Gilbert Jay

Bio: Gilbert Jay is an academic researcher from American Red Cross. The author has contributed to research in topics: Antigen & Gene. The author has an hindex of 44, co-authored 102 publications receiving 9521 citations. Previous affiliations of Gilbert Jay include National Institutes of Health & Harvard University.

HBx gene of hepatitis B virus induces liver cancer in transgenic mice

Abstract: The exact role of hepatitis B virus in the development of liver cancer is not known The recent identification of a viral regulatory gene HBx suggests a possible direct involvement of the virus whereby the HBx protein, acting as a transcriptional transactivator of viral genes, may alter host gene expression and lead to the development of hepatocellular carcinoma We have tested this possibility of placing the entire HBx gene under its own regulatory elements directly into the germline of mice Transgenic animals harbouring this viral gene succumbed to progressive histopathological changes specifically in the liver, beginning with multifocal areas of altered hepatocytes, followed by the appearance of benign adenomas, and proceeding to the development of malignant carcinomas Male mice developed disease and died much earlier than females This transgenic animal model appears ideal for defining the molecular events that follow the expression of the viral HBx gene and are responsible for the development of liver cancer

Detection of a transformation-related antigen in chemically induced sarcomas and other transformed cells of the mouse.

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

The Alzheimer's A Beta Peptide Induces Neurodegeneration and Apoptotic Cell Death in Transgenic Mice

Abstract: To test whether the hypothesis that the Alzheimer's Aβ peptide is neurotoxic, we introduced a transgene into mice to direct expression of this peptide to neurons. We show that the transgene is expressed in brain regions which are severely affected in Alzheimer's disease resulting in extensive neuronal degeneration. Morphological and biochemical evidence indicates that the eventual death of these cells occurs by apoptosis. Coincident with the cell degeneration and cell death is the presence of a striking reactive gliosis. Over 50% of the transgenic mice die by 12 months of age, half the normal life span of control mice. These data show that Aβ is neurotoxic in vivo and suggest that apoptosis may be responsible for the accompanying neuronal loss, the principal underlying cellular feature of Alzheimer's disease.

The HIV tat gene induces dermal lesions resembling Kaposi's sarcoma in transgenic mice.

Abstract: When the human immunodeficiency virus transactivating gene under the control of the viral regulatory region is introduced into the germline of mice, skin lesions are induced that resemble Kaposi's sarcoma seen in AIDS. Our findings indicate that HIV could play a direct part in causing cancer.

The tat Gene of Human T-Lymphotropic Virus Type 1 Induces Mesenchymal Tumors in Transgenic Mice

Abstract: Human T-lymphotropic virus type 1 (HTLV-1) is a suspected causative agent of adult T-cell leukemia. One of the viral genes encodes a protein (tat) that not only results in transactivation of viral gene expression but may also regulate the expression of certain cellular genes that are important for cell growth. Transgenic mice that expressed the authentic tat protein under the control of the HTLV-1 long terminal repeat were generated, and cell types that are permissive for the viral promoter and the effects of the tat gene on these cells were studied. Three of eight founder mice with high levels of expression of the transgene in muscle were bred and then analyzed. All developed soft tissue tumors at multiple sites between 13 to 17 weeks of age. This phenotype was transmitted to nine of nine offspring that inherited the tat gene and were available for analysis. The remaining five founders expressed the transgene in the thymus, as well as in muscle. This second group of mice all exhibited extensive thymic depletion and growth retardation; in all of these mice, death occurred between 3 to 6 weeks of age before tumors became macroscopically visible. The tat gene under the control of the HTLV-1 regulatory region showed tissue-specific expression and the tat protein efficiently induced mesenchymal tumors. The data establish tat as an oncogenic protein and HTLV-1 as a transforming virus.

Identification of herpesvirus-like DNA sequences in AIDS-associated Kaposi's sarcoma

Abstract: Representational difference analysis was used to isolate unique sequences present in more than 90 percent of Kaposi's sarcoma (KS) tissues obtained from patients with acquired immunodeficiency syndrome (AIDS). These sequences were not present in tissue DNA from non-AIDS patients, but were present in 15 percent of non-KS tissue DNA samples from AIDS patients. The sequences are homologous to, but distinct from, capsid and tegument protein genes of the Gammaherpesvirinae, herpesvirus saimiri and Epstein-Barr virus. These KS-associated herpesvirus-like (KSHV) sequences appear to define a new human herpesvirus.

Mice deficient for p53 are developmentally normal but susceptible to spontaneous tumours

Abstract: Mutations in the p53 tumour-suppressor gene are the most frequently observed genetic lesions in human cancers. To investigate the role of the p53 gene in mammalian development and tumorigenesis, a null mutation was introduced into the gene by homologous recombination in murine embryonic stem cells. Mice homozygous for the null allele appear normal but are prone to the spontaneous development of a variety of neoplasms by 6 months of age. These observations indicate that a normal p53 gene is dispensable for embryonic development, that its absence predisposes the animal to neoplastic disease, and that an oncogenic mutant form of p53 is not obligatory for the genesis of many types of tumours.

Normal keratinization in a spontaneously immortalized aneuploid human keratinocyte cell line.

Abstract: In contrast to mouse epidermal cells, human skin keratinocytes are rather resistant to transformation in vitro. Immortalization has been achieved by SV40 but has resulted in cell lines with altered differentiation. We have established a spontaneously transformed human epithelial cell line from adult skin, which maintains full epidermal differentiation capacity. This HaCaT cell line is obviously immortal (greater than 140 passages), has a transformed phenotype in vitro (clonogenic on plastic and in agar) but remains nontumorigenic. Despite the altered and unlimited growth potential, HaCaT cells, similar to normal keratinocytes, reform an orderly structured and differentiated epidermal tissue when transplanted onto nude mice. Differentiation-specific keratins (Nos. 1 and 10) and other markers (involucrin and filaggrin) are expressed and regularly located. Thus, HaCaT is the first permanent epithelial cell line from adult human skin that exhibits normal differentiation and provides a promising tool for studying regulation of keratinization in human cells. On karyotyping this line is aneuploid (initially hypodiploid) with unique stable marker chromosomes indicating monoclonal origin. The identity of the HaCaT line with the tissue of origin was proven by DNA fingerprinting using hypervariable minisatellite probes. This is the first demonstration that the DNA fingerprint pattern is unaffected by long-term cultivation, transformation, and multiple chromosomal alterations, thereby offering a unique possibility for unequivocal identification of human cell lines. The characteristics of the HaCaT cell line clearly document that spontaneous transformation of human adult keratinocytes can occur in vitro and is associated with sequential chromosomal alterations, though not obligatorily linked to major defects in differentiation.

Mutations in the p53 Tumor Suppressor Gene: Clues to Cancer Etiology and Molecular Pathogenesis

Abstract: The p53 tumor suppressor gene has come to the forefront of cancer research because it is commonly mutated in human cancer and the spectrum of p53 mutations in these cancers is providing clues to the etiology and molecular pathogenesis of neoplasia (1—3). Detection of p53 abnormalities may have diagnostic, prognostic, and therapeutic implications (4). The 15-year history of p53 investigations is a paradigm in cancer research, illustrating the convergence of previously parallel lines of basic, clinical, and epidemiological investigation and the rapid trans fer of research findings from the laboratory to the clinic. p53 is clearly a component in biochemical pathways central to human carcinogen esis; p53 protein alterations due to missense mutations and loss of p53 protein by nonsense or frameshift mutations provide a selective ad vantage for clonal expansion of preneoplastic and neoplastic cells (5). The potential for a missense mutation to cause loss of tumor suppres sor function and gain of oncogenic activity, i.e., to transform cells by two mechanisms, is one explanation for the commonality of p53 mutations in human cancer. Recent studies investigating the mecha nisms underlying the biological activity of p53 indicate that the protein is involved in gene transcription, DNA synthesis and repair, genomic plasticity, and programmed cell death (1—6).These complex biochemical processes are performed by multicomponent protein ma chines; therefore, it is not surprising that the p53 protein forms complexes with other cellular proteins (Fig. 1) and that some viral oncoproteins alter the functions of these machines by binding to p53 and perturbing its interaction with other cellular protein components. In this Perspective, we will focus on the origin of p.53 mutations, the mutational spectrum of p.53 in human cancers, and the hypotheses generated by the analysis of p53 mutations in premalignant and malignant cells. The interpretation ofp53 mutations in human cancers is based on observations of the patterns of DNA damage induced by chemical and physical mutagens in model systems. In this Introduc tion, we will review these data, which provide the background for many of the inferences drawn from p53 mutational analysis.