Fibroblast growth factor receptor is a portal of cellular entry for herpes simplex virus type 1

Herpes simplex virus type 1 (HSV-1) is a ubiquitous pathogen responsible for considerable morbidity in the general population. The results presented herein establish the basic fibroblast growth factor (FGF) receptor as a means of entry of HSV-1 into vertebrate cells. Inhibitors of basic FGF binding to its receptor and competitive polypeptide antagonists of basic FGF prevented HSV-1 uptake. Chinese hamster ovary (CHO) cells that do not express FGF receptors are resistant to HSV-1 entry; however, HSV-1 uptake is dramatically increased in CHO cells transfected with a complementary DNA encoding a basic FGF receptor. The distribution of this integral membrane protein in vivo may explain the tissue and cell tropism of HSV-1.     

Mapping the main immunogenic region and toxin-binding site of the nicotinic acetylcholine receptor

The alpha-chain of the nicotinic acetylcholine receptor carries the binding sites both for cholinergic ligands and for most experimentally induced or naturally occurring antibodies to the native receptor. By means of expression cloning in Escherichia coli, fusion proteins were derived from specific fragments of a complementary DNA encoding the mouse alpha-chain, allowing the mapping of the toxin-binding site to residues 160-216 and the main immunogenic region to residues 6-85. This approach permits the independent study of different functional domains of a complex receptor molecule and should be generally applicable to other proteins for which complementary DNA clones are available.     

Nucleotide sequence of a bovine clone encoding the angiogenic protein, basic fibroblast growth factor

Basic and acidic fibroblast growth factors (FGF's) are potent mitogens for capillary endothelial cells in vitro, stimulate angiogenesis in vivo, and may participate in tissue repair. An oligonucleotide probe for bovine basic FGF was designed from the nucleotide sequence of the amino-terminal exon of bovine acidic FGF, taking into account the 55 percent amino acid sequence homology between the two factors. With this oligonucleotide probe, a full length complementary DNA for basic FGF was isolated from bovine pituitary. Basic FGF in bovine hypothalamus was shown to be encoded by a single 5.0-kilobase messenger RNA; in a human hepatoma cell line, both 4.6- and 2.2-kilobase basic FGF messenger RNA's were present. Both growth factors seem to be synthesized with short amino-terminal extensions that are not found on the isolated forms for which the amino acid sequences have been determined. Neither basic nor acidic FGF has a classic signal peptide.     

After insulin binds

Three recent advances pertinent to the mechanism of insulin action include (i) the discovery that the insulin receptor is an insulin-dependent protein tyrosine kinase, functionally related to certain growth factor receptors and oncogene-encoded proteins, (ii) the molecular cloning of the insulin proreceptor complementary DNA, and (iii) evidence that the protein tyrosine kinase activity of the receptor is essential for insulin action. Efforts are now focusing on the physiological substrates for the receptor kinase. Experience to date suggests that they will be rare proteins whose phosphorylation in intact cells may be transient. The advantages of attempting to dissect the initial biochemical pathway of insulin action include the wealth of information about the metabolic consequences of insulin action and the potential for genetic analysis in Drosophila and in man.     

A cDNA for a protein that interacts with the human immunodeficiency virus Tat transactivator

The human immunodeficiency virus (HIV) tat protein (Tat) is a positive regulator of virus gene expression and replication. Biotinylated Tat was used as a probe to screen a lambda gt11 fusion protein library, and a complementary DNA encoding a protein that interacts with Tat was cloned. Expression of this protein, designated TBP-1 (for Tat binding protein-1), was observed in a variety of cell lines, with expression being highest in human cells. TBP-1 was localized predominantly in the nucleus, which is consistent with the nuclear localization of Tat. In cotransfection experiments, expression of TBP-1 was able to specifically suppress Tat-mediated transactivation. The strategy described may be useful for direct identification and cloning of genes encoding proteins that associate with other proteins to modulate their activity in a positive or negative fashion.     

A common PDGF receptor is activated by homodimeric A and B forms of PDGF

The human platelet-derived growth factor (PDGF) receptor complementary DNA was cloned and expressed by transfection of Chinese hamster ovary (CHO) fibroblasts. The ability of CHO cells expressing the human receptor complementary DNA (CHO-HR5) to interact with different recombinant forms of PDGF (AA and BB homodimers) was tested. Both forms of PDGF bind to the transfected receptor, stimulate the receptor tyrosine kinase activity, and elicit a mitogenic response in a manner that was indistinguishable from the responses of Balb/c 3T3 cells to AA and BB forms of PDGF can be attributed to a single type of receptor and show that the AA form, like the BB form, is a true mitogen.     

Molecular cloning of the zeta chain of the T cell antigen receptor

The T cell antigen receptor is a multi-subunit receptor complex present on the surface of all mature and many developing T cells. It consists of clonotypic heterodimers noncovalently linked to five invariant chains that are encoded by four genes and referred to as the CD3 complex. The CD3 gamma, delta, and epsilon chains have been molecularly characterized. In this report the molecular cloning of a complementary DNA encoding the zeta chain of the murine T cell antigen receptor is described. The predicted protein sequence of the zeta chain suggests a structure distinct from those of any of the previously described receptor subunits.     

An LRR receptor kinase involved in perception of a peptide plant hormone,phytosulfokine

The sulfated peptide phytosulfokine (PSK) is an intercellular signal that plays a key role in cellular dedifferentiation and proliferation in plants. Using ligand-based affinity chromatography, we purified a 120-kilodalton membrane protein, specifically interacting with PSK, from carrot microsomal fractions. The corresponding complementary DNA encodes a 1021-amino acid receptor kinase that contains extracellular leucine-rich repeats, a single transmembrane domain, and a cytoplasmic kinase domain. Overexpression of this receptor kinase in carrot cells caused enhanced callus growth in response to PSK and a substantial increase in the number of tritium-labeled PSK binding sites, suggesting that PSK and this receptor kinase act as a ligand-receptor pair.     

Sequence and expression of human estrogen receptor complementary DNA

The mechanism by which the estrogen receptor and other steroid hormone receptors regulate gene expression in eukaryotic cells is not well understood. In this study, a complementary DNA clone containing the entire translated portion of the messenger RNA for the estrogen receptor from MCF-7 human breast cancer cells was sequenced and then expressed in Chinese hamster ovary (CHO-K1) cells to give a functional protein. An open reading frame of 1785 nucleotides in the complementary DNA corresponded to a polypeptide of 595 amino acids and a molecular weight of 66,200, which is in good agreement with published molecular weight values of 65,000 to 70,000 for the estrogen receptor. Homogenates of transformed Chinese hamster ovary cells containing a protein that bound [3H]estradiol and sedimented as a 4S complex in salt-containing sucrose gradients and as an 8 to 9S complex in the absence of salt. Interaction of this receptor-[3H]estradiol complex with a monoclonal antibody that is specific for primate ER confirms the identity of the expressed complementary DNA as human estrogen receptor. Amino acid sequence comparisons revealed significant regional homology among the human estrogen receptor, the human glucocorticoid receptor, and the putative v-erbA oncogene product. This suggests that steroid receptor genes and the avian erythroblastosis viral oncogene are derived from a common primordial gene. The homologous region, which is rich in cysteine, lysine, and arginine, may represent the DNA-binding domain of these proteins.     

Targets for dioxin: genes for plasminogen activator inhibitor-2 and interleukin-1 beta

Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD), a widespread environmental contaminant, may elicit its effects by altering gene expression in susceptible cells. Five TCDD-responsive complementary DNA clones were isolated from a human keratinocyte cell line. One of these clones encodes plasminogen activator inhibitor-2, a factor that influences growth and differentiation by regulating proteolysis of the extracellular matrix. Another encodes the cytokine interleukin-1 beta. Thus, TCDD alters the expression of growth regulatory genes and has effects similar to those of other tumor-promoting agents that affect both inflammation and differentiation.     

A role for skin gammadelta T cells in wound repair

Gammadelta T cell receptor-bearing dendritic epidermal T cells (DETCs) found in murine skin recognize antigen expressed by damaged or stressed keratinocytes. Activated DETCs produce keratinocyte growth factors (KGFs) and chemokines, raising the possibility that DETCs play a role in tissue repair. We performed wound healing studies and found defects in keratinocyte proliferation and tissue reepithelialization in the absence of wild-type DETCs. In vitro skin organ culture studies demonstrated that adding DETCs or recombinant KGF restored normal wound healing in gammadelta DETC-deficient skin. We propose that DETCs recognize antigen expressed by injured keratinocytes and produce factors that directly affect wound repair.     

Molecular cloning of complementary DNA encoding the avian receptor for vitamin D

Vitamin D3 receptors are intracellular proteins that mediate the nuclear action of the active metabolite 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Two receptor-specific monoclonal antibodies were used to recover the complementary DNA (cDNA) of this regulatory protein from a chicken intestinal lambda gt11 cDNA expression library. The amino acid sequences that were deduced from this cDNA revealed a highly conserved cysteine-rich region that displayed homology with a domain characteristic of other steroid receptors and with the gag-erbA oncogene product of avian erythroblastosis virus. RNA selected via hybridization with this DNA sequence directed the cell-free synthesis of immunoprecipitable vitamin D3 receptor. Northern blot analysis of polyadenylated RNA with these cDNA probes revealed two vitamin D receptor messenger RNAs (mRNAs) of 2.6 and 3.2 kilobases in receptor-containing chicken tissues and a major cross-hybridizing receptor mRNA species of 4.2 kilobases in mouse 3T6 fibroblasts. The 4.2-kilobase species was substantially increased by prior exposure of 3T6 cells to 1,25(OH)2D3. This cDNA represents perhaps the rarest mRNA cloned to date in eukaryotes, as well as the first receptor sequence described for an authentic vitamin.