Induction of lipolysis in murine white adipocytes, and stimulation of adenylate cyclase in adipocyte plasma membranes, by a tumour-produced lipid mobilizing factor, was attenuated by low concentrations (10 77 -10 75 M) of the specific b3-adrenoceptor antagonist SR59230A. Lipid mobilizing factor (250 nM) produced comparable increases in intracellular cyclic AMP in CHOK1 cells transfected with the human b3-adrenoceptor to that obtained with isoprenaline (1 nM). In both cases cyclic AMP production was attenuated by SR59230A confirming that the effect is mediated through a b3-adrenoceptor. A non-linear regression analysis of binding of lipid mobilizing factor to the b3-adrenoceptor showed a high affinity binding site with a Kd value 78+45 nM and a B max value (282+1 fmole mg protein 71 ) comparable with that of other b3-adrenoceptor agonists. These results suggest that lipid mobilizing factor induces lipolysis through binding to a b3-adrenoceptor.
Granulated metrial gland (GMG) cells are a major immune cell population in the murine pregnant uterus, and contribute to the maintenance of pregnancy by functioning as uterus-specific natural killer (NK) cells. In order to reveal their kinetics, activation, and functional roles in pregnancy, we conducted quantitative and immunohistochemical analyses in normal and immuno-modulator-treated mice. Under a light microscope, GMG cells were identified by red cytoplasmic granules in periodic-acid-Schiff (PAS)-stained sections. They progressively increased in number and size with the peak at day 12-14 of pregnancy in the decidua and metrial gland. New vessel formation was most prominent around day 8, and the total vascular area reached the peak at day 13. GMG cells were often located near the blood vessels, and expressed vascular endothelial growth factor (VEGF), suggesting their possible inducing role in angiogenesis during the development of decidua/metrial gland. While blood vessels in the non-pregnant uterus were negative for vascular cell adhesion molecule (VCAM)-1, those in the pregnant one were positive. Treatment with neutralizing antibody against VCAM-1, however, did not decrease the number of GMG cells. On the other hand, mitosis of GMG cells was frequently observed. These data suggest that the increment of GMG cells during pregnancy may largely result from local proliferation in the uterus rather than an increased influx of precursor cells. Although we attempted to induce in vivo activation of GMG cells by administration of interleukin-12 (IL-12) or alpha-galactosylceramide, a potent activator for natural killer-T (NK-T) cells, the number of GMG cells did not appreciably increase. The present study has demonstrated that GMG cells locally proliferate in the pregnant uterus, not being related to VCAM-1 expression by the uterine vasculature or systemic activation of NK cells and NK-T cells, and seem to be involved in angiogenesis in the pregnant uterus through VEGF production.
The CD45 antigen is a haemopoietic cell specific tyrosine phosphatase essential for antigen receptor mediated signalling in lymphocytes. Expression of different patterns of alternatively spliced CD45 isoforms is associated with distinct functions. We recently identified a polymorphism in exon 6 (A138G) of the gene encoding CD45 (PTPRC) that results in altered CD45 splicing. The 138G allele is present at a high frequency among Japanese (23.7%), with 5.1% individuals homozygous for the G allele. In this study we show that the A138G polymorphism is the cause of altered CD45 isoform expression, promoting splicing towards low molecular weight CD45 isoforms. We further report that the frequency of A138G heterozygotes is significantly reduced in number in cohorts of patients with autoimmune Graves' disease or hepatitis B infection, whereas G138G homozygotes are absent from a cohort of Hashimoto's thyroiditis patients. We also show that 138G individuals exhibit altered cytokine production in vitro and an increased proportion of memory T cells. These data suggest that the 138G variant allele strongly influences these diseases by modulation of immune mechanisms and may have achieved its high frequency as a result of a natural selection probably related to pathogen resistance.
Microwave endometrial ablation improves menorrhagia caused by large submucous myomas when the microwave applicator reaches all parts of the uterine cavity.
CD45 (leukocyte common)T he leukocyte common antigen CD45 is an abundant tyrosine phosphatase expressed on all leukocytes (1). The phosphatase activity of CD45 is essential for lymphocyte antigen receptor signal transduction. CD45 can also function as a Janus kinase phosphatase, negatively regulating cytokine receptor signaling (2). Both CD45 knockout mice (3, 4) and humans lacking CD45 expression (5, 6) are severely immunodeficient, with very few peripheral T lymphocytes and impaired T and B cell responses. These studies provide evidence for the crucial role of CD45 in the proper functioning of the immune system. Multiple CD45 isoforms can be generated by alternative splicing of exons 4 (A), 5 (B), and 6 (C) of the extracellular domain (7). CD45 alternative splicing is highly conserved between species and is tightly regulated. In humans, naive T cells express high-molecular-weight CD45 isoforms recognized by CD45RA mAbs. Activation of the cells results in a change of expression to low-molecular-weight isoforms detected by a CD45R0 mAb (8).These two major subsets of T lymphocytes expressing CD45RA and CD45R0 have been termed naive and memory cells. A polymorphism (C77G) in exon 4 of CD45 causing abnormal CD45 splicing has been described in humans (9). Activated or memory lymphocytes in these individuals continue to express both high-CD45RA and low-molecular-weight CD45R0 isoforms, in contrast to the normal pattern of lowmolecular-weight CD45R0 isoform expression. Recently, another point mutation in exon 4 of CD45 (C59A) causing aberrant splicing has been identified, but it appears to be relatively rare (10).The C77G polymorphism and abnormal CD45 splicing have been further linked to the development of multiple sclerosis in German (11) and Italian (12) patient cohorts, although other studies do not support such an association (13,14). We have shown an increased frequency of the C77G variant allele in HIV-1-infected individuals in the United Kingdom (15). All of these observations suggest that abnormal CD45 splicing is associated with altered immunological function, autoimmunity, and viral infections.Here we report a polymorphism in exon 6 A138G in the gene encoding CD45 with a very high prevalence in Japanese and Korean populations. We analyzed the expression of CD45 isoforms in peripheral blood mononuclear cells (PBMC) of individuals homozygous and heterozygous for the A138G variant. Our results show that T cells in individuals carrying the A138G allele display altered cell-surface CD45 isoform expression because of changes in alternative splicing. Analysis of exon 6 A138G and exon 4 C77G variants in different populations showed striking differences in the frequency and distribution of these mutations, suggesting effects of natural selection. Materials and MethodsMaterials. One hundred seventy-five Japanese genomic DNAs were collected from Osaka City University Medical School (Osaka), of which 49 were from patients with malignant gynecological cancer. PBMC were isolated by centrifugation on a Ficoll-Paque (Amers...
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