SV40 transformation of Swiss 3T3 cells can cause a stable reduction in the calcium requirement for growth.

A well-characterized SV40-transformed Swiss 3T3 line, SV101, and its revertants were tested for the ability to grow in reduced Ca++ (0.01 mM). Transformants and revertants did not differ from the parent 3T3 line in their Ca++ requirements. All three classes of cells grew less well in low Ca++ than in regular Ca++ (2.0 mM). SV40 transformants were then selected for the ability to grow in reduced Ca++. This new class of transformants was found to grow in 1% serum, grow in soft agarose, have a reorganized actin cytoskeleton, and express viral T antigens, as well as grow well in low Ca++. One of the selected clones was found to be T antigen-negative, yet was transformed in the serum, anchorage, actin, and Ca++ assays. It is possible that this clone was a spontaneous transformant. However, Southern blot analysis revealed the presence of integrated SV40 DNA. In addition, this analysis revealed the absence of an intact early region fragment, which codes for the viral T antigens. One explanation of this result may be that the mechanism of viral transformation for growth in low Ca++ involves viral-host DNA interactions that may not require a fully functional T antigen. In this case SV40 integration may be acting as a nonspecific cellular mutagen.

A new cluster of genes within the human major histocompatibility complex.

A 435-kilobase (kb) DNA segment, which is centromeric to HLA-B in the human major histocompatibility complex, was isolated by chromosome walking with overlapping cosmids. Within the cloned region, the genes for the tumor necrosis factors (TNFs) alpha and beta and HLA-B were 210 kb apart. The human homolog of a mouse gene, B144, was located next to TNF alpha. Moreover, the presence of additional genes was suggested by a large cluster of CpG islands. With cosmid probes, several distinct transcripts were detected in RNA samples from a variety of cell lines. Altogether, five novel genes were identified by isolation of corresponding complementary DNA clones. These "HLA-B-associated transcripts" (BATs) were mapped to different locations within a 160-kb region that includes the genes for TNF alpha and TNF beta. The presence of the genes for BAT1 and BAT5 in the vicinity of HLA-B again raises the question of which gene in this region determines susceptibility to ankylosing spondylitis.

Human respiratory syncytial virus reduces the number of cells in S-phase and increases GADD153 expression in HEp-2 cells.

Human respiratory syncytial virus (HRSV) associated with bronchiolitis and asthma is known to replicate actively in ciliated epithelial cells. However, little is known about the influence of HRSV replication on the cell cycle. We found that HRSV infection of HEp-2 cells led to a reduction of the number of cells in S-phase, to an increase in the number of cells in G1-phase, together with an increase of GADD153 mRNA levels and GADD153 protein expression. These results implied that a shorter S-phase supported HRSV replication suggesting possible strategies for interfering with productive HRSV infection.

DNase I sensitivity of integrated simian virus 40 DNA.

We undertook an analysis of integrated simian virus 40 (SV40) DNA to learn whether the DNase I-sensitive region is retained in the integrated array of mouse transformants. Our results indicate that full-length integrated SV40 chromatin retains a DNase I-hypersensitive region at the same point as in nonintegrated SV40 chromatin. Thus, the lack of a DNase I-hypersensitive region is not likely to be the reason for nonpermissivity of SV40 in mouse cells. In addition, results reported here indicate that a deletion of about 200 base pairs of DNA in the region of the DNase I-hypersensitive site severely reduces the sensitivity of integrated SV40 chromatin. This result is similar to a previously reported result obtained with deletion mutants of SV40 analyzed in the lytic cycle. It is the first report of a DNA lesion affecting DNase I hypersensitivity of a mammalian chromosome.

Reacquisition of a functional early region by a mouse transformant containing only defective simian virus 40 DNA.

Viral DNA in simian virus 40-transformed mouse cells is capable of rearranging with passage. In this report, we show that such rearrangement can include an alteration in viral protein expression. SVT2, a simian virus 40-transformed mouse BALB/c 3T3 cell line, synthesizes only a super T antigen of molecular weight 100,000 without synthesizing the lytic-size large T or small t antigens with molecular weights of 94,000 and 17,000, respectively. Analyses of the integrated viral DNA revealed an early region of 4.4 kilobases instead of the lytic-size 2.7 kilobases. However, upon subcloning in either plastic or agarose or after being in culture for several passages, the appearance of lytic-size large T and small t antigens was detected. Concurrently, an early region of 2.7 kilobases, in addition to one of 4.4 kilobases, was observed.

Two integrated partial repeats of simian virus 40 together code for a super-T antigen.

We determined that the coding sequence for a 100-kilodalton super-T antigen found in Simian virus 40 mouse transformants spanned two separate partial repeats of the viral genome. The downstream repeat contained a complete Simian virus 40 large-T-antigen gene, whereas the upstream repeat was a truncated copy of the same gene. When the repeats were separated by subcloning, the capacity to code for the super-T antigen was lost. A small insertion or deletion in the origin-control region which preceded the second repeat could also destroy the ability to code for the 100-kilodalton protein. Our data suggest that differential splicing between parts of two gene copies was responsible for the additional molecular weight of this super-T antigen.

Histone deacetylase activity represses gamma interferon-inducible HLA-DR gene expression following the establishment of a DNase I-hypersensitive chromatin conformation.

Expression of the retinoblastoma tumor suppressor protein (Rb) is required for gamma interferon (IFN-gamma)-inducible major histocompatibility complex class II gene expression and transcriptionally productive HLA-DRA promoter occupancy in several human tumor cell lines. Treatment of these Rb-defective tumor cell lines with histone deacetylase (HDAC) inhibitors rescued IFN-gamma-inducible HLA-DRA and -DRB mRNA and cell surface protein expression, demonstrating repression of these genes by endogenous cellular HDAC activity. Additionally, Rb-defective, transcriptionally incompetent tumor cells retained the HLA-DRA promoter DNase I-hypersensitive site. Thus, HDAC-mediated repression of the HLA-DRA promoter occurs following the establishment of an apparent nucleosome-free promoter region and before transcriptionally productive occupancy of the promoter by the required transactivators. Repression of HLA-DRA promoter activation by HDAC activity likely involves a YY1 binding element located in the first exon of the HLA-DRA gene. Chromatin immunoprecipitation experiments localized YY1 to the HLA-DRA gene in Rb-defective tumor cells. Additionally, mutation of the YY1 binding site prevented repression of the promoter by HDAC1 and partially prevented activation of the promoter by trichostatin A. Mutation of the octamer element also significantly reduced the ability of HDAC1 to confer repression of inducible HLA-DRA promoter activation. Treatment of Rb-defective tumor cells with HDAC inhibitors greatly reduced the DNA binding activity of Oct-1, a repressor of inducible HLA-DRA promoter activation. These findings represent the first evidence that HDAC activity can repress IFN-gamma-inducible HLA class II gene expression and also demonstrate that HDAC activity can contribute to promoter repression following the establishment of a DNase I-hypersensitive chromatin conformation.

Impaired class II transactivator expression in mice lacking interferon regulatory factor-2.

Class II transactivator (CIITA) is required for both constitutive and inducible expression of MHC class II genes. IFN-gamma induced expression of CIITA in various cell types is directed by CIITA type IV promoter. The two transactivators, STAT1 and IRF-1, mediate the IFN-gamma activation of the type IV promoter by binding to the GAS and IRF-E of the promoter, respectively. In addition to IRF-1, IRF-2, another member of the IRF family, also activates the human CIITA type IV promoter, and IRF-2 cooperates with IRF-1 to activate the promoter in transient transfection assays. IRF-1 and IRF-2 can co-occupy the IRF-E of the human CIITA type IV promoter. To understand the effect of loss of IRF-2 on the endogenous CIITA expression, we assayed for CIITA expression in IRF-2 knock-out mice. Both basal and IFN-gamma induced CIITA expression were reduced in IRF-2 knock-out mice. At least half of the amount of inducible CIITA mRNA depends on IRF-2. The reduction of IFN-gamma induced CIITA mRNA in IRF-2 knock-out mice was due to the reduction of the type IV CIITA mRNA induction. The reduction of basal CIITA mRNA was apparently due to the reduction of CIITA mRNA originating from other promoters. These data indicate that IRF-2, like IRF-1, plays a critical role in the regulation of the endogenous CIITA gene. The implications in understanding the previously described phenotypes of IRF-2 defective mice are discussed.

Evidence for retinoblastoma protein (RB) dependent and independent IFN-gamma responses: RB coordinately rescues IFN-gamma induction of MHC class II gene transcription in noninducible breast carcinoma cells.

The class II major histocompatibility (MHC) genes encode cell surface heterodimers that present processed antigen to CD4 positive T-cells. The class II genes are expressed constitutively on B-cells and can be induced by IFN-gamma on a variety of other cell types. Because the class II genes are aberrantly expressed on many mesenchymal tumors, which are frequently defective for the retinoblastoma tumor suppressor protein (RB), we investigated the role of RB in the regulation of HLA-DR and -DP. The RB defective breast carcinomas cell line, MDA-468-S4 (S4), as well as S4 subclones reconstituted with RB coding sequences under the control of a zinc inducible promoter, were treated with IFN-gamma and examined for DR and DP expression. Surface DR is not inducible in S4 cells, but inducibility is rescued by RB. DP is only slightly inducible in S4, but inducible to a much higher level in the RB positive subclones of S4. IFN-gamma induction of DR and DP mRNAs are correspondingly dependent on RB. IFN-gamma receptors are present on S4 cells, and the guanylate binding protein and ICAM-1 genes respond to IFN-gamma, ruling out the possibility that all IFN-gamma signal transduction pathways are defective in S4 cells. These data indicate RB regulates the coordinate response of class II genes to IFN-gamma. Possible roles for RB in this process are discussed, as well as the role of the class II-noninducible phenotype in tumor rejection.

Co-occupancy of the interferon regulatory element of the class II transactivator (CIITA) type IV promoter by interferon regulatory factors 1 and 2.

Class II transactivator (CIITA) activates the expression of major histocompatibility class II genes, which encode antigen-presenting molecules recognized by the T-cell receptor of CD4+ T cells. IFN-gamma induced CIITA transcription in many cell types is directed by the CIITA Type IV promoter. Here we report that the human CIITA Type IV promoter IRF-E binds IRF-1 and can be activated by exogenous expression of IRF-1. Surprisingly, the CIITA Type IV promoter IRF-E is also activated by IRF-2, another member of the IRF family that generally acts as a transcriptional repressor. In addition, we found that IRF-1 and IRF-2 synergistically activate the CIITA Type IV promoter. Electrophoretic mobility shift assays revealed that IRF-1 and IRF-2 can simultaneously occupy the IRF-E of the CIITA Type IV promoter, suggesting a novel mechanism for the role of these two proteins in promoter activation. Our results also indicate that IRF-1 and IRF-2 can cooperatively activate and co-occupy the IRF-E of the guanylate binding protein (GBP) promoter. Finally, CIITA induction by IFN-gamma does not occur in a pancreatic tumor cell line that expresses a mutated IRF-2, representing the first IRF-2 mutation identified in a human tumor cell line.

Retinoblastoma protein inhibits IFN-gamma induced apoptosis.

Regulation of apoptosis (programmed cell death) is critical for maintaining tissue homeostasis. Recent studies indicate a tight coupling between cellular proliferation and apoptosis as cell cycle regulators such as Cyclin D, E1A and E7 appear to influence both events. Each of these modulators is able to bind to and inhibit the function of the retinoblastoma tumor suppressor protein (RB). RB functions, in part, by binding to and inactivating E2F transcription factors, preventing expression of E2F-activated genes associated with G1/S cell-cycle progression. Loss of functional RB deregulates E2F activity and, depending on cell type and environmental factors, promotes tumorigenesis or apoptotic death. To determine the effect of RB on IFN-gamma induced apoptosis, we treated RB-defective carcinoma cell lines and their respective RB-constituted sister clones with IFN-gamma and examined the cells for alterations characteristic of apoptosis. We observed that RB-defective cells, but not the RB-reconstituted clones, decreased in size following IFN-gamma treatment. IFN-gamma treatment caused increased cell detachment in the RB-defective lines but did not affect adherence of the RB-reconstituted clones. Assays for DNA fragmentation revealed lower molecular weight DNA and the apoptosis-associated oligo-nucleosomal ladder following IFN-gamma treatment of the RB-defective cells while higher molecular weight DNA was present in the IFN-gamma treated, RB-reconstituted lines. IFN gamma-induced apoptosis in RB-defective cells was enhanced by serum stimulation, which is also characteristic of p53-dependent E2F-1-mediated apoptosis. However, IFN-gamma induced apoptosis in RB-defective lines does not require wild-type p53 suggesting that, upon IFN-gamma induction, deregulated E2F-mediated apoptosis can also proceed via p53-independent pathways.

Interferon regulatory factor 1 tryptophan 11 to arginine point mutation abolishes DNA binding.

Interferon regulatory factor-1 (IRF-1) is a transcriptional activator of genes induced by a variety of cytokines and growth factors. Defects in IRF-1 occur frequently in human cancers and may contribute to tumorigenesis. The IRF family of transcription factors share invariant tryptophan residues that have been proposed to function by orienting the DNA contacting residues of IRF-1 with the DNA core sequence of the IRF element. Here we describe a point mutation in IRF-1 that converts the tryptophan at codon 11 to arginine (W11R). The IRF-1 (W11R) mutation abolishes IRF-1 DNA binding and transactivating activities demonstrating the critical role of this invariant tryptophan in IRF-1 function.

Retinoblastoma protein regulation of surface CD74 (invariant chain) expression in breast carcinoma cells.

The HLA class II genes encode heterodimeric cell surface proteins which bind peptide antigen recognized by T-cell receptors on CD4+ T-cells. The class II proteins are inducible by IFN-gamma, and this induction requires, or is strongly enhanced, by retinoblastoma protein (RB) in a series of breast carcinoma cell lines. Loading of peptide onto the class II protein appears to be regulated by CD74, which associates with class II during their transition to the endosomal compartment, where class II binds peptide. Class II proteins and CD74 are largely regulated in concert, provoking the question, is CD74 induction by IFN-gamma affected by RB? Results described here indicate that IFN-gamma induction of CD74 surface expression in a series of breast carcinoma lines is enhanced by RB, while RB has no effect on CD74 mRNA induction. Also, neither the class II nor the CD74 promoter regions are activated by RB in cotransfection experiments where RB activates the SV40 promoter.

Vitamin D3 reduces the apoptotic effect of IFN-gamma but does not facilitate HLA class II inducibility in RB-defective cells.

The retinoblastoma protein (RB) regulates the cell cycle by binding and inactivating the E2F transcription factors, which prevents transcription of genes required for DNA synthesis. RB has been shown to inhibit IFN-gamma-mediated apoptosis, possibly by regulating premature entry into S phase. RB is also required for high level IFN-gamma induction of HLA class II genes, which encode antigen presenting molecules, but not for other IFN-gamma inducible genes as demonstrated in previous reports describing the analysis of RB-transformants of the RB-defective cell lines, MDA-468-S4 (S4) and H2009. The IFN-gamma response of the HLA class II genes takes much longer than does the response of the other IFN-gamma inducible genes, raising the question of whether RB facilitates HLA class II inducibility by maintaining cell viability over the long time course required for HLA class II induction. Thus, we sought to learn whether IFN-gamma induced apoptosis in an RB-defective cell line could be prevented independently of RB and whether doing so would facilitate HLA class II inducibility in the RB-defective line. Our results indicated that cotreating the RB-defective S4 cells with IFN-gamma and Vitamin D3 decreased the number of cells containing subdiploid DNA compared to cells treated with IFN-gamma alone, suggesting that Vitamin D3 reduced IFN-gamma-mediated apoptosis. S4 cells cotreated with Vitamin D3 and IFN-gamma also had decreased cell detachment, further indicating that Vitamin D3 decreased IFN-gamma induced apoptosis. However, Vitamin D3 cotreatment resulted in no detectable increase in HLA-DR, the most prominent HLA class II molecule, indicating that the effect of RB on HLA class II induction is not exclusively due to its ability to inhibit IFN-gamma induced apoptosis.

Loss of MHC class II inducibility in hyperplastic tissue in Rb-defective mice.

Retinoblastoma gene (Rb) defects occur frequently in human tumors. Studies of Rb-defective human tumor cell lines and Rb-/- murine embryonic fibroblasts demonstrate that Rb is required for interferon-gamma (IFN-gamma) induced major histocompatibility complex (MHC) class II expression. MHC class II expressing tumors generate anti-tumor immune responses associated with tumor-specific infiltrating lymphocytes. The role of Rb in IFN-gamma induced MHC class II expression on an endogenous tumor was examined by immunohistochemical staining for IAbeta and Rb on tissues from Rb+/- mice. MHC class II IAbeta is not induced by IFN-gamma in Rb-deficient neoplastic cells, but remains inducible in related normal tissue.

The contribution of ego psychology to understanding the process of termination in psychoanalysis and psychotherapy.

Ego psychology is presented as an integrated psychoanalytic developmental theory, including a theory of object relations. The process of termination is employed as one of the many possible illustrations of the usefulness of this theory. Termination is regarded as a process that pervades the treatment from the outset, rather than as the final phase of treatment only, because the treatment process, whether psychoanalysis or psychotherapy, includes continuous promotion of ever-increasing autonomy. Ideally, by the time termination proper takes place, maximum autonomy has been attained. To the definition of autonomy as intersystemic, involving relative independence of the ego from the drives (and from the super-ego), an object-relations dimension is added which extends that definition to include an intrasystemic consideration--namely, relative independence of the self-representation from the object representations. Especially in the treatment of the borderline conditions is the intrasystemic factor cogent because borderline states are characterized by varying degrees of incompletely differentiated self- and object representations. The objective, in the psychoanalysis of neurosis, where self- and object constancy already exist to a large degree, is ego autonomy in the intersystemic sense. In the psychotherapy of the borderline conditions, the objective is greater differentiation of the self-representation from the object representations.

The complete oedipus complex.

The 'Complete Oedipus Complex' is shown to be a critical period in Spitz' sense of convergence of drive maturation with ego development. It is proposed that competence to venture into the heart of the oedipal conflict is acquired in the practising subphase of the separation-individuation process where traits such as venture-someness, courage, initiative and the like become part of the self representations. Also proposed is that tension between drive need and object relations need at the anal phase results in compromise that establishes a pattern for taming the drive because of object relations considerations. The so-called negative oedipal position is seen as a regression to a pre-oedipal level of object need that is tinged with sexual wishes carried back from the oedipal position. Finally, the waning of the Oedipus complex is regarded as another developmental thrust terminating in identification with and love for the parent of the same sex, with transfer of functions of the object representations to the self representations, which results in diminution of primary object need and frees the individual to make new libidinal connexions at adult levels of object need.