Pure duplication 21q21.2-->qter due to a rea(21) in a Down syndrome girl. Remarks on nomenclature

We report on an 8-year-old girl with a typical Down syndrome phenotype and a 46,XX,rea(21)(qter-->p12::q21.2-->qter).ish rea(21)(qter-->pl2::q21.2-->qter)(LSI 21++,AML1++) karyotype; the mother had normal chromosomes but the father was unavailable. The great resemblance of the patient's rearranged chromosome to the rec(21)dup(q) from a parental pericentric inversion suggests that it would be better depicted as a recombinant-like chromosome. Altogether, 13 recombinant-like chromosomes of de novo or unknown (parents not karyotyped) origin have been described. Although these rearranged chromosomes should formally be described as derivatives because no parental inversion is identified, we underlie that the unofficial term recombinant-like would be more appropriate because no "multiple aberrations within a single chromosome" (as required by the ISCN) have been proved, not to mention that the term derivative usually designates abnormal chromosomes resulting from a translocation between non homologous chromosomes. Accordingly, we prefer to identify such rearrangements of a single chromosome precisely with the more neutral and sanctioned term rea (expanding its use to designate a rearranged chromosome) coupled with the lengthy description of the abnormal chromosome. We assume that the rea(21) chromosomes result from illegitimate recombination between non allelic homologous LCRs located in both the short and long arms.

Interchange trisomy 21 by t(1;21)(p22;q22)mat

Interchange trisomy 21 by t(1:21)(p22:q22)mat: Interchange trisomy 21 by t(1;21)(p22;q22)mat was identified in a sporadic patient with Down syndrome. With a 21q22 specific probe, we observed signals on both normal 21 chromosomes and on the der. We reviewed the 23 published reports of families with reciprocal translocations leading to viable offspring with interchange trisomy 21. The breakpoints in chromosome 21 were mainly located in 21q (19/24 instances, including the present report) and in 19/23 cases the other chromosome involved in the translocation was <<large>> (pairs 1-12). The underlying 3:1 segregation occurred mainly in carrier mothers; only one patient presented a de novo imbalance and in another case the father was the carrier. In addition, there were 4 instances of concurrence with another unbalanced segregation (adjacent-1 or tertiary trisomy) and 3 families with recurrence of interchange trisomy 21. The mean age of 14 female carriers at birth of interchange trisomy 21 offspring (24.8 yr) was lower that the mean (28.3 yr) found in a larger sample of mothers of unbalanced offspring due to 3:1 segregation (mostly tertiary trisomics) and was not increased with respect to the general population average. Overall, these data agree with previous estimates regarding recurrence risk (9-15%) and abortion rate (about 28%) in female carriers ascertained through an interchange trisomic 21 child.

Rescue of the colony-stimulating factor 1 (CSF-1)-nullizygous mouse (Csf1(op)/Csf1(op)) phenotype with a CSF-1 transgene and identification of sites of local CSF-1 synthesis

Colony-stimulating factor 1 (CSF-1) regulates the survival, proliferation, and differentiation of mononuclear phagocytes. It is expressed as a secreted glycoprotein or proteoglycan found in the circulation or as a biologically active cell-surface glycoprotein. To investigate tissue CSF-1 regulation, CSF-1-null Csf1(op)/Csf1(op) mice expressing transgenes encoding the full-length membrane-spanning CSF-1 precursor driven by 3.13 kilobases of the mouse CSF-1 promoter and first intron were characterized. Transgene expression corrected the gross osteopetrotic, neurologic, weight, tooth, and reproductive defects of Csf1(op)/Csf1(op) mice. Detailed analysis of one transgenic line revealed that circulating CSF-1, tissue macrophage numbers, hematopoietic tissue cellularity, and hematopoietic parameters were normalized. Tissue CSF-1 levels were normal except for elevations in 4 secretory tissues. Skin fibroblasts from the transgenic mice secreted normal amounts of CSF-1 but also expressed some cell-surface CSF-1. Also, lacZ driven by the same promoter/first intron revealed beta-galactosidase expression in hematopoietic, reproductive, and other tissue locations proximal to CSF-1 cellular targets, consistent with local regulation by CSF-1 at these sites. These studies indicate that the 3.13-kilobase promoter/first intron confers essentially normal CSF-1 expression. They also pinpoint new cellular sites of CSF-1 expression, including ovarian granulosa cells, mammary ductal epithelium, testicular Leydig cells, serous acinar cells of salivary gland, Paneth cells of the small intestine, as well as local sites in several other tissues.

The Cbl protooncoprotein stimulates CSF-1 receptor multiubiquitination and endocytosis, and attenuates macrophage proliferation

Colony-stimulating factor-1 (CSF-1) activation of the CSF-1 receptor (CSF-1R) causes Cbl protooncoprotein tyrosine phosphorylation, Cbl-CSF-1R association and their simultaneous multiubiquitination at the plasma membrane. The CSF-1R is then rapidly internalized and degraded, whereas Cbl is deubiquitinated in the cytoplasm without being degraded. We have used primary macrophages from gene-targeted mice to study the role of Cbl. Cbl-/- macrophages form denser colonies and, at limiting CSF-1 concentrations, proliferate faster than Cbl+/+ macrophages. Their CSF-1Rs fail to exhibit multiubiquitination and a second wave of tyrosine phosphorylation previously suggested to be involved in preparation of the CSF-1-CSF-1R complex for endocytosis. Consistent with this result, Cbl-/- macrophage cell surface CSF-1-CSF-1R complexes are internalized more slowly, yet are still lysosomally degraded, and the CSF-1 utilization by Cbl-/- macrophages is reduced approximately 2-fold. Thus, attenuation of proliferation by Cbl is associated with its positive regulation of the coordinated multiubiquitination and endocytosis of the activated CSF-1R, and a reduction in the time that the CSF-1R signals from the cell surface. The results provide a paradigm for studies of the mechanisms underlying Cbl attenuation of proliferative responses induced by ligation of receptor tyrosine kinases.

The effects of colony-stimulating factor-1 on the distribution of mononuclear phagocytes in the developing osteopetrotic mouse

Colony-stimulating factor-1 (CSF-1), the primary regulator of mononuclear phagocyte (Mphi) production, exists as either a circulating or cell surface, membrane-spanning molecule. To establish transplacental transfer of maternal CSF-1, gestational day-17 mothers were injected intravenously with 125I-mouse CSF-1 or human rCSF-1, and the 125I-cpm or human CSF-1 concentrations were measured in fetal tissue, placenta, and fetal/maternal sera. Biologically active CSF-1 crossed the placenta and peaked in fetal tissue, placenta, and serum 10 minutes after injection. The role of CSF-1 in perinatal Mphi development was examined by studying the CSF-1-deficient osteopetrotic (csfmop/csfmop) mouse. Fetal/neonatal mice, derived from matings of either +/csfmop females with csfmop/csfmop males or the reciprocal pairings, were genotyped and tissue Mphi identified and quantified. In the presence of circulating maternal CSF-1 (+/csfmop mother), Mphi development in csfmop/csfmop liver was essentially complete at birth relative to +/csfmop littermates, but significantly reduced in spleen, kidney, and lung. In the absence of circulating maternal CSF-1 (csfmop/csfmop mother), Mphi numbers at birth were reduced in csfmop/csfmop liver relative to the offspring of +/csfmop mothers, but were similar in spleen, kidney, and lung. We conclude that CSF-1 is required for the perinatal development of most Mphi in these tissues. Compensation for total absence of local CSF-1 production by circulating, maternal CSF-1 is tissue-specific and most prominent in liver, the first fetal organ perfused by placental blood. However, because some Mphi developed in the complete absence of CSF-1, other factors must also be involved in the regulation of macrophage development.

A further microchromosome with centromeric association

A 46,XY/47,XY,+mar karyotype was found in a 5-year-old boy with mental retardation and minor dysmorphisms. The marker was present in 68% of lymphocyte metaphases, was about the size of Yp, appeared pale with G- and C-bands and had a single pair of centromeric dots; it was never seen in two or more copies and appeared larger and clearly annular in a few cells. This microchromosome was associated (interchromosomal distance equal to or smaller than 18p) with any other chromosome(s) in 295/344 cells. Among a total of 457 associations, 240 (52%) were centromeric. Such a proportion as well as the mostly random distribution of centromeric associations was similar to 3 previous instances. The paucity of markers with centromeric association may reflect a relative unawareness on the subject but more probable indicates that such a phenomenon is confined to nonsatellited, monocentric and annular microchromosomes.

Effect of the colony-stimulating factor-1 null mutation, osteopetrotic (csfm(op)), on the distribution of macrophages in the male mouse reproductive tract

Macrophages are found throughout the male reproductive tract and its accessory glands. Mice homozygous for a null mutation (csfm(op)) in the gene for the mononuclear phagocytic growth factor colony-stimulating factor-1 (CSF-1) have a significantly lower density of macrophages, defined by the mononuclear phagocytic antigen F4/80, in the testis, cauda and caput epididymis, prostate, seminal vesicles, and vas deferens. These data indicate that CSF-1 is the major growth factor regulating the occurrence of macrophages in male reproductive tissues. The residual macrophages were correctly located in the tissue except in the caput epididymis, where they failed to take up positions adjacent to the tubular epithelium. Restoration of circulating CSF-1 concentrations in csfm(op)/csfm(op) males totally restored F4/80+ cell density in the testis and caput and cauda epididymis and partially restored their density in the vas deferens and seminal vesicles but failed to affect density in the prostate. This failure to correct all populations with circulating CSF-1 suggests the requirement for local synthesis of CSF-1 at appropriate developmental stages and/or its expression in a cell surface-associated form. The absence of macrophages in the testis and epididymis of csfm(op)/csfm(op) mice correlates with dysfunction in these tissues, suggesting that macrophages play important nonimmunological roles in these tissues.

Increased circulating colony-stimulating factor-1 (CSF-1) in SJL/J mice with radiation-induced acute myeloid leukemia (AML) is associated with autocrine regulation of AML cells by CSF-1

The SJL/J mouse strain has a high spontaneous incidence of a B-cell neoplasm, reticulum cell neoplasm type B (RCN B). In addition, following irradiation, 10% to 30% of these mice develop acute myelomonocytic leukemia (radiation-induced acute myeloid leukemia [RI-AML]), an incidence that can be increased to 50% by treatment of the mice with corticosteroids after irradiation. The role played by the mononuclear phagocyte growth factor, colony-stimulating factor-1 (CSF-1), in the development of RI-AML in SJL/J mice was investigated. Mice dying of RI-AML, but not those dying of RCN B or without disease, possessed elevated concentrations of circulating CSF-1. In addition, in mice developing RI-AML with a more prolonged latency, circulating CSF-1 concentrations were increased before overt expression of RI-AML. First-passage tumors from 14 different RI-AMLs all contained high concentrations of CSF-1, and six of six different first- or second-passage tumors expressed the CSF-1 receptor (CSF-1 R). Furthermore, in vitro colony formation by first- or second-passage tumor cells from 20 of 20 different RI-AMLs was blocked by neutralizing anti-CSF-1 antibody, and four of four of these tumors were inhibited by anti-CSF-1R antibody. The results of these antibody neutralization studies, coupled with the observation of elevated circulating CSF-1 in mice developing RI-AML, show an autocrine role for CSF-1 in RI-AML development in SJL/J mice. Southern blot analysis of tumor DNA from six of six of these tumors failed to reveal any rearrangements in the genes for CSF-1 or the CSF-1R. Studies in humans have shown that patients with AML possess elevated levels of circulating CSF-1 and that AML cells can express CSF-1 and the CSF-1R. Thus, RI-AML in the SJL/J mouse appears to be a useful model for human AML.

A heteromorphic protein-tyrosine phosphatase, PTP phi, is regulated by CSF-1 in macrophages

A novel protein-tyrosine phosphatase, PTP phi, was cloned from a murine macrophage cDNA library. As a result of alternative splicing, macrophage PTP phi mRNAs are predicted to encode two membrane-spanning molecules and a cytosolic enzyme with identical catalytic domains. The membrane-spanning forms differ in the juxtamembrane region, while a start codon downstream of this region is utilized in the translation of the putative cytosolic form. Expression of PTP phi mRNA is low and restricted to macrophage cell lines, macrophage-rich tissues, and brain, kidney, and heart. The mRNA in macrophages and heart is approximately 2.8 kilobases (kb). However, a approximately 5.5-kb transcript in brain and kidney indicates a fourth isoform encoding a large extracellular domain. The approximately 5.5-kb PTP phi brain mRNA encodes the mouse homolog of GLEPP1, a recently reported glomerular epithelial protein. The level of expression of the mRNA encoding the cytosolic form was very low, and only the membrane-spanning proteins (43 and 47 kDa) could be detected in macrophages. Following addition of colony stimulating factor-1 to quiescent BAC1.2F5 macrophages, PTP phi mRNA and protein were down-regulated. The restricted expression of the shorter isoforms of PTP phi and their regulation by colony stimulating factor-1 in macrophages suggest that PTP phi may play a role in mononuclear phagocyte survival, proliferation, and/or differentiation.

Role of colony stimulating factor-1 in the establishment and regulation of tissue macrophages during postnatal development of the mouse

Colony stimulating factor-1 (CSF-1) regulates the survival, proliferation and differentiation of mononuclear phagocytes. The osteopetrotic (op/op) mutant mouse is devoid of CSF-1 due to an inactivating mutation in the CSF-1 gene and is deficient in several mononuclear phagocyte subpopulations. To analyze more fully the requirement for CSF-1 in the establishment and maintenance of mononuclear phagocytes, the postnatal development of cells bearing the macrophage marker antigens F4/80 and MOMA-1, in op/op mice and their normal (+/op or +/+) littermates, were studied during the first three months of life. In normal mice, maximum expression of tissue F4/80+ cells was generally correlated with the period of maximum organogenesis and/or cell turnover. Depending on the tissue, the F4/80+ cell density either decreased, transiently increased or gradually increased with age. In op/op mice, tissues that normally contain F4/80+ cells could be classified into those in which F4/80+ cells were absent and those in which the F4/80+ cell densities were either reduced, normal or initially normal then subsequently reduced. To assess which F4/80+ populations were regulated by circulating CSF-1 in normal mice, op/op mice in which the circulating CSF-1 concentration was restored to above normal levels by daily subcutaneous injection of human recombinant CSF-1 from day 3 were analyzed. These studies suggest that circulating CSF-1 exclusively regulates both the F4/80+ cells in the liver, spleen and kidney and the MOMA-1+ metallophilic macrophages in the spleen. Macrophages of the dermis, bladder, bone marrow and salivary gland, together with a subpopulation in the gut, were partially restored by circulating CSF-1, whereas macrophages of the muscle, tendon, periosteum, synovial membrane, adrenals and the macrophages intimately associated with the epithelia of the digestive tract, were not corrected by restoration of circulating CSF-1, suggesting that they are exclusively locally regulated by this growth factor. Langerhans cells, bone marrow monocytes and macrophages of the thymus and lymph nodes were not significantly affected by circulating CSF-1 nor decreased in op/op mice, consistent with their regulation by other growth factors. These results indicate that important differences exist among mononuclear phagocytes in their dependency on CSF-1 and the way in which CSF-1 is presented to them. They also suggest that the prevalent role of CSF-1 is to influence organogenesis and tissue turnover by stimulating the production of tissue macrophages with local trophic and/or scavenger (physiological) functions. Macrophages involved in inflammatory and immune (pathological) responses appear to be dependent on other factors for their ontogenesis and function.(ABSTRACT TRUNCATED AT 400 WORDS)

Mammalian-like differentiation of gastric cells in the shark Hexanchus griseus

Gastric glands of submammalian vertebrates are formed by one single cell type known as the oxyntopeptic cell. This cell secretes both hydrochloric acid and pepsinogen. In mammals, this cell differentiates into an acid secreting cell and a pepsinogen secreting one. In the elasmobranch fish Hexanchus griseus we observed, by means of histological studies at the light- and electron-microscopic levels, two different cell types for the secretion of acid and zymogen. This organization represents an evolutionary divergence in a primitive animal, i.e., the appearance of a feature that is acquired much later in evolution, in mammals.