro and in promoting yeast cell growth in vivo

TFIID is a multiprotein complex composed of TBP and several TAFIIs. Small amino-terminal segments (TAF N-terminal domain (TAND)) of Drosophila TAFII230 (dTAFII230) and yeast TAFII145 (yTAFII145) bind strongly to TBP and inhibit TBP-DNA interactions. yTAFII145 TAND (yTAND) was divided into two subdomains, yTANDI10-37 and yTANDII46-71, that function cooperatively. Here, we identify dTANDII within the amino terminus of dTAFII230 at 118-143 amino acids in addition to dTANDI18-77, reported previously. dTANDII exhibits pronounced sequence similarity to yTANDII, and the two were shown to be functionally equivalent in binding to TBP and inhibiting TBP-DNA interactions in vitro. Alanine scanning mutation analysis demonstrated that Phe-57 (yTANDII) and Tyr-129 (dTANDII) are critically required for the interaction with TBP. Yeast strains containing mutant yTAFII145 lacking yTANDI or yTANDII showed a temperature-sensitive growth phenotype. The conserved core of dTANDII could substitute for the yTANDII core, and Phe-57 or Tyr-129 described above was critically required for the function of this segment in promoting normal cell growth at 37 degreesC. In these respects, the impact of yTANDII mutations on cell growth paralleled their effects on TBP binding in vitro, strongly suggesting that the yTAFII145-TBP interaction and its negative effects on TFIID binding to core promoters are physiologically important.

Long-distance transcriptional enhancement by the histone acetyltransferase PCAF

Enhancers are defined by their ability to stimulate gene activity from remote sites and their requirement for promoter-proximal upstream activators to activate transcription. Here we demonstrate that recruitment of the p300/CBP-associated factor PCAF to a reporter gene is sufficient to stimulate promoter activity. The PCAF-mediated stimulation of transcription from either a distant or promoter-proximal position depends on the presence of an upstream activator (Sp1). These data suggest that acetyltransferase activity may be a primary component of enhancer function, and that recruitment of polymerase and enhancement of transcription are separable. Transcriptional activation by PCAF requires both its acetyltransferase activity and an additional activity within its N terminus. We also show that the simian virus 40 enhancer and PCAF itself are sufficient to counteract Mad-mediated repression. These results are compatible with recent models in which gene activity is regulated by the competition between deacetylase-mediated repression and enhancer-mediated recruitment of acetyltransferases.

Xenopus NF-Y pre-sets chromatin to potentiate p300 and acetylation-responsive transcription from the Xenopus hsp70 promoter in vivo

We identify Xenopus NF-Y as a key regulator of acetylation responsiveness for the Xenopus hsp70 promoter within chromatin assembled in Xenopus oocyte nuclei. Y-box sequences are required for the assembly of DNase I-hypersensitive sites in the hsp70 promoter, and for transcriptional activation both by inhibitors of histone deacetylase and by the p300 acetyltransferase. The viral oncoprotein E1A interferes with both of these activation steps. We clone Xenopus NF-YA, NF-YB and NF-YC and establish that NF-Y is the predominant Y-box-binding protein in Xenopus oocyte nuclei. NF-Y interacts with p300 in vivo and is itself a target for acetylation by p300. Transcription from the hsp70 promoter in chromatin can be enhanced further by heat shock factor. We suggest two steps in chromatin modification at the Xenopus hsp70 promoter: first the binding of NF-Y to the Y-boxes to pre-set chromatin and second the recruitment of p300 to modulate transcriptional activity.

Segmental mediolytic arteritis [correction of arteries]: a case report with review of the literature

Segmental mediolytic arteritis is a very rare vascular disease which causes sudden intraabdominal hemorrhage. The disease is characterized by degeneration of the arterial media, followed by aneurysmal dilatation and rupture of the involved artery. Up to now, only 13 cases have been reported, and this unique disease is not fully recognized among general pathologists and physicians. Here, we present a case of segmental mediolytic arteritis involving the propria hepatic artery, which resulted in intraabdominal hemorrhage, and consequently hypovolemic circulatory disturbance. Histologically, the rupture focus showed degeneration and desquamation of the intima and media with fibrin-like material covering the exposed adventitia. Inflammatory infiltrates were only noted in the rupture focus as a secondary reactive change. Other than the rupture focus, there were two foci showing similar findings. This disease has rarely been reported and is seldom recognized as a cause of arterial rupture. In cases of sudden intraabdominal hemorrhage, segmental mediolytic arteritis should be considered as a possible cause in addition to atherosclerotic and mycotic aneurysm, traumatic injury and vasculitis syndromes.

HIV-1 tat binds TAFII250 and represses TAFII250-dependent transcription of major histocompatibility class I genes

HIV Tat, a transactivator of viral transcription, represses transcription of major histocompatibility (MHC) class I genes. Repression depends exclusively on the C-terminal domain of Tat, although the mechanism of this repression has not been known. We now show that repression results from the interaction of Tat with the TAFII250 component of the general transcription factor, TFIID. The C-terminal domain of Tat binds to a site on TAFII250 that overlaps the histone acetyl transferase domain, inhibiting TAFII250 histone acetyl transferase activity. Furthermore, promoters repressed by Tat, including the MHC class I promoter, are dependent on TAFII250 whereas those that are not repressed by Tat, such as SV40 and MuLV promoters, are independent of functional TAFII250. Thus, Tat repression of MHC class I transcription would be one mechanism by which HIV avoids immune surveillance.

Activation of integrated provirus requires histone acetyltransferase. p300 and P/CAF are coactivators for HIV-1 Tat

A unique aspect of the retrovirus life cycle is the obligatory integration of the provirus into host cell chromosomes. Unlike viruses that do not integrate, retroviruses must conserve an ability to activate transcription from a chromatin context. Human immunodeficiency virus (HIV)-1 encodes an unusual and an unusually potent transcriptional transactivator, Tat, which binds to a nascent viral leader RNA, TAR. The action of Tat has been well studied in various reductive model systems; however, the physiological mechanism through which Tat gains access to chromatin-associated proviral long terminal repeats (LTRs) is not understood. We show here that a nuclear histone acetyltransferase activity associates with Tat. Intracellularly, we found that Tat forms a ternary complex with p300 and P/CAF, two histone acetyltransferases (HATs). A murine cell defect in Tat transactivation of the HIV-1 LTR was linked to the reduced abundance of p300 and P/CAF. Thus, overexpression of p300 and P/CAF reconstituted Tat transactivation of the HIV-1 LTR in NIH3T3 cells to a level similar to that observed for human cells. By using transdominant p300 or P/CAF mutants that lack enzymatic activity, we delineated a requirement for the HAT component from the latter but not the former in Tat function. Finally, we observed that Tat-associated HAT is preferentially important for transactivation of integrated, but not unintegrated, HIV-1 LTR.

Solution structure of a TBP-TAF(II)230 complex: protein mimicry of the minor groove surface of the TATA box unwound by TBP

General transcription factor TFIID consists of TATA box-binding protein (TBP) and TBP-associated factors (TAF(II)s), which together play a central role in both positive and negative regulation of transcription. The N-terminal region of the 230 kDa Drosophila TAF(II) (dTAF(II)230) binds directly to TBP and inhibits TBP binding to the TATA box. We report here the solution structure of the complex formed by dTAF(II)230 N-terminal region (residues 11-77) and TBP. dTAF(II)230(11-77) comprises three alpha helices and a beta hairpin, forming a core that occupies the concave DNA-binding surface of TBP. The TBP-binding surface of dTAF(II)230 markedly resembles the minor groove surface of the partially unwound TATA box in the TBP-TATA complex. This protein mimicry of the TATA element surface provides the structural basis of the mechanism by which dTAF(II)230 negatively controls the TATA box-binding activity within the TFIID complex.

Correlation of prognosis of breast cancer patients and expression of Ley which acts as a cofactor of tumor procoagulant

Association between Ley expression and prognosis of breast cancer was investigated using monoclonal antibody (MoAb) FS01, which recognizes Ley as an epitope, inhibits the procoagulant activity of cancer cell-derived coagulating activity 1 (CCA-1). Expression intensity and procoagulant activity of CCA-1, tissue factor and HLA-DR on breast cancer cell lines were also examined. Immunohistochemical staining of Ley was performed on primary lesions of 223 breast cancer patients who received absolute curative operation. Flow cytometric analysis and clot timer was used to detect expression and activity of each procoagulant on cancer cell lines. The Ley expression was 73.5%, and no significant relation was observed between clinicopathological factors and intensity of Ley expression. The group showing strong Ley positivity had a significantly poorer prognosis than the Ley-negative group in 5-year disease-free survival (p=0.019). Multivariate analysis using the Cox's proportional hazards' regression model showed that Ley expression is an independent prognostic factor (p=0.018), following tumor size and lymph node metastasis. Ley expression on cancer cell surface is higher than tissue factor and HLA-DR. FS01 and anti-tissue factor MoAb inhibited the coagulating activity of tissue factor-expressing lines, but no cells were inhibited by staphylococcal enterotoxin A, which is known to inhibit the coagulating activity of HLA-DR. CCA-1 and tissue factor plays a important role in the blood coagulating activity of breast cancer cell lines. Breast cancer patients are thought to have a poor prognosis because Ley expression on the surface of the cancer cell induces blood coagulation via CCA-1.

An exposed KID-like domain in human T-cell lymphotropic virus type 1 Tax is responsible for the recruitment of coactivators CBP/p300

Human T-cell lymphotropic virus type 1 (HTLV-1) transcriptional activation is mediated by the viral transactivator, Tax, and three 21-bp repeats (Tax response element [TxRE]) located in the U3 region of the viral long terminal repeat (LTR). Each TxRE contains a core cyclic AMP response element (CRE) flanked by 5' G-rich and 3' C-rich sequences. The TxRE binds CREB (CRE-binding protein) and Tax to form a ternary complex and confers Tax-dependent transactivation. Recent data indicate that Tax functions as a specific link to connect CREB-binding protein (CBP)/p300 in a phosphorylation-independent manner to CREB/ATF-1 assembled on the viral 21-bp repeats. Glutathione S-transferase pull-down performed with Tax deletion mutants and peptide competition have localized the site in Tax critical for binding CBP/p300 to a highly protease-sensitive region around amino acid residues 81 to 95 (81QRTSKTLKVLTPPIT95) which lies between the domains previously proposed to be important for CREB binding and Tax subunit dimerization. Amino acid residues around the trypsin- and chymotrypsin-sensitive sites (88KVL90) of Tax bear resemblance to those in the kinase-inducible domain of CREB (129SRRPSYRKILNE140) surrounding Ser-133, which undergoes signal-induced phosphorylation to recruit CBP/p300. Site-directed mutagenesis of residues in this domain (R82A, K85A, K88A, and V89A) resulted in proteins which failed to transactivate from the HTLV-1 LTR in vivo. These mutants (K85A, K88A, and V89A) bind CREB with similar affinities as wild-type Tax, yet interaction with CBP/p300 is abrogated in various biochemical assays, indicating that the recruitment of CBP/p300 is crucial for Tax transactivation. A Tax mutant, M47, defective in the COOH-terminal transactivation domain, continued to interact with CBP/p300, suggesting that interactions with additional cellular factors are required for proper Tax function.

A human RNA polymerase II complex containing factors that modify chromatin structure

We have isolated a human RNA polymerase II complex that contains chromatin structure remodeling activity and histone acetyltransferase activity. This complex contains the Srb proteins, the Swi-Snf complex, and the histone acetyltransferases CBP and PCAF in addition to RNA polymerase II. Notably, the general transcription factors are absent from this complex. The complex was purified by two different methods: conventional chromatography and affinity chromatography using antibodies directed against CDK8, the human homolog of the yeast Srb10 protein. Protein interaction studies demonstrate a direct interaction between RNA polymerase II and the histone acetyltransferases p300 and PCAF. Importantly, p300 interacts specifically with the nonphosphorylated, initiation-competent form of RNA polymerase II. In contrast, PCAF interacts with the elongation-competent, phosphorylated form of RNA polymerase II.

Vagal paraganglioma. A case report

Vagal paragangliomas are rare tumors and difficult to differentiate from carotid body tumors or schwannomas of the vagus nerve. We present a patient who could be preoperatively diagnosed as having a vagal paraganglioma by ultrasonography and color Doppler sonography.

Crystal structure of a GCN5-related N-acetyltransferase: Serratia marcescens aminoglycoside 3-N-acetyltransferase

The X-ray structure of a canonical GCN5-related N-acetyltransferase (GNAT), Serratia marcescens aminoglycoside 3-N-acetyltransferase, bound to coenzyme A (CoA) has been determined at 2.3 A resolution. The single domain alpha/beta protein resembles a cupped right hand wrapped around a cylinder and consists of a highly curved, six-stranded beta sheet of mixed polarity that is sandwiched between four alpha helices. The structure includes all four conserved GNAT motifs (C, D, A, and B) and represents the catalytic core of this large enzyme superfamily. Acetyl CoA recognition is mediated by a betaalpha structure derived from GNAT motif A, which presents an invariant Arg/Gln-X-X-Gly-X-Gly/Ala segment for hydrogen bonding with the cofactor. Motif B contributes acidic residues to the binding site for the positively charged antibiotic substrate.

Histone-like TAFs within the PCAF histone acetylase complex

PCAF histone acetylase plays a role in regulation of transcription, cell cycle progression, and differentiation. Here, we show that PCAF is found in a complex consisting of more than 20 distinct polypeptides. Strikingly, some polypeptides are identical to TBP-associated factors (TAFs), which are subunits of TFIID. Like TFIID, histone fold-containing factors are present within the PCAF complex. The histone H3- and H2B-like subunits within the PCAF complex are identical to those within TFIID, namely, hTAF(II)31 and hTAF(II)20/15, respectively. The PCAF complex has a novel histone H4-like subunit with similarity to hTAF(II)80 that interacts with the histone H3-like domain of hTAF(II)31. Moreover, the PCAF complex has a novel subunit with WD40 repeats having a similarity to hTAF(II)100.

Anisakidosis: a cause of intestinal obstruction from eating sushi

We report a case of strangulating small bowel obstruction in a 60-yr-old Japanese woman caused by anisakidosis (previously known as anisakiasis). With the increasing popularity of Japanese cuisine such as sushi in the United States, the incidence of anisakidosis is expected to increase. Intestinal anisakidosis can now be treated temporarily, but this condition may cause a serious obstruction afterwards, as evidenced by this particular case. Over 13,500 cases were reviewed in both the Japanese and English literature, and we discuss the prevention of anisakidosis without negatively altering the taste of the raw fish.

Cloning of Drosophila GCN5: conserved features among metazoan GCN5 family members

PCAF and hGCN5 are distinct human genes that encode proteins related to the yeast histone acetyltransferase and transcriptional adapter GCN5. The PCAF protein shares extensive similarity with the 439 amino acids of yGCN5, but it has an approximately 350 amino acid N-terminal extension that interacts with the transcriptional co-activator p300/CBP. Adenoviral protein E1a can disrupt PCAF-CBP interactions and prevent PCAF-dependent cellular differentiation. In this report, we describe the cloning and initial characterization of a Drosophila homolog of yGCN5. In addition to the homology to yGCN5, the Drosophila protein shares sequencesimilarity with the N-terminal portion of human PCAF that is involved in binding to CBP. In the course of characterizing dGCN5, we have discovered that hGCN5 also contains an N-terminal extension with significant similarity to PCAF. Interestingly, in the case of the h GCN5 gene, alternative splicing may regulate the production of full-length hGCN5. The presence of the N-terminal domain in a Drosophila GCN5 homolog and both human homologs suggests that it was part of the ancestral form of metazoan GCN5.

The histone acetylase PCAF is a nuclear receptor coactivator

Whereas the histone acetylase PCAF has been suggested to be part of a coactivator complex mediating transcriptional activation by the nuclear hormone receptors, the physical and functional interactions between nuclear receptors and PCAF have remained unclear. Our efforts to clarify these relationships have revealed two novel properties of nuclear receptors. First, we demonstrate that the RXR/RAR heterodimer directly recruits PCAF from mammalian cell extracts in a ligand-dependent manner and that increased expression of PCAF leads to enhanced retinoid-responsive transcription. Second, we demonstrate that, in vitro, PCAF directly associates with the DNA-binding domain of nuclear receptors, independently of p300/CBP binding, therefore defining a novel cofactor interaction surface. Furthermore, our results show that dissociation of corepressors enables ligand-dependent PCAF binding to the receptors. This observation illuminates how a ligand-dependent receptor function can be propagated to regions outside the ligand-binding domain itself. On the basis of these observations, we suggest that PCAF may play a more central role in nuclear receptor function than previously anticipated.

Fas-induced arachidonic acid release is mediated by Ca2+-independent phospholipase A2 but not cytosolic phospholipase A2, which undergoes proteolytic inactivation

Fas-mediated apoptosis of human leukemic U937 cells was accompanied by increased arachidonic acid (AA) and oleic acid release from membrane glycerophospholipids, indicating phospholipase A2 (PLA2) activation. During apoptosis, type IV cytosolic PLA2 (cPLA2), a PLA2 isozyme with an apparent molecular mass of 110 kDa critical for stimulus-coupled AA release, was converted to a 78-kDa fragment with concomitant loss of catalytic activity. Cleavage of cPLA2 correlated with increased caspase-3-like protease activity in apoptotic cells and was abrogated by a caspase-3 inhibitor. A mutant cPLA2 protein in which Asp522 was replaced by Asn, which aligns with the consensus sequence of the caspase-3 cleavage site (DXXD downward arrowX), was resistant to apo-ptosis-associated proteolysis. Moreover, a COOH-terminal deletion mutant of cPLA2 truncated at Asp522 comigrated with the 78-kDa fragment and exhibited no enzymatic activity. Thus, caspase-3-mediated cPLA2 cleavage eventually leads to destruction of a catalytic triad essential for cPLA2 activity, thereby terminating its AA-releasing function. In contrast, the activity of type VI Ca2+-independent PLA2 (iPLA2), a PLA2 isozyme implicated in phospholipid remodeling, remained intact during apoptosis. Inhibitors of iPLA2, but neither cPLA2 nor secretory PLA2 inhibitors, suppressed AA release markedly and, importantly, delayed cell death induced by Fas. Therefore, we conclude that iPLA2-mediated fatty acid release is facilitated in Fas-stimulated cells and plays a modifying although not essential role in the apoptotic cell death process.

Intraoperative radiation therapy for a patient with bulky disease of mesenteric non-Hodgkin's lymphoma

A long survival is rarely observed in patients demonstrating recurrent malignant lymphoma with bulky disease because of the appearance of chemoresistant tumor cells after extensive chemotherapy, and moreover the presence of bulky disease has also been consistently associated with a poorer response rate and a shortened survival, due to the fact that tumor size is the most significant factor for the treatment of non-Hodgkin's lymphoma. We herein describe a case of a 53-year-old woman presenting with the chief complaint of abdominal fullness, who underwent intraoperative radiation therapy (IORT) for recurrent bulky non-Hodgkin's lymphoma in the mesenterium. The patient has had no evidence of tumor recurrence, based on the findings of regular abdominal computed tomographic scans, 60 months after initial chemotherapy and 28 months after IORT.

Primary structure of porcine spleen ribonuclease: sequence homology

The primary structure of porcine spleen RNase (RNase Psp1) was investigated as a mean of assessing the structure-function relationship of base non-specific ribonucleases of animal origin. N-terminal analysis of RNase Psp1 yielded three N-terminal sequences. These peptides were separated by gel-filtration on Superdex 75HR, after reduction and S-carboxymethylation of RNase Psp1. Determination of the amino-acid sequence of these peptides indicated that the RNase Psp1 preparation consisted of three peptides having 20 (RCM RNase Psp1 pep1), 15 (RCM RNase Psp1 pep2), and 164 (RCM RNase Psp1 pro) amino-acid residues, respectively. It possessed two unique segments containing most of the active site amino-acid residues of the RNases of the RNase T2 family. The alignment of these three peptides in RNase Psp1 was determined by comparison with the other enzymes in the RNase T2 family. The overall results showed that RCM RNase Psp1 pep1 and RCM RNase Psp1 pep2 are derived from the N-terminal and C-terminal regions of RNase Psp1, respectively, probably by processing by some protease. The molecular mass of the protein moiety of RNase Psp1 was 23235 Da.

Solitary fibrous tumour: significance of p53 and CD34 immunoreactivity in its malignant transformation

AIMS

To clarify the association of p53 and CD34 expression with development of malignant solitary fibrous tumour we have studied 10 cases of solitary fibrous tumour arising in the pleura, retroperitoneum and pelvic cavity with clinicopathological features of malignancy.

METHODS AND RESULTS

Tumours were localized solid masses with or without necrosis in eight and they nearly totally occupied the pleural cavity in two. Basic histology of the tumours was the proliferation of spindle cells arranged in 'patternless' pattern or in interlacing bundles with nuclear atypia and mitotic activities of various degree. In two, high-grade foci were present within low or intermediate-grade tumours. Recurrent tumours also showed more atypical features than primary tumours in two. Immunohistochemical studies showed CD34 positivity in seven, but three of them showed marked diminution or complete loss of CD34 expression in high-grade foci or a recurrent tumour. Three high-grade cases showed totally negative staining for CD34. p53 was strongly expressed in cases with fatal outcome, clinical recurrence, nuclear atypia, high mitotic activity or local invasion, whereas almost negative in benign tumours.

CONCLUSIONS

Malignant solitary fibrous tumours may occur de novo or by transformation within benign or low-grade tumours and may be associated with p53 mutation. Although CD34 is a useful marker in the diagnosis of solitary fibrous tumour, one should bear in mind that its expression can be lost in high-grade tumours.

Generation of a monoclonal antibody that inhibits the procoagulant activity of various cancer cell lines

BACKGROUND

Tumor procoagulant is one of the factors responsible for disseminated intravascular coagulation and metastasis. The authors found procoagulant activity in LK52 human squamous cell carcinoma cells, which they designated cancer cell-derived blood coagulating activity 1 (CCA-1). A monoclonal antibody (MoAb) was generated to characterize this CCA-1 procoagulant activity. To date, antibodies that show an inhibitory effect on procoagulant activity as well as high reactivity in cancer cells are well known for their tissue factor specificity.

METHODS

Characterization of the procoagulant activity of CCA-1 was performed and an anti-CCA-1 MoAb, FS01, was generated. CCA-1 expression on the cancer cell surface was examined by flow cytometry. Procoagulant activity of various cancer cell lines and the inhibitory effect of the FS01 MoAb on this procoagulant activity was monitored by a clot timer.

RESULTS

The enzymologic character differed from that of cancer procoagulant (CP). The FS01 MoAb inhibited the procoagulant activity of CCA-1, but did not inhibit that of tissue factor. A positive correlation was observed between the expression intensity of CCA-1 and the inhibitory effect of the FS01 MoAb on the procoagulant activity of cancer cell lines. Expression of CCA-1 was observed more frequently than that of tissue factor in human cancer cell lines.

CONCLUSIONS

The FS01 MoAb generated in the current study is a new antibody that reacts with various cancer cell lines, but not with normal cells. FS01 inhibits cancer cell-derived procoagulant activity and does not react with tissue factor and CP. CCA-1, which is recognized by the FS01 MoAb, appears to play a major role in cancer cell-derived procoagulant activity.

Pulmonary adenocarcinomas of the fetal lung type: a clinicopathologic study indicating differences in histology, epidemiology, and natural history of low-grade and high-grade forms

Seven cases of high-grade adenocarcinoma of fetal lung type (H-FLAC) are compared with nine cases of pulmonary endodermal tumor resembling fetal lung or low-grade adenocarcinoma of fetal lung type (L-FLAC). Of the seven patients with of H-FLAC, four were men and three were women. All of the patients but one were in their 60s or 70s. Five patients were smokers. After resection of the tumor, three patients died of metastases, two patients are alive with no evidence of disease, and two patients died of a postoperative complication. Histologically, H-FLAC and L-FLAC have both complex glandular structures resembling fetal lung and neuroendocrine differentiation. Two cases of H-FLAC had stromal proliferation typical of biphasic pulmonary blastoma. The H-FLAC was distinguished from L-FLAC by the presence of disorganized glands, large vesicular nuclei, prominent nucleoli, pronounced anisonucleosis, absence of morules, transition to conventional adenocarcinoma, broad areas of necrosis, desmoplastic stroma, overexpression of p53 protein, and production of alpha-fetoprotein. High and low grades of FLAC explain discrepancies in previously reported clinicopathologic features of FLAC. The H-FLAC needs to be distinguished from L-FLAC. Both forms may have stromal components, so both have been referred to as blastomas. The H-FLAC represents the prototype of so-called pulmonary blastoma predominantly seen in the elderly, whereas L-FLAC and its biphasic form predominate in the middle-aged population.

[Impact of duration of caregiving on stress among primary caregivers of elderly]

This study examined (1) the direct effect of the duration of caregiving on caregiver psychological distress, and (2) two- or three-way interactions between duration, stressors (elderly's physical and cognitive impairments), and personal (caregiver's economic or work status) or social (informal or formal supports) resources. We interviewed 833 primary family caregivers of non-institutionalized frail elderly who had been selected through a screening process of all residents aged 65 and over (21,567 persons) in a suburban area of Tokyo. Caregiver psychological distress was evaluated by "Caregiving Burden Scale" as a caregiving-specific psychological measurement, and "Center for Epidemiologic Studies Depression Scale (CES-D)" as a general psychological measurement. The results were as follows. 1. For Caregiving Burden, duration showed a direct effect, as those who had been providing care for a longer duration of time reported higher burden. We found no interactions between duration, stressors, and resources on caregiving burden. 2. For CES-D, duration had interactions, but no direct effect. (1) Two-way interactions were observed between duration and caregiver's economic or work status, as caregivers with a low economic status or who were unemployed showed a stronger negative impact from duration of caregiving. (2) Three-way interactions were observed between duration, the elderly's ADL impairment, and informal support. Informal support, such as a secondary caregiver, buffered the negative impact of the elderly's ADL impairment in cases with a shorter duration of caregiving, but not for those with longer duration. (3) Three-way interactions were observed between duration, the elderly's cognitive impairment, and formal emotional support. Formal emotional support buffered the negative impact of the elderly's cognitive impairment for those with a longer duration of caregiving, but not for those with a shorter duration. These findings suggest that stress-buffering resources differ according to duration of caregiving.

Adult ganglioneuroblastoma of the anterior mediastinum

A case of ganglioneuroblastoma occurring in the anterior mediastinum of a 79 year-old man is reported. The tumor was mainly composed of neuroblasts with occasional ganglion cells. Foci of melanin-laden cells were also identified. Immunohistochemistry revealed that the tumor cells showed both schwannian and melanocytic differentiation with immunoreactivity to anti-S100 protein and anti-HMB45 antibodies. In addition, the tumor contained several microcysts lined by squamous epithelial and one lymphoid tissue abundant in T lymphocytes, which appeared to be derived from thymic tissue. This case is unique in that neuroblastoma group tumors including ganglioneuroblastoma is uncommon in the elderly and in the thymic region, and rarely shows melanocytic differentiation. To the best of our knowledge, this case is a tumor of neuroblastoma group occurring in the eldest patient.

The Gcn4p activation domain interacts specifically in vitro with RNA polymerase II holoenzyme, TFIID, and the Adap-Gcn5p coactivator complex

The Gcn4p activation domain contains seven clusters of hydrophobic residues that make additive contributions to transcriptional activation in vivo. We observed efficient binding of a glutathione S-transferase (GST)-Gcn4p fusion protein to components of three different coactivator complexes in Saccharomyces cerevisiae cell extracts, including subunits of transcription factor IID (TFIID) (yeast TAFII20 [yTAFII20], yTAFII60, and yTAFII90), the holoenzyme mediator (Srb2p, Srb4p, and Srb7p), and the Adap-Gcn5p complex (Ada2p and Ada3p). The binding to these coactivator subunits was completely dependent on the hydrophobic clusters in the Gcn4p activation domain. Alanine substitutions in single clusters led to moderate reductions in binding, double-cluster substitutions generally led to greater reductions in binding than the corresponding single-cluster mutations, and mutations in four or more clusters reduced binding to all of the coactivator proteins to background levels. The additive effects of these mutations on binding of coactivator proteins correlated with their cumulative effects on transcriptional activation by Gcn4p in vivo, particularly with Ada3p, suggesting that recruitment of these coactivator complexes to the promoter is a cardinal function of the Gcn4p activation domain. As judged by immunoprecipitation analysis, components of the mediator were not associated with constituents of TFIID and Adap-Gcn5p in the extracts, implying that GST-Gcn4p interacted with the mediator independently of these other coactivators. Unexpectedly, a proportion of Ada2p coimmunoprecipitated with yTAFII90, and the yTAFII20, -60, and -90 proteins were coimmunoprecipitated with Ada3p, revealing a stable interaction between components of TFIID and the Adap-Gcn5p complex. Because GST-Gcn4p did not bind specifically to highly purified TFIID, Gcn4p may interact with TFIID via the Adap-Gcn5p complex or some other adapter proteins. The ability of Gcn4p to interact with several distinct coactivator complexes that are physically and genetically linked to TATA box-binding protein can provide an explanation for the observation that yTAFII proteins are dispensable for activation by Gcn4p in vivo.

Differential expression of trypsin in human ovarian carcinomas and low-malignant-potential tumors

It is widely recognized that matrix metalloproteinases and serine proteinases play an important role in cancer invasion and metastasis. We have reported that trypsin is synthesized in ovarian carcinomas as well as in some other types of cancers. In general, ovarian cancers easily tend to invade, metastasize, and spread widely into the peritoneal cavity. However, low-malignant-potential (LMP, borderline tumor) ovarian tumors are known to have limited malignant potential for progression, although microinvasion and distant metastasis have been reported among them. To analyze the relationship between varied degrees of trypsin expression and malignant behavior of ovarian tumors, immunohistochemical studies with monoclonal antibodies to human trypsin and clinicopathologic analysis were performed in human ovarian carcinomas, low-malignant-potential tumors, and benign cystadenomas. Thirteen (44.8%) cases of 29 ovarian carcinomas showed prominent trypsin expression, while only 2 (18.2%) cases of 11 LMP ovarian tumors demonstrated low levels of expression. Benign tumors and normal ovaries did not show any positivity for trypsin. These data suggest that tumor-derived heterotropic trypsin may be associated with ovarian tumors in parallel with malignant potential or behavior such as invasiveness or metastasis. At least in some ovarian carcinomas, prominent stromal invasion or metastasis might require the acquisition of or association with tumor-derived trypsin production.

The yeast TAF145 inhibitory domain and TFIIA competitively bind to TATA-binding protein

The Drosophila 230-kDa TFIID subunit (dTAF230) interacts with the DNA binding domain of TATA box-binding protein (TBP) which exists in the same complex. Here, we characterize the inhibitory domain in the yeast TAF145 (yTAF145), which is homologous to dTAF230. Mutation studies show that the N-terminal inhibitory region (residues 10 to 71) can be divided into two subdomains, I (residues 10 to 37) and II (residues 46 to 71). Mutations in either subdomain significantly impair function. Acidic residues in subdomain II are important for the interaction with TBP. In addition, yTAF145 interaction is impaired by mutating the basic residues on the convex surface of TBP, which are crucial for interaction with TFIIA. Consistently, TFIIA and yTAF145 bind competitively to TBP. A deletion of the inhibitory domain of yTAF145 leads to a temperature-sensitive growth phenotype. Importantly, this phenotype is suppressed by overexpression of the TFIIA subunits, indicating that the yTAF145 inhibitory domain is involved in TFIIA function.

Cytosolic phospholipase A2 is required for cytokine-induced expression of type IIA secretory phospholipase A2 that mediates optimal cyclooxygenase-2-dependent delayed prostaglandin E2 generation in rat 3Y1 fibroblasts

Activation of rat fibroblastic 3Y1 cells with interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) induced delayed prostaglandin (PG) E2 generation over 6-48 h, which occurred in parallel with de novo induction of type IIA secretory phospholipase A2 (sPLA2) and cyclooxygenase (COX)-2, without accompanied by changes in the constitutive expression of type IV cytosolic PLA2 (cPLA2) and COX-1. Types V and IIC sPLA2s were barely detectable in these cells. Studies using an anti-type IIA sPLA2 antibody, sPLA2 inhibitors, and a type IIA sPLA2-specific antisense oligonucleotide revealed that IL-1 beta/TNF alpha-induced delayed PGE2 generation by these cells was largely dependent on inducible type IIA sPLA2, which was functionally linked to inducible COX-2. Delayed PGE2 generation was also suppressed markedly by the cPLA2 inhibitor arachidonoyl trifluoromethyl ketone (AACOCF3), which attenuated induction of type IIA sPLA2, but not COX-2, expression. AACOCF3 inhibited the initial phase of cytokine-stimulated arachidonic acid release, and supplementing AACOCF3-treated cells with exogenous arachidonic acid partially restored type IIA sPLA2 expression. These results suggest that certain metabolites produced by the cPLA2-dependent pathway are crucial for the subsequent induction of type IIA sPLA2 expression and attendant delayed PGE2 generation. Some lipoxygenase-derived products might be involved in this event, since IL-1 beta/TNF alpha-induced type IIA sPLA2 induction and PGE2 generation were reduced markedly by lipoxygenase, but not COX, inhibitors. In contrast, Ca2+ ionophore-stimulated immediate PGE2 generation was regulated predominantly by the constitutive enzymes cPLA2 and COX-1, even when type IIA sPLA2 and COX-2 were maximally induced after IL-1 beta/TNF alpha treatment, revealing functional segregation of the constitutive and inducible PG biosynthetic enzymes.

Disturbance of consciousness due to methamphetamine abuse. A study of 2 patients

The present paper reports 2 cases of methamphetamine abuse. Following consecutive methamphetamine administration, the patients developed acute intoxication, during which time they showed a unique type of disturbance of consciousness: delirium and twilight state. In both cases, mental status changed, passing through three distinct stages: restlessness and insomnia, hallucinatory paranoid state, and disturbance of consciousness. A review of the literature suggests that disturbance of consciousness may occur occasionally during the course of amphetamine and methamphetamine intoxication, although these symptoms can be overlooked easily due to confounding symptomatology.

Primary structure of porcine spleen ribonuclease: sequence homology

The primary structure of porcine spleen RNase (RNase Psp1) was investigated as a mean of assessing the structure-function relationship of base non-specific ribonucleases of animal origin. N-terminal analysis of RNase Psp1 yielded three N-terminal sequences. These peptides were separated by gel-filtration on Superdex 75HR, after reduction and S-carboxymethylation of RNase Psp1. Determination of the amino-acid sequence of these peptides indicated that the RNase Psp1 preparation consisted of three peptides having 20 (RCM RNase Psp1 pep1), 15 (RCM RNase Psp1 pep2), and 164 (RCM RNase Psp1 pro) amino-acid residues, respectively. It possessed two unique segments containing most of the active site amino-acid residues of the RNases of the RNase T2 family. The alignment of these three peptides in RNase Psp1 was determined by comparison with the other enzymes in the RNase T2 family. The overall results showed that RCM RNase Psp1 pep1 and RCM RNase Psp1 pep2 are derived from the N-terminal and C-terminal regions of RNase Psp1, respectively, probably by processing by some protease. The molecular mass of the protein moiety of RNase Psp1 was 23235 Da.

Cancer cells isolated from malignant pleural and peritoneal effusions inhibit phospholipase A2 activity in human polymorphonuclear leukocytes

We studied the influence of cancer cells on the LTB4 production by human polymorphonuclear leukocytes (PMN). The cancer cells were isolated from malignant pleural effusion specimens taken from two patients or from a peritoneal effusion specimen of one patient. While human PMN produced LTB4 following stimulation with A23187, the addition of cancer cells inhibited LTB4, 5-HETE and 12-HETE production by PMN in a cell number-dependent manner, while the cancer cell lines also showed a similar inhibition. The addition of lysate of the breast cancer cells also inhibited in a dose-dependent manner the production of LTB4 by PMN following stimulation with A23187. The addition of arachidonic acid completely reversed the inhibition of PMN-LTB4 production by the addition of the breast cancer cell lysates, thus suggesting inhibition at the phospholipase A2 level. The addition of this lysate to the partially purified human cytosolic PLA2 also inhibited the PLA2 activity. In contrast, the addition of lymphoma cells isolated from metastatic lymphnodes did not inhibit the LTB4 production from PMN. Since LTB4 is one of the important chemotactic factors for PMN and monocytes, these findings suggest that the inhibition of the PLA2 activity by the cancer cells thus results in a reduced production of LTB4 from PMN and contributes to a predisposition to develop severe infection in patients with advanced cancer.

Human histone acetyltransferase GCN5 exists in a stable macromolecular complex lacking the adapter ADA2

Acetylation of core histones is an important regulatory step in transcriptional activation from chromatin templates. The yeast transcriptional coactivator protein GCN5 was recently shown to be a nuclear histone acetyltransferase (HAT). Genetic and biochemical studies in yeast suggest that GCN5 functions with the adapter proteins ADA1, ADA2, ADA3, and ADA5 in a heteromeric complex. We have established conditions for chromatographic fractionation of HATs and ADA2 from human K562 erythroleukemia cells. Gel-filtration chromatography revealed two populations of GCN5 with Stokes' radii of 67 and 33 A, consistent with a large macromolecular complex and a monomer, respectively. The GCN5-related HAT, PCAF, was resolved as a stable complex with a Stokes' radius of 74 A. The HAT complexes were resistant to 0.3 M NaCl and DNase I. ADA2 was characterized by a Stokes' radius of 35 A, consistent with a monomer. Thus, in contrast to the stable GCN5-adapter complex in yeast, human GCN5 and ADA2 are not stably associated with each other. The implications of this result are discussed vis-a-vis the mechanism of recruitment of GCN5 to regulatory regions of genes.

Large cell carcinoma of the lung metastatic to nuchal muscle

Clinically apparent hematogenous skeletal muscle metastases from lung cancer are extremely rare. We present a 72-year-old man with a large cell lung carcinoma metastatic to nuchal muscle. Cervical computed tomography (CT) and magnetic resonance imaging (MRI) revealed the presence of a well-defined mass in the left splenius capitis muscle. A percutaneous needle biopsy was performed to establish a diagnosis. Localized skeletal muscle swelling may rarely prove to be metastases in patients with lung cancer, but should be investigated in the case of muscle swelling.

Segmental pericholangial fibrosis: a peculiar benign fibrosing disease at the hepatic hilum

The authors report on a 9-year-old child who underwent surgery to remove a tumor of the hepatic hilum with preoperative radiographic studies suggestive of malignancy, but whose surgical specimens showed a peculiar fibrosing disease. The lesion was localized to the bifurcation of the hepatic duct, where the bile duct wall and the surrounding tissue was markedly fibrotic. No malignant cells or epithelial destruction were seen. The patient's postoperative course was uneventful, and he is without any sign of recurrence 2 years after surgery. Because the histological features of this case do not correspond to any established disease, including primary sclerosing cholangitis, the authors believe it represents a new entity, segmental pericholangial fibrosis. Local resection resulted in a good outcome. A review of the literature disclosed a few similar cases with a benign clinical course.

Differential roles of p300 and PCAF acetyltransferases in muscle differentiation

PCAF is a histone acetyltransferase that associates with p300/CBP and competes with E1A for access to them. While exogenous expression of PCAF potentiates both MyoD-directed transcription and myogenic differentiation, PCAF inactivation by anti-PCAF antibody microinjection prevents differentiation. MyoD interacts directly with both p300/CBP and PCAF, forming a multimeric protein complex on the promoter elements. Viral transforming factors that interfere with muscle differentiation disrupt this complex without affecting the MyoD-DNA interaction, indicating functional significance of the complex formation. Exogenous expression of PCAF or p300 promotes p21 expression and terminal cell-cycle arrest. Both of these activities are dependent on the histone acetyltransferase activity of PCAF, but not on that of p300. These results indicate that recruitment of histone acetyltransferase activity of PCAF by MyoD, through p300/CBP, is crucial for activation of the myogenic program.

Cytodifferentiation of atypical adenomatous hyperplasia and bronchioloalveolar lung carcinoma: immunohistochemical and ultrastructural studies

We used immunohistochemistry and electron microscopy to evaluate the differentiation of cells comprising atypical adenomatous hyperplasia (AAH; n = 26), early bronchioloalveolar lung carcinoma (BAC; n = 11), and overt BAC (n = 16), which are assumed to constitute a continuous spectrum of developmental steps of BAC. Surfactant apoprotein (SAP), a marker for type 2 alveolar cells, was expressed in cells from all the lesions of AAH, early BAC, and overt BAC. However, the proportion of SAP-positive cells decreased and their distribution became more heterogeneous with advancing lesion grade. Urine protein 1, which is identical to the Clara cell-specific 10 kDa protein, was expressed in 70% of overt BAC, whereas only 20% of early BAC showed weak reactivity and none of AAH lesions showed any reactivity at all. Ultrastructurally, type 2 alveolar cell differentiation was predominant among cells from AAH and early BAC. Our results suggest that precursor cells of BAC differentiate predominantly towards type 2 alveolar cells. Cells comprising overt BAC retain this differentiation phenotype, but to a reduced extent. In contrast, concomitantly with progression, cells with Clara cell differentiation emerge and their proportion increases. Such phenotypic changes may reflect metaplasia occurring in tumour cells during the development of BAC.

Ras is an essential component for notochord formation during ascidian embryogenesis

In ascidian embryos, inductive interactions are necessary for the fate specification of notochord cells. Previous studies have shown that notochord induction occurs at the 32-cell stage and that basic fibroblast growth factor (bFGF) has notochord-inducing activity in ascidian embryos. In vertebrate, it is known that bFGF receptors have tyrosine kinase domain and the signaling pathway is mediated by the small-GTP binding protein, Ras. To study the role of Ras in ascidian embryos, we injected dominant negative Ras (RasN17) into fertilized eggs. RasN17 inhibited the formation of notochord, suggesting that the Ras signaling pathway is involved in signal transduction in the induction of notochord cells. When the presumptive-notochord (A6.2) blastomere was co-isolated with the inducer (A6.1) blastomere and then RasN17 was injected into the A6.2 blastomere, notochord differentiation was suppressed. The presumptive-notochord blastomeres injected with RasN17 were treated with bFGF. Many of them failed to develop notochord-specific features. Next, we examined the effect of injecting constitutively active Ras (RasV12) into the A6.2 blastomeres. However, microinjection of RasV12 into these cells did not bypass notochord induction. These results suggest that the Ras signaling pathway is essential for the formation of notochord and that another signaling pathway also must be activated simultaneously in notochord formation during ascidian embryogenesis.

The histone acetyltransferase activity of human GCN5 and PCAF is stabilized by coenzymes

Here we report that PCAF and human GCN5, two related type A histone acetyltransferases, are unstable enzymes that under the commonly used assay conditions are rapidly and irreversibly inactivated. In addition, we report that free histone H1, although not acetylated in vivo, is a preferred and convenient in vitro substrate for the study of PCAF, human GCN5, and possibly other type A histone acetyltransferases. Using either histone H1 or histone H3 as substrates, we find that preincubation with either acetyl-CoA or CoA stabilizes the acetyltransferase activities of PCAF, human GCN5 and an enzymatically active PCAF deletion mutant containing the C-terminal half of the protein. The stabilization requires the continuous presence of coenzyme, suggesting that the acetyltransferase-coenzyme complexes are stable, while the isolated apoenzymes are not. Human GCN5 and the N-terminal deletion mutant of PCAF are stabilized equally well by preincubation with either CoA or acetyl-CoA, while intact PCAF is better stabilized by acetyl-CoA than by CoA. Intact PCAF, but not the N-terminal truncation mutant or human GCN5, is autoacetylated. These findings raise the possibility that the intracellular concentrations of the coenzymes affect the stability and therefore the nuclear activity of these acetyltransferases.

[An elderly woman with chronic pigeon-breeder's disease]

A 64-year-old woman had been feeding more than 60 pigeons in a coop in her back yard for 35 years. Diffuse reticulonodular shadows were found on a chest radiograph obtained as part of an annual check-up eight years before admission to the hospital. She was given a tentative diagnosis of idiopathic pulmonary fibrosis and was observed. She was admitted to our hospital because she noticed dry coughing and shortness of breath. A chest CT scan revealed segmentally distributed honeycombing and bronchi-bronchioloectasis. Tests for IgA and IgG antibodies to extracts of pigeon droppings in serum samples and in samples of bronchoalveolar lavage fluid were strongly positive, as were tests for lymphocyte blastogenic responses to samples of pigeon serum Examination of lung-biopsy specimens obtained by video-assisted thoracoscopic surgery revealed bronchiolitis, alveolitis, and honeycombing in a centrilobular distribution. The patient was given a diagnosis of pigeon-breeder's disease. Chronic hypersensitivity pneumonitis without acute episodes might be misdiagnosed as idiopathic interstitial pneumonia or bronchiectasis, as happened in this case. The possibility of chronic hypersensitivity pneumonitis should be considered when patients are suspected to have pulmonary fibrosis. It is important to obtain the detailed information on past or current avian contact, working history, and the home environment.

Acetylation of general transcription factors by histone acetyltransferases

The acetylation of histones increases the accessibility of nucleosomal DNA to transcription factors [1,2], relieving transcriptional repression [3] and correlating with the potential for transcriptional activity in vivo [4 - 7]. The characterization of several novel histone acetyltransferases - including the human GCN5 homolog PCAF (p300/CBP-associated factor) [8], the transcription coactivator p300/CBP [9], and TAFII250 [10] - has provided a potential explanation for the relationship between histone acetylation and transcriptional activation. In addition to histones, however, other components of the basal transcription machinery might be acetylated by these enzymes and directly affect transcription. Here, we examine the acetylation of the basal transcriptional machinery for RNA polymerase II by PCAF, p300 and TAFII250. We find that all three acetyltransferases can direct the acetylation of TFIIEbetaand TFIIF, and we identify a preferred site of acetylation in TFIIEbeta. Human TFIIE consists of two subunits, alpha(p56) and beta(p34), which form a heterotetramer (alpha2 beta2) in solution ([11], reviewed in [12]). TFIIE enters the preinitiation complex after RNA polymerase II and TFIIF, suggesting that TFIIE may interact directly with RNA polymerase II and/or TFIIF [13,14]. In addition, TFIIE can facilitate promoter melting either in the presence or absence of TFIIH and can stimulate TFIIH-dependent phosphorylation of the carboxy-terminal domain of RNA polymerase II [15-18]. TFIIF has an essential role in both transcription initiation and elongation ([19,20], for review see [21]). We discuss the implications of the acetylation of TFIIEbetaand TFIIF for transcriptional control by PCAF, p300 and TAFII250.

Nuclear receptor coactivator ACTR is a novel histone acetyltransferase and forms a multimeric activation complex with P/CAF and CBP/p300

We report here the identification of a novel cofactor, ACTR, that directly binds nuclear receptors and stimulates their transcriptional activities in a hormone-dependent fashion. ACTR also recruits two other nuclear factors, CBP and P/CAF, and thus plays a central role in creating a multisubunit coactivator complex. In addition, and unexpectedly, we show that purified ACTR is a potent histone acetyltransferase and appears to define a distinct evolutionary branch to this recently described family. Thus, hormonal activation by nuclear receptors involves the mutual recruitment of at least three classes of histone acetyltransferases that may act cooperatively as an enzymatic unit to reverse the effects of histone deacetylase shown to be part of the nuclear receptor corepressor complex.