Peg5/Neuronatin is an imprinted gene located on sub-distal chromosome 2 in the mouse

We have established a systematic screen for imprinted genes using a subtraction-hybridization method with day 8.5 fertilized and parthenogenetic embryos. Two novel imprinted genes, Peg1/Mest and Peg3, were identified previously by this method, along with the two known imprinted genes, Igf2 and Snrpn. Recently three additional candidate imprinted genes, Peg5-7 , were detected and Peg5 is analyzed further in this study. The cDNA sequence of Peg5 is identical to Neuronatin, a gene recently reported to be expressed mainly in the brain. Two novel spliced forms were detected with some additional sequence in the middle of the known Neuronatin sequences. All alternatively spliced forms of Peg5 were expressed only from the paternal allele, confirmed using DNA polymorphism in a subinterspecific cross. Peg5/Neuronatin maps to sub-distal Chr 2, proximal to the previously established imprinted region where imprinted genes cause abnormal shape and behavior in neonates.     

Murine Stim1 maps to distal chromosome 7 and is not imprinted

STIM1 (GOK) maps to a region of human Chromosome (Chr) 11p15.5 that is implicated in several embryonal tumors, and some evidence indicates that STIM1 may have a growth suppressor role in rhabdomyosarcoma. In this study we have mapped the murine homolog, Stim1, to the same position as Hbb on distal mouse Chr 7. This region is separated by 20 cM from the region of distal Chr 7 that contains Igf2, H19, and other imprinted genes. Using strain-specific polymorphisms, we have shown that Stim1 is expressed from both parental alleles in fetal and neonatal mouse tissues. Similar analyses of human Wilms' tumor and normal kidney tissues demonstrated biallelic expression of STIM1 in the majority of samples. These data demonstrate that Stim1 expression is not regulated by genomic imprinting in either mouse or human tissues. Thus, if STIM1 is a tumor suppressor at 11p15.5, loss of expression is not due to imprinting effects.     

Further evidence for an imprinted gene for neonatal diabetes localised to chromosome 6q22-q23

Transient neonatal diabetes mellitus (TNDM) is a rare form of childhood diabetes which usually resolves in the first 6 months of life but which predisposes to type 2 diabetes of adult onset. We recently reported paternal uniparental isodisomy of chromosome 6 (UPD6) in two children with TNDM and proposed that there may be an imprinted gene important in the aetiology of diabetes on chromosome 6. We now describe two unrelated families which independently suggest that the gene is imprinted, is paternally expressed and maps to 6q22-q23. One family has a duplication while the other, with familial TNDM, shows linkage to a marker in this region.     

Refined mapping of the psoriasin gene S100A7 to chromosome 1cen-q21

Psoriasin is a low molecular weight protein of the S100 family, which is highly upregulated in psoriatic epidermis, and whose function is related to skin inflammatory responses. We have applied a cDNA probe from the corresponding psoriasin gene S100A7 in a refined localisation analysis. S100A7 was mapped physically by human/rodent somatic cell hybrid analysis, and more precisely genetically by multilocus linkage analysis of 40 CEPH (Centre d'Etude du Polymorphisme Humain) families. The resulting 12-point linkage map was supported by odds of at least 1000:1, where S100A7 could be placed with a multipoint lodscore of 27.4 in an approximately 7-cM interval. The order of the 12 loci was as follows (with the best estimates of recombination frequencies given in between): AMY2B-0.091-D1S73(0.039)-D1S11(-0.053)-D1S189(-0 .017)-D1S1252 (-0.017)-D1S13(-0.078)-D1Z5(-0.051)-S100A7(-0.022)- MUC1(-0.026)-SPTA1 (-0.066)-ATP1A2(-0.014)-APOA2. Furthermore, from this map S100A7 could be assigned to the regional position of chromosome 1cen-q21. The linkage information presented should be of great value in association and linkage studies of diseases where psoriasin, or some of the several other very closely linked and functionally related genes, are seen as candidate genes, e.g. in psoriasis.     

Mouse U2af1-rs1 is a neomorphic imprinted gene

The mouse U2af1-rs1 gene is an endogenous imprinted gene on the proximal region of chromosome 11. This gene is transcribed exclusively from the unmethylated paternal allele, while the methylated maternal allele is silent. An analysis of genome structure of this gene revealed that the whole gene is located in an intron of the Murr1 gene. Although none of the three human U2af1-related genes have been mapped to chromosome 2, the human homolog of Murr1 is assigned to chromosome 2. The mouse Murr1 gene is transcribed biallelically, and therefore it is not imprinted in neonatal mice. Allele-specific methylation is limited to a region around U2af1-rs1 in an intron of Murr1. These results suggest that in chromosomal homology and genomic imprinting, the U2af1-rs1 gene is distinct from the genome region surrounding it. We have proposed the neomorphic origin of the U2af1-rs1 gene by retrotransposition and the particular mechanism of genomic imprinting of ectopic genes.     

Human high affinity, Na(+)-dependent L-glutamate/L-aspartate transporter GLAST-1 (EAAT-1): gene structure and localization to chromosome 5p11-p12

Controversies remain over which ion channels are the most sensitive to ethanol. We have found that ethanol potently modulates the neuronal nicotinic acetylcholine receptor-channel at micromolar concentrations with an EC50 of 88.5 microM, which is significantly lower than most values previously reported for other ion channels. Prolonged application of ethanol accelerated the decay phase of acetylcholine-induced currents, caused single-channels to open in bursts, and shortened the mean open time, all of which reflect increased receptor desensitization. However, ethanol slowed the decay phase of the current induced by a brief application of acetylcholine, which may indicate that ethanol manifests its action by causing an increase in the affinity of the receptor for acetylcholine. These results suggest that neuronal nicotinic acetylcholine receptors may be important target sites of ethanol, particularly in the early stages of ethanol intoxication.     

The gene encoding LERK-7 (EPLG7, Epl7), a ligand for the Eph-related receptor tyrosine kinases, maps to human chromosome 5 at band q21 and to mouse chromosome 17

The human uterine glandular epithelium undergoes a sequence of well characterized changes during the menstrual cycle that presumably play an important role in preparation for blastocyst implantation. The aim of this study was to measure objectively glandular volume over the entire menstrual cycle and compare the results with eight different clinical superovulation or hormone replacement therapy (HRT) subject groups. Endometrial biopsies were taken from control normal menstrual cycle subjects (n = 96), and eight other smaller groups of women who had received different in-vitro fertilization (IVF) related treatments. The total area of glandular epithelium was objectively measured from routine histological slides using computerized image analysis. Control menstrual cycle results showed a significantly greater gland area in the early secretory stage of the cycle than at any time between the early proliferative through to the mid-late proliferative stages (P < 0.05). IVF patients receiving clomiphene citrate and human menopausal gonadotrophin had a significantly smaller glandular area than those in the control groups at equivalent stages of the menstrual cycle. The use of progesterone supplementation removed this significant difference. Patients on the ?Flare' regime had the highest gland area, although this was not significantly different from controls. Buserelin down-regulation gave a gland area that was closest to the normal cycle controls. The three HRT groups showed high variability in gland volume between patients. The results from this study demonstrate that superovulation can cause significant alterations in endometrial gland volume, but that these do not necessarily preclude implantation.     

Inactivation of H19, an imprinted and putative tumor repressor gene, is a preneoplastic event during Wilms' tumorigenesis

Genetic evidence shows that the parent of origin-dependent expression patterns of the Igf2 and H19 genes is coordinated in mouse, such that H19 controls the activity of Igf2 in cis. Equally compelling evidence for a similar situation in humans is absent, although the frequently observed activation of the maternal IGF2 allele (ie., loss of imprinting) in Wilms' tumors has been attributed to the silencing of the maternal H19 locus. We show here that loss of H19 activity is generally a preneoplastic event, which may be linked with an overgrowth lesion that has been proposed to be permissive for tumor formation. Although our results document one instance in which a postneoplastic loss of H19 activity correlates with loss of IGF2 imprinting at the cellular level, it appears that inactivation of H19 is more generally independent of loss of imprinting of IGF2, at least in our specimens. Our results imply that inactivation of H19 correlates with blastema overgrowth and can be independent of a regulatory role with respect to IGF2 imprinting status in cis.     

The human growth factor-inducible immediate early gene, CYR61, maps to chromosome 1p

Complementary DNA encoding the human CYR61 protein was isolated from human embryonic tissues and mapped to chromosome 1p22-p31. We show that CYR61 encodes a 381 amino acid protein rich in cysteine and proline residues that is strongly conserved with the mouse homologue. Sequence analysis reveals the presence of several distinct protein domains which confer a mosaic structure to this protein and makes human CYR61 a member of a recently described growth regulator family that includes several proto-oncogene products. From our results we hypothesize that this new immediate early gene may play a role in cell commitment during embryogenesis and more generally in the control of cell proliferation.     

Assignment of the human connexin43 gene, GJA1, to chromosome 6q22.3

Metabolism is probably disturbed in patients with abnormal liver function who have undergone a successful Kasai procedure. We examined bone mineral metabolism in patients who have successfully undergone Kasai procedure. Bone mineral metabolism was examined in 8 patients with biliary atresia after a successful Kasai procedure. Five patients were female and 3 were male. The ages at Kasai procedure ranged from 50 to 80 days, and the follow-up periods ranged from 3 to 27 years after the operation. All patients eat a normal oral diet. We examined plasma levels of 25-OH-D3, 1, 25-(OH)2-D3, Ca and phosphorus (P). Bone mineral content of the lumbar spine (L2-L4) was assessed by dual energy x-ray absorptiometry (DEXA), and the data were expressed as a bone mineral density (BMD). Two patients showed abnormal levels on hepatic function tests. Plasma levels of 1, 25-(OH)2-D3, Ca, and P were normal in all patients. The level of 25-OH-D3 was normal in 7 patients. BMD levels were normal in 6 patients, but low in 2 who had undergone partial splenic embolization and splenectomy, respectively, due to hypersplenism. In long-term survivors of Kasai procedure, measurement of BMD may detect bone mineral deficiency earlier than measurements of serum levels of 25-OH-D, 1, 25-(OH)2-D, Ca and P.     

Cloning, expression, and chromosome mapping of human galectin-7

The galectins are a family of beta-galactoside-binding proteins implicated in modulating cell-cell and cell-matrix interactions. Here we report the cloning and expression of a novel member of this family (galectin-7) that correspond to IEF (isoelectric focusing) 17 (12,700 Da; pI, 7.6) in the human keratinocyte protein data base, and that is strikingly down-regulated in SV40 transformed keratinocytes (K14). The cDNA was cloned from a lambda gt11 cDNA expression library using degenerated oligodeoxyribonucleotides back-translated from an IEF 17 peptide sequence. The protein encoded by the galectin-7 clone comigrated with IEF 17 as determined by two-dimensional (two-dimensional gel electrophoresis) analysis of proteins expressed by transiently transfected COS-1 cells, and bound lactose. Alignment of the amino acid sequences with other members of the family showed that the amino acids central to the beta-galactoside interaction are conserved. Galectin-7 was partially externalized to the medium by keratinocytes although it has no typical secretion signal peptide. Immunoblotting as well as immunofluorescence analysis of human tissues with a specific galectin-7 antibody revealed a narrow distribution of the protein which was found mainly in stratified squamous epithelium. The antigen localized to basal keratinocytes, although it was also found, albeit at lower levels, in the suprabasal layers where it concentrated to areas of cell to cell contact. Both, its cellular localization as well as its striking down-regulation in K14 keratinocytes imply a role in cell-cell and/or cell-matrix interactions necessary for normal growth control. The galectin-7 gene was mapped to chromosome 19.