We report the cDNA cloning and characterization of mouse GATA-4, a new member of the family of zinc finger transcription factors that bind a core GATA motif. GATA-4 cDNA was identified by screening a 6.5-day mouse embryo library with oligonucleotide probes corresponding to a highly conserved region of the finger domains. Like other proteins of the family, GATA-4 is approximately 50 kDa in size and contains two zinc finger domains of the form C-X-N-C-(X17)-C-N-X-C. Cotransfection assays in heterologous cells demonstrate that GATA-4 trans activates reporter constructs containing GATA promoter elements. Northern (RNA) analysis and in situ hybridization show that GATA-4 mRNA is expressed in the heart, intestinal epithelium, primitive endoderm, and gonads. Retinoic acid-induced differentiation of mouse F9 cells into visceral or parietal endoderm is accompanied by increased expression of GATA-4 mRNA and protein. In vitro differentiation of embryonic stem cells into embryoid bodies is also associated with increased GATA-4 expression. We conclude that GATA-4 is a tissue-specific, retinoic acid-inducible, and developmentally regulated transcription factor. On the basis of its tissue distribution, we speculate that GATA-4 plays a role in gene expression in the heart, intestinal epithelium, primitive endoderm, and gonads.

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We report the cDNA cloning and characterization of mouse GATA-4, a new member of the family of zinc finger transcription factors that bind a core GATA motif. GATA-4 cDNA was identified by screening a 6.5-day mouse embryo library with oligonucleotide probes corresponding to a highly conserved region of the finger domains. Like other proteins of the family, GATA-4 is approximately 50 kDa in size and contains two zinc finger domains of the form C-X-N-C-(X17)-C-N-X-C. Cotransfection assays in heterologous cells demonstrate that GATA-4 trans activates reporter constructs containing GATA promoter elements. Northern (RNA) analysis and in situ hybridization show that GATA-4 mRNA is expressed in the heart, intestinal epithelium, primitive endoderm, and gonads. Retinoic acid-induced differentiation of mouse F9 cells into visceral or parietal endoderm is accompanied by increased expression of GATA-4 mRNA and protein. In vitro differentiation of embryonic stem cells into embryoid bodies is also associated with increased GATA-4 expression. We conclude that GATA-4 is a tissue-specific, retinoic acid-inducible, and developmentally regulated transcription factor. On the basis of its tissue distribution, we speculate that GATA-4 plays a role in gene expression in the heart, intestinal epithelium, primitive endoderm, and gonads.

Northern blot analysis has identified granulocyte macrophage colony stimulating factor (GM-CSF) mRNA in monocytes and both GM-CSF and interleukin-3 (IL-3) mRNA in lymphocytes. However, these results have not addressed whether all cells or a subset of the population is capable of hematopoietic growth factor (HGF) production. To resolve this question, we applied in situ hybridization of radiolabeled antisense RNA probes to centrifuged preparations of total blood mononuclear cells (BMCs) and fractionated lymphocyte subpopulations. Without stimulation, no circulating cells expressed detectable levels of GM-CSF or IL-3 mRNA. On stimulation of BMCs with phorbol myristate acetate (PMA) and phytohemagglutinin or PMA and the calcium ionophore ionomycin, approximately 5% expressed GM-CSF mRNA and approximately 1% IL-3 mRNA. Control sense probes produced no labeled cells. To determine the subsets of lymphocytes capable of GM-CSF and IL-3 expression, BMCs were fractionated by FACS into CD8+ and CD4+ lymphocyte subsets and CD16+ (NK) cells. The unfractionated cells and cell fractions were then stimulated with PMA and ionomycin. Results demonstrated that 3% to 5% of the CD16+, CD8+, and CD4+ lymphocytes produced GM-CSF mRNA. However, the number of IL-3 mRNA-positive cells in the FACS-sorted subsets was greatly reduced (0.02% to 0.05%) as compared with the unseparated cells (1%). Treatment of BMCs with high-dose interleukin-2 (IL-2) for 1 week followed by PMA plus ionomycin resulted in a lymphocyte population in which 50% and 3% of cells expressed GM-CSF and IL-3 mRNA, respectively. Thus, GM-CSF and IL-3 mRNA expression in T cells and NK cells is restricted to a small fraction of cells that can be greatly expanded by IL-2 stimulation. These results suggest a possible physiologic mechanism for increasing HGF production by circulating lymphocytes.

A highly malignant human T-cell leukemia was identified by cell surface analysis as a member of the T-cell receptor (TCR) gamma delta lineage. Cytogenetic and molecular analysis showed a novel t(8;14)(q24;q11) rearrangement involving the J delta 1 gene segment on chromosome 14 and the distal end of chromosome 8 near the c-myc proto-oncogene locus. The gamma delta TCR of the leukemia blasts was functionally intact and could be activated to generate intracellular calcium flux and to target Fc receptor-mediated redirected tumor cell lysis. In addition, non- major histocompatibility complex restricted lysis of a limited target cell panel was shown by fresh leukemic blasts and by the in vitro- maintained leukemia cells that was comparable to known T-cell lines with natural killer-like activity. These data suggest that the T-cell leukemia potentially had in vivo functional cytolytic activity. However, whether this activity did contribute to the patient's clinical condition could not be determined.

Using oligonucleotide primers specific for the human MDR 1 gene, we were able to identify a specific amplicon using RT-PCR from total bovine growth plate chondrocyte RNA. The identification of MDR mRNA in growth plate chondrocytes led us to examine the precise distribution of MDR P-glycoprotein in bone and cartilage. We applied two monoclonal antibodies (C219 and C494) to human fetal, neonatal, and childhood growth plates and bone. In growth plates, P-glycoprotein was detected at high levels in a perilacunar distribution in the calcifying zone and at lower levels in hypertrophic, but not proliferative or reserve zone, chondrocytes. P-glycoprotein was also observed in perichondrial chondrocytes, in perivascular chondrocytes and matrix in the fetal cartilage anlage, and in osteoblasts and the surface osteoid matrix of newly formed bone trabeculae in the primary spongiosa. The recently described chloride channel of P-glycoprotein suggests a potential role of P-glycoprotein in growth plate chondrocyte hypertrophy.

We prospectively documented the development of a fatal, secondarily acquired severe immunodeficiency in a 19-year-old man who underwent uncomplicated bone marrow transplantation. He had no graft v host disease (GVHD) and had normal recovery of his immune system as determined by lymphocyte phenotyping, mitogenic responses of his peripheral blood lymphocytes, and his ability to secrete immunoglobulin. This alteration in immunity was associated with the acquisition of antibody to HTLV-III. His only risk factor for the development of HTLV-III infection was the transfusions he had received during the transplant and recovery period. Two of his 54 transfusions were from an asymptomatic individual at high risk for acquired immunodeficiency syndrome (AIDS), who was subsequently found to be seropositive for anti-HTLV-III and from whom HTLV-III was isolated. The loss of immunocompetence in patients without chronic GVHD disease is unusual, and our data support the view that this patient's immunodeficiency was due to HTLV-III. When bone marrow transplant recipients without chronic GVHD develop late opportunistic infections, consideration should be given to transfusion-associated AIDS.

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