Identification of regulatory sequences in the promoter of the PDGF B-chain gene in malignant mesothelioma cell lines

Platelet-derived growth factor (PDGF) B-chain mRNA is readily detectable in malignant mesothelioma (MM) cell lines, but not in normal mesothelial (NM) cell lines. The high affinity receptor for PDGF B-chain dimers, the PDGF beta-receptor, is expressed in MM cell lines. NM cell lines predominantly express the PDGF alpha-receptor. Coexpression of the PDGF beta-receptor and its ligand may lead to an autocrine growth stimulating loop in the malignant cell type. In nuclear run off experiments, PDGF B-chain mRNA was detectable in MM cells only, indicating an increased level of transcription in this cell type. The proximal promoter of the PDGF B-chain gene contains DNaseI hypersensitive (DH) sites and mediates reporter gene activation in both normal and malignant cells. Nuclear proteins, extracted from both cell types, interact with DNA sequences within the proximal promoter around bp-64 to -61 relative to the transcription start site. Electrophoretic mobility shift assays (EMSAs) indicate that these factors are more abundantly present in the malignant than in the normal cell type. A DH site around -9.9 kb was found in both cell types. When tested in CAT assays, this region exerted a stimulatory effect on transcription in malignant cells. The elevated level of transcription of the PDGF B-chain gene in malignant cells may well be the result of interaction of regulatory sites in the proximal promoter and an enhancing element located at -9.9 kb from the transcription start site.

Crosses of NOD mice with the related NON strain. A polygenic model for IDDM

Chromosome locations of non-major histocompatibility complex (MHC) genes contributing to insulin-dependent diabetes mellitus (IDDM) in mice have been determined by outcrossing NOD mice to other inbred strains congenic for the NOD MHC haplotype (H2g7). At least nine non-MHC IDDM susceptibility genes (Idd) were previously identified at first backcross (BC1) after outcross of NOD to C57BL/10.H2g7 congenic mice (B10.H2g7). We investigated whether the same set of Idd loci segregated with IDDM susceptibility after outcross of NOD to NON.H2g7 congenic mice. Since the outcrosses to NON.H2g7 and B10.H2g7 were performed in the same vivarium, direct comparisons were made of the chromosomal locations and relative strengths of Idd alleles in diabetic progeny from the two different outcrosses. In comparison with the NOD x B10.H2g7 outcross, the NOD x NON.H2g7 outcross produced significantly higher IDDM frequencies in F1, F2, and BC1 generations. The high F2 diabetes frequency allowed evaluation of the effects of homozygous expression of both the susceptibility and the resistance allele at Idd loci. This analysis demonstrated that no single non-MHC Idd locus was essential for the onset of diabetes in this cross. After outcross to NON.H2g7, Idd4 (chromosome [Chr] 11), Idd5 (Chr 1), and Idd8 (Chr 14) did not segregate with IDDM in either the BC1 or the F2 generation. Diabetogenic NOD-derived alleles at Idd2 (Chr 9), Idd3 (Chr 3), and Idd10 (Chr 3) were segregating in the BC1. An NON-derived allele contributing to susceptibility on Chr 7 (Idd7) was also detected. Dominant traits, detectable only in the F2 cross, were encoded by Chr 4 (Idd9) and two newly mapped loci on Chr 13 (Idd14) and 5 (Idd15). A third dominant trait was encoded by Chr 6 (possibly Idd6), but here, in contrast to Idd9, Idd14, and Idd15, the NON allele was diabetogenic. Stepwise logistic regression analysis of the BC1 and F2 data confirmed that the ability to identify certainty of the non-MHC Idd loci was contingent on the extent of homozygosity for NOD background genes. This study shows that the diabetogenic phenotype can be achieved through the actions of variable combinations of MHC-unlinked genes and a diabetogenic MHC haplotype.

Mapping the diabetes polygene Idd3 on mouse chromosome 3 by use of novel congenic strains

Development of novel congenic mouse strains has allowed us to better define the location of the diabetogenic locus, Idd3, on Chromosome (Chr) 3. Congenic strains were identified by use of published and newly developed microsatellite markers, their genomes fingerprinted by a rapid, fluorescence-based approach, and their susceptibility to type 1 diabetes evaluated. The maximum interval containing Idd3 is now approximately 4 cM.

Human adipocyte apoptosis occurs in malignancy

Rapid weight loss is frequently seen in malignancy. This weight loss is considered to result from enhanced lipolysis. Here, we show that adipocyte deletion by apoptosis, demonstrated by electron microscopy and DNA gel electrophoresis, occurs in some patients. Adipocyte apoptosis could not be demonstrated in patients without malignancy. These findings suggest that fat cell loss by apoptosis plays a role in malignancy-associated weight loss.

Resistance alleles at two non-major histocompatibility complex-linked insulin-dependent diabetes loci on chromosome 3, Idd3 and Idd10, protect nonobese diabetic mice from diabetes

Development of diabetes in NOD mice is polygenic and dependent on both major histocompatibility complex (MHC)-linked and non-MHC-linked insulin-dependent diabetes (Idd) genes. In (F1 x NOD) backcross analyses using the B10.H-2g7 or B6.PL-Thy1a strains as the outcross partner, we previously identified several non-MHC Idd loci, including two located on chromosome 3 (Idd3 and Idd10). In the current study, we report that protection from diabetes is observed in NOD congenic strains having B6.PL-Thy1a- or B10-derived alleles at Idd3 or Idd10. It is important to note that only partial protection is provided by two doses of the resistance allele at either Idd3 or Idd10. However, nearly complete protection from diabetes is achieved when resistance alleles are expressed at both loci. Development of these congenic strains has allowed Idd3 to be localized between Glut2 and D3Mit6, close to the Il2 locus.

Insulin gene region-encoded susceptibility to type 1 diabetes is not restricted to HLA-DR4-positive individuals

Type 1 or insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease of the insulin-producing pancreatic beta-cells which is determined by both genetic and environmental factors. The major histocompatibility complex and the insulin gene region (INS) on human chromosomes 6p and 11p, respectively, contain susceptibility genes. Using a mostly French data set, evidence for linkage of INS to IDDM was recently obtained but only in male meioses (suggesting involvement of maternal imprinting) and only in HLA-DR4-positive diabetics. In contrast, we find evidence for linkage in both male and female meioses and that the effect of the susceptibility gene(s) in the INS region is not dependent on the presence of HLA-DR4.

Apoptosis of human adipocytes in vitro

Large increases in fat stores involve an increase in adipocyte number via the replication and differentiation of preadipocytes, with the resultant cell gain widely regarded as irreversible. To date, there has been no clearly defined process or mechanism reported by which adipocyte deletion may occur. Here, we show that human adipocytes undergo apoptosis following growth factor deprivation or mild heat injury in vitro, thus demonstrating a cellular mechanism by which normal adipocyte loss could occur in vivo. The findings have implications for the understanding of adipose tissue kinetics and its derangement as well as for the potential development of methods for modifying fat store size.

Polygenic control of autoimmune diabetes in nonobese diabetic mice

Partial exclusion mapping of the nonobese (NOD) diabetic mouse genome has shown linkage of diabetes to at least five different chromosomes. We have now excluded almost all of the genome for the presence of susceptibility genes with fully recessive effects and have obtained evidence of linkage of ten distinct loci to diabetes or the prediabetic lesion, insulitis, indicative of a polygenic mode of inheritance. The relative importance of these loci and their interactions have been assessed using a new application of multiple polychotomous regression methods. A candidate disease gene, interleukin-2 (Il-2), which is closely linked to insulitis and diabetes, is shown to have a different sequence in NOD, including an insertion and a deletion of tandem repeat sequences which encode amino acid repeats in the mature protein.

Linkage on chromosome 3 of autoimmune diabetes and defective Fc receptor for IgG in NOD mice

A congenic, non-obese diabetic (NOD) mouse strain that contains a segment of chromosome 3 from the diabetes-resistant mouse strain B6.PL-Thy-1a was less susceptible to diabetes than NOD mice. A fully penetrant immunological defect also mapped to this segment, which encodes the high-affinity Fc receptor for immunoglobulin G (IgG), Fc gamma RI. The NOD Fcgr1 allele, which results in a deletion of the cytoplasmic tail, caused a 73 percent reduction in the turnover of cell surface receptor-antibody complexes. The development of congenic strains and the characterization of Mendelian traits that are specific to the disease phenotype demonstrate the feasibility of dissecting the pathophysiology of complex, non-Mendelian diseases.

Adrenocorticotropic hormone-secreting pituitary tumor associated with pregnancy: case report

A patient with an adrenocorticotropic hormone-secreting pituitary adenoma diagnosed at the same time as pregnancy is reported. Treatment was by transsphenoidal tumor resection, which has only been described once previously in such a case. Treatment rationale is discussed, and transsphenoidal tumor resection is recommended as the therapy of choice.

Type 1 diabetes in mice is linked to the interleukin-1 receptor and Lsh/Ity/Bcg genes on chromosome 1

Human type 1 (insulin-dependent) diabetes is a common auto-immune disease of the insulin-producing beta cells of the pancreas which is caused by both genetic and environmental factors. Several features of the genetics and immunopathology of diabetes in nonobese diabetic (NOD) mice are shared with the human disease. Of the three diabetes-susceptibility genes, Idd-1 -3 and -4 that have been mapped in mice to date, only in the case of Idd-1 is there any evidence for the identity of the gene product: allelic variation within the murine immune response I-A beta gene and its human homologue HLA-DQB1 correlates with susceptibility, implying that I-A beta is a component of Idd-1. We report here the mapping of Idd-5 to the proximal region of mouse chromosome 1. This region contains at least two candidate susceptibility genes, the interleukin-1 receptor gene and Lsh/Ity/Bcg, which encodes resistance to bacterial and parasitic infections and affects the function of macrophages.

Genetic variation within and between lines of diabetes-prone and non-diabetes-prone BB rats; allele distribution of 8 protein markers

Twenty-four inbred and 2 outbred lines of the BB rat have been genetically characterized by establishing the allele distribution of 8 monogenic protein markers. The marker genes are: plasma alkaline phosphatase-1 (Alp-1), catalase-1 (Cs-1), carboxylesterases (Es-1, Es-2, Es-14), glyoxalase I (Glo-1), group specific component (Gc), and haemoglobin-beta-chain (Hbb). At least 3 linkage groups are represented by this set of markers. Genetic variation was found both within and between lines. Within-line variation was observed in 4 lines, including the 2 outbred lines. The other 22 lines could be subdivided into 4 groups, each representing a unique allele distribution pattern.

Genetic analysis of autoimmune type 1 diabetes mellitus in mice

Two genes, Idd-3 and Idd-4, that influence the onset of autoimmune type 1 diabetes in the nonobese diabetic mouse have been located on chromosomes 3 and 11, outside the chromosome 17 major histocompatibility complex. A genetic map of the mouse genome, analysed using the polymerase chain reaction, has been assembled specifically for the study. On the basis of comparative maps of the mouse and human genomes, the homologue of Idd-3 may reside on human chromosomes 1 or 4 and Idd-4 on chromosome 17.

Additional microsatellite markers for mouse genome mapping

Mouse sequence information from the EMBL and GenBank databases, published sequences and genomic clones have been analyzed for simple repetitive elements or microsatellites. Each microsatellite has been amplified by the polymerase chain reaction (PCR) as a single locus marker. PCR primers were designed from unique sequence flanking each repeat. Size variation of PCR products less than 750 base pairs (bp) between mouse strains has been determined using ethidium bromide-stained acrylamide or agarose gels. A further 74 newly characterized microsatellites are presented in this paper, bringing to 185 the total we have analyzed. Of these, 157/185 (85%) have more than one allele, 143/178 (80%) vary in length between C57BL/6J and Mus spretus, and 82/168 (49%) vary between DBA/2J and C57BL/6J. Microsatellites provide informative single locus probes for linkage analysis in the construction of a genetic map of the mouse genome.

A comparative study of apolipoproteins in mouse and rat

1. Apolipoproteins isolated from plasma samples of 10 inbred strains of mice and 17 inbred strains of rats were subjected to isoelectric focusing and second-dimension-pore-gradient-SDS-electrophoresis. 2. All major HDL apolipoproteins could be identified by their isoelectric point and mol. wt. 3. In inbred strains of mice polymorphism could be demonstrated for apo A-I and apo A-II. 4. In inbred strains of rats no apolipoprotein polymorphism could be demonstrated.

A successful technique for the preservation of rabbit embryos

A technique for successfully freezing, thawing and transferring rabbit embryos has been developed. Morula stage embryos were collected from super-ovulated female rabbits by flushing both oviducts and uterine horns with a tissue culture medium. Well developed, viable embryos were then transferred to freezing vials and a cryoprotectant, dimethyl sulfoxide (DMSO) was added in several steps to bring its final concentration to 1.6 molar. To freeze the embryos the temperature was lowered slowly (either 0.5 degrees C/min or 1.0 degrees C/min) to -80 degrees C at which point the vials were transferred directly to liquid nitrogen (-196 degrees C). Thawing was done at 8 degrees C/min. After thawing, phosphate buffered saline was added in a stepwise manner to dilute the DMSO. The thawed embryos were then cultured at 37 degrees C. Transfer of the embryos was accomplished by laparotomizing a pseudopregnant doe and introducing the embryos into the fimbriated ends of the oviducts. The 101 positively transferred embryos resulted in 45 implantations and 34 live born young.

Meiotic behavior of alloxan-treated diabetic and nondiabetic T(;13)70H/+ mice

The influence of diabetes on first meiotic segregation behavior in female and male T(1;13)70H/+ mice was studied. By treatment with alloxan 60 mg/kg bodyweight both diabetic and non-diabetic control mice were obtained. All female mice were treated with gonadotropins to obtain reasonable numbers of secondary oocytes per female. As a result of this treatment the number of oocytes ovulated and the percentage that could be analyzed were not different in diabetics and controls, indicating that no severe selection occurred as a result of the diabetic state. Male mice were not treated with gonadotropins, and here the low quality of the air-dried preparations and the scarcity of secondary spermatocytes in diabetics suggest that degeneration occurs. In primary spermatocytes we found higher chiasma frequencies in the translocation multivalent in diabetic males than in controls, probably as a result of reduced chiasma terminalization. The analysis of metaphase-II cells in the females revealed less 3:1 segregation and more adjacent-II segregation in the diabetics. In the males no 3:1 segregation was found in either group, but here adjacent-II segregation was lower in diabetics than in controls. No significant differences were found in nondisjunction frequencies of non-translocation-involved bivalents. We conclude that diabetes influences the meiotic segregation behavior of chromosomes and that chromosomes showing higher incidences of unbalanced segregation behavior (i.e., multivalent involved chromosomes) are more susceptible to this influence than other chromosomes. In the diabetic males this influence is undone by the severe selection, affecting primarily the cells, that would give rise to unbalanced metaphase II cells, resulting in even lower frequencies of adjacent-II segregation than in controls.