Cyclin A1 is predominantly expressed in hematological malignancies with myeloid differentiation

OBJECTIVE: To document the frequency of conduction defects and their influence on prognosis in a large series of patients with acute myocardial infarction who underwent coronary care during a period when thrombolytic therapy was in common usage. BACKGROUND: Conduction defects have been associated with an adverse prognosis following acute myocardial infarction, but there are few data on the incidence and outcome of conduction defects since the introduction of thrombolytic therapy. PATIENTS AND METHODS: The study group comprised 1225 consecutive patients with acute myocardial infarction treated in the coronary care unit from 1 January 1988 to 31 December 1994. Conduction defects were recorded prospectively and were classified as follows: complete atrioventricular node block associated with narrow complex escape rhythms; left or right bundle branch block; bifascicular block; complete heart block involving both bundle branches. RESULTS: Electrocardiographic data were available in 1220 patients. Complete atrioventricular node block occurred in 65 (5.3%), left and right bundle branch block in 29 (2.4%) and 44 (3.6%) bifascicular block in 36 (2.9%) and complete heart block involving both bundle branches in 20 (1.6%). The more advanced degrees of block in the bundle branches occurred more commonly in patients with diabetes, previous infarction. Q-wave infarction, anterior infarction and left ventricular failure. Survival analysis showed an increased short- and long-term cardiac mortality in patients with conduction defects, prognosis worsening as the severity of the conduction defect increased. CONCLUSION: Conduction defects complicated acute myocardial infarction in 16% of cases and had a graded impact on the short- and long-term prognosis, patients with advanced bundle branch involvement faring worst. The data showed a small decline in the rate of severe conduction defects compared with previous studies, possibly reflecting the beneficial effects of thrombolytic therapy on infarct size.     

PCTAIRE 2, a Cdc2-related serine/threonine kinase, is predominantly expressed in terminally differentiated neurons

PCTAIRE are members of a subfamily of Cdc2-related kinases that have been shown to be preferentially expressed in post-mitotic cells. To examine the neural functions of PCTAIRE, rat cDNA clones encoding PCTAIRE 1, 2, and 3 were isolated, and their expression patterns in the brain were analyzed. Among the three rat PCTAIREs, only PCTAIRE 2 was found to be specifically expressed in the brain. Furthermore, its expression was transiently increased during brain development, peaking 7-15 days after birth. Within the brain, PCTAIRE 2 was concentrated in the neuronal layers of the hippocampus and olfactory bulb, which mostly consist of post-mitotic neurons. In an immunocytochemical experiment, immunoreactivity for PCTAIRE 2 was detected in the cell bodies and extended neurites of neurons, but not in astrocytes. The PCTAIRE 2 protein was recovered in the particulate fraction and resistant to solubilization with non-ionic detergent, suggesting that PCTAIRE 2 might be present as a component of a large protein complex. An immunoprecipitation assay revealed that the PCTAIRE 2 was associated with Ser/Thr-phosphorylating activity for histone H1, and that its activity depended on association with a regulatory partner that can be released under high-salt conditions. These findings suggest that PCTAIRE 2 is a Ser/Thr kinase that might play a unique role in terminally differentiated neurons.     

A novel cdc2-related protein kinase expressed in the nervous system

We report the cloning and characterization of a cDNA encoding a cdc2-related protein kinase, named PFTAIRE, that is expressed primarily in the postnatal and adult nervous system. We have demonstrated by in situ hybridization and indirect immunofluorescence that several populations of terminally differentiated neurons and some neuroglia expressed PFTAIRE mRNA and protein. In neurons, PFTAIRE protein was localized in the nucleus and cytoplasm of cell bodies. The anatomical, cellular, and ontogenic patterns of PFTAIRE expression in the nervous system differed from those of p34cdc2 and cdk5, which are expressed in brain and several other mitotic tissues. Proteins of approximately 58-60 kDa coprecipitated specifically with PFTAIRE from cytosolic protein preparations of adult mouse brain and transfected cells. These proteins appeared to be the major endogenous substrates associated with this kinase activity. The temporal and spatial expression patterns of PFTAIRE in the postnatal and adult nervous system suggest that PFTAIRE kinase activity may be associated with the postmitotic and differentiated state of cells in the nervous system and that its function may be distinct from those of p34cdc2 and cdk5.     

Muc-1 core protein is expressed on multiple myeloma cells and is induced by dexamethasone

Monoclonal antibodies (MoAbs) that selectively identify Muc-1 core protein (MoAbs DF3-P, VU-4H5) determinants were used to identify the Muc-1 glycoform present on 7 multiple myeloma (MM) cell lines, 5 MM patient plasma cells, 12 MM patient B cells, as well as 32 non-MM cell lines and normal hematopoietic cells. Flow cytometry studies demonstrated that all MM cell lines, MM patient plasma cells, and MM patient B cells expressed Muc-1 core protein epitopes. Circulating B cells from 4 normal donors also expressed Muc-1 core protein. In contrast, Muc-1 core protein was absent on 28 of 32 non-MM neoplastic cell lines, 17 of which expressed Muc-1. Splenic and tonsillar B cells, CD34(+) stem cells, resting T cells, and bone marrow plasma cells obtained from normal donors both lacked Muc-1 glycoforms. We next studied the effects of estrogen, progesterone, and glucocorticoid receptor agonists and antagonists on Muc-1 expression, because consensus sequences for the response elements of these steroids are present on the Muc-1 gene promoter. These studies showed that dexamethasone (Dex) induced Muc-1 expression on MM cell lines, as determined by both flow cytometry and Western blot analyses. Dex also induced upregulation of Muc-1 on prostate and ovarian cancer cell lines. Time and dose-response studies demonstrated that Dex induced maximal cell surface Muc-1 expression by 24 hours at concentrations of 10(-8) mol/L. Dex induced Muc-1 upregulation could be blocked with a 10-fold excess of the glucocorticoid receptor antagonist RU486, confirming that Dex was acting via the glucocorticoid receptor. No changes in Muc-1 expression were observed on MM cells treated with estrogen and progesterone receptor agonists and antagonists or with RU486. These studies provide the framework for targeting Muc-1 core protein in vaccination and serotherapy trials in MM. In addition, the finding that Muc-1 expression on MM cells can be augmented by Dex at pharmacologically achievable levels suggests their potential utility in enhancing treatments targeting Muc-1 in MM.     

TRANCE (tumor necrosis factor [TNF]-related activation-induced cytokine), a new TNF family member predominantly expressed in T cells, is a dendritic cell-specific survival factor

We investigated the potential for 9-cis-retinoic acid in the differentiation therapy of neuroblastoma using an N-type neuroblastoma cell line, SH SY 5Y, as an experimental model. In these cells, 9-cis-retinoic acid is more effective than other isomers at inducing the expression of RAR-beta. An RAR-alpha-specific antagonist inhibited the induction of RAR-beta in response to all-trans-but not to 9-cis-retinoic acid. This indicates that the mechanism of gene induction by 9-cis-retinoic acid differs markedly from all-trans-retinoic acid. 9-cis-retinoic acid is also better than all-trans at producing sustained morphological differentiation and inhibition of proliferation of SH SY 5Y cells. Although N-type neuroblastoma cells are not thought to undergo apoptosis in response to all-trans-retinoic acid, we observed a significant degree of apoptosis in SH SY 5Y cells treated with 9-cis-retinoic acid for 5 days and then cultured in the absence of retinoid, an effect not observed in cells treated with the all-trans isomer. These results suggest that 9-cis- and all-trans-retinoic acid have distinct biological properties and that 9-cis retinoic acid may be clinically effective in neuroblastoma by inducing both differentiation and apoptosis under an appropriate treatment regimen.     

Glycosylation-dependent cell adhesion molecule 1 (GlyCAM 1) mucin is expressed by lactating mammary gland epithelial cells and is present in milk

Glycosylation-dependent cell adhesion molecule 1 (GlyCAM 1) is a mucinlike endothelial glycoprotein that acts as an adhesive ligand for L selectin by presenting one or more O-linked carbohydrates to the lectin domain of this leukocyte cell surface selectin. The GlyCAM 1 glycoprotein has been previously shown to be expressed specifically by the endothelial cells of peripheral and mesenteric lymph nodes and in an unknown site in lung. Here we report that this protein is also expressed during lactation by mammary epithelial cells. Northern blot analysis has shown that the mRNA for GlyCAM 1 appears to be induced during pregnancy in a manner similar to that previously described for hormonally induced milk proteins. In situ hybridization analysis reveals that the site of GlyCAM 1 synthesis in the mammary gland is in the epithelial cells that produce these same milk proteins. Immunohistochemistry of mammary glands using antisera directed against GlyCAM 1 peptides demonstrates that these epithelial cells contain GlyCAM 1 protein, and that this protein is also found lumenally in the milk of the secreting mammary gland. Analysis of murine milk shows that immunoreactive GlyCAM 1 is found in the soluble whey fraction. Finally, labeling analysis of milk GlyCAM 1 has demonstrated that this form of the glycoprotein lacks the sulfate-modified carbohydrate that has recently been shown to be required for the ligand binding activity to L selectin. The nonsulfated mammary GlyCAM 1 is unable to interact with L selectin, consistent with the hypothesis that milk GlyCAM 1 has a different function than endothelial GlyCAM 1. These data thus suggest that milk GlyCAM 1 is a hormonally regulated milk protein that is part of the milk mucin complex. In addition, the finding that the mammary form of GlyCAM 1 contains different carbohydrate modifications than the endothelial form suggests that this glycoprotein may be a scaffold for carbohydrates that mediate functions in addition to cell adhesion.     

Signal-regulatory protein is selectively expressed by myeloid and neuronal cells

Signal-regulatory proteins (SIRP) are transmembrane glycoproteins with three extracellular Ig-like domains, closely related to Ag receptors Ig, TCR, and MHC, and a cytoplasmic domain with two immunoreceptor with tyrosine-based inhibition motifs that can interact with src homology 2 domain-containing phosphatases. SIRP have previously been shown to inhibit signaling through receptor tyrosine kinases, but their physiologic function is unknown. Here we demonstrate by expression cloning that the mAbs ED9, ED17, and MRC-OX41 recognize rat SIRP. In addition, we show for the first time that rat SIRP is selectively expressed by myeloid cells (macrophages, monocytes, granulocytes, dendritic cells) and neurons. Moreover, SIRP ligation induces nitric oxide production by macrophages. This implicates SIRP as a putative recognition/signaling receptor in both immune and nervous systems.     

Human GBF1 is a ubiquitously expressed gene of the sec7 domain family mapping to 10q24

True recurrence of anti-glomerular basement membrane (anti-GBM) nephritis is very rare, both in native kidneys and after renal transplantation. We report the recurrence of fulminant anti-GBM nephritis in a kidney graft recipient after the spontaneous withdrawal of immunosuppressive treatment more than 5 years after renal transplantation. The initial episode of anti-GBM nephritis had destroyed the native kidneys 7 years earlier. Circulating anti-GBM antibodies had disappeared for 14 months at the time of transplantation and reappeared with recurrence. This observation challenges the concept of anti-GBM nephritis as a single-shot illness and emphasises the need to consider the possibility of recurrence, even in the long term, among patients who underwent transplantation for anti-GBM nephritis.     

A homolog of the mammalian GTPase Rab2 is present in Arabidopsis and is expressed predominantly in pollen grains and seedlings

Vesicle traffic between the endoplasmic reticulum and the Golgi apparatus in mammals requires the small GTP-binding protein Rab2, but Saccharomyces cerevisiae appears not to have a Rab2 homolog. Here it is shown that the higher plant, Arabidopsis thaliana, contains a gene, At-RAB2, whose predicted product shares 79% identity with human Rab2 protein. Transgenic plants containing fusions between beta-glucuronidase and sequences upstream of At-RAB2 demonstrated histochemical staining predominantly in maturing pollen and rapidly growing organs of germinating seedlings. beta-glucuronidase activity in pollen is first detectable at microspore mitosis and increases thereafter. In this respect, the promoter of At-RAB2 behaves like those of class II pollen-specific genes, whose products are often required after germination for pollen tube growth. Seedling germination and pollen tube growth are notable for their unusually high rates of cell wall and membrane biosynthesis. These results are consistent with a role for At-RAB2 in secretory activity.     

A microtubule-associated protein in maize is expressed during phytochrome-induced cell elongation

Plants can adapt their shape to environmental stimuli. This response is mediated by the reorganization of cortical microtubules, a unique element of the cytoskeleton. However, the molecular base of this response has remained obscure so far. In an attempt to solve this problem, signal-dependent changes in the pattern of microtubule-binding proteins were analysed during coleoptile elongation in maize, that is, under the control of the plant photoreceptor phytochrome. Two putative MAPs of 100 kDa (P100) and 50 kDa apparent molecular weights were identified in cytosolic extracts from non-elongating and elongating cells. Both proteins co-assembled with endogenous tubulin, bound to neurotubules and were immunologically related to the neural MAP tau: the P100 protein, depending on the physiological situation, was manifest as a double band and was always found to be heat-stable. In contrast, the 50 kDa MAP was heat-stable only for particular tissues and physiological treatments. The P100 protein was present in all tissues, however in a reduced amount in elongating coleoptiles. The 50 kDa MAP was expressed exclusively upon induction of phytochrome-dependent cell elongation. As shown by immunofluorescence double-staining, an epitope shared by both proteins colocalized with cortical microtubules in situ, but exclusively in elongating cells. In non-elongating cells, only the nuclei were stained. Partially purified nuclei from elongating cells were enriched in P100, whereas the 50 kDa MAP became enriched in a partially purified plasma membrane fraction.     

A distinct cyclin A is expressed in germ cells in the mouse

We have shown previously that a novel cell cycle-regulated histone H1 kinase activity, retinoblastoma kinase (RbK), associates with and phosphorylates the amino terminus of the Rb protein in G2-M. We have shown also that the amino terminus of p107, a Rb-related protein, does not associate with a similar kinase in vitro or in vivo. Here, we report that a RbK-like kinase associates with the amino terminus of p130, another Rb-related protein, only marginally. Moreover, the association of RbK with Rb in vitro is shown to require a discrete portion of the Rb amino terminus, amino acids 89-202. This region has been shown previously to be subject to inactivating mutations in retinoblastoma and to be required for Rb-mediated growth suppression in vitro. Taken together, these data indicate that the formation of Rb-RbK complexes may play an important role in Rb-mediated growth suppression. We have mapped two in vitro sites of Rb phosphorylation by RbK to sites that are phosphorylated in vivo and are targets of cyclin-dependent kinase phosphorylation in vitro. As such, at least some sites of RbK phosphorylation overlap with those of other proline-directed serine and threonine kinases. Consistent with this latter observation, we report that the trans-activation domain of c-myc is phosphorylated specifically by RbK in vitro at a site (serine 62) that is phosphorylated in vivo during G2-M, cell-cycle phases in which RbK activity is maximal.     

Overexpression of protein kinase C epsilon is oncogenic in rat colonic epithelial cells

Multidrug resistance gene (mdrl) expression is associated with a poor prognosis in acute myelocytic leukaemia (AML). Whether expression of the recently described multidrug resistance-associated gene (mrp) has any prognostic importance in AML is still unclear. The aim of the present study was to investigate the functional role of the mdr1 and mrp mRNA levels in peripheral leukaemic cell populations from patients with AML. Peripheral leukaemic cells from 10 patients with AML were incubated with daunorubicin (DNR). Cellular DNR content was analysed with a fluorescence-activated cell sorter (FACS). From each cell population the 20-25% cells with the lowest and highest DNR content were sorted out, and mdr1 and mrp RNA were quantified in these subpopulations with competitive polymerase chain reaction. The ratio between the mean DNR content in the cell populations with high and low DNR content varied between 1.9 and 6.6. the cell fraction with low DNR content had higher (3.8-40 times)mdr1 mRNA levels in 10/10 patients and higher (1.4-26 times) mrp mRNA levels in 8/10, as compared to the cell fraction with high DNR accumulation. In conclusion, mdr1 and mrp mRNA expressions are heterogenous in leukaemic cell populations from patients with AML. The mdr1 expression, and to some extent mrp expression, is inversely correlated to DNR accumulation in vitro.     

A soluble form of Wnt-1 protein with mitogenic activity on mammary epithelial cells

The proto-oncogene Wnt-1 plays an essential role in fetal brain development and causes hyperplasia and tumorigenesis when activated ectopically in the mouse mammary gland. When expressed in certain mammary epithelial cell lines, the gene causes morphological transformation and excess cell proliferation at confluence. Like other members of the mammalian Wnt family, Wnt-1 encodes secretory glycoproteins which have been detected in association with the extracellular matrix or cell surface but which have not previously been found in a soluble or biologically active form. We show here that conditioned medium harvested from a mammary cell line expressing Wnt-1 contains soluble Wnt-1 protein and induces mitogenesis and transformation of mammary target cells. By immunodepletion of medium containing epitope-tagged Wnt-1, we show that at least 60% of this activity is specifically dependent on Wnt-1 protein. These results provide the first demonstration that a mammalian Wnt protein can act as a diffusible extracellular signaling factor.