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Upregulation of interleukin-17 receptor B (IL-17RB) is known to be oncogenic, while other IL-17 receptors and ligands are generally involved in pro-inflammatory pathways. We identify a mouse neutralizing monoclonal antibody (mAb) D9, which blocks the IL-17RB/IL-17B pathway and inhibits pancreatic tumorigenesis in an orthotopic mouse model. The X-ray crystal structure of the IL-17RB ectodomain in complex with its neutralizing antibody D9 shows that D9 binds to a predicted ligand binding interface and engages with the A'-A loop of IL-17RB fibronectin III domain 1 in a unique conformational state. This structure also provides important paratope information to guide the design of antibody humanization and affinity maturation of D9, resulting in a humanized 1B12 antibody with marginal affinity loss and effective neutralization of IL-17B/IL-17RB signaling to impede tumorigenesis in a mouse xenograft model.

Faced with the rise of environmental awareness and carbon reduction trends, green hotels have become an important business direction for the hospitality industry. Because of the special service properties of green hotels, past the hotel service quality scale is not sufficient to measure the service quality performance of green hotel. This problem resulted in a serious gap for measuring the service quality of green hotel. The purpose of this study is to construct a Green Lodging Service Quality scale (GLSERV scale). This study used systematic and scientific procedures to develop the dimensions and items of the GLSERV scale. The GLSERV scale included six dimensions: reliability, empathy, environmental communication, green energy saving, assurance, and tangible, which contained a total of 25 items. This study provides a new insight for measuring the service quality of green hotels.

KRAS mutations are the earliest events found in approximately 90% of pancreatic ductal adenocarcinomas (PDACs). However, little is known as to why KRAS mutations preferentially occur in PDACs and what processes/factors generate these mutations. While abnormal carbohydrate metabolism is associated with a high risk of pancreatic cancer, it remains elusive whether a direct relationship between KRAS mutations and sugar metabolism exists. Here, we show that under high-glucose conditions, cellular O-GlcNAcylation is significantly elevated in pancreatic cells that exhibit lower phosphofructokinase (PFK) activity than other cell types. This post-translational modification specifically compromises the ribonucleotide reductase (RNR) activity, leading to deficiency in dNTP pools, genomic DNA alterations with KRAS mutations, and cellular transformation. These results establish a mechanistic link between a perturbed sugar metabolism and genomic instability that induces de novo oncogenic KRAS mutations preferentially in pancreatic cells.

NPGPx is a member of the glutathione peroxidase (GPx) family; however, it lacks GPx enzymatic activity due to the absence of a critical selenocysteine residue, rendering its function an enigma. We report that NPGPx is a novel stress sensor that transmits oxidative stress signals by transferring the disulfide bond between its Cys57 and Cys86 residues to downstream effectors. Oxidized NPGPx binds and oxidizes the chaperone glucose-regulated protein (GRP)78 in the endoplasmic reticulum through covalent bonding between Cys86 of NPGPx and Cys41/Cys420 of GRP78, and facilitates the refolding of misfolded proteins by GRP78 to alleviate stress. NPGPx-deficient cells display impaired GRP78 chaperone activity, accumulate misfolded proteins, and suffer oxidative stress. Complete loss of NPGPx in animals causes systemic oxidative stress, increases carcinogenesis, and shortens lifespan. These results, for the first time, suggest that NPGPx is essential for mediating the oxidative stress response by modulating GRP78 chaperone activity to maintain physiological homeostasis.

The group package tour is one of the main modes of outbound travel in many parts of Asia. Tour leaders are part of the product and are therefore key front-line players in the tourism industry as they service guests during a journey. A tour leader’s style of leadership transforms a tourist visit from a tour into an experience and is a critical factor affecting a tourist’s satisfaction with their tour. This study identifies the various different styles of tour leadership using in-depth interviews to collect data. Three dimensions of leadership style in tour leaders were found: concern for tasks, concern for customers, and concern for controlling the group climate. The authors discuss the implications of their findings and make recommendations for travel agencies.

The high mobility group AT-hook 2 (HMGA2), a DNA architectural protein, is highly regulated during development and plays an important role in tumorigenesis. Indeed, HMGA2 was overexpressed in many different kinds of tumors. However, the mechanisms regulating HMGA2 expression remain elusive. Using microarray analysis, we found that HMGA2, along with a dozen of other genes, was co-repressed by ZBRK1, BRCA1, and CtIP. BRCA1 exerts its transcriptional repression activity through interaction with the transcriptional repressor ZBRK1 in the central domain, and with CtIP in the C-terminal BRCT domain. Here, we show that ZBRK1, BRCA1, and CtIP form a repression complex that coordinately regulates HMGA2 expression via a ZBRK1 recognition site in the HMGA2 promoter. Depletion of any of the proteins in this complex via adenoviral RNA interference in MCF10A mammary epithelial cells activates HMGA2 expression, resulting in increased colony formation in soft agar. Similarly, depletion of ZBRK1, or ectopic overexpression of HMGA2, in MCF10A cells induces abnormal acinar size with increased cell number and inhibits normal acinar formation. Consistently, many BRCA1-deficient mouse breast tumors express higher levels of HMGA2 than BRCA1-proficient tumors. These results suggest that activation of HMGA2 gene expression through derepression of the ZBRK1/BRCA1/CtIP complex is a significant step in accelerating breast tumorigenesis.

Efficient turnover of unnecessary and misfolded RNAs is critical for maintaining the integrity and function of the mitochondria. The mitochondrial RNA degradosome of budding yeast (mtEXO) has been recently studied and characterized; yet no RNA degradation machinery has been identified in the mammalian mitochondria. In this communication, we demonstrated that purified human SUV3 (suppressor of Var1 3) dimer and polynucleotide phosphorylase (PNPase) trimer form a 330-kDa heteropentamer that is capable of efficiently degrading double-stranded RNA (dsRNA) substrates in the presence of ATP, a task the individual components cannot perform separately. The configuration of this complex is similar to that of the core complex of the E. coli RNA degradosome lacking RNase E but very different from that of the yeast mtEXO. The hSUV3-hPNPase complex prefers substrates containing a 3′ overhang and degrades the RNA in a 3′-to-5′ directionality. Deleting a short stretch of amino acids (positions 510–514) compromises the ability of hSUV3 to form a stable complex with hPNPase to degrade dsRNA substrates but does not affect its helicase activity. Furthermore, two additional hSUV3 mutants with abolished helicase activity because of disrupted ATPase or RNA binding activities were able to bind hPNPase. However, the resulting complexes failed to degrade dsRNA, suggesting that an intact helicase activity is essential for the complex to serve as an effective RNA degradosome. Taken together, these results strongly suggest that the complex of hSUV3-hPNPase is an integral entity for efficient degradation of structured RNA and may be the long sought RNA-degrading complex in the mammalian mitochondria.

Studies of breast cancer stem cells are in their infancy and many fundamental questions have yet to be fully addressed. The molecular distinction between normal and cancerous breast stem cells is not clear. While there have been recent breakthroughs in mouse mammary stem cells and lineage determination in mammary glands, little has been determined in human cells. Microarray analyses have provided molecular categorization of breast cancer. However, the cellular origin of different types of breast cancer is largely unknown. In addition, the relationship between breast cancer stem cells and mammary progenitor cells has yet to be clarified. One of the key questions is how a normal mammary stem cell becomes a breast cancer stem cell. Importantly, the existence of different types of human breast cancers with distinct pathologic and molecular signatures suggests the possibility that different types of breast cancer stem cells may exist. Here, we aim to review the current evidence for the existence of different subtypes of breast cancer stem cells and provide further insight into how tumor suppressors might be involved in the initiation of breast cancer stem cells.

In yeast mitochondria, RNA degradation takes place through the coordinated activities of ySuv3 helicase and yDss1 exoribonuclease (mtEXO), whereas in bacteria, RNA is degraded via RNaseE, RhlB, PNPase, and enolase. Yeast lacking the Suv3 component of the mtEXO form petits and undergo a toxic accumulation of omega intron RNAs. Mammalian mitochondria resemble their prokaryotic origins by harboring a polyadenylation-dependent RNA degradation mechanism, but whether SUV3 participates in regulating RNA turnover in mammalian mitochondria is unclear. We found that lack of hSUV3 in mammalian cells subsequently yielded an accumulation of shortened polyadenylated mtRNA species and impaired mitochondrial protein synthesis. This suggests that SUV3 may serve in part as a component of an RNA degradosome, resembling its yeast ancestor. Reduction in the expression levels of oxidative phosphorylation components correlated with an increase in reactive oxygen species generation, whereas membrane potential and ATP production were decreased. These cumulative defects led to pleiotropic effects in mitochondria such as decreased mtDNA copy number and a shift in mitochondrial morphology from tubular to granular, which eventually manifests in cellular senescence or cell death. Thus, our results suggest that SUV3 is essential for maintaining proper mitochondrial function, likely through a conserved role in mitochondrial RNA regulation.

Human DHRS6 is a previously uncharacterized member of the short chain dehydrogenases/reductase family and displays significant homologies to bacterial hydroxybutyrate dehydrogenases. Substrate screening reveals sole NAD(+)-dependent conversion of (R)-hydroxybutyrate to acetoacetate with K(m) values of about 10 mm, consistent with plasma levels of circulating ketone bodies in situations of starvation or ketoacidosis. The structure of human DHRS6 was determined at a resolution of 1.8 A in complex with NAD(H) and reveals a tetrameric organization with a short chain dehydrogenases/reductase-typical folding pattern. A highly conserved triad of Arg residues ("triple R" motif consisting of Arg(144), Arg(188), and Arg(205)) was found to bind a sulfate molecule at the active site. Docking analysis of R-beta-hydroxybutyrate into the active site reveals an experimentally consistent model of substrate carboxylate binding and catalytically competent orientation. GFP reporter gene analysis reveals a cytosolic localization upon transfection into mammalian cells. These data establish DHRS6 as a novel, cytosolic type 2 (R)-hydroxybutyrate dehydrogenase, distinct from its well characterized mitochondrial type 1 counterpart. The properties determined for DHRS6 suggest a possible physiological role in cytosolic ketone body utilization, either as a secondary system for energy supply in starvation or to generate precursors for lipid and sterol synthesis.

The aryl hydrocarbon receptor nuclear translocator/hypoxia-inducible factor (ARNT/HIF-1 beta) mediates an organism's response to various environmental cues, including those to chemical carcinogens, such as 2,3,7,8-tetrachlorodibenzo-rho-dioxin (TCDD or dioxin), via its formation of a functional transcription factor with the ligand activated aryl hydrocarbon receptor (AHR). Similarly, tissue responses to hypoxia are largely mediated through the HIF-1 heterodimeric transcription factor, comprising hypoxia-inducible factor-1 alpha (HIF-1 alpha) and ARNT. The latter response is essential for a metabolic switch from oxidative phosphorylation to glycolytic anaerobic metabolism as well as for angiogenesis and has been implicated as necessary for growth in many solid tumors. In this report, we demonstrate that the thyroid hormone receptor/retinoblastoma-interacting protein 230 (TRIP230) interacts directly with ARNT and is essential for both hypoxic and TCDD-mediated transcriptional responses. We initially identified TRIP230 as an ARNT-interacting protein in a yeast two-hybrid assay screen. This interaction was confirmed in mammalian cell systems using co-immunoprecipitation and in mammalian two-hybrid assays. Furthermore, TRIP230 could be recorded at sites of activated transcription of either TCDD- or hypoxia-inducible genes in a stimulus-dependent fashion by chromatin immunoprecipitation analysis. Finally, using single-cell microinjection and RNA interference assays, we demonstrate that TRIP230 is indispensable for TCDD- and hypoxia-dependent gene transcription.

Breast carcinoma is the leading cause of cancer incidence, and second in cancer mortality to lung cancer, in women of the Western hemisphere. Germ line mutations in the breast cancer susceptibility gene, BRCA1, is responsible for half of all cases of hereditary breast cancer, which constitutes about 5-10% of all cases of breast cancer. Current hypothesis has ascribed a role for Brca1 in maintaining genomic stability, through its involvement in cellular response pathway to the DNA double-strand breaks (DSB). DNA DSB, which are the most deleterious form of DNA damage, are repaired through a series of coordinated steps embedded in a signal transduction pathway that ultimately ensure the elimination of potentially harmful mutations to the genome. This pathway can be crudely divided into a primary and secondary phase. The primary response phase is initiated by sensor proteins that activate transducer protein kinases Atm and Atr, which target downstream effector proteins, such as Chk1 and Chk2, to elicit the secondary response phase. Brca1 has been intimately linked with various aspects of this signaling pathway. However, the precise role of Brca1 in this process remains unclear. In this review, we will provide a simple model in an attempt to clarify the role of Brca1 during cellular response to DNA DSB.

The breast- and ovarian-specific tumor suppressor BRCA1 has been implicated in both activation and repression of gene transcription by virtue of its direct interaction with sequence-specific DNA-binding transcription factors. However, the mechanistic basis by which BRCA1 mediates the transcriptional activity of these regulatory proteins remains largely unknown. To clarify this issue, we have examined the functional interaction between BRCA1 and ZBRK1, a BRCA1-dependent KRAB eight zinc finger transcriptional repressor. We report here the identification and molecular characterization of a portable BRCA1-dependent transcriptional repression domain within ZBRK1 composed of zinc fingers 5-8 along with sequences in the unique ZBRK1 C terminus. This C-terminal repression domain functions in a BRCA1-, histone deacetylase-, and promoter-specific manner and is thus functionally distinguishable from the N-terminal KRAB repression domain in ZBRK1, which exhibits no BRCA1 dependence and broad promoter specificity. Significantly, we also find that the BRCA1-dependent transcriptional repression domain on ZBRK1 includes elements that modulate its sequence-specific DNA binding activity. These findings thus reveal the presence within ZBRK1 of functionally bipartite zinc fingers with dual roles in sequence-specific DNA-binding and BRCA1-dependent transcriptional repression. We discuss the implications of these findings for the role of BRCA1 as ZBRK1 co-repressor.

Hec1 (highly expressed in cancer) plays essential roles in chromosome segregation by interacting through its coiled-coil domains with several proteins that modulate the G(2)/M phase. Hec1 localizes to kinetochores, and its inactivation either by genetic deletion or antibody neutralization leads to severe and lethal chromosomal segregation errors, indicating that Hec1 plays a critical role in chromosome segregation. The mechanisms by which Hec1 is regulated, however, are not known. Here we show that human Hec1 is a serine phosphoprotein and that it binds specifically to the mitotic regulatory kinase Nek2 during G(2)/M. Nek2 phosphorylates Hec1 on serine residue 165, both in vitro and in vivo. Yeast cells are viable without scNek2/Kin3, a close structural homolog of Nek2 that binds to both human and yeast Hec1. When the same yeasts carry an scNek2/Kin3 (D55G) or Nek2 (E38G) mutation to mimic a similar temperature-sensitive nima mutation in Aspergillus, their growth is arrested at the nonpermissive temperature, because the scNek2/Kin3 (D55G) mutant binds to Hec1 but fails to phosphorylate it. Whereas wild-type human Hec1 rescues lethality resulting from deletion of Hec1 in Saccharomyces cerevesiae, a human Hec1 mutant or yeast Hec1 mutant changing Ser(165) to Ala or yeast Hec1 mutant changing Ser(201) to Ala does not. Mutations changing the same Ser residues to Glu, to mimic the negative charge created by phosphorylation, partially rescue lethality but result in a high incidence of errors in chromosomal segregation. These results suggest that cell cycle-regulated serine phosphorylation of Hec1 by Nek2 is essential for faithful chromosome segregation.

Genome instability has been implicated in the generation of multiple somatic mutations that underlie cancer. Germline mutation in the retinoblastoma (RB) gene leads to tumor formation in both human and experimental animal models, and reintroduction of wild-type RB is able to suppress neoplastic phenotypes. Rb governs the passage of cells through the G1 phase-restriction point and this control is lost in most cancer cells. Rb has also been shown to promote terminal differentiation and prevent cell cycle reentry. Recent studies implicate Rb in mitotic progression, faithful chromosome segregation, checkpoint control, and chromatin remodeling, suggesting that Rb may function in the maintenance of genome integrity. It is likely that Rb suppresses tumor formation by virtue of its multiple biological activities. A single protein capable of performing multiple antioncogenic functions may be a common characteristic of other tumor suppressors including p53 and BRCA1/2.

Nijmegen breakage syndrome, a chromosomal instability disorder, is characterized in part by cellular hypersensitivity to ionizing radiation. The NBS1 gene product, p95 (NBS1 or nibrin) forms a complex with Rad50 and Mre11. Cells deficient in the formation of this complex are defective in DNA double-strand break repair, cell cycle checkpoint control, and telomere length maintenance. How the NBS1 complex is involved in telomere length maintenance remains unclear. Here we show that the C-terminal region of NBS1 interacts directly with a telomere repeat binding factor, TRF1, by both yeast two-hybrid and in vivo DNA-coimmunoprecipitation assays. NBS1 and Mre11 colocalize with TRF1 at promyelocytic leukemia (PML) nuclear bodies in immortalized telomerase-negative cell lines, but rarely in telomerase-positive cell lines. The translocation of NBS1 to PML bodies occurs specifically during late S to G(2) phases of the cell cycle and coincides with active DNA synthesis in these NBS1-containing PML bodies. These results suggest that NBS1 may be involved in alternative lengthening of telomeres in telomerase-negative immortalized cells.

The BRCA1 gene product is a nuclear phosphoprotein that is aberrantly localized in the cytoplasm of most breast cancer cells. In an attempt to elucidate the potential mechanism for the nuclear transport of BRCA1 protein, three regions of highly charged, basic residues, 503KRKRRP508, 606PKKNRLRRKS615, and 651KKKKYN656, were identified as potential nuclear localization signals (NLSs). These three regions were subsequently mutated to 503KLP508, 607KLS615, and 651KLN656, respectively. Wild-type and mutated proteins were tagged with the flag epitope, expressed in human DU145 cells, and detected with the M2 monoclonal antibody. In DU145 cells, the KLP mutant completely fails to localize in nuclei, whereas the KLS mutant is mostly cytoplasmic with occasional nuclear localization. The KLN protein is always located in nuclei. Consistently, hSRP1alpha (importin-alpha), a component of the NLS receptor complex, was identified in a yeast two-hybrid screen using BRCA1 as the bait. The specificity of the interaction between BRCA1 and importin-alpha was further demonstrated by showing that the 503KRKRRP508 and 606PKKNRLRRKS615 regions, but not 651KKKKYN656, are critical for this interaction. To determine if the cytoplasmic mislocation of endogenous BRCA1 in breast cancer cells is due to a deficiency of the cells, wild-type BRCA1 protein tagged with the flag epitope was ectopically expressed in six breast cancer cell lines. The analysis demonstrated that, in all six, this protein localized in the cytoplasm of these cells. In contrast, expression of the construct in four non-breast cancer cell lines resulted in nuclear localization. These data support the possibility that the mislocation of the BRCA1 protein in breast cancer cells may be due to a defect in the cellular machinery involved in the NLS receptor-mediated pathway of nuclear import.

With sequence homology to the SV40 T antigen-binding domain of the retinoblastoma protein (Rb), p107 and p130 constitute two additional members of the Rb family. To explore the potential function of p130 in mouse development, we cloned the full-length mouse cDNA for p130 and characterized p130 mRNA expression in mice. The deduced mouse p130 protein sequence shares a higher degree of similarity with mouse p107 than with mouse Rb. In adult mice, p130 mRNA is found in all tissues examined. Levels of p130 mRNA vary among different adult tissues, with the highest level in testis. Within testis, p130 mRNA is found predominantly in Leydig cells. Additionally, p130 expression in testis correlates with sexual maturation, suggesting p130 is important for the development of testis and, in particular, Leydig cells. In situ hybridization shows that in post coitus day 12.5 and 14.5 mouse embryos, distribution of p130 mRNA is quite uniform with the exception of a few tissues. Little differences in mRNA levels of either p130 or p107 were found between normal and Rb-deficient embryos, suggesting that p130 and p107 are expressed independently of Rb. Our data are consistent with the hypothesis that p130 and p107 do not compensate for the loss of Rb and support the view that p130 is related to, yet distinct from, the RB gene.

The retinoblastoma protein, Rb, is detected in extracts of monkey CV-1 cells complexed with Pur alpha, a sequence-specific single-stranded DNA-binding protein implicated in control of gene transcription and DNA replication. These complexes can be immunoextracted from cell lysates using monoclonal antibodies to either Pur alpha or Rb. The Pur alpha-Rb complexes contain a form of Pur alpha with extensive post-synthetic modification, as demonstrated following expression of Pur alpha cDNA fused to a 9-amino acid epitope tag. Human Pur alpha, expressed as a glutathione S-transferase fusion protein, specifically binds to the hypophosphorylated form of Rb with an affinity as high as that of SV40 large T-antigen. In the absence of DNA, glutathione S-transferase-Pur alpha binds to p56RB, an NH2-terminal-truncated Rb protein purified from Escherichia coli, containing the T-antigen binding domain, to form multimeric complexes. The single-stranded DNA Pur alpha recognition element disrupts these complexes. Conversely, high concentrations of p56RB prevent Pur alpha binding to DNA. Through use of a series of deletion mutants, the DNA binding activity of Pur alpha is localized to a series of modular amino acid repeats. Rb binding involves a Pur alpha region with limited homology to the Rb-binding region of SV40 large T-antigen. Binding of Pur alpha to p56RB, the COOH-terminal portion of Rb, is inhibited by a synthetic peptide containing the T-antigen Rb-binding motif.

To characterize the protein product of the retinoblastoma tumor suppressor gene biochemically, a recombinant human protein was produced in an Escherichia coli expression system. The full-length protein, p110RB, and an amino-terminal truncated form, p56RB, were expressed and purified to near homogeneity by conventional chromatographic procedures. To probe the structural organization of the retinoblastoma protein the purified proteins were subjected to partial proteolysis by trypsin, chymotrypsin, and subtilisin. Four discrete structural domains were revealed in p110RB by this method. Two of these structural domains, found in both p56RB and p110RB, were mapped to the carboxyl-terminal half of the protein and corresponded to the SV40 large T binding domains defined previously by genetic methods. In addition two distinct domains in the amino-terminal half of the protein were also defined. A potential role for these newly defined amino-terminal domains was uncovered upon analysis of the purified proteins by nondenaturing polyacrylamide gel electrophoresis. p110RB revealed multiple bands by this method, suggesting the formation of oligomeric structures by the protein, while this property was not observed for p56RB. Electron microscopy of p110RB revealed linearly extended, macromolecular structures, further supporting the formation of homologous higher order structures by the full-length retinoblastoma protein. Analysis of the interactions between retinoblastoma protein molecules using the yeast two-hybrid system confirmed that the retinoblastoma protein could self-associate and that this association was mediated by interactions between the amino- and carboxyl-terminal ends of the protein. These observations suggest that the retinoblastoma protein contains multiple structural domains with the amino-terminal domains being required for oligomerization of the full-length protein.

Rapid progress in several areas of molecular biology has led to the realization that the retinoblastoma protein may play a pivotal role in the coordination between cell cycle control and regulation of gene expression. This role is a subtle one, and is important in only certain mammalian cell types. Exploring the details of these connections, and why only some cells rely on them, is already beginning to shed light on the regulation of cell multiplication.

Deregulation of the cell cycle may contribute one of the primary mechanisms through which cancer arises. Eukaryotic cell division has been found to be a strictly controlled process, involving response to both positive and negative external signals and assessment of the cell's internal state. Several recent discoveries have strengthened and refined the theory that the retinoblastoma protein is involved in the decision between cell division and differentiation, and have begun to provide an outline of the nature of this involvement.

The RB gene product is a nuclear phosphoprotein that undergoes cell cycle-dependent changes in its phosphorylation status. To test whether RB regulates cell cycle progression, purified RB proteins, either full-length or a truncated form containing the T antigen-binding region, were injected into cells. Injection of either protein early in G1 inhibits progression into S phase. Co-injection of anti-RB antibodies antagonizes this effect. Injection of RB into cells arrested at G1/S or late in G1 has no effect on BrdU incorporation, suggesting that RB does not inhibit DNA synthesis in S phase. These results indicate that RB regulates cell proliferation by restricting cell cycle progression at a specific point in G1 and establish a biological assay for RB activity. Neither co-injection of RB with a T antigen peptide nor injection into cells expressing T antigen prevents cells from progressing into S phase, which supports the hypothesis that T antigen binding has functional consequences for RB.

Extracts of monkey cells (CV-1P) synthesizing SV40 large T antigen (T) were immunoprecipitated with monoclonal antibodies to T or p110-114Rb, the product of the retinoblastoma susceptibility gene (Rb). While a family of p110-114Rb proteins can be detected in anti-Rb immunoprecipitates, only one member of this family, p110Rb, was found in anti-T precipitates of these extracts. Identical results were obtained with extracts of CV-1P cells which had been previously mixed in vitro with highly purified T. The p110-114Rb family is composed of two sets--p110Rb, an un- or under-phosphorylated species, and pp112-114Rb, a group of overtly phosphorylated proteins. Thus, T bound preferentially to the un- or underphosphorylated member of the family. In addition, T failed to alter the relative abundances of these species. These results suggest a model in which the growth suppression function of Rb is down modulated either by phosphorylation or T antigen binding.

Abnormal or absent expression of the human retinoblastoma susceptibility (RB) gene has been implicated in the genesis of retinoblastoma. In addition to a 90% chance of developing retinoblastoma, patients inheriting a mutant RB gene have a high incidence of second nonocular malignancies, suggesting a role for this gene in other tumors as well. This report describes a patient without a previous history of retinoblastoma who developed metastatic synovial sarcoma. Analysis of RNA from this tumor revealed the presence of an abnormally long RB gene transcript in addition to an RB transcript of normal length. On the basis of findings in retinoblastoma, we propose that alteration of RB gene expression was significantly related to the formation of this patient's synovial sarcoma.