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D Nathans

Publications and source records attributed to D Nathans.

At least 37 records · Page 2Linked to original sources
PubMed1989

jun-D: a third member of the jun gene family.

The protooncogene c-jun encodes a component of the transcription factor AP-1. Both murine c-jun and a related gene (jun-B) are rapidly activated in BALB/c3T3 cells by serum growth factors. We report here the cloning and analysis of a cDNA encoding a third member of the murine jun family, jun-D. The amino acid sequence encoded by jun-D has two extensive regions of homology with the other Jun proteins. One homology region includes the DNA-binding domain and sequences required for dimer formation and interaction with the Fos oncoprotein; the other includes the acidic sequence thought to be involved in gene activation. All three jun mRNAs are present in a variety of murine tissues and cell lines. In resting 3T3 cells, jun-D is expressed at a higher level compared to c-jun and jun-B, and its transcription is stimulated only slightly by serum growth factors. Thus, jun-D appears to be regulated differently than c-jun and jun-B.

Amino Acid Sequence↗
PubMed1989

Functional serum response elements upstream of the growth factor-inducible gene zif268.

The zif268 gene, which encodes a protein with three typical zinc finger sequences, is induced in mouse 3T3 cells by serum, phorbol 12-myristate 13-acetate platelet-derived growth factor, and fibroblast growth factor. The induction is coordinate with that of c-fos. The 5'-flanking region of zif268 contains sequences that resemble known regulatory elements, including four CC(A or T)6GG sequences similar to the core serum response elements (SREs) found upstream of c-fos and actin genes. To determine whether the zif268 SRE-like elements mediate induction, CAT (chloramphenicol acetyltransferase) plasmids with different lengths of zif268 upstream sequences were tested for inducibility in 3T3 cells by serum, platelet-derived growth factor, or phorbol 12-myristate 13-acetate. In addition, double-stranded oligonucleotides corresponding to each of the four zif268 putative SREs were tested individually for responsiveness when placed upstream of a thymidine kinase gene promoter. Each of the four SREs conferred inducibility by the agents tested, and multiple SREs resulted in greater inducibility than did a single element. Each of the zif268 SREs also competed with the c-fos SRE for binding by serum response factor present in HeLa cell nuclear extract. We conclude that the zif268 SRE-like sequences are functional and probably account for the coordinate induction of zif268 and c-fos.

Animals↗
PubMed1989

An endothelial cell growth factor from the mouse neuroblastoma cell line NB41.

A growth factor that stimulates the proliferation of endothelial cells from human umbilical vein but is not mitogenic for fibroblastic cells is present in medium conditioned by the mouse neuroblastoma cell line NB41. In a partially purified preparation, factor activity coeluted from a reverse-phase high-pressure liquid chromatography (HPLC) column with a reduced protein of about 24 kd. Activity recovered following electrophoresis of HPLC fractions corresponded to protein of 43-51 kd in the absence of reducing agent and to protein of 23-29 kd after reduction. Antiserum raised against a peptide corresponding to the putative N-terminal amino acid sequence of the 24-kd protein reacted with the 24-kd protein and with a protein of about 47 kd in the nonreduced preparation. After N-glycanase treatment, the immunoreactive 24-kd protein had a mobility corresponding to 19 kd. We infer that the native NB41 factor is a glycosylated dimer whose biochemical and biological properties distinguish if from other endothelial cell growth factors.

Animals↗
PubMed1988

DNA binding activities of three murine Jun proteins: stimulation by Fos.

Three members of the Jun/AP-1 family have been identified in mouse cDNA libraries: c-Jun, Jun-B, and Jun-D. We have compared the DNA binding properties of the Jun proteins by using in vitro translation products in gel retardation assays. Each protein was able to bind to the consensus AP-1 site (TGACTCA) and, with lower affinity, to related sequences, including the cyclic AMP response element TGACGTCA. The relative binding to the oligonucleotides tested was similar for the different proteins. The Jun proteins formed homodimers and heterodimers with other members of the family, and they were bound to the AP-1 site as dimers. When Fos translation product was present, DNA binding by Jun increased markedly, and the DNA complex contained Fos. The C-terminal homology region of Jun was sufficient for DNA binding, dimer formation, and interaction with Fos. Our general conclusion is that c-Jun, Jun-B, and Jun-D are similar in their DNA binding properties and in their interaction with Fos. If there are functional differences between them, they are likely to involve other activities of the Jun proteins.

Animals↗
PubMed1988

Proliferin secreted by cultured cells binds to mannose 6-phosphate receptors.

Proliferin is a prolactin-related glycoprotein secreted by proliferating mouse cell lines and by mouse placenta. In an attempt to identify target sites for proliferin action, we looked for proliferin receptors in murine fetal and maternal tissues during pregnancy using proliferin purified from the conditioned medium of a constructed Chinese hamster ovary cell line carrying amplified copies of proliferin cDNA. Purified proliferin bound to membrane preparations from fetal or maternal liver and from placenta with a Kd of 1 to 2 nM. The amount of proliferin bound per microgram of membrane protein varied markedly during pregnancy; maximal binding to day 16 fetal liver membranes was approximately 25 times that to liver membranes from adult animals. Binding to fetal and maternal receptors was specifically and completely inhibited by mannose 6-phosphate, with half-maximal inhibition at 10 microM. Furthermore, non-glycosylated proliferin did not inhibit the binding of the glycosylated protein. A approximately 300 Kd proliferin receptor was purified from the liver of pregnant mice using a proliferin affinity column and elution with mannose 6-phosphate. This receptor reacted with antibodies directed against the rat cation-independent mannose 6-phosphate receptor. We conclude that 1) proliferin secreted by cultured cell binds to cation-independent mannose 6-phosphate receptors and therefore may be a lysosomal protein or targeted to lysosomes, and 2) the concentration or activity of mannose 6-phosphate receptors in murine fetal and maternal liver and in placenta is regulated during pregnancy.

Animals↗
PubMed1988

A gene activated in mouse 3T3 cells by serum growth factors encodes a protein with "zinc finger" sequences.

We have recently identified by cDNA cloning a set of genes that are rapidly activated in mouse 3T3 cells by serum or purified growth factors. Here we report that the cDNA (clone 268) derived from one of these immediate early genes (zif/268) encodes a protein with three tandem "zinc finger" sequences typical of a class of eukaryotic transcription factors. The mRNA of zif/268 is present in many organs and tissues of the mouse and is especially abundant in the brain and thymus tissue. The 5' genomic flanking sequence of zif/268 has sequences related to binding sites for known regulatory proteins, including four sequences that resemble the core of the serum response elements (SREs) upstream of the c-fos and actin genes. The SRE-like sequences could be responsible for the coordinate activation of zif/268 and fos after serum stimulation of 3T3 cells.

Amino Acid Sequence↗
PubMed1988

A gene inducible by serum growth factors encodes a member of the steroid and thyroid hormone receptor superfamily.

We previously identified, by cDNA cloning, a set of genes that are expressed during the G0/G1 transition (cell cycle reentry) in mouse fibroblasts. These immediate early genes are transcriptionally activated within minutes of addition of serum or purified growth factors, and their mRNAs are superinduced in the presence of protein-synthesis inhibitors. We report here that one of these genes, represented by nur/77 cDNA (originally called 3CH77), encodes a member of the superfamily of ligand-binding transcription factors that includes the steroid and thyroid hormone receptors. The nur/77 cDNA sequence encodes a protein of 601 amino acids containing two regions of sequence similarity to members of this nuclear receptor superfamily, corresponding to their DNA-binding and ligand-binding domains. These results suggest that the growth factor-inducible immediate early gene nur/77 encodes a ligand-binding protein that regulates the genomic response to growth factors.

Amino Acid Sequence↗
PubMed1988

Induction of protooncogene c-jun by serum growth factors.

We have previously reported that one of the genes that is rapidly induced in mouse 3T3 cells by serum growth factors (jun-B) encodes a protein related to the onco-protein v-jun. By using jun-B as a probe, we have isolated a cDNA encoding a second member of the jun family (jun-A) that is the murine version of the protooncogene c-jun, which encodes the mammalian transcription factor AP-1. jun-B and jun-A (c-jun) have two highly conserved regions and two regions with little sequence similarity. Like jun-B, jun-A (c-jun) is rapidly activated by serum, platelet-derived growth factor, or fibroblast growth factor and is superinduced by serum in the presence of an inhibitor of protein synthesis. Both jun proteins are likely to play a role in regulating the genetic program induced by growth factors.

Amino Acid Sequence↗
PubMed1988

A gene activated by growth factors is related to the oncogene v-jun.

We have recently identified by cDNA cloning a set of genes that are rapidly activated in cultured mouse cells by protein growth factors. Here we report that the nucleotide sequence of a cDNA (clone 465) derived from one of these immediate early genes (hereafter called jun-B) encodes a protein homologous to that encoded by the avian sarcoma virus 17 oncogene v-jun. Homology between the jun-B and v-jun proteins is in two regions: one near the N terminus and the other at the C terminus. The latter sequence was shown by Vogt et al. [Vogt, P. K., Bos, T. J. & Doolittle, R. F. (1987) Proc. Natl. Acad. Sci. USA 84, 3316-3319] to have regions of sequence similarity to the DNA-binding domain of the yeast transcriptional regulatory protein GCN4 and to the oncogenic protein fos. Southern blots of human, mouse, and chicken DNA demonstrate that jun-B and c-jun are different genes and that there may be other vertebrate genes related to jun-B and c-jun. These findings suggest that there is a jun family of genes encoding related transcriptional regulatory proteins. The jun-B protein, and perhaps other members of the jun family, may play a role in regulating the genomic response to growth factors.

Amino Acid Sequence↗
PubMed1988

Trophoblastic giant cells of the mouse placenta as the site of proliferin synthesis.

Proliferin (PLF) is a PRL-related glycoprotein secreted by a number of mouse cell lines and by minced mouse placenta. To further investigate the hormone-like characteristics of PLF, we have determined the site of PLF synthesis and storage in the placenta and its concentration in blood serum during pregnancy. By immunohistochemical staining and in situ hybridization PLF protein and messenger RNA (mRNA) were localized to the trophoblastic giant cells. Individual cells contained both PLF and placental lactogen II. Trophoblastic giant cells appear to secrete PLF into the circulation since PLF was found at levels up to 5 micrograms/ml in the serum of pregnant mice by RIA and at somewhat lower concentrations in the amniotic fluid. Moreover, the serum concentration of PLF during pregnancy varied directly with the level of PLF mRNA in the placenta and with the number of placentas per animal. These findings are consistent with the hypothesis that PLF is a placental hormone; its function is not known.

Animals↗
PubMed1987

Expression of a set of growth-related immediate early genes in BALB/c 3T3 cells: coordinate regulation with c-fos or c-myc.

We have previously identified by cDNA cloning 5 mRNAs that appear in resting BALB/c 3T3 cells soon after growth stimulation by serum or platelet-derived growth factor. Five additional mRNAs of this class are described in this report. The mRNAs reached peak levels between 40 and 120 min after serum addition and rapidly decayed thereafter. All 10 RNAs were superinduced in the presence of cycloheximide. Nuclear run-on experiments indicated that the increase in the mRNAs is the result of rapid transcriptional activation of their genes on stimulation by serum or platelet-derived growth factor. Superinducibility by cycloheximide is due to two effects: prolonged transcription and stabilization of mRNAs. This overall pattern of regulation is similar to that of the c-fos or c-myc protooncogenes reported previously. We hypothesize that these newly identified "immediate early" genes play a role in the proliferative response induced by growth factors.

Animals↗
PubMed1987

trans-dominant defective mutants of simian virus 40 T antigen.

We constructed a collection of linker insertion mutants in the simian virus 40 (SV40) genome and studied several of these with changes limited to a part of the large T antigen gene corresponding to an amino acid sequence shared with other ATPases. Two of these mutants were found to have a novel phenotype in that they could not be complemented for plaque formation by a late-region deletion mutant. These two mutants, in contrast to other mutants in this region, were able to transform rat cells in culture at a frequency close to that of the wild-type gene. The noncomplementing mutants were found to be potent inhibitors of SV40 DNA replication despite the presence of wild-type T antigen in the transfected cells. This inhibition was shown to be the result of the introduced mutations in the large T antigen gene. We conclude that the large T antigens of the noncomplementing mutants can act as inhibitors of SV40 DNA replication.

Amino Acid Sequence↗
PubMed1987

Secretion of proliferin.

Proliferin (PLF) is a member of the PRL-GH family whose mRNA has been detected in proliferating mouse cells in culture and in mouse placenta. Suspensions of murine placental tissue have been shown to produce PLF detectable by immunoprecipitation. Here we report that PLF is secreted as a heterogeneous glycoprotein by growing mouse cell lines and placental tissue and that the first 29 amino acids of the preprotein serve as a signal peptide. Placental PLF is immunologically distinguishable from the 2 previously described mouse placental lactogens.

Amino Acid Sequence↗
PubMed1985

Translational regulation of mammalian ornithine decarboxylase by polyamines.

Ornithine decarboxylase, which catalyses the formation of putrescine, is the first and rate-limiting enzyme in the biosynthesis of polyamines in mammalian cells. The enzyme is highly regulated, as indicated by rapid changes in its mRNA and protein during cell growth. Here we report that ornithine decarboxylase is regulated at the translational level by polyamines in difluoromethylornithine-resistant mouse myeloma cells that overproduce the enzyme due to amplification of an ornithine decarboxylase gene. When such cells are exposed to putrescine or other polyamines, there is a rapid and specific decrease in the rate of synthesis of ornithine decarboxylase, assayed by pulse-labeling. Neither the cellular content of ornithine decarboxylase mRNA nor the half-life of ornithine decarboxylase protein is affected. Our results indicate that polyamines negatively regulate the translation of ornithine decarboxylase mRNA, thereby controlling their own synthesis.

Animals↗
PubMed1985

Identification of a set of genes expressed during the G0/G1 transition of cultured mouse cells.

To identify previously undetected genes that may be involved in the transition from a resting state (G0) to a proliferative state (G1) of mammalian cells, we set out to isolate cDNA clones derived from mRNAs that appear in serum-stimulated cells in the absence of protein synthesis. A lambda cDNA library was prepared using poly(A)+ RNA from BALB/c 3T3 cells that had been brought to quiescence and subsequently stimulated with serum in the presence of cycloheximide. Approximately 50 000 recombinant phage plaques were screened, and 357 clones were isolated that hybridized to probes derived from stimulated-cell RNA but not to probes from resting-cell RNA. Cross hybridization analysis showed that four RNA sequence families account for approximately 90% of these clones. One of the clones hybridized to an actin probe; none hybridized to any of 13 oncogene probes tested. Five different RNAs that appear to be previously uncharacterized have been further analyzed. These RNAs accumulate and decay rapidly following stimulation by serum or purified growth factors, or by a tumor promoter, and they are superinduced by serum in the presence of cycloheximide. Three of the RNAs could be enriched by hybridization to cDNAs and translated in vitro, yielding proteins of approximately 43, 40 and 35 kd, respectively.

Animals↗
PubMed1985

A new member of the prolactin-growth hormone gene family expressed in mouse placenta.

Mouse placenta has been found to contain an mRNA that encodes a previously unidentified member of the prolactin-growth hormone family. This 1.1-kb mRNA (designated PRP mRNA) was detected as a cDNA clone that hydridized to a cDNA clone of mouse proliferin, a recently described growth-associated placental protein related to prolactin. PRP mRNA levels are highest in the fetal part of the placenta and peak at day 12 of gestation, decreasing gradually until term. The 972-bp sequence of PRP mRNA, determined from two cDNA clones, encodes a protein of 244 amino acid residues that has a hydrophobic leader sequence. The protein encoded by PRP mRNA has significant homology to all of the members of the prolactin family, yet is different from each of them; it also differs from mouse placental lactogen. Nucleotide sequence homology is most extensive between PRP and proliferin mRNAs, particularly at their 5' ends, where they share 92 of the first 97 nucleotides.

Amino Acid Sequence↗
PubMed1985

Identification of proliferin mRNA and protein in mouse placenta.

Proliferin is a recently described, prolactin-related protein whose mRNA appears in several murine cell lines during active growth. We have surveyed a number of mouse organs or tissues for the presence of mRNAs that hybridize to cloned proliferin cDNA. Of the tissues tested, only the placenta yielded proliferin-related mRNA. This placental RNA is about 1 kilobase in length, increases sharply between days 8 and 10 of pregnancy, and then gradually declines through day 18. It is more abundant in RNA extracted from the fetal, compared to the maternal, part of the placenta. From a cDNA plasmid library prepared from poly(A)+ placental RNA, two types of proliferin-related clones were isolated, differing in intensity of hybridization to proliferin cDNA. By nucleotide sequence analysis, a strongly hybridizing clone was found to be nearly identical to the proliferin cDNA clone isolated from a library prepared from mRNA of a growing mouse fibroblastic cell line. Using an antiserum prepared against a synthetic proliferin fusion protein, we show that proliferin is secreted as a glycoprotein by minced placental tissue and that it differs from mouse placental lactogen. We conclude that proliferin is a placental hormone that is synthesized in certain mouse cell lines during active growth. Its function during pregnancy and during the growth of cultured cells is presently unknown.

Amino Acid Sequence↗