Biomedical subjects

D S Friend

Publications and source records attributed to D S Friend.

At least 37 records · Page 2Linked to original sources

PubMed1997

Mouse mast cell protease 9, a novel member of the chromosome 14 family of serine proteases that is selectively expressed in uterine mast cells.

Mouse mast cell protease (mMCP) 1, mMCP-2, mMCP-4, and mMCP-5 are members of a family of related serine proteases whose genes reside within an approximately 850 kilobase (kb) complex on chromosome 14 that does not readily undergo crossover events. While mapping the mMCP-1 gene, we isolated a novel gene that encodes a homologous serine protease designated mMCP-9. The mMCP-9 and mMCP-1 genes are only approximately 7 kb apart on the chromosome and are oriented back to back. The proximity of the mMCP-1 and mMCP-9 genes now suggests that the low recombination frequency of the complex is due to the closeness of some of its genes. The mMCP-9 transcript and protein were observed in the jejunal submucosa of Trichinella spiralis-infected BALB/c mice. However, in normal BALB/c mice, mMCP-9 transcript and protein were found only in those mast cells that reside in the uterus. Thus, the expression of mMCP-9 differs from that of all other chymases. The observation that BALB/c mouse bone marrow-derived mast cells developed with interleukin (IL) 10 and c-kit ligand contain mMCP-9 transcript, whereas those developed with IL-3 do not, indicates that the expression of this particular chymase is regulated by the cytokine microenvironment. Comparative protein structure modeling revealed that mMCP-9 is the only known granule protease with three positively charged regions on its surface. This property may allow mMCP-9 to form multimeric complexes with serglycin proteoglycans and other negatively charged proteins inside the granule. Although mMCP-9 exhibits a >50% overall amino acid sequence identity with its homologous chymases, it has a unique substrate-binding cleft. This finding suggests that each member of the chromosome 14 family of serine proteases evolved to degrade a distinct group of proteins.

Amino Acid Sequence↗

PubMed1997

Human peripheral blood eosinophils express a functional c-kit receptor for stem cell factor that stimulates very late antigen 4 (VLA-4)-mediated cell adhesion to fibronectin and vascular cell adhesion molecule 1 (VCAM-1).

We evaluated mature peripheral blood eosinophils for their expression of the surface tyrosine kinase, c-kit, the receptor for the stromal cell-derived cytokine, stem cell factor (SCF). Cytofluorographic analysis revealed that c-kit was expressed on the purified peripheral blood eosinophils from 8 of 8 donors (4 nonatopic and 4 atopic) (mean channel fluorescence intensity 2.0- 3. 6-fold, average 2.8 +/- 0.6-fold, greater than the negative control). The uniform and selective expression of c-kit by eosinophils was confirmed by immunohistochemical analysis of peripheral blood buffy coats. The functional integrity of c-kit was demonstrated by the capacity of 100 ng/ml (5 nM) of recombinant human (rh) SCF to increase eosinophil adhesion to 3, 10, and 30 microg/ml of immobilized FN40, a 40-kD chymotryptic fragment of plasma fibronectin, in 15 min by 7.7 +/- 1.4-, 5.3 +/- 3.3-, and 5.4 +/- 0. 2-fold, respectively, and their adhesion to 0.1, 0.5, and 1.0 microg/ml vascular cell adhesion molecule-1 (VCAM-1), by 12.7 +/- 9. 2-, 3.8 +/- 2.5-, and 1.7 +/- 0.6-fold, respectively. The SCF-stimulated adhesion occurred without concomitant changes in surface integrin expression, thereby indicating an avidity-based mechanism. rhSCF (100 ng/ml, 5 nM) was comparable to rh eotaxin (200 ng/ml, 24 nM) in stimulating adhesion. Cell adhesion to FN40 was completely inhibited with antibodies against the alpha4 and beta1 integrin subunits, revealing that the SCF/c-kit adhesion effect was mediated by a single integrin heterodimer, very late antigen 4 (VLA-4). Thus, SCF represents a newly recognized stromal ligand for the activation of eosinophils for VLA-4-mediated adhesion, which could contribute to the exit of these cells from the blood, their tissue localization, and their prominence in inflammatory lesions.

Cell Adhesion↗

PubMed1997

Mouse mast cells that possess segmented/multi-lobular nuclei.

Because in humans mast cells and basophils tend to possess nonsegmented and segmented/multi-lobular nuclei, respectively, nuclear morphology has been a major criterion for assessing the lineage of metachromatic cells of hematopoietic origin. Immature metachromatic cells with mono- and multi-lobular nuclei were both obtained when bone marrow cells from BALB/c mice were cultured for 3 weeks in the presence of interleukin-3. Analogous to the indigenous mature mast cells that reside in the peritoneal cavity and skin, both populations of in vitro-derived cells expressed the surface receptor c-kit, the chymase mouse mast cell protease (mMCP) 5, the tryptase mMCP-6, and the exopeptidase carboxypeptidase A (mMC-CPA). Immunogold electron microscopy confirmed the granule location of mMC-CPA and mMCP-6 in both populations of cells, and cytochemical analysis confirmed the presence of chymotryptic enzymes in the granules. Because mature mast cells possessing multi-lobular nuclei also were occasionally found in the skeletal muscle and jejunum of the BALB/c mouse, the V3 mouse mast cell line was used to investigate the developmental relationship of mast cells that have very different nuclear structures. After the adoptive transfer of V3 mast cells into BALB/c mice, v-abl-immortalized mast cells with mono- and multi-lobular nuclei were detected in the lymph nodes and other tissues of the mastocytosis mice that expressed c-kit, mMCP-5, mMCP-6, and mMC-CPA. These studies indicate that mouse mast cells can exhibit varied nuclear profiles. Moreover, the nuclear morphology of this cell type gives no insight as to its protease phenotype or stage of development.

Animals↗

PubMed1997

Glucocorticoids inhibit the cytokine-induced proliferation of mast cells, the high affinity IgE receptor-mediated expression of TNF-alpha, and the IL-10-induced expression of chymases.

Mast cells are a heterogeneous family of immune cells that, when activated through their high affinity IgE receptors (Fc epsilonRI), release various granule mediators (e.g., neutral proteases and serglycin proteoglycans) and proinflammatory cytokines (e.g., IL-6 and TNF-alpha). We and others have shown that the growth and differentiation of immature, nontransformed mouse bone marrow-derived mast cells (mBMMC) can be regulated in vitro by IL-3, IL-10, and c-kit ligand. We now report that glucocorticoids inhibit the c-kit ligand- and IL-3-induced proliferation of mBMMC, the Fc epsilonRI-mediated expression of TNF-alpha, and the IL-10-mediated expression of the two chymases designated mouse mast cell protease (mMCP)-1 and mMCP-2. In contrast, glucocorticoids induce mBMMC to increase their expression of serglycin proteoglycan and carboxypeptidase A. As assessed by nuclear run-on and RNA blot analyses, dexamethasone inhibited the IL-10-mediated expression of mMCP-1 and mMCP-2, primarily by inducing rapid degradation of their transcripts. The stimulative effect on serglycin proteoglycan expression and the inhibitory effect on chymase expression were dose and time dependent and glucocorticoid specific. These findings indicate that glucocorticoids exert profound and diverse effects on the growth, cytokine expression, and granule differentiation of mouse mast cells, and that at least some of this regulation occurs through a post-transcriptional mechanism.

Animals↗

PubMed1996

Expression of LTC4 synthase during the development of eosinophils in vitro from cord blood progenitors.

The expression of leukotriene C4 synthase (LTC4S) was examined during the development of eosinophils in vitro from cord blood mononuclear cells. At 7 days, the cells contained mRNA and sodium dodecyl sulfate-polyacrylamide gel electrophoresis immunoblot signals for cytosolic phospholipase A2 (cPLA2), 5-lipoxygenase (5-LO), and 5-lipoxygenase-activating protein (FLAP), but lacked LTC4S and did not generate cysteinyl leukotrienes when stimulated with 20 mumol/L calcium ionophore. At 14 days, 94% of the cells were of eosinophil lineage, both LTC4S mRNA transcript and protein were present, and ionophore stimulation resulted in the generation of 23.9 +/- 6.0 pmol cysteinyl leukotrienes/10(6) eosinophil-lineage cells (mean +/- SEM, n = 6). At 28 days, progressive eosinophil maturation was accompanied by further increments in 5-LO, FLAP, and LTC4S proteins, and by the ionophore-induced production of 94.6 +/- 9.0 pmol cysteinyl leukotrienes/10(6) eosinophil-lineage cells (n = 6). Cells selected for CD34 expression lacked detectable 5-LO/LTC4S pathway proteins, and with culture generally expressed immunodetectable cPLA2 and 5-LO proteins by 3 days, FLAP protein by 7 days, and LTC4S protein by 10 days. Thus, during the development of eosinophils in vitro, cPLA2, 5-LO, and FLAP are expressed before LTC4S. Once the lineage is established by morphologic criteria, the eosinophilopoietic cytokines mediate upregulation of FLAP and LTC4S, members of a newly recognized gene family, and of 5-LO, during ongoing cell maturation.

5-Lipoxygenase-Activating Proteins↗

PubMed1996

An intrinsic adrenergic system in mammalian heart.

We have identified a previously undescribed intrinsic cardiac adrenergic (ICA) cell type in rodent and human heart. Northern and Western blot analyses demonstrated that ICA cell isolates contain mRNA and protein of enzymes involved in catecholamine biosynthesis. Radioenzymatic catecholamine assays also revealed that the catecholamine profile of adult rat ICA cell isolates differed from that of sympathetic neurons. Unlike sympathetic neuronal cells, isolated ICA cells have abundant clear vesicles on electron microscopy. Endogenous norepinephrine and epinephrine constitutively released by ICA cells in vitro affect the spontaneous beating rate of neonatal rat cardiac myocytes in culture. Finally, ICA cells could be identified in human fetal hearts at a developmental stage before sympathetic innervation of the heart has been documented to occur. These findings support the concept that these cells constitute an ICA signaling system capable of participating in cardiac regulation that appears to be independent of sympathetic innervation.

Adult↗

PubMed1996

Fate of two mast cell tryptases in V3 mastocytosis and normal BALB/c mice undergoing passive systemic anaphylaxis: prolonged retention of exocytosed mMCP-6 in connective tissues, and rapid accumulation of enzymatically active mMCP-7 in the blood.

The mouse mast cell protease granule tryptases designated mMCP-6 and mMCP-7 are encoded by highly homologous genes that reside on chromosome 17. Because these proteases are released when mast cells are activated, we sought a basis for distinctive functions by examining their fates in mice undergoing passive systemic anaphylaxis. 10 min-1 h after antigen (Ag) was administered to immunoglobulin (Ig)E-sensitized mice, numerous protease/proteoglycan macromolecular complexes appeared in the extracellular matrix adjacent to most tongue and heart mast cells of normal BALB/c mice and most spleen and liver mast cells of V3 mastocytosis mice. These complexes could be intensively stained by anti-mMCP-6 Ig but not by anti-mMCP-7 Ig. Shortly after Ag challenge of V3 mastocytosis mice, large amounts of properly folded, enzymatically active mMCP-7 were detected in the plasma. This plasma-localized tryptase was approximately 150 kD in its multimeric state and approximately 32 kD in its monomeric state, possessed an NH2 terminus identical to that of mature mMCP-7, and was not covalently bound to any protease inhibitor. Comparative protein modeling and electrostatic calculations disclosed that mMCP-6 contains a prominent Lys/Arg-rich domain on its surface, distant from the active site. The absence of this domain in mMCP-7 provides an explanation for its selective dissociation from the exocytosed macromolecular complex. The retention of exocytosed mMCP-6 in the extracellular matrix around activated tissue mast cells suggests a local action. In contrast, the rapid dissipation of mMCP-7 from granule cores and its inability to be inactivated by circulating protease inhibitors suggests that this tryptase cleaves proteins located at more distal sites.

Anaphylaxis↗

PubMed1996

Endocytosis and intracellular processing accompanying transfection mediated by cationic liposomes.

Cationic liposomes mediate efficient transfection of mammalian cells, but the manner in which cells internalize and process cationic liposome-DNA complexes has not been well characterized. We exposed several cell types, including human and murine erythroleukemia cells. African green monkey kidney cells (CV-1), isolated rat alveolar type II cells and alveolar macrophages to DNA-cationic liposome complexes containing N-(1-2,3-dioleyloxypropyl)-N,N,N-triethylammonium (DOTMA) and Dioleylphosphatidylethanolamine (DOPE). The morphology of liposome-cell interactions was assessed by electron microscopy. Liposome preparations were complexed to colloidal gold particles or to both plasmid DNA and gold particles. Cells treated with DOTMA liposome-DNA complexes demonstrated endocytosis of the liposome-DNA complexes in coated pits, which were seen in early endosomes, late endosomes, and lysosomes. In isolated alveolar type II cells, the gold-labelled DOTMA lipid apparently mixed with the contents of lamellar bodies. In most cells, gold particles were dispersed throughout the cytoplasmic matrix. In a small proportion of CV-1 and U937 cells, a membrane system resembling the endoplasmic reticulum developed within the nucleus. This novel structure was also present in nuclei after they were isolated from CV-1 cells and then mixed with DOTMA-containing liposomes. Membranes which form after exposure to DOTMA-containing liposomes were 10 nm in thickness as compared to the approx. 8 nm thickness of endogenous cellular membranes. Based on these morphologic observations, we propose that the main route of entry of cationic liposomes into cells is by endocytosis. In some instances, the endosomal compartment releases its cationic liposome-DNA contents into the cytoplasmic matrix. Occasionally, liposomes may enter the nucleus by fusion with the nuclear envelope, creating vesicular and reticular intranuclear membranes. It is not clear at present which, if any of these morphological observations correlates with transfection mediated by cationic liposomes.

Animals↗

PubMed1996

The presence of membrane-bound stem cell factor on highly immature nonmetachromatic mast cells in the peripheral blood of a patient with aggressive systemic mastocytosis.

BACKGROUND: Systemic mastocytosis is characterized by mast cell infiltration of bone marrow and tissues in the absence of identified circulating bone marrow-derived progenitors. A 58-year-old man was first seen with aggressive systemic mastocytosis manifested by urticaria pigmentosa, hepatosplenomegaly, generalized bone lesions, anemia, thrombocytopenia, monoclonal gammopathy, and increased urine histamine levels. OBJECTIVES AND METHODS: A rapidly progressive anemia and thrombocytopenia dictated a splenectomy. We sought to identify the mast cell progenitors in the peripheral blood and to provide evidence of their maturation in tissues with immunohistochemical and ultrastructural analyses. RESULTS: The peripheral blood contained 1% to 3% nonmetachromatic mononuclear cells with eccentric nuclei that expressed the mast cell proteases, tryptase and carboxypeptidase A, along with c-kit, stem cell factor (SCF), and high-affinity IgE receptor (Fc epsilon RI), but not chymase. Similar mononuclear cells colocalized in the spleen and lymph nodes with mature, metachromatic mast cells that expressed tryptase, chymase, carboxypeptidase A, c-kit, SCF, and Fc epsilon RI. Electron microscopy disclosed, at each site, a mature mast cell population with electron-dense, scroll-poor granules. CONCLUSIONS: The peripheral blood of a patient with aggressive systemic mastocytosis contained immature mononuclear cells of the mast cell lineage that express c-kit, SCF, tryptase, carboxypeptidase A, and Fc epsilon RI. These cells were also found in the skin, spleen, and lymph nodes where they presumably expand, differentiate, and mature, assuming the mast cell phenotype for those tissues characterized by metachromasia, expression of a full range of mast cell-related secretory granule proteases, and ultrastructural appearance. The presence of SCF on the surface membrane of the circulating, highly immature mast cells suggests an autocrine regulation of the c-kit-SCF interaction.

Cell Differentiation↗

PubMed1996

Tissue-dependent differences in the asynchronous appearance of mast cells in normal mice and in congenic mast cell-deficient mice after infusion of normal bone marrow cells.

The time courses of the appearance of tissue mast cells in six sites were compared in normal WBB6F1(-)+/+ mice (+/+) and in congenic mast cell-deficient WBB6F1-W/Wv mice (W/Wv) that received an intravenous infusion of bone marrow cells from +/+ mice (BM-->W/Wv). As assessed by morphometric analysis of Carnoy's solution-fixed, methylene blue-stained tissue sections, the density of mast cells in the stomach mucosa, stomach submucosa, and spleen of +/+ mice reached maximal levels by 8 weeks of age, whereas the density of mast cells in the skin, extraparenchymal airway walls, and lung parenchyma did not reach maximal levels until 18 weeks of age. When 8-week-old W/Wv mice were infused with 2 x 10(7) bone marrow cells from /+/ mice, mast cells appeared in the stomach mucosa and submucosa after 2.5 weeks, in the spleen and extraparenchymal airway walls after 5 weeks, and in the lung parenchyma after 10 weeks. Twenty weeks after bone marrow infusion, the mast cell densities in the spleen, stomach mucosa, and stomach submucosa were seven-, 13-, and five-fold greater, respectively, than those in age-matched +/+ mice, but were eight-, two-, and five-fold lower in the skin, extraparenchymal airway walls, and lung parenchyma, respectively. Thus, those tissues that in +/+ mice reached maximal mast cell densities earlier exhibited abnormally high mast cell densities in BM-->W/Wv mice, and those that reached maximal mast cell densities later in +/+ mice had abnormally low mast cell densities in BM-->W/Wv mice. Immunological and inflammatory responses are often compared in W/Wv and BM-->W/Wv mice to assess mast cell dependency. Our results indicate that the capacity to restore a mast cell-dependent response in a particular tissue of the latter mice may relate to the local mast cell density and whether the immunological challenge activates mast cells only in that tissue or systemically with attendant widespread release of proinflammatory mediators.

Animals↗

PubMed1996

Mast cells that reside at different locations in the jejunum of mice infected with Trichinella spiralis exhibit sequential changes in their granule ultrastructure and chymase phenotype.

Whether or not a nontransformed, mature mouse mast cell (MC) or its committed progenitor can change its granule protease phenotype during inflammatory responses, has not been determined. To address this issue, the granule morphology and protease content of the MC in the jejunum of BALB/c mice exposed to Trichinella spiralis were assessed during the course of the infection. Within 1 wk after helminth infection of the mice, increased numbers of MC appeared in the crypts at the base of the villi, and by wk 2 the number of MC throughout the villi increased by approximately 25-fold. Shortly after the peak of the mastocytosis, the intraepithelial population of MC disappeared, followed by a progressive loss of lamina propria MC. The presence of stellate-shaped granules containing crystalline structures in intraepithelial MC at the height of infection and the retention of such granules with fragmented crystals in lamina propria MC during resolution of the mastocytosis suggest that MC migrate during the various phases of the inflammation. As assessed by immunohistochemical analyses of serial sections, predominant chymase phenotypes were observed at the height of the infection in the muscle that expressed mouse MC protease (mMCP) 5 without mMCP-1 or mMCP-2 and in the epithelium that expressed mMCP-1 and mMCP-2 without mMCP-5. Accompanying these two MC populations were transitional forms in the submucosa that expressed mMCP-2 and mMCP-5 without mMCP-1 and in the lamina propria that expressed mMCP-2 alone. These data suggest that jejunal MC sequentially express mMCP-2, cease expressing mMCP-5, and finally express mMCP-1 as the cells progressively appear in the submucosa, lamina propria, and epithelium, respectively. In the recovery phase of the disease, MC sequentially cease expressing mMCP-1, express mMCP-5, and finally cease expressing mMCP-2 as they present at the tips of the villi, the base of the villi, and the submucosa, respectively. That MC can reversibly alter their protease phenotypes suggests that a static nomenclature with fixed functional implications is inadequate to describe MC populations during an inflammatory process within a particular tissue.

Amino Acid Sequence↗

PubMed1995

Interleukin-3 regulates development of the 5-lipoxygenase/leukotriene C4 synthase pathway in mouse mast cells.

To study cytokine regulation of the 5-lipoxygenase (5-LO)/leukotriene (LT) synthase pathway we have developed mouse bone marrow-derived mast cells (BMMC) that minimally express each protein of the pathway by using a novel culture system, lacking interleukin (IL)-3. When mouse bone marrow cells were cultured for 5 weeks with 100 ng/ml c-kit ligand (KL) and 10 units/ml IL-10, a population of > 95% mast cells was obtained. These cells generated 8.3 +/- 4.5 ng of LTC4/10(6) cells and 8.1 +/- 2.4 ng of prostaglandin (PG) D2/10(6) cells after IgE-dependent activation. When these BMMC were cultured for 2-5 weeks more with 100 units/ml IL-3 in the continued presence of KL and IL-10, the IgE-dependent generation of LTC4 and PGD2 increased to 212 +/- 36 and 25.5 +/- 8.6 ng/10(6) cells, respectively. The dramatic increase in the IgE-dependent generation of LTC4 in response to IL-3 was accompanied by a concomitant increase in expression of 5-LO and 5-LO-activating protein and preceded the increased expression of cytosolic phospholipase A2 and LTC4 synthase. The recognition that IL-3 up-regulates the expression of each protein of the 5-LO pathway for the generation of LTC4 contrasts with our recent finding that KL up-regulates the expression of cytosolic phospholipase A2, prostaglandin endoperoxide synthase-1, and hematopoietic PGD2 synthase and increases the IgE-dependent generation of PGD2 in BMMC developed from bone marrow with IL-3. Thus, developmentally segregated regulation of the prostanoid and cysteinyl leukotriene pathways in lineage-related committed mast cell progenitors reveals the pleiotropism of this effector cell of allergic inflammation, a cytokine/growth factor basis for preferential expression of pathways of eicosanoid biosynthesis, and the particular role of IL-3 in regulating the expression of the proteins of the 5-LO/LTC4 synthase pathway.

Animals↗

PubMed1995

Purification of human lung leukotriene C4 synthase and preparation of a polyclonal antibody.

Leukotriene (LT) C4 synthase is an integral membrane protein that catalyzes the conjugation of LTA4 to reduced glutathione to form LTC4. LTC4 synthase has been cloned and characterized from transformed cell lines, but the protein has not been defined from a tissue source. LTC4 synthase was purified to homogeneity from human lung tissue, utilizing S-hexyl glutathione chromatography followed by LTC4 affinity chromatography. A greater than 100,000-fold purification with a yield of 8 to 25% (n = 4) was achieved. The purified LTC4 synthase migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as an 18-kD protein, and its 19 N-terminal amino acid sequence is identical to that of purified LTC4 synthase from KG-1 myeloid cells or from expression cloning of a KG-1 library in COS cells. Using a rabbit polyclonal IgG raised against purified LTC4 synthase, SDS-PAGE immunoblotting of LTC4 synthase from human lung tissue, eosinophils, KG-1 cells, and platelets showed an 18-kD protein. Immunofluorescence staining of alveolar macrophages in human lung sections with the anti-LTC4 synthase IgG revealed LTC4 synthase to be largely perinuclear in distribution. Thus, LTC4 synthase, the biosynthetic enzyme responsible for the formation of cysteinyl LTs, is present in lung tissue in a form apparently identical to that of hematopoietic cells.

Amino Acid Sequence↗

PubMed1995

Synthesis and assembly of human beta 1 gap junctions in BHK cells by DNA transfection with the human beta 1 cDNA.

Gap junctional communication is important in many physiological processes, including growth control, patterning, and the synchronization of cell-to-cell activities. It has been difficult to study the synthesis and assembly of gap junctions due to their low abundance. To overcome this limitation, baby hamster kidney cells (BHK) have been transfected with a human beta 1 (Cx32) connexin cDNA construct. Expression was placed under the control of the mouse metallothionein promoter that can be induced by heavy metals. The transfected cells were characterized by DNA, RNA and protein analysis, as well as by scrape loading to detect functional channels. Functional beta 1 connexin was detected only in cells transfected with beta 1 connexin cDNA in the correct orientation (beta 1-BHK). Analysis of the cells by light microscopic immunocytochemistry indicated that beta 1 connexin antigen was localized to the plasma membrane and to several intracellular compartments. Characterization with thin section electron microscopy revealed extensive areas of assembled double membrane gap junctions between cells (on the cell surface), in the endoplasmic reticulum (ER), and the nuclear envelope. This unusual intracellular distribution for assembled gap junction protein was confirmed by freeze fracture analysis, which revealed large particle aggregates, characteristic of gap junction plaques, on the fracture faces of all these membranes. The presence of gap junction particle aggregates in the ER suggests that the oligomerization of connexin can occur at its site of synthesis. Further, the process of assembly into double membrane junction structures in intracellular membranes may be driven by connexin protein concentration.

Animals↗

PubMed1994

Lack of expression of the tryptase mouse mast cell protease 7 in mast cells of the C57BL/6J mouse.

Although the steady-state level of the mouse mast cell protease (mMCP) 7 transcript is below detection in the serosal and mucosal mast cells of the BALB/cJ mouse, the IL-3-dependent, bone marrow-derived mast cells (mBMMC) of this strain and four other strains contain a high steady-state level of the mMCP-7 transcript. To further analyze the expression of this mast cell tryptase, a mMCP-7-specific IgG was obtained by immunizing a rabbit with a 19-residue synthetic peptide that corresponds to its unique amino acid sequence at residues 160 to 178 (anti-mMCP-7(160-178). In a SDS-PAGE/immunoblot analysis of lysates of BALB/cJ mBMMC, anti-mMCP-7(160-178) IgG recognized a diffuse 31- to 36-kDa protein, which shifted to a sharp 27-kDa protein after treatment with N-glycanase. As assessed immunohistochemically, mMCP-7 protein is present not only in the secretory granules of BALB/cJ mBMMC, but also in the ear mast cells of this strain. In contrast, the ear mast cells of the C57BL/6J mouse do not contain detectable levels of mMCP-7 protein, although the ear mast cells of both mouse strains contain mMCP-5 protein. Because mMCP-7 mRNA and protein also were not detected in mBMMC from the C57BL/6J mouse, the failure of the ear mast cells of this strain to express mMCP-7 is most likely a consequence of an intrinsic abnormality in the mast cell-committed progenitor cells themselves, or in the bone marrow microenvironment that induces its mast cell progenitor cells to express this tryptase.

Amino Acid Sequence↗

PubMed1994

Mouse bone marrow-derived mast cells (mBMMC) obtained in vitro from mice that are mast cell-deficient in vivo express the same panel of granule proteases as mBMMC and serosal mast cells from their normal littermates.

The ear, skin, and purified serosal mast cells of WBB6F1/J-(+/+) (WB-(+/+)) and WCB6F1/J-(+/+) (WC-(+/+)) mice contain high steady-state levels of the transcripts that encode mouse mast cell protease (mMCP) 2, mMCP-4, mMCP-5, mMCP-6, and mouse mast cell carboxypeptidase A (mMC-CPA). In contrast, no mast cell protease transcripts are present in abundance in the ear and skin of WBB6F1/J-W/Wv (W/Wv) and WCB6F1/J-Sl/Sld (Sl/Sld) mice which are mast cell-deficient in vivo due to defects in their c-kit and c-kit ligand genes, respectively. We now report that the immature bone marrow-derived mast cells (mBMMC) obtained in vitro with recombinant interleukin 3 (rIL-3) or WEHI-3 cell conditioned medium from WB-(+/+), WC-(+/+), W/Wv, and Sl/Sld mice all contain high steady-state levels of the mMCP-2, mMCP-4, mMCP-5, mMCP-6, and mMC-CPA transcripts. As assessed immunohistochemically, mMCP-2 protein and mMCP-5 protein are also present in the granules of mBMMC from WB-(+/+), WC-(+/+), and W/Wv mice. That Sl/Sld and W/Wv mBMMC contain high steady-state levels of five granule protease transcripts expressed by the mature serosal, ear, and skin mast cells of their normal +/+ littermates suggests that c-kit-mediated signal transduction is not essential for inducing transcription of these protease genes. Because rIL-4 inhibits the rIL-10-induced expression of mMCP-1 and mMCP-2 in BALB/cJ mBMMC, the ability of rIL-4 to influence protease mRNA levels in WC-(+/+) mBMMC and W/Wv mBMMC was investigated. Although rIL-10 induced expression of the mMCP-1 transcript in WC-(+/+) and W/Wv mBMMC, rIL-4 was not able to suppress the steady-state levels of the mMCP-1 transcript or any other protease transcript in these cultured mast cells. Thus, not only do BALB/cJ mBMMC express fewer granule proteases than mBMMC from mast cell-deficient strains and their normal littermates but the subsequent induction of late-expressed proteases in BALB/cJ mBMMC is more tightly regulated by IL-3 and IL-4.

Animals↗

PubMed1994

Strain-specific and tissue-specific expression of mouse mast cell secretory granule proteases.

As assessed by RNA blot analyses with gene-specific probes, we report that the perivascular connective tissue mast cells (CTMCs) in the ear and skin of BALB/cJ mice contain abundant levels of the mouse mast cell protease (mMCP) 7 transcript, in addition to those protease transcripts present in their serosal mast cells (SMCs). High levels of the mMCP-7 transcript also were detected in the ears of WBB6F1/J(-)+/+, WCB6F1/J(-)+/+, WB/ReJ(-)+/+, and WC/ReJ(-)+/+ mice. However, the ears of these four strains and the SMCs from the WCB6F1/J(-)+/+ strain but not the BALB/cJ strain also contained high steady-state levels of the mMCP-2 transcript. The mMCP-2, mMCP-4, mMCP-5, mMCP-6, and mMCP-7 transcripts were not detected in the ears of mast-cell-deficient WBB6F1/J-W/Wv and WCB6F1/J-Sl/Sld mice, indicating that mast cells were the source of these protease transcripts in the +/+ animals. When immunohistochemical analyses of serial sections of ear and skin from WBB6F1/J(-)+/+ mice were performed with anti-mMCP-2 IgG and anti-mMCP-5 IgG, the perivascular CTMCs in these tissues were found to express both mMCP-2 and mMCP-5 in their granules. The prominent expression of mMCP-7 in constitutive perivascular CTMCs indicates that this mast cell has an extended protease phenotype relative to the SMCs of the same strains. Further, the perivascular CTMCs and SMCs of the +/+ strains differ from those in BALB/cJ mice in their prominent expression of mMCP-2.

Animals↗

PubMed1993

Reversible expression of mouse mast cell protease 2 mRNA and protein in cultured mast cells exposed to IL-10.

BALB/cJ mouse mast cells derived by culturing bone marrow progenitor cells in WEHI-3 cell-conditioned medium (BMMCW) do not contain mouse mast cell protease 2 (mMCP-2) mRNA, but these cells can be induced to express this transcript after exposure to rIL-10. To study the translation and granule accumulation of mMCP-2 in rIL-10-treated BMMC (BMMCW+IL-10), a rabbit antibody was developed to a synthetic peptide that corresponds to the novel amino acid sequence in mMCP-2 at residues 56 to 71. After affinity purification, this antibody, anti-mMCP-2(56-71) IgG, reacted in SDS-PAGE/immunoblots against a 28-kDa protein in BMMCW+IL-10 that had the N-terminal amino acid sequence of mMCP-2. As assessed immunohistochemically, mMCP-2 protein accumulated in the secretory granules of Kirsten sarcoma virus-immortalized mouse mast cells, BMMCW+IL-10, and the mucosal mast cells present in the jejunum of Trichinella spiralis-infected BALB/cJ mice. Time course analyses of the induction of mMCP-2 mRNA and protein in BMMCW+IL-10 revealed that these cells contain a high steady-state level of mMCP-2 mRNA 24 h after their exposure to rIL-10. Although a small amount of immunodetectable mMCP-2 protein is present in the cells treated for 24 h, large amounts of this protease are not obtained until 7 days of treatment of the cells with rIL-10. Time course analyses of the loss of mMCP-2 mRNA and protein in BMMCW+IL-10 revealed that the steady-state level of mMCP-2 mRNA decreased dramatically 24 h after rIL-10 was removed from the culture medium, but that the level of mMCP-2 protein did not decline measurably until day 5 of culture. The fact that the steady-state levels of mMCP-2 mRNA and protein in BMMC can both be reversibly altered by culturing these mast cells in the presence and absence of rIL-10 suggests that the phenotype of mast cells is not fixed. Rather, it is in a dynamic state regulated by the cytokine network to which mast cells are exposed in their different microenvironments.

Amino Acid Sequence↗