Complete structure of the murine p36 (annexin II) gene. Identification of mRNAs for both the murine and the human gene with alternatively spliced 5' noncoding exons.

p36 (also termed annexin II) is a 39 kDa Ca2+/phospholipid-binding, membrane-associated protein that is a protein-tyrosine kinase substrate. We report here studies of the noncoding exons of p36, which combined with our earlier studies of the coding exons, allow us to conclude that the murine p36 gene is 34 kb in length with 14 exons. Comparison of the genes coding for mouse and human p36 (annexin II) and mouse, rat and human p35 (annexin I) and pigeon cp35 (an annexin I-related protein) shows strong genomic structural conservation supporting the hypothesis that these genes had a common ancestor. Both human and murine p36 mRNAs were found to be alternatively spliced in their 5' noncoding region. In both cases exon 2 is a cassette exon, which is present in a small fraction of p36 mRNAs. In type 1 mouse p36 mRNA the first noncoding 44 base exon 1 is joined to exon 3, the first of the 12 coding exons. In type 2 mRNA a 70 base noncoding exon (exon 2) is inserted between exon 1 and exon 3. Type 1 mRNA was present in all cell types studied as revealed by Northern analysis and primer extension, whereas type 2 mRNA could only be detected by RACE or PCR, indicating that it is of very low abundance. The major transcription start site of the mouse p36 gene was mapped by primer extension to be 61 bp upstream of the AUG initiation codon, which corresponds to type 1 mRNA, The murine p36 gene enhancer/promoter region contains a putative TATA box and several other potential regulatory sequences. The two alternatively-spliced human p36 mRNAs differ by the presence or absence of a noncoding 81 base exon (exon 2) inserted after exon 1, with exon 2-containing mRNAs representing approximately 10% of total p36 mRNA. The 300 bp spanning the promoter and exons 1-3 of the human and murine p36 genes show strong sequence homology immediately before and after the major transcription start site except in the region corresponding to exon 2, where homology is more limited.

Analysis of Pim-1 function in mutant mice.

The Pim-1 gene has frequently been found activated by proviral insertion in haematopoietic tumors in mice. The fact that overexpression of Pim-1 can contribute to lymphomagenesis was formally proven by overexpressing a Pim-1 transgene in lymphoid cells. The transgene induces a low incidence of T cell lymphomas and an increased susceptibility to chemically (ENU) and virally (MoMuLV) induced lymphomas. The mouse Pim-1 gene encodes two cytoplasmic protein-serine/threonine kinases. Northern analysis shows the highest expression to be in haematopoietic tissues, especially early in development. High expression has also been noted in testis and ES cells. Expression can be induced by growth factors and mitogens. The gene is evolutionarily highly conserved. Inactivation of both Pim-1 alleles in ES cells or mice did not reveal any obvious abnormalities. In order to look more closely for possible haematopoietic abnormalities specific growth factor response were studied in vitro. The IL-3 response of bone marrow-derived mast-cell cultures (BMMC) was found to be severely impaired in mast cells derived from Pim-1 deficient mice.

The pim-1 oncogene encodes two related protein-serine/threonine kinases by alternative initiation at AUG and CUG.

The pim-1 gene is frequently found activated by proviral insertion in murine T cell lymphomas. Overexpression of pim-1 in lymphoid cells by transgenesis formally proved its oncogenic potential. The pim-1 cDNA sequence predicts that both murine and human pim-1 encode a 34 kd protein with homology to protein kinases. In this study, we show that the murine pim-1 gene encodes a 44 kd protein in addition to the predicted 34 kd protein. The 44 kd protein is an amino-terminal extension of the 34 kd protein and is synthesized by alternative translation initiation at an upstream CUG codon. Contrary to previous findings by others, we provide evidence that both murine and human pim-1 gene products are protein-serine/threonine kinases. Murine 44 kd and 34 kd pim-1 proteins exhibit comparable in vitro kinase activity and are both mainly cytoplasmic, but they differ in in vivo association state and half-life.

3Y1 rat cells are defective in processing of the envelope precursor protein of AKR virus.

Rat 3Y1 cells were infected by AKR virus through microinjection of molecularly cloned proviral DNA. Based on a strong immunofluorescence using anti-p30 as an antiserum a cell clone (RESA-2) was selected that had a high expression of viral antigens. Subsequent restriction analysis of its DNA revealed that the RESA-2 clone contained at least 30 apparently intact integrated proviruses per genome. There was an apparently normal synthesis and processing of gag and pol gene products. The viral envelope precursor polyprotein gPr82env, however, did not yield the major envelope glycoprotein gp70. The gag precursor polyprotein, Pr65gag, as well as the gPr82env from RESA-2 cells were identified as AKR viral proteins by gel electrophoresis of hydroxylamine cleavage fragments. The virions formed by RESA-2 cells lacked gp70 and were noninfectious. After fusion of RESA-2 cells and mouse cells an infectious N-tropic virus was produced. The results indicate that rat 3Y1 cells lack (a) factor(s) necessary for the correct processing of gPr82env. The high incidence of abortive infections of murine leukemia virus (MLV) in susceptible rat cells reported by others is therefore probably due to defective particles in the virus stock and/or to the lack of (a) cellular factor(s) necessary for reverse transcription and subsequent integration of the viral genome.

The cDNA sequence for the protein-tyrosine kinase substrate p36 (calpactin I heavy chain) reveals a multidomain protein with internal repeats.

We have isolated and sequenced a full-length cDNA clone for the protein-tyrosine kinase substrate p36 (calpactin I heavy chain). This sequence predicts a 339 amino acid (Mr 38,493) protein containing an N-terminal region of 20 amino acids, known to interact with a 10 kd protein (light chain), and a C-terminal region, found to contain two Ca2+/phospholipid-binding sites, that can be aligned as four 70 amino acid repeats. A single p36 gene was detected in the mouse genome, and a major p36 mRNA of 1.6 kb was found to be expressed in different mouse tissues. Unexpectedly, p36 and the phospholipase A2 inhibitor lipocortin I were found to be 50% identical in sequence over the C-terminal 300 residues. The function of p36 and its relation to other proteins are discussed.

Structure of glycosylated and unglycosylated gag and gag-pol precursor proteins of Moloney murine leukemia virus.

Precursor polyproteins containing translational products of the gag gene of Moloney murine leukemia virus were purified by gel electrophoresis and cleaved into large fragments by hydroxylamine, mild acid hydrolysis, or cyanogen bromide. The hydroxylamine cleavage method (specific for asparagine-glycine bonds) was adapted especially for this study. The electrophoretic mobility and antigenicity of the fragments and, in some cases, the presence or absence of [35S]methionine revealed detailed information on the structure of Pr65gag, gPr80gag, and Pr75gag (the unglycosylated variant of gPr80gag formed in vivo in the presence of tunicamycin or in vitro in a reticulocyte cell-free system). When compared with Pr65gag, gPr80gag contains 7,000 daltons of additional amino acids, presumably as, or as part of, a leader sequence at or very close to its N terminus. We present evidence that this leader may have replaced part of the p15 sequence. Furthermore, gPr80gag contains three separate carbohydrate groups. One is attached to the presumed leader sequence or to the p15 domain, and two are attached to the p30 domain. Each of the Moloney murine leukemia virus gag precursor proteins Pr65gag, gPr80gag, and Pr75gag corresponds with a read-through product into the pol gene. We designated these products Pr180gag-pol, gPr200gag-pol, and Pr190gag-pol (the unglycosylated variant of gPr200gag-pol), respectively. gPr200gag-pol contains all of the extra amino acids and carbohydrate groups present in gPr80gag and at least one carbohydrate group in its pol sequences.

Hydroxylamine cleavage of proteins in polyacrylamide gels.

A modification of the hydroxylamine cleavage of proteins is presented in which proteins were cleaved while immobilized in the matrix of a polyacrylamide gel. The reaction under these conditions retains its high specificity for Asn-Gly bonds and has the advantage that the gel matrix, acting as a carrier, facilitates simultaneous treatment of many samples, and contributes to a high recovery efficiency (60-90%) of the cleavage products. The cleavage is performed with individual protein bands excised from dried slab gels after detection by staining, autoradiography, or fluorography. The procedure can be easily combined with other techniques to further characterize the cleavage fragments. Also a two-dimensional version of the cleavage method was developed, which allows rapid recognition of interrelationships between proteins in a complicated mixture. The versatility of the procedure is demonstrated in a number of applications. Highly related strains of murine leukemia viruses were easily distinguished from one another by the unique cleavage patterns of their gag- and env-precursor polypeptides. Comparing the env-precursor gPr82env synthesized in the presence or absence of tunicamycin with its cell-free synthesized counterpart, revealed the presence of an amino-terminal signal sequence. Cleavage patterns of pro-opiomelanocortin (POMC) from three different species revealed a high degree of homology between rat and mouse POMC, whereas Xenopus POMC was very different. Regions to which carbohydrates are attached could be identified by comparing glycosylated and unglycosylated forms of POMC. Combining the hydroxylamine cleavage procedure with immunological characterization of the fragments showed a small but significant difference between the amino-terminal sequences of the recombinant transforming protein P120 of Abelson murine leukemia virus and of its parent molecule Pr65gag of Moloney murine leukemia virus.

Blotting of RNA onto ion exchange paper allowing subsequent characterization by in situ translation in addition to blot hybridization.

We present the preparation of an ion exchange paper which can be used as a solid carrier in the transfer of RNA from gels. In addition to detection by blot hybridization to specific probes, transferred RNA can be characterized by cell-free translation in situ. Preparation of the paper is simple, inexpensive and reproducible. Examples of applications are shown and possible other applications are discussed.

Structure and chromosome assignment of the murine p36 (calpactin I heavy chain) gene.

p36 is a major substrate of both viral and growth factor receptor associated protein kinases. This protein has recently been named calpactin I heavy chain since it is the large subunit of a Ca2(+)-dependent phospholipid and actin binding heterotetramer. The primary structure of p36 has been determined from analysis of cloned cDNA. The protein contains 338 amino acids, has an approximate molecular weight of 39,000, and is comprised of several distinct domains, including four 75 amino acid repeats. From two overlapping cosmid clones isolated from different mouse genomic liver libraries, the complete intron/exon structure of the p36 gene was determined and the 5' and 3' noncoding regions of the gene were analyzed. The coding and 3' untranslated region of the p36 gene contains 12 exons which range in size from 48 to 322 base pairs (bp) with an average size of 107 bp. The repeat structures found at the protein level are not delineated by single exons, but the N-terminal p11-binding domain is encoded by a single exon. Structural mapping of the gene demonstrated that the lengths of the first two introns in the coding region are together approximately 6 kilobases (kb), while the other introns range in size from 600 to 3600 bp with an average size of 1650 bp. The p36 gene is at least 22 kb in length and has a coding sequence of approximately 1 kb, representing only 4.5% of the gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired interleukin-3 response in Pim-1-deficient bone marrow-derived mast cells.

The mouse Pim-1 gene encodes two cytoplasmic serine-threonine-specific protein kinases. The gene has been found to be activated (overexpressed) by retroviral insertion in hematopoietic tumors in mice. Transgenic mice that overexpress Pim-1 (E mu-Pim-1) have a low incidence of spontaneous T-cell lymphomas and an increased susceptibility to Moloney murine leukemia virus and N-ethyl-N-nitrosourea-induced lymphomas. Apart from a slight enlargement of the spleen, no abnormalities were found in prelymphomatous transgenic mice. Inactivation of the Pim-1 gene in the germline of mice resulted in mice with a surprisingly subtle phenotype. Therefore, we investigated whether subtle effects of the absence of Pim-1 could be made visible during in vitro culturing of hematopoietic cells. We found that bone marrow-derived mast cells (BMMC) lacking Pim-1 had a distinct growth disadvantage when grown on interleukin (IL)-3, but not when stimulated by the factors IL-4, IL-9, or Steel factor (SF). This indicates a role for Pim-1 as a modulator of the IL-3 signal transduction pathway.

cDNA sequence and tissue distribution of the mRNA for bovine and murine p11, the S100-related light chain of the protein-tyrosine kinase substrate p36 (calpactin I).

We have isolated and sequenced cDNA clones of bovine and murine p11 mRNAs. The nonpolyadenylated mRNAs are predicted to be 614 and 600 nucleotides, respectively. The p11 mRNAs both contain a 291 nucleotide open reading frame, preceded by a 5'-untranslated region of 73 nucleotides in bovine p11 mRNA and of 68 nucleotides in murine p11 mRNA. The deduced bovine p11 amino acid sequence is identical to the previously published partial bovine and complete porcine p11 protein sequence except for an additional COOH-terminal lysine residue. The bovine and murine p11 proteins are 92% homologous, whereas at the nucleotide level the conservation is 89% in the coding region and 75% in the 3'-untranslated region. Southern analysis of murine genomic DNA detected a single p11 gene, less than 10 kilobase pairs in size, containing as many as three introns. The p11 gene has been assigned to mouse chromosome 3 by analysis of interspecific hybrid cell panels and recombinant inbred mouse strains. The p11 gene is closely linked to the Xmmv-65 endogenous leukemia virus env gene and the guanylate binding protein-1 gene. Northern analyses of RNAs from mouse tissues and cell lines indicated that p11 mRNA levels vary widely. They are very low in liver, heart, and testes, moderate in brain, spleen, and thymus, and high in kidney, intestine, and lung. Analysis of the same RNA samples for p36 mRNA levels showed that expression of p11 and p36 mRNAs is not always coordinated. Brain and the mouse embryonal carcinoma cell line F9 contain moderate to high levels of p11 mRNA with very low levels of p36 mRNA. Sequence homology between p11 and the S100 proteins, and the serum-induced 2A9 gene product, as well as possible functions of p11 are discussed.

Primary structure of bovine calpactin I heavy chain (p36), a major cellular substrate for retroviral protein-tyrosine kinases: homology with the human phospholipase A2 inhibitor lipocortin.

An amplified Okayama-Berg plasmid cDNA library was constructed from total poly(A)+ RNA isolated from the Madin-Darby bovine kidney cell line MDBK. This library was screened with a partial murine calpactin I heavy chain (p36) cDNA clone, the identification of which was based on bovine p36 tryptic peptide sequences generated during the course of these studies. The largest p36 cDNA insert (p36/6 of 1.6 kilobase pairs) was fully sequenced by the dideoxy method. The DNA sequence of this insert had an open reading frame of 1014 base pairs and coded for a protein with a molecular weight of 38 481. The deduced protein sequence of 338 residues was concordant with 173 residue positions of p36 determined at the protein level. The 5'- and 3'-ends of p36/6 contained 54 and 307 base pairs of untranslated sequence, respectively. Examination of poly(A)+ RNA prepared from the Madin-Darby cell line indicated a p36 mRNA species of about 1.6 kilobases. Four regions of internal homology, each about 70 amino acid residues in length, were observed in the deduced protein sequence for p36. Thirty-three of the 70 residue positions were conserved in at least three of the four repeating units. A comparison of derived amino acid sequence for bovine p36 with that previously determined for human lipocortin [Wallner, B. P., Mattaliano, R. J., Hession, C., Cate, R. L., Tizard, R., Sinclair, L. K., Foeller, C., Chow, E. P., Browning, J. L., Ramachandran, K. L., & Pepinsky, R. B. (1986) Nature (London) 320, 77-81] revealed extensive homology (66% overall) and the presence of four repetitive regions in the lipocortin structure.(ABSTRACT TRUNCATED AT 250 WORDS)

The tsA58 simian virus 40 large tumor antigen disrupts megakaryocyte differentiation in transgenic mice.

Thrombocytopenia is a condition of multiple etiologies affecting the megakaryocyte lineage. To perturb this lineage in transgenic mice, the tsA58 mutation of the simian virus 40 large tumor antigen was targeted to megakaryocytes using the platelet factor 4 promoter. Ten of 17 transgenic lines generated exhibited low platelet levels, each line displaying a distinct, heritable level of thrombocytopenia. Within a line, the degree of the platelet reduction correlated directly with transgene zygosity. The platelet level could be further reduced by the inactivation of one copy of the endogenous retinoblastoma gene. Western blot analysis detected large tumor antigen protein in the most severely affected lines; less affected lines were below the level of detection. Platelets and megakaryocytes from thrombocytopenic mice exhibited morphological abnormalities. Mice with either normal or reduced platelet levels developed megakaryocytic malignancies with a mean age of onset of about 8 months. There was no correlation between severity of thrombocytopenia and onset of malignancy. These mice provide a defined genetic model for thrombocytopenia, and for megakaryocytic neoplasia, and implicate the retinoblastoma protein in the process of megakaryocyte differentiation.

Megakaryocyte growth and development factor and interleukin-3 induce patterns of protein-tyrosine phosphorylation that correlate with dominant differentiation over proliferation of mpl-transfected 32D cells.

Recently, the ligand for c-mpl, a member of the family of cytokine receptors, was cloned and found to be a physiologic regulator of platelet homeostasis. We report that megakaryocyte growth and development factor (MGDF, thrombopoietin [TPO], c-mpl ligand ) induces differentiation in a majority of mpl-transfected 32D cells, while interleukin (IL)-3 is exclusively mitogenic in this system. MGDF differentiation, as measured by decreased proliferation, changes in cellular morphology, increased adherence, and downregulation of very late antigen (VLA)-4, is dominant over IL-3 proliferation. MGDF induces tyrosine-phosphorylation of mpl, JAK2, SHC, SHPTP-1 (HCP, motheaten) and SHPTP-2 (Syp, PTP-1D) within 30 seconds of stimulation, as well as of vav and MAPK with slightly delayed kinetics. A fraction of mpl and JAK2 is preassociated, and the stoichiometry of this complex is unaltered by cytokine stimulation. After MGDF stimulation, we detect interactions among SHC, grb2, SHPTP-1, SHPTP-2, and the mpl/JAK2 complex. IL-3 induces phosphorylation of the above proteins with the exception of mpl and also causes weak JAK1 phosphorylation. Although similar in composition, the MGDF- and IL-3-induced complexes of signal transducers appear to be assembled in different configurations, especially with respect to SHPTP-2. Both MGDF and IL-3 induce tyrosine phosphorylation of STAT3 (APRF) and STAT5 (MGF), with MGDF favoring STAT3 while IL-3 predominantly causes STAT5 phosphorylation. In addition, some proteins become tyrosine-phosphorylated in response to MGDF only, suggesting that we may have detected differentiation-specific signal transducers. These include a number of high-molecular-weight proteins (140 to 200 kD) and one 28-kD protein that becomes tyrosine-phosphorylated only briefly.

Transcription factor NF-E2 is required for platelet formation independent of the actions of thrombopoietin/MGDF in megakaryocyte development.

Despite the importance of blood platelets in health and disease, the mechanisms regulating their formation within megakaryocytes are unknown. We generated mice lacking the hematopoietic subunit (p45) of the heterodimeric erythroid transcription factor NF-E2. Unexpectedly, NF-E2-/- mice lack circulating platelets and die of hemorrhage; their megakaryocytes show no cytoplasmic platelet formation. Though platelets are absent, serum levels of the growth factor thrombopoietin/MGDF are not elevated above controls. Nonetheless, NF-E2-/- megakaryocytes proliferate in vivo in response to thrombopoietin administration. Thus, as an essential factor for megakaryocyte maturation and platelet production, NF-E2 must regulate critical target genes independent of the action of thrombopoietin. These findings provide insight into the genetic analysis of megakaryocyte maturation and thrombopoiesis.

WSX-1 is required for the initiation of Th1 responses and resistance to L. major infection.

WSX-1 is a class I cytokine receptor with homology to the IL-12 receptors. The physiological role of WSX-1, which is expressed mainly in T cells, was investigated in gene-targeted WSX-1-deficient mice. IFN-gamma production was reduced in isolated WSX-1(-/-) T cells subjected to primary stimulation in vitro to induce Th1 differentiation but was normal in fully differentiated and activated WSX-1(-/-) Th1 cells that had received secondary stimulation. WSX-1(-/-) mice were remarkably susceptible to Leishmania major infection, showing impaired IFN-gamma production early in the infection. However, IFN-gamma production during the later phases of the infection was not impaired in the knockout. WSX-1(-/-) mice also showed poorly differentiated granulomas with dispersed accumulations of mononuclear cells when infected with bacillus Calmette-Guerin (BCG). Thus, WSX-1 is essential for the initial mounting of Th1 responses but dispensable for their maintenance.