Protein tyrosine phosphatase (PC12, Br7,S1) family: expression characterization in the adult human and mouse.

Protein tyrosine phosphatases (PTPs) play important roles in modulating signals transduced by tyrosine kinases. Certain phosphatases have been implicated as having important roles in embryonic development as well as in adult physiology. Although both kinases and phosphatases are equally important in regulating signal transduction, phosphatases as a group have not been well characterized. Thus, characterization of sequence, expression, and biological function for additional phosphatases is informative. PTPBr7/PC12 and PTPSl are mouse receptor PTPs sharing similar amino acid sequences. Northern blot analysis demonstrated expression of these genes in adult rodent brain and revealed previously uncharacterized transcripts in the brain and other tissues. Our results demonstrate that PTPBr7/PC12 and PTPSl are members of a larger family of PTPs. We have identified two novel family members as well as several novel transcriptional splice variants from both human and mouse colon cDNA libraries. Expression analysis demonstrated that the various mRNA transcripts are differentially expressed, with the highest levels found in the brain, intestinal tract, uterus, and placenta. In situ hybridization analysis of mouse brain and intestinal tissues established that each isoform has a unique expression pattern in specific cell populations as well as in tissue regions. Furthermore, these restricted patterns suggest that the encoded family of phosphatases may play roles in modulating signal transduction pathways important for specific cell types and biological processes.

Long-term impaired neutrophil migration in mice overexpressing human interleukin-8.

The proinflammatory chemokine interleukin-8 (IL-8/NAP-1) has been implicated in recruiting neutrophils to sites of acute and chronic tissue inflammation. In transgenic mice, elevated serum IL-8 levels ranging from 1 to 118 ng/ml were correlated with proportional increases in circulating neutrophils and proportional decreases in L-selectin expression on the surface of blood neutrophils. No change in the expression of the beta 2-integrins Mac-1 and LFA-1 was apparent on peripheral blood neutrophils of the IL-8 transgenic mice. Additionally, L-selectin expression on bone marrow neutrophils and neutrophil precursors was normal in all transgenic lines. IL-8 transgenic mice demonstrated an accumulation of neutrophils in the microcirculation of the lung, liver and spleen. Moreover, there was no evidence of neutrophil extravasation, plasma exudation or tissue damage in any IL-8 transgenic mice. Neutrophil migration into the inflamed peritoneal cavity was severely inhibited in IL-8 transgenic mice, but not in nontransgenic littermates. The IL-8 transgenic mice should serve as useful models for studying the putative role of neutrophils in mediating tissue damage in models of inflammation, such as hepatic ischemia and reperfusion injury, cecal puncture and ligation, and glomerulonephritis.

Isolation of rat bone marrow mast lineage cells using Thy 1.1 and rat stem cell factor.

Recent reports have shown that various marrow-derived cell populations respond vigorously to recombinant rat stem cell factor (rrSCF164), one form of the kit-ligand. In the present study, we isolated cell populations from rat bone marrow using the Thy 1.1 antigen (an antigen that in the rat is differentially expressed on primitive hemopoietic progenitor cells) and fluorescently conjugated rrSCF164 (rrSCF164-PE). We show that rrSCF164 only stimulates cells that are enriched in the brightest Thy 1.1 populations (Thy 1.1bright). Numerous cell lines were generated by serial passage in rrSCF164 containing medium, and the prototypic cell lines have been designated SRT002 and SRT003. Each cell line retains the Thy 1.1bright phenotype and does not respond to interleukins (IL) 1-8, IL-10, granulocyte (G) colony-stimulating factor (CSF), granulocyte macrophage (GM) CSF, M-CSF, or crude preparations of mitogen-stimulated T-cell supernatants. The Thy 1.1bright population of rat marrow was subdivided into a subset that binds rrSCF164-PE (Thy 1.1bright, rrSCF164+). The majority of these cells possess certain characteristics in common with marrow-derived mast cells and the Thy 1.1bright, rrSCF164 responsive cell lines, having similar granule morphology, being metachromatic, and reacting positively with alcian blue. Moreover, rats treated with rrSCF164 displayed significant increases in Thy 1.1bright, rrSCF164+ cells in the bone marrow. These studies show that the combination of Thy 1.1 and rrSCF164 makes possible the isolation of a unique subset of rat bone marrow cells that differentially express the Thy 1.1 antigen and the cell surface receptor c-kit, the majority of which are morphologically similar to marrow-derived mast cells.

Rat stem-cell factor induces splenocytes capable of regenerating the thymus.

Cytokine regulation of prethymic T-lymphoid progenitor-cell proliferation and/or differentiation has not been well-defined, although much is known of cytokine regulation of hemopoietic stem- and progenitor-cell development. Here we use a recently identified hemopoietic growth factor, stem-cell factor (SCF) (a form of the c-kit ligand), and a transplant model of thymocyte regeneration to assess the effect of SCF on the in vivo generation of prethymic, thymocyte progenitor-cell activity. We show that recombinant rat SCF (rrSCF164) administered to weanling rats selectively induces an increase in thymocyte progenitor activity in the spleens of treated rats as compared to rats treated with vehicle, polyethylene glycol (PEG)-conjugated rat albumin, or recombinant human granulocyte colony-stimulating factor (rhG-CSF). These data demonstrate that administration of SCF in vivo affects extrathymic-origin thymocyte regenerating cells and may influence, directly or indirectly, early prethymic stages of T-cell lymphopoiesis in addition to its known effect on early stages of myelopoiesis and erythropoiesis.