PubMed Health⌕ Search

Biomedical subjects

C Kozak

Publications and source records attributed to C Kozak.

At least 19 recordsLinked to original sources
PubMed1999

Loss of Daxx, a promiscuously interacting protein, results in extensive apoptosis in early mouse development.

The mammalian Daxx gene has been identified in a diverse set of yeast interaction trap experiments. Although a facilitating role for Daxx in Fas-induced apoptosis has been suggested, Daxx's physiologic function remains unknown. To elucidate the in vivo role of Daxx, we have generated Daxx-deficient mice. Surprisingly, rather than a hyperproliferative disorder expected from the loss of a pro-apoptotic gene, mutation of Daxx results in extensive apoptosis and embryonic lethality. These findings argue against a role for Daxx in promoting Fas-induced cell death and suggest that Daxx either directly or indirectly suppresses apoptosis in the early embryo.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Cloning and characterization of a cell surface receptor for xenotropic and polytropic murine leukemia viruses.

Xenotropic and polytropic murine leukemia viruses (X-MLVs and P-MLVs) cross-interfere to various extents in non-mouse species and in wild Asian mice, suggesting that they might use a common receptor for infection. Consistent with this hypothesis, the susceptibility of some wild mice to X-MLVs has been mapped to the P-MLV receptor locus at the distal end of mouse chromosome 1. In this study, we report the isolation and characterization of a cDNA for the human X-MLV cell surface receptor (X-receptor) by using a human T lymphocyte cDNA library in a retroviral vector. The predicted X-receptor contains 696 amino acids with multiple hydrophobic potential membrane-spanning sequences and with weak homologies to the yeast proteins SYG1, of unknown function, and PHO81, which has been implicated in a system that regulates transport of inorganic phosphate. Expression of the X-receptor in Chinese hamster ovary cells, which are substantially resistant to P-MLVs and to X-MLVs, made them susceptible to both of these virus groups. The mouse homologue of the X-receptor was mapped by hybridization to the distal end of chromosome 1 at the same position as the P-MLV receptor gene Rmc1. These results strongly support the hypothesis that a common gene encodes the receptors for X-MLVs and P-MLVs, with the human X-receptor preferentially mediating X-MLV infections and the homologous protein of inbred mice mediating only P-MLV infections. We propose that X-MLVs and P-MLVs comprise a single family of retroviruses that have coevolved in response to diversification in X-receptor genes of the host.

Amino Acid Sequence↗
PubMed1999

Cloning and chromosomal mapping of a gene isolated from thymic stromal cells encoding a new mouse type II membrane serine protease, epithin, containing four LDL receptor modules and two CUB domains.

We cloned and sequenced a mouse gene encoding a new type of membrane bound serine protease (epithin) containing a multidomain structure. The initial cDNA clone was found previously in a polymerase chain reaction (PCR)-based subtractive library generated from fetal thymic stromal cells, and the message was shown to be highly expressed in a thymic epithelial nurse cell line. A clone isolated from a severe combined immunodeficiency (SCID) thymus library and extended to its full length at the 5' end with the RACE technique contains an open reading frame of 902 amino acids. Based on the sequence of this clone, the predicted protein structure is a type II membrane protein with a C-terminal serine protease domain linked to the membrane by four low density lipoprotein receptor modules and two CUB domains. High message expression by northern blotting was detected in intestine, kidney, lung, SCID, and Rag-2(-/-) thymus, and 2-deoxyguanosine-treated fetal thymic rudiment, but not in skeletal muscle, liver, heart, testis, and brain. Sorted MHC class II+ and II- fetal thymic stromal cells were positive for expression by reverse transcriptase-PCR, whereas CD45(+) thymocytes were not. The gene was found in chicken and multiple mammalian species under low stringency Southern hybridization conditions. Under high stringency conditions, only a single gene per haploid genome was identified in the mouse. This gene, Prss14 (protease, serine, 14), was mapped to mouse chromosome 9 and is closely linked to the Fli1 (Friend leukemia integration 1) gene.

Amino Acid Sequence↗
PubMed1998

Stage-specific apoptosis, developmental delay, and embryonic lethality in mice homozygous for a targeted disruption in the murine Bloom's syndrome gene.

Bloom's syndrome is a human autosomal genetic disorder characterized at the cellular level by genome instability and increased sister chomatid exchanges (SCEs). Clinical features of the disease include proportional dwarfism and a predisposition to develop a wide variety of malignancies. The human BLM gene has been cloned recently and encodes a DNA helicase. Mouse embryos homozygous for a targeted mutation in the murine Bloom's syndrome gene (Blm) are developmentally delayed and die by embryonic day 13.5. The fact that the interrupted gene is the homolog of the human BLM gene was confirmed by its homologous sequence, its chromosomal location, and by demonstrating high numbers of SCEs in cultured murine Blm-/- fibroblasts. The proportional dwarfism seen in the human is consistent with the small size and developmental delay (12-24 hr) seen during mid-gestation in murine Blm-/- embryos. Interestingly, the growth retardation in mutant embryos can be accounted for by a wave of increased apoptosis in the epiblast restricted to early post-implantation embryogenesis. Mutant embryos do not survive past day 13.5, and at this time exhibit severe anemia. Red blood cells and their precursors from Blm-/- embryos are heterogeneous in appearance and have increased numbers of macrocytes and micronuclei. Both the apoptotic wave and the appearance of micronuclei in red blood cells are likely cellular consequences of damaged DNA caused by effects on replicating or segregating chromosomes.

Animals↗
PubMed1997

Effects of exercise on the macrophage MHC II response to inflammation.

The purpose of this investigation was to determine the effects of different doses of exercise on the ability of Propionibacterium acnes (P. acnes) to induce major histocompatibility complex (MHC) II antigen expression on macrophages (M phi's). Pathogen-free male Balb/c mice were exercised on a treadmill moderately (MOD, 15-17 m/min, 5% grade, 30 min/day) or exhaustively (EXH, 15-40m/min, 5% grade, 2-4hr/day) for a period of 7 days during P. acnes-induced inflammation. A control group (CON) consisted of animals exposed to the treadmill environment and handling. Sub-optimal (0.03 mg/g b.wt., i.p.) and optimal (0.08 mg/g b.wt.) doses of P. acnes were used to increase M phi MHC II expression. Animals were sacrified on Day 7 and M phi's were harvested by peritoneal lavage. Direct immunofluorescent staining was performed by incubating peritoneal exudate cells (10[6]) with an FITC-labeled anti-mouse MHC II (I-A[d]) antibody. Basal expression of MHC II was not affected by exercise. There were no significant differences among the groups in the percentage of M phi's expressing MHC II at any dose of P. acnes. However, EXH significantly (p < 0.05) suppressed the expression (mean fluorescent intensity, MFI) of MHC II when compared to MOD (37.1+/-1.95 [mean+/-sem] vs 49.1+/-2.15, p < 0.05) at the suboptimal P. acnes dosage. At the optimal P. acnes dose, both MOD and EXH significantly suppressed (27+/-1.6, 25+/-2.2 and 41.5+/-3.2, for EXH, MOD, and CON, respectively, p<0.0001) P. acnes-induced M phi MHC II MFI. Plasma corticosterone was highly (r=-0.71, p = 0.001) inversely correlated with M phi MHC II expression. However, exercise failed to affect P. acnes-induced production of interferon-gamma. These data suggest that, dependent on the degree of stimulation, exercise can negatively affect M phi expression of MHC II, an effect that may be detrimental to the M phi's ability to present antigen to T lymphocytes.

Animals↗
PubMed1995

Cloning of the murine homolog of the leukemia-associated PML gene.

PML, a Ring-finger protein, participates in the disruption of normal myeloid differentiation when fused to the retinoic acid receptor alpha (RAR alpha) by the translocation between chromosomes (Chrs) 15 and 17 in acute promyelocytic leukemia (APL). As an initial step in the characterization of PML in species other than human, a murine cDNA clone of the PML gene was isolated and sequenced, and the intron/exon organization of the murine locus determined. The predicted amino acid sequence of the mouse PML protein shows 80% similarity to that of its human homolog. However, the mouse and human proteins show greater than 90% similarity in the proposed functional domains of the proteins. Despite its role in the etiology of APL, PML expression is not detectably altered during granulocytic differentiation in a murine in vitro system. Chromosomal localization of the Pml locus by somatic cell hybrids and by linkage analysis indicates that the gene maps to a region of mouse Chr 9 with known linkage homology to the region on human Chr 15q to which PML has been localized.

3T3 Cells↗
PubMed1995

Nursing care and management of the elderly hip fractured patient.

1. This study examined the effects of a geriatric orthopaedic nursing education program of care for the elderly hip fractured patient on select patient outcomes using a post-test nonequivalent control group design. 2. Nursing staff of a 26-bed orthopaedic unit attended a day long education workshop focusing on common clinical problems the elderly patient experiences in the acute care setting. 3. This program provided nursing staff with sound knowledge for the provision of effective care to the acutely ill elderly patient, which resulted in improved patient outcomes and use of health care resources.

Aged↗
PubMed1991

The mouse transition protein 1 gene contains a B1 repetitive element and is located on chromosome 1.

The gene for mouse transition protein 1 (mTP1) was isolated, sequenced, and chromosomally mapped. The nucleotide sequence of 1895 bp of a 6.4-kb mTP1 genomic subclone was determined to include 788 bp of 5' flanking region, 564 bp of coding region including a 396-bp intron and a TAA stop codon, and 543 bp of 3' flanking region. The mTP1 gene contains a B1 repeat sequence within the only intron of the gene. The transcriptional start site of the mTP1 mRNA was determined to be located 31 bases upstream of the ATG translational start codon. Southern blot analysis demonstrated the presence of sequences homologous to the mTP1 cDNA in the genomes of the rat, hamster, bull, boar, dog, horse, ram, human, and two marsupials (the American opossum and Monodelphis), suggesting that the mTP1 gene sequence is widely conserved. The TP1 gene has been mapped by analysis of restriction fragment length variants (RFLV) in an interspecific backcross to a position 0.7 +/- 0.4 cM telomeric of Mylf and 1.2 +/- 0.5 cM centromeric of Vil on mouse chromosome 1.

Amino Acid Sequence↗
PubMed1990

Cloning, chromosomal assignment, and regulation of the rat thyrotropin receptor: expression of the gene is regulated by thyrotropin, agents that increase cAMP levels, and thyroid autoantibodies.

A rat thyrotropin (thyroid-stimulating hormone, TSH) receptor cDNA was isolated that encoded a protein of 764 amino acids, Mr 86,528. Transfection of the cDNA caused COS-7 cells to develop a TSH-sensitive adenylate cyclase response and the ability to bind 125I-labeled TSH; both activities were similar to those of rat FRTL-5 thyroid cells and not duplicated by lutropin. The gene represented by the cDNA was assigned to mouse chromosome 12 and human chromosome 14. Northern analyses identified two species of mRNA, 5.6 and 3.3 kilobases, in FRTL-5 thyroid cells; the transcripts appeared to differ only in the extent of their 3' noncoding sequences. There were minimal amounts of the two mRNAs in rat ovary, and neither was detected in RNA preparations from rat testis, liver, lung, brain, spleen, and FRT thyroid cells, which do not have a functional TSH receptor. TSH decreased both mRNA species 3- to 4-fold within 8 hr in FRTL-5 thyroid cells; down-regulation was dependent on TSH concentration and duplicated by forskolin, cholera toxin, or 8-bromo-cAMP but not by a phorbol ester. Down-regulation was also duplicated by thyroid-stimulating autoantibodies, which increased cAMP levels, but not by thyrotropin binding-inhibiting auto-antibodies, which actually increased TSH receptor mRNA levels.

Amino Acid Sequence↗
PubMed1990

Characterization and expression of the complementary DNA encoding rat histidine decarboxylase.

Histamine is a neurotransmitter in the central nervous system and an important modulator of gastric acid secretion, vasomotor control, inflammation, and allergic reactions. In biological systems the formation of histamine from its precursor histidine is catalyzed by the enzyme L-histidine decarboxylase (HDC; L-histidine carboxy-lyase, EC 4.1.1.22). We have cloned HDC-encoding cDNA from a fetal rat liver cDNA library (phage lambda gt11) have deduced the amino acid sequence from the nucleotide sequence. The clone was proven to be HDC cDNA by expression of active recombinant enzyme in COS cells and by chromosomal mapping. The cDNA encodes a protein of Mr 73,450 (655 amino acid residues). The discrepancy between this molecular weight and the size of the purified fetal liver protein subunits [Taguchi, Y., Watanabe, T., Kubota, H., Hayashi, H. & Wada, H. (1984) J. Biol. Chem. 259, 5214-5221] (Mr = 54,000) suggests that HDC may be posttranslationally processed. The 469 amino acid residues from the amino-terminal portion of the protein share 50% identity with rat and Drosophila L-dopa decarboxylases and much less homology with other characterized amino acid decarboxylases.

Amino Acid Sequence↗
PubMed1990

Molecular cloning of microtubule-associated protein 1 (MAP1A) and microtubule-associated protein 5 (MAP1B): identification of distinct genes and their differential expression in developing brain.

cDNA clones encoding microtubule-associated proteins 1 (MAP1/MAP1A) and 5 (MAP5/MAP1B) were isolated and have been used to study their structural relationship as well as their regulated expression in developing rat brain. cDNA clones specific for MAP1 hybridized to a single 10-kb rat brain mRNA, and analysis of genomic DNA by Southern blotting indicated the existence of a single MAP1 gene. A second set of cDNAs specific for MAP5 hybridized to a single 11-kb mRNA in rat brain and also detected a single gene. By analysis of hybrid mouse-hamster cell lines, the MAP1 gene was located to mouse chromosome 2, designated Mtap-1, and the MAP5 gene to chromosome 13, designated Mtap-5. MAP1 and MAP5 mRNAs were expressed with different temporal patterns during rat brain development that mirrored the appearance of their protein products, suggesting that expression of these proteins is under transcriptional control. These results taken together demonstrate that although MAP1 and MAP5 have some properties that are similar, they are structurally distinct proteins whose transcription is differently regulated from separate genes.

Animals↗
PubMed1989

Cloning and comparative mapping of a human class III (chi) alcohol dehydrogenase cDNA.

A cDNA encoding human class III (chi ADH5) alcohol dehydrogenase was isolated, sequenced and used to comparatively map this unusual ADH. In their coding sequences, the three major ADH classes were approximately equisimilar, class II and III ADHs sharing the highest sequence identity (67%). A class III-like ADH was mapped to mouse chromosome 3, site of the ADH gene complex, and synteny of ADH5 with four other ADH loci on human chromosome 4 was confirmed. The nearly full-length 1613 nucleotide cDNA contained 433 nucleotides of 3' nontranslated sequence and two possible initiation sites for translation. A protein of 374 amino acid residues could be synthesized using the potential initiation codon at nucleotide 59. However, use of the likely initiation codon at nucleotide 5 would produce a protein of 392 residues with 19 additional N-terminal residues as compared to the known protein sequence. The derived protein sequence also differs at residue 166, where Tyr is found. This difference, due to a single base substitution, could result from cloning artifact, polymorphism, or two expressed class III ADH genes.

Alcohol Oxidoreductases↗
PubMed1989

Murine 86- and 84-kDa heat shock proteins, cDNA sequences, chromosome assignments, and evolutionary origins.

The two forms of the approximately 90-kDa murine heat shock protein, referred to as HSP86 and HSP84, are coded for by separate but related genes. A full-length nucleotide sequence of the cDNA coding for HSP86 from a chemically induced tumor, Meth A, was determined. Sequences from a number of peptides from HSP86 were found to be in complete agreement with the nucleotide sequence. The HSP84 sequence from the same tumor was also completed. HSP86 and HSP84 are acidic polypeptides 733 and 724 amino acids long with calculated molecular weights of 84,796 and 83,290, respectively. The two proteins are 86% homologous. HSP86 was found to contain internal peptide repeats of Glu-Lys-Glu within a region of highly charged amino acid residues. The coding regions of the cDNAs were 76% homologous; however, this homology did not extend to the 5'- and 3'-untranslated regions. The 5'-untranslated region of hsp86 cDNA was considerably longer than that of hsp84 cDNA and, unlike that of hsp84, contained extraneous ATG triplets. Hsp86-related sequences were assigned to chromosomes 12, 11, and 3. An evolutionary tree constructed from HSP90-related protein sequences indicated that HSP86 and HSP84 were likely to have diverged more than 500 million years ago. The findings presented herein suggest that HSP86 and HSP84 may have different functions.

Amino Acid Sequence↗
PubMed1989

The murine Il-6 gene maps to the proximal region of chromosome 5.

Murine Il-6 cDNAs were isolated by cross-hybridization with a human IL-6 cDNA from an IL-1 activated bone marrow stromal cell line (W20). Mouse-hamster somatic cell hybrids were utilized to localize murine Il-6 to chromosome 5. Genetic mapping with respect to En-2, AlbH, and Gus in backcross progeny from an interspecific mating between C57BL/6J and Mus spretus positioned Il-6 3 cM distal to En-2. The syntenic relationships of Il-6 and En-2 in mouse and man, as well as the potential role of IL-6 in tumorigenesis, are discussed.

Amino Acid Sequence↗
PubMed1989

The gene coding for the p68 calcium-binding protein is localised to bands q32-q34 of human chromosome 5, and to mouse chromosome 11.

The gene coding for human p68, a membrane-associated calcium-binding protein, has been assigned to chromosome 5, using a cDNA clone to probe genomic DNA from rodent-human somatic cell hybrids by Southern hybridisation. The gene was localised, by in situ hybridisation, to 5q32-34. The murine gene was assigned to chromosome 11, using a murine cDNA clone to probe genomic DNA from rodent-rodent somatic cell hybrids.

Animals↗