Dissociation of mitogenesis and transforming activity by C-terminal truncation of the insulin-like growth factor-I receptor.

We have investigated the mitogenic and transforming ability of an IGF-I receptor with a 108-amino-acid C-terminal truncation in R- cells, which are 3T3-like cells derived from mouse embryos in which the IGF-I receptor genes have been disrupted by targeted homologous recombination. R- cells stably transfected with expression plasmids encoding either a wild-type or a truncated human IGF-I receptor were capable of growing in serum-free medium supplemented solely with IGF-I. This response was observed over a wide range of receptor levels.

Transforming potential of the insulin receptor substrate 1.

The role of the insulin receptor substrate 1 (IRS-1) in cellular transformation was studied in R- cells, which are 3T3-like fibroblasts derived from mouse embryos with a targeted disruption of the insulin-like growth factor I receptor gene. These cells cannot be transformed by oncogenes that readily transform cells originating from wild-type littermate embryos (or other 3T3-like cells). In the present study, we demonstrate that in R- cells, the overexpression of the functional IRS-1 protein was sufficient to induce a mitogenic response to insulin but did not promote transformation, as measured by colony formation in soft agar.

Mutagenesis of the putative alpha-helical domain of the Vpr protein of human immunodeficiency virus type 1: effect on stability and virion incorporation.

vpr is one of the auxiliary genes of human immunodeficiency virus type 1 (HIV-1) and is conserved in the related HIV-2/simian immunodeficiency virus lentiviruses. The unique feature of Vpr is that it is the only nonstructural protein incorporated into the virus particle. Secondary structural analysis predicted an amphipathic alpha-helical domain in the amino terminus of Vpr (residues 17-34) which contains five acidic and four leucine residues.

Detection of myc translocations in lymphoma cells by fluorescence in situ hybridization with yeast artificial chromosomes.

Translocations involving chromosome 8 at band q24 and one of the Ig loci on chromosomes 14q32, 22q11, and 2p11 are the hallmark of Burkitt's lymphoma (BL). It has been previously observed that the exact localization of the breakpoints at chromosome 8q24 can vary significantly from patient to patient, scattering over a distance of more than 300 kb upstream of c-myc and about 300 kb downstream of c-myc. To generate probes for fluorescence in situ hybridization (FISH) that detect most c-myc translocations, we screened a yeast artificial chromosome (YAC) library from normal human lymphocytes by colony hybridization, using three markers surrounding the c-myc gene as probes.

CCAAT-box contributions to human thymidine kinase mRNA expression.

In order to examine the role of two inverted CCAAT boxes near the start of transcription of the human thymidine kinase (TK) gene, a series of constructs were prepared in which one or both CCAAT boxes were deleted or mutated. These altered promoters (1.2 kb of 5'-flanking sequence) were used to express a TK minigene containing the first two exons and introns followed by the remainder of the cDNA.

Sequestration of a G-protein beta gamma subunit or ADP-ribosylation of Rho can inhibit thrombin-induced activation of platelet phosphoinositide 3-kinases.

Stimulation of platelets by thrombin leads to an increased association of activated phosphoinositide 3-kinase (PI 3-K) with a membrane cytoskeletal fraction (CSK). Activation of PI 3-K is dependent upon GTP-binding protein(s), since PI 3-K in permeabilized platelets is stimulated by GTP gamma S (guanosine 5'-3-O-(thio)triphosphate), and stimulation of platelet cytosolic PI 3-K by GTP gamma S requires a functional small G-protein, Rho. Recent reports indicate that cytosolic PI 3-Ks can also be activated by the beta gamma subunits of heterotrimeric G-proteins (G beta gamma).

Hypervariable yellow (Ahvy), a new murine agouti mutation: Ahvy displays the largest variation in coat color phenotypes of all known agouti alleles.

A new coat color mutation, which occurred spontaneously in the C3H/HeJ strain, has been identified. The original C3H/HeJ male mouse carrying the mutation was unusual because its coat color appeared mostly yellow, in contrast to the wild-type agouti coat normally exhibited by mice of the C3H/HeJ strain. Genetic crosses showed that the mutant phenotype was inherited as a single autosomal dominant gene.

Ligand binding to Fc gamma R induces c-myc-dependent apoptosis in IL-2-stimulated NK cells.

The role of signals transduced via Fc gamma RIIIA in the modulation of the proliferative potential of NK cells has been investigated. Fc gamma R stimulation does not induce NK cell proliferation, and inhibits that induced by IL-2, but not by IL-12, as measured by [3H]TdR incorporation, without affecting entrance or progression through cell cycle. The inhibitory effect depends, at least in part, on induced apoptosis of the cells, detected by both light and electron microscopy examination.

In situ DNA PCR and RNA hybridization detection of herpes simplex virus sequences in trigeminal ganglia of latently infected mice.

The presence of herpes simplex virus (HSV-1) DNA in the trigeminal ganglia of latently infected mice was detected by an in situ DNA polymerase chain reaction (PCR), which includes a DNA:DNA hybridization step (indirect in situ PCR). These results were compared to the number of neurons possessing the HSV-1 latency associated transcript (LAT), as detected by in situ RNA hybridization with LAT probes. Sensitivity assays were shown to detect a single copy cellular gene in 48% of neuronal cell bodies.

Cyclins, cyclin-dependent kinases and cdk inhibitors: implications in cell cycle control and cancer.

A significant portion of cell scientific literature published is dedicated to describing the cloning, the link to cancer, or the characterization of proteins involved in the progression of the cell cycle. With this abundance of information, the cascading pathways of molecular events that occur in the cell cycle are proving to be exceedingly complicated. Originally, the sole regulator of the fission yeast cells division cycle, cdc2, was thought to also regulate mammalian cell cycles in the same manner.

Phospholipase C gamma-2 (Plcg2) and phospholipase C gamma-1 (Plcg1) map to distinct regions in the human and mouse genomes.

The phospholipase C gamma-2 (Plcg2) gene encodes an enzyme that plays a crucial role in intracellular signal transduction pathways. This enzyme is important because of its role in the generation of second messengers following the hydrolysis of phosphatidylinositol 4,5-bisphosphate. We have now determined the chromosomal location of this gene in the mouse and human genomes.

Mitogenicity and transforming activity of the insulin-like growth factor-I receptor with mutations in the tyrosine kinase domain.

We have investigated the effect of mutations in tyrosines 1131, 1135, and 1136 of the human insulin-like growth factor-I receptor (IGF-IR) on the growth and transformation of mammalian cells. We have used for this purpose R- cells, which are 3T3-like fibroblasts derived from mouse embryos with a targeted disruption of the IGF-IR genes. These cells have no IGF-IR, do not grow in serum-free medium supplemented with the growth factors that sustain the growth of 3T3 cells, and cannot be transformed by simian virus 40 large tumor antigen or other oncogenes.

Identification of the TCL1 gene involved in T-cell malignancies.

The TCL1 locus on chromosome 14q32.1 is frequently involved in chromosomal translocations and inversions with one of the T-cell receptor loci in human T-cell leukemias and lymphomas. The chromosome 14 region translocated or rearranged involves approximately 350 kb of DNA at chromosome band 14q32.

DNA binding and transactivation activity of A-myb, a c-myb-related gene.

A partial-length A-myb complementary DNA recently cloned by low-stringency hybridization with a c-myb probe to complementary DNA libraries derived from human cell lines showed a high degree of homology with the DNA-binding domain of c-myb and B-myb, suggesting that A-myb also encoded a DNA-binding protein. We report here the sequence of the entire coding region of A-myb complementary DNA and show that the full-length GST-A-myb fusion protein or a truncated derivative corresponding only to the putative DNA-binding domain interacts specifically with Myb-binding sites of the c-myb responsive promoters, MIM-1 and CD34. In transient transfection assays, A-myb transactivated the bound promoters.

Characterization and localization of the TCL-1 oncogene product.

The TCL-1 gene maps at chromosome 14q32.1 and is activated in T cell leukemias and lymphomas by either chromosome translocations or inversions that juxtapose the TCL-1 gene to the alpha/delta or the beta locus of the T cell receptor. The open reading frame of the TCL-1 gene, coding for a protein of 114 amino acids, was expressed in bacteria and antisera were raised against it.

FKBP46, a novel Sf9 insect cell nuclear immunophilin that forms a protein-kinase complex.

Recently, we identified a 59-kDa nuclear phosphoprotein that is associated with a recombinant mouse FKBP-52 (Alnemri, E. S., Fernandes-Alnemri, T.

TLS/FUS fusion domain of TLS/FUS-erg chimeric protein resulting from the t(16;21) chromosomal translocation in human myeloid leukemia functions as a transcriptional activation domain.

EWS and TLS/FUS genes, which code for RNA binding proteins are involved in a wide variety of human solid tumors. The TLS/FUS gene is involved both in human myxoid liposarcomas which carry a characteristic chromosomal translocation, t(12;16)(q13;p11) and in human myeloid leukemias with recurrent chromosomal translocation, t(16;21)(p11:q22). The TLS/FUS gene is fused to a transcriptional repressor, CHOP (in human myxoid liposarcomas) or transcriptional activator, erg (in human myeloid leukemias).

Identification and characterization of a novel GGA/C-binding protein, GBP-i, that is rapidly inducible by cytokines.

Immunosuppressive states with accompanying alterations in cytokine profiles have been postulated to play a vital role in the reactivation of viruses from latency. Cytokines regulate gene expression by activating transcription factors via well-characterized signal transduction pathways. In this study, we report the identification of a novel inducible protein, GBP-i, that binds to a double-stranded GGA/C-rich region of the transcriptional control region of the human papovavirus JC virus (JCV), specifically within the origin of viral DNA replication.

Analysis of a herpes simplex virus type 1 LAT mutant with a deletion between the putative promoter and the 5' end of the 2.0-kilobase transcript.

A herpes simplex virus type 1 strain 17 mutant with a deletion between genomic nucleotides 118880 and 119250 was constructed and called 17 delta Sty. The deletion removes most of a putative secondary LAT promoter (called LAPII) as well as 370 of the first 449 nucleotides of the proposed 8.5-kb transcript believed to be the precursor of 2.

Loss of heterozygosity at 11q22-q23 in breast cancer.

Studies of loss of heterozygosity (LOH) in breast tumor DNA suggest that several tumor suppressor genes participate in the pathogenesis of breast cancer. Although the short arm of chromosome 11 has been implicated in breast cancer development, no previous LOH studies have indicated the involvement of a suppressor gene on 11q in breast carcinoma. To this end, tumor samples and corresponding normal tissue were collected from 62 unselected patients with primary breast cancer, and the extracted DNA was analyzed by polymerase chain reaction using microsatellite markers on chromosome 11.

The agouti gene: turned on to yellow.

The agouti locus was first identified as a result of its effects on the type and temporal deposition of coat color pigments in mammals. Many mutations at the murine agouti locus have now been found, some of which not only affect coat color, but also interfere with diverse biological processes leading to diabetes, obesity, tumor susceptibility and embryonic lethality. Correlations between the genotype and phenotype of agouti mutants, as well as reasons for the pleiotropy of effects caused by agouti mutations, have begun to unfold with the molecular cloning of the agouti gene and its surrounding genomic region.