Characterization of the human gene that encodes the peptide core of secretory granule proteoglycans in promyelocytic leukemia HL-60 cells and analysis of the translated product. J Biol Chem. 1990;265:5889-5896. [PMID: 2180935 DOI: 10.1016/s0021-9258(19)39446-3]

A Novel Feature Selection Method Based on MRMR and Enhanced Flower Pollination Algorithm for High Dimensional Biomedical Data

Background:

The massive amount of biomedical data accumulated in the past decades can be utilized for diagnosing disease.

Objective:

However, the high dimensionality, small sample sizes, and irrelevant features of data often have a negative influence on the accuracy and speed of disease prediction. Some existing machine learning models cannot capture the patterns on these datasets accurately without utilizing feature selection.

Methods:

Filter and wrapper are two prevailing feature selection methods. The filter method is fast but has low prediction accuracy, while the latter can obtain high accuracy but has a formidable computation cost. Given the drawbacks of using filter or wrapper individually, a novel feature selection method, called MRMR-EFPATS, is proposed, which hybridizes filter method Minimum Redundancy Maximum Relevance (MRMR) and wrapper method based on an improved Flower Pollination Algorithm (FPA). First, MRMR is employed to rank and screen out some important features quickly. These features are further chosen for individual populations following the wrapper method for faster convergence and less computational time. Then, due to its efficiency and flexibility, FPA is adopted to further discover an optimal feature subset.

Result:

FPA still has some drawbacks, such as slow convergence rate, inadequacy in terms of searching new solutions, and tends to be trapped in local optima. In our work, an elite strategy is adopted to improve the convergence speed of the FPA. Tabu search and Adaptive Gaussian Mutation are employed to improve the search capability of FPA and escape from local optima. Here, the KNN classifier with the 5-fold-CV is utilized to evaluate the classification accuracy.

Conclusion:

Extensive experimental results on six public high dimensional biomedical datasets show that the proposed MRMR-EFPATS has achieved superior performance compared to other state-of-theart methods.

Proteoglycans and their functions in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a highly malignant disease that has a poor prognosis. Its high lethality is mainly due to the lack of symptoms at early stages, which culminates in diagnosis at a late stage when the tumor has already metastasized. Unfortunately, the common cancer biomarkers have low sensitivity and specificity in esophageal cancer. Therefore, a better understanding of the molecular mechanisms underlying ESCC progression is needed to identify novel diagnostic markers and therapeutic targets for intervention. The invasion of cancer cells into the surrounding tissue is a crucial step for metastasis. During metastasis, tumor cells can interact with extracellular components and secrete proteolytic enzymes to remodel the surrounding tumor microenvironment. Proteoglycans are one of the major components of extracellular matrix. They are involved in multiple processes of cancer cell invasion and metastasis by interacting with soluble bioactive molecules, surrounding matrix, cell surface receptors, and enzymes. Apart from having diverse functions in tumor cells and their surrounding microenvironment, proteoglycans also have diagnostic and prognostic significance in cancer patients. However, the functional significance and underlying mechanisms of proteoglycans in ESCC are not well understood. This review summarizes the proteoglycans that have been studied in ESCC in order to provide a comprehensive view of the role of proteoglycans in the progression of this cancer type. A long term goal would be to exploit these molecules to provide new strategies for therapeutic intervention.

Serglycin proteoglycan deletion in mouse platelets: physiological effects and their implications for platelet contributions to thrombosis, inflammation, atherosclerosis, and metastasis

Serglycin is found in all nucleated hematopoietic cells and platelets, blood vessels, various reproductive and developmental tissues, and in chondrocytes. The serglycin knockout mouse has demonstrated that this proteoglycan is required for proper generation and function of secretory granules in several hematopoietic cells. The effects on platelets are profound, and include diminishing platelet aggregation responses and formation of platelet thrombi. This chapter will review cell-specific aspects of serglycin structure, its gene regulation, cell and tissue localization, and the effects of serglycin deletion on hematopoietic cell granule structure and function. The effects of serglycin knockout on platelets are described and discussed in detail. Rationales for further investigations into the contribution of serglycin to the known roles of platelets in thrombosis, inflammation, atherosclerosis, and tumor metastasis are presented.

Serglycin proteoglycan in hematologic malignancies: a marker of acute myeloid leukemia

Serglycin is the major cell-associated proteoglycan of hematopoietic cells. Previous work has demonstrated that serglycin may be involved in targeting some proteins to granules of cytotoxic lymphocytes, mast cells and neutrophils. We characterized the expression of serglycin in various hematologic malignancies by immunohistochemistry and ELISA. Serglycin expression was found to distinguish acute myeloid leukemia (AML) from acute lymphoblastic leukemia. In contrast to myeloperoxidase, serglycin was found to be a selective marker for immature myeloid cells, distinguishing AML from Philadelphia chromosome-negative chronic myeloproliferative disorders.

Protease-proteoglycan complexes of mouse and human mast cells and importance of their beta-tryptase-heparin complexes in inflammation and innate immunity

Approximately 50% of the weight of a mature mast cell (MC) consists of varied neutral proteases stored in the cell's secretory granules ionically bound to serglycin proteoglycans that contain heparin and/or chondroitin sulfate E/diB chains. Mouse MCs express the exopeptidase carboxypeptidase A3 and at least 15 serine proteases [designated as mouse MC protease (mMCP) 1-11, transmembrane tryptase/tryptase gamma/protease serine member S (Prss) 31, cathepsin G, granzyme B, and neuropsin/Prss19]. mMCP-6, mMCP-7, mMCP-11/Prss34, and Prss31 are the four members of the chromosome 17A3.3 family of tryptases that are preferentially expressed in MCs. One of the challenges ahead is to understand why MCs express so many different protease-proteoglycan macromolecular complexes. MC-like cells that contain tryptase-heparin complexes in their secretory granules have been identified in the Ciona intestinalis and Styela plicata urochordates that appeared approximately 500 million years ago. Because sea squirts lack B cells and T cells, it is likely that MCs and their tryptase-proteoglycan granule mediators initially appeared in lower organisms as part of their innate immune system. The conservation of MCs throughout evolution suggests that some of these protease-proteoglycan complexes are essential to our survival. In support of this conclusion, no human has been identified that lacks MCs. Moreover, transgenic mice lacking the beta-tryptase mMCP-6 are unable to combat a Klebsiella pneumoniae infection effectively. Here we summarize the nature and function of some of the tryptase-serglycin proteoglycan complexes found in mouse and human MCs.

Early detection of breast cancer based on gene-expression patterns in peripheral blood cells

Introduction

Existing methods to detect breast cancer in asymptomatic patients have limitations, and there is a need to develop more accurate and convenient methods. In this study, we investigated whether early detection of breast cancer is possible by analyzing gene-expression patterns in peripheral blood cells.

Methods

Using macroarrays and nearest-shrunken-centroid method, we analyzed the expression pattern of 1,368 genes in peripheral blood cells of 24 women with breast cancer and 32 women with no signs of this disease. The results were validated using a standard leave-one-out cross-validation approach.

Results

We identified a set of 37 genes that correctly predicted the diagnostic class in at least 82% of the samples. The majority of these genes had a decreased expression in samples from breast cancer patients, and predominantly encoded proteins implicated in ribosome production and translation control. In contrast, the expression of some defense-related genes was increased in samples from breast cancer patients.

Conclusion

The results show that a blood-based gene-expression test can be developed to detect breast cancer early in asymptomatic patients. Additional studies with a large sample size, from women both with and without the disease, are warranted to confirm or refute this finding.

Localization of serglycin in human neutrophil granulocytes and their precursors

Serglycin is a major proteoglycan of hematopoietic cells. It is thought to play a role in the packaging of granule proteins in human neutrophil granulocytes. The presence of serglycin in myeloid cells has been demonstrated only at the transcriptional level. We generated a polyclonal antibody against recombinant human serglycin. Here, we show the localization of serglycin in humans during neutrophil differentiation. Immunocytochemistry revealed serglycin immunoreactivity in the Golgi area of promyelocytes (PM) and myelocytes (MC), as well as in a few band cells and mature neutrophil granulocytes. Granular staining was detected near the Golgi apparatus in some of the PM, and the major part of the cytoplasm was negative. Immunoelectron microscopy showed serglycin immunoreactivity located to the Golgi apparatus and a few immature granules of PM and MC. The decreasing level of serglycin protein during myeloid differentiation coincided with a decrease of mRNA expression, as evaluated by Northern blotting. Subcellular fractions of neutrophil granulocytes were obtained. Serglycin immunoreactivity was detected in the fraction containing Golgi apparatus, plasma membrane, and secretory vesicles by Western blotting and enzyme-linked immunosorbent assay. Serglycin was not detected in subcellular fractions containing primary, secondary, or tertiary granules. Together, these findings indicate that serglycin is located to the Golgi apparatus and a few immature granules during neutrophil differentiation. This is consistent with a function for serglycin in formation of granules in neutrophil granulocytes. Our findings contrast the view that native serglycin is present in mature granules and plays a role in packaging and regulating the activity of proteolytic enzymes there.

Targeting myeloperoxidase to azurophilic granules in HL-60 cells

Myeloperoxidase (MPO) is a cationic protein and one of the major constituents of azurophilic granules in neutrophils. Here, we examined whether intracellular transport of MPO and serglycin, a chondroitin sulfate (CS)-bearing proteoglycan, is correlated. First, we examined binding of MPO to CS-Sepharose and measured an ionic interaction, which was disrupted by 200-400 mM NaCl. Next, HL-60 promyelocytes were activated with a phorbol ester, which induced an almost complete rerouting of serglycin from the granular to the secretory pathway, concomitant with a similar effect on MPO transport and secretion. We then used the membrane-permeable cross-linker dithiobis(succininmidylpropionate; DSP) after labeling HL-60 cells with [35S]methionine and [35S]cysteine for 19 h. Immunoprecipitation of MPO revealed its cross-linking to high molecular material having the appearance of a proteoglycan in sodium dodecyl sulfate-polyacrylamide gels. This assumption was confirmed by labeling HL-60 cells with [35S]sulfate for 10 min followed by DSP cross-linking and immunoprecipitation. From three granular enzymes immunoprecipitated, only the cationic MPO was cross-linked to [35S]sulfate-labeled serglycin in appreciable quantities, whereas cathepsin D or beta-N-acetylhexosaminidase was not. Thus, intracellular transport of MPO appears to be linked to that of serglycin. Extracts from high buoyant density organelles from human placenta containing MPO activity were subjected to CS-affinity chromatography. Proteins binding to CS were identified by mass spectrometry as MPO, lactoferrin, cathepsin G, and azurocidin/cationic antimicrobial protein of molecular weight 37 kDa, suggesting that serglycin may be a general transport vehicle for the cationic granular proteins of neutrophils.

DNase I hypersensitivity patterns of the serglycin proteoglycan gene in resting and phorbol 12-myristate 13-acetate-stimulated human erythroleukemia (HEL), CHRF 288-11, and HL-60 cells compared with neutrophils and human umbilical vein endothelial cells

We mapped the DNase I-hypersensitive sites (DHSS) of the serglycin gene in resting and phorbol 12-myristate 13-acetate (PMA)-stimulated human erythroleukemia (HEL) and CHRF 288-11 cells, which have megakaryocytic characteristics, and HL-60 promyelocytic leukemia cells. We compared these DHSS with those of normal primary neutrophils and human umbilical vein endothelial cells. Several DHSS appear to be involved in regulating the level of endogenous expression and in the PMA response of hematopoietic cell lines. A DHSS unique to resting HL-60 cells and induced in CHRF 288-11 by PMA may explain the high degree of endogenous expression in HL-60 relative to HEL and CHRF (Schick, B. P., Petrushina, I., Brodbeck, K. C., and Castronuevo, P. (2001) J. Biol. Chem. 276, 24726-24735). A total of 4 DHSS in intron 1 and 6 in intron 2 are associated with the PMA response in a cell-specific manner. A DHSS in the 5'-flanking region and another in intron 1 lie in areas that have high homology with the orthologous murine serglycin locus and are rich in potential transcription factor binding sites. One DHSS in intron 1 and one in intron 2 are located within Alu repeats. Two DHSS found in DNA of normal primary neutrophils were different from those of the cell lines. One DHSS in exon 2 unique to neutrophils correlated with a previously unrecognized alternative splicing that removes exon 2. Human umbilical vein endothelial cells had a DHSS in intron 1 that was common with the cell lines. The different patterns of DHSS exhibited by the cells studied suggest that cell- and differentiation-specific alterations in chromatin structure may control serglycin gene expression.

Serglycin proteoglycan is sorted into zymogen granules of rat pancreatic acinar cells

Serglycin is known as a secretory granule proteoglyean in hematopoietic cells. In this study we identified a high-molecular-weight molecule in aggregated content proteins of zymogen granules of pancreatic acinar cells. The amino acid composition of the isolated protein showed high similarity to serglycin proteoglycan core protein. To confirm the expression of serglycin proteoglycan in pancreatic acinar cells we cloned the rat pancreas cDNA of serglycin core protein and detected the serglycin mRNA in pancreas tissue and AR4-2J cells by reverse transcription-PCR. In AR4-2J cells, transfected with serglycin fused to green fluorescent protein (EGFP), serglycin localized within a web-like pattern in the perinuclear space as well as with a punctate pattern distributed in the cytoplasm. The perinuclear structures colocalized with the Golgi membrane-associated protein p115 and the punctate structures with the secretory enzyme procarboxypeptidase A, indicating that the serglycin-EGFP fusion protein travels through compartments of the secretory pathway and is sorted into secretory granules. Using an antiserum against serglycin core protein immunofluorescence as well as immunogold electron microscopy analysis conrirmed the subcellular distribution of serglycin proteoglycan in zymogen granules of pancreatic acinar cells. To prevent glycosylation of serglycin core protein we incubated AR4-2J cells with 2 mM p-nitrophenyl-beta-D-xylopyranoside (PNP-xyloside), which serves as alternate substrate for glycosaminoglycan chain attachment. Furthermore, we deleted the serine/glycine repeat region in the serglycin core protein. In both approaches the transfected serglycin-EGFP fusion protein could be detected predominantly in perinuclear Golgi membrane structures, while in control cells the serglycin fusion protein was mostly sorted into the secretory granules. Additionally, we show that sorting of secretory enzymes like amylase

Promoter regulatory elements and DNase I-hypersensitive sites involved in serglycin proteoglycan gene expression in human erythroleukemia, CHRF 288-11, and HL-60 cells

We have compared regulation of the serglycin gene in human erythroleukemia (HEL) and CHRF 288-11 cells, which have megakaryocytic characteristics, with promyelocytic HL-60 cells. Deletion constructs were prepared from the region -1123/+42 to -20/+42, and putative regulatory sites were mutated. In all three cell lines, the two major regulatory elements for constitutive expression were the (-80)ets site and the cyclic AMP response element (CRE) half-site at -70. A protein from HEL and CHRF, but not HL60, nuclear extracts bound to the (-80)ets site. Another protein from all three cell lines bound to the (-70)CRE. Phorbol 12-myristate 13-acetate (PMA) and dibutyryl cyclic AMP (dbcAMP) increased expression of the reporter in HEL cells 2.5-3- and 4.5-fold, respectively, from all constructs except those with (-70)CRE mutations. PMA virtually eliminated expression of serglycin mRNA and promoter constructs, but dbcAMP increased expression in HL-60 cells. The effects of PMA and dbcAMP on promoter expression correlated with mRNA expression. The strengths of two DNase I-hypersensitive sites in the 5'-flanking region and the first intron in all three cells correlated with relative endogenous serglycin mRNA expression. An additional DNase I-hypersensitive site in HL60 DNA in the first intron may be related to the high serglycin expression in HL60 relative to HEL or CHRF cells.

Regulation of expression of megakaryocyte and platelet proteoglycans

The existence of proteoglycans in hematopoietic cells has been recognized for many years. However, elucidation of the structure and function of these molecules has only begun to be explored in recent years. This paper reviews the current status of knowledge of the structure, function and metabolism of the serglycin proteoglycan in megakaryocytes and megakaryocytic tumor cells. We have identified complex metabolic patterns of the serglycin proteoglycan in terms of regulation of overall hydrodynamic size, glycosaminoglycan chain length and disaccharide composition, and processing of the core protein in control cells or in the presence of phorbol 12-myristate 13-acetate or dimethylsulfoxide. We are currently studying the regulation of synthesis of this protein by analysis of promoter constructs in megakaryocytic and non-megakaryocytic hematopoietic cells. We have also tentatively identified a second proteoglycan, betaglycan, which is known also as the Type III transforming growth factor beta receptor. We have identified this molecule in human erythroleukemia and CHRF 288-11 cells by the presence of characteristic core proteins between 92-120 kDa, by its ability to adhere to Octyl Sepharose and by detection of mRNA. We hope to apply studies of proteoglycan metabolism in these cells to understanding the development of alpha granules and membrane elements in megakaryocytes.

Stimulation of serglycin and CD44 mRNA expression in endothelial cells exposed to TNF-alpha and IL-1alpha

Serglycin is a widely distributed proteoglycan, previously assumed to be hematopoietic cell specific. However, the results presented show that serglycin mRNA is expressed outside the hematopoietic cell system. High levels of serglycin mRNA were detected in endothelial cells and smooth muscle cells, whereas low levels were detected in skin fibroblasts. To further analyze the importance of serglycin in endothelial cells, the expression of serglycin mRNA was measured following activation of an endothelial cell line derived from human umbilical cord vein (HUV-EC-C), by the proinflammatory cytokines TNF-alpha and IL-1alpha. The level of serglycin mRNA increased in a time- and dose-dependent way. TNF-alpha (7 ng/ml) was the most potent inducer, increasing the level of serglycin mRNA 2.5 times after 24 h of stimulation. Serglycin has been shown to be a ligand for CD44, a membrane protein expressed in endothelial cells. Following stimulation of the endothelial cells, the level of CD44 mRNA also increased. Again, TNF-alpha (7 ng/ml) turned out to be the most potent inducer, increasing the level of CD44 mRNA 5.5 times after 24 h of stimulation. Both TNF-alpha and IL-1alpha stimulation of the endothelial cells resulted in an increase in the total incorporation of [(35)S]sulfate into macromolecules, which probably indicates an increase in the total production of proteoglycans. A stimulation of endothelial cells by proinflammatory agents resulted in an increase in both serglycin and CD44 mRNA expression, indicating that serglycin, as well as CD44, may participate in the inflammatory process of leukocyte migration.

Transcriptional and posttranscriptional regulation of proteoglycan gene expression

Proteoglycans are among the most complex and sophisticated molecules of mammalian systems in terms of their protein and carbohydrate moieties. These macromolecules are in a continuous interplay with each other and the cell surface signal-transducing pathways, some of which are beginning to be elucidated. Because of their domain structure, catalytic potential, and diversity, these molecules appear to be designed for integrating numerous signaling events. For example, some proteoglycans interact with hyaluronan and lectins, thereby linking cell surfaces and distant matrix molecules. Some interact with collagen during the complex process of fibrillogenesis and regulate this biological process fundamental to animal life. Others interact with growth factors and serve as depot available during growth or tissue remodeling. In this review, we center on the most recent developments of proteoglycan biology, focusing primarily on genomic organization and transcriptional and posttranscriptional control. We discuss only those proteoglycans whose gene and promoter elements have been characterized and proved to be functional. When possible, we correlate the effects of growth factors and cytokines on proteoglycan gene expression with the topology of cis-acting elements in their genomic control regions. The analysis leads to a comprehensive critical appraisal of the principles that underlie the regulation of proteoglycan gene expression and to the delineation of common regulatory mechanisms.

Serglycin expression during monocytic differentiation of U937-1 cells

Serglycin is the major proteoglycan in most hematopoietic cells, including monocytes and macrophages. The monoblastic cell line U937-1 was used to study the expression of serglycin during proliferation and differentiation. In unstimulated proliferating U937-1 cells serglycin mRNA is nonconstitutively expressed. The level of serglycin mRNA was found to correlate with the synthesis of chondroitin sulfate proteoglycan (CSPG). The U937-1 cells were induced to differentiate into different types of macrophage-like cells by exposing the cells to PMA, RA, or VitD3. These inducers of differentiation affected the expression of serglycin mRNA in three different ways. The initial upregulation seen in the normally proliferating cells was not observed in PMA treated cells. In contrast, RA increased the initial upregulation, giving a reproducible six times increase in serglycin mRNA level from 4 to 24 h of incubation, compared to a four times increase in the control cells. VitD3 had no effect on the expression of serglycin mRNA. The incorporation of (35S)sulfate into CSPG decreased approximately 50% in all three differentiated cell types. Further, the (35S)CSPGs expressed were of larger size in PMA treated cells than controls, but smaller after RA treatment. This was due to the expression of CSPGs, with CS-chains of 25 and 5 kDa in PMA and RA treated cells, respectively, compared to 11 kDa in the controls. VitD3 had no significant effect on the size of CSPG produced. PMA treated cells secreted 75% of the (35S)PGs expressed, but the major portion was retained in cells treated with VitD3 or RA. The differences seen in serglycin mRNA levels, the macromolecular properties of serglycin and in the PG secretion patterns, suggest that serglycin may have different functions in different types of macrophages.

ETS target genes: identification of egr1 as a target by RNA differential display and whole genome PCR techniques

ETS transcription factors play important roles in hematopoiesis, angiogenesis, and organogenesis during murine development. The ETS genes also have a role in neoplasia, for example in Ewing's sarcomas and retrovirally induced cancers. The ETS genes encode transcription factors that bind to specific DNA sequences and activate transcription of various cellular and viral genes. To isolate novel ETS target genes, we used two approaches. In the first approach, we isolated genes by the RNA differential display technique. Previously, we have shown that the overexpression of ETS1 and ETS2 genes effects transformation of NIH 3T3 cells and specific transformants produce high levels of the ETS proteins. To isolate ETS1 and ETS2 responsive genes in these transformed cells, we prepared RNA from ETS1, ETS2 transformants, and normal NIH 3T3 cell lines and converted it into cDNA. This cDNA was amplified by PCR and displayed on sequencing gels. The differentially displayed bands were subcloned into plasmid vectors. By Northern blot analysis, several clones showed differential patterns of mRNA expression in the NIH 3T3-, ETS1-, and ETS2-expressing cell lines. Sixteen clones were analyzed by DNA sequence analysis, and 13 of them appeared to be unique because their DNA sequences did not match with any of the known genes present in the gene bank. Three known genes were found to be identical to the CArG box binding factor, phospholipase A2-activating protein, and early growth response 1 (Egr1) genes. In the second approach, to isolate ETS target promoters directly, we performed ETS1 binding with MboI-cleaved genomic DNA in the presence of a specific mAb followed by whole genome PCR. The immune complex-bound ETS binding sites containing DNA fragments were amplified and subcloned into pBluescript and subjected to DNA sequence and computer analysis. We found that, of a large number of clones isolated, 43 represented unique sequences not previously identified. Three clones turned out to contain regulatory sequences derived from human serglycin, preproapolipoprotein C II, and Egr1 genes. The ETS binding sites derived from these three regulatory sequences showed specific binding with recombinant ETS proteins. Of interest, Egr1 was identified by both of these techniques, suggesting strongly that it is indeed an ETS target gene.

Functional characterization of mouse syndecan-1 promoter

The members of the syndecan family are temporally and spatially expressed heparan sulfate proteoglycans of various tissues, where they mediate extracellular influences on cell morphology and behavior. Functional characterization of the mouse syndecan-1 promoter was carried out in order to elucidate the mechanisms involved in the maintenance of the high transcription levels of syndecan-1 gene in various epithelia. For that 9.5 kilobase pairs of the upstream region of mouse syndecan-1 gene were cloned, sequenced, and used to prepare chimaeric constructs with a reporter gene followed by transient or stable transfections into NMuMG cells, cultured either in the presence or absence of serum, the 2.5-kilobase pair promoter region resulted in the constitutive transcription activity, whereas in 3T3 cells the serum depletion decreased the promoter activity significantly. Deletion of the upstream sequences to -437 base pairs relative to the translation initiation site had little effect on this promoter activity. Further deletion to -365 base pairs removed three GT boxes and slightly increased the promoter activity, whereas the deletion of the next two GC boxes (to -326 base pair) reduced the promoter activity dramatically. All of the GC or GT box sequences bound the same set of Sp1-like nuclear protein in gel shift assays. Nuclear protein binding was also demonstrated around both of the most intense transcription initiation sites. Mutation of these regions separately resulted in total loss of transcription initiation from the deleted site and decreased the promoter activity in relation to the intensity of the abolished start site. This indicates that the transcription initiation of the syndecan-1 gene is directed through initiator-like elements directly overlapping the start sites, as shown for several TATA-less housekeeping and growth regulated genes. We assume that the constitutive high level gene expression in epithelial cells is achieved by the proximal promoter, which is controlled by members of Sp1 transcription factor family.

Small proteoglycans

In this review the structure and functions of two non-related proteoglycan families are discussed. One family represents a group of extracellular matrix macromolecules characterized by core proteins with leucine-rich repeat motifs. Within this family special attention is given to those members which carry chondroitin or dermatan sulfate glycosaminoglycan chains. The second family is characterized by repeat sequences of serine and glycine. Their members are products of a single core protein gene and are characteristic constituents of secondary vesicles in cells of the haematopoietic lineage.

Small proteoglycans

In this review the structure and functions of two non-related proteoglycan families are discussed. One family represents a group of extracellular matrix macromolecules characterized by core proteins with leucine-rich repeat motifs. Within this family special attention is given to those members which carry chondroitin or dermatan sulfate glycosaminoglycan chains. The second family is characterized by repeat sequences of serine and glycine. Their members are products of a single core protein gene and are characteristic constituents of secretory vesicles in cells of the haematopoietic lineage.

The human serglycin gene. Nucleotide sequence and methylation pattern in human promyelocytic leukemia HL-60 cells and T-lymphoblast Molt-4 cells

The complete nucleotide sequence of the 16.7-kb human gene that encodes the peptide core (serglycin) of a secretory granule proteoglycan was determined, thus representing the first proteoglycan peptide core gene to be sequenced in its entirety. The exons, intron 1, and intron 2 comprised 7, 53, and 40% of the gene, respectively. Nineteen Alu-repetitive DNA sequences were interspersed in the gene, accounting for 28% of the total nucleotides in intron 1 and 40% of the nucleotides in intron 2. The nucleotide sequence was then used in an examination of the methylation pattern of the human serglycin gene in human promyelocytic leukemia HL-60 cells that contain serglycin mRNA and in T-lymphoblast Molt-4 cells that do not. With polymerase chain reaction methodology, 13 DNA probes of 250-880 base pairs in length were generated that corresponded to unique, non-Alu sequences spaced throughout the entire human serglycin gene. When blots containing genomic DNA digested with HpaII or MspI were examined with these genomic probes, it was discovered that the 5'-flanking region and intron 1 of the serglycin gene in HL-60 cells were both substantially less methylated than intron 2. In contrast, the entire serglycin gene in Molt-4 cells was highly methylated. Because hypomethylated genes generally are transcribed more efficiently than hypermethylated genes, the high level of serglycin mRNA in HL-60 cells probably is a consequence of the low level of methylation of intron 1 and the 5'-flanking region of the serglycin gene in these cells.

Expression pattern of a hematopoietic proteoglycan core protein gene during human hematopoiesis

Expression of the hematopoietic proteoglycan core protein (HpPG) gene was examined in normal peripheral blood, normal bone marrow, and leukemic peripheral blood leukocytes samples to assess the expression pattern of the HpPG gene in these cells and to ascertain points of regulation of this gene during hematopoiesis. In situ hybridization to normal bone marrow and peripheral blood leukocytes demonstrated that the gene was expressed in the promyelocytes at a approximately two fold greater level than in the segmented neutrophils and the expression decreased as the granulocytes matured. The ratio of expression in the other leukocytes to expression in the segmented neutrophils were as follows: eosinophils/basophils approximately 7; monocytes approximately 2; lymphocytes less than 1. Expression of the HpPG gene during myeloblast differentiation was assessed by Northern blot analysis of acute myelogenous leukemia (AML) RNA samples. The expression of this gene, when compared to the levels in HL-60 cells, was approximately ten fold lower in the poorly differentiated blast cells obtained from three AML patients classified M"0". Conversely, the expression in the more differentiated blast cells obtained from 10 of 11 AML patients classified as M1 and M2 were at levels similar to the levels in HL-60 cells. The expression level found in eight lymphoid leukemias was approximately ten fold or more lower than in HL-60 cells. Gene copy number determination confirmed that the HpPG gene is present in one copy per haploid genome. Thus the HpPG gene's expression pattern denotes a single copy gene being differentially expressed during hematopoiesis with initial regulation occurring very early in this developmental process and an additional up-regulatory event occurring during granule genesis.

Proteoglycans in haemopoietic cells

Proteoglycans are produced by all types of haemopoietic cells including mature cells and the undifferentiated stem cells. The proteinase-resistant secretory granule proteoglycan (serglycin; Ref. 14), is the most prevalent and best characterised of these proteoglycans. Although its complete pattern of distribution in the haemopoietic system is unknown, serglycin has been identified in the mast cells, basophils and NK cells, in which secretion is regulated, and in HL-60 cells and a monocytoid cell line (Kolset, S.O., unpublished data) in which secretion is constitutive. Proteinase-resistant proteoglycans have been detected in human T-lymphocytes and murine stem cells (FDCP-mix) and the core proteins may be closely related to serglycin. A variety of glycosaminoglycan chains are assembled on the serglycin protein and it is likely that this class of proteoglycan can carry out a wide variety of functions in haemopoietic cells including the regulation of immune responses, inflammatory reactions and blood coagulation. There is strong evidence that in mast cells, NK cells and platelets, the proteoglycans are complexed to basic proteins (including enzymes and cytolytic agents) and amines in secretory granules and such complexes may dissociate following secretion from the cell. The stability of the complexes may be regulated by the ambient pH which may be acidic in the granules and neutral or above in the external medium. However, proteinase-proteoglycan complexes in mast cell granules seem to remain stable after secretion and it has been proposed that the proteoglycan regulates activity of proteinases released into the pericellular domain. The functions of proteoglycans which are constitutively secreted from cells are less clear. If cells have no requirement for storage of basic proteins why do they utilise the same design of proteoglycan as cells which accumulate secretory material prior to regulated release? We should stress that the so-called constitutive secretory pathway has been identified in haemopoietic cells in culture, which are usually maintained and grown in the presence of mitogenic factors (e.g., IL-2, IL-3). the cells are therefore activated and it has not been established that continuous proteoglycan secretion occurs in quiescent cells circulating in the peripheral blood. It is possible that lymphocytes, monocytes and macrophages, in which the constitutive secretion pathway operates in vitro, may store proteoglycan in vivo unless stimulated by mitogens or other activating agents.(ABSTRACT TRUNCATED AT 400 WORDS)

Proteoglycan-targeted antibodies as markers on non-Hodgkin lymphoma xenografts

A family of mono- and polyclonal antibodies raised against proteoglycans or their "subcomponents" served as novel markers to characterize the phenotypes of three non-Hodgkin lymphoma xenograft lines (HT 58 lymphoblastic, HT 117 centroblastic, HT 130 centrocytic) together with normal, human peripheral blood B lymphocytes. These xenografted NHL lines, maintained by serial transplantations on artificially immunosuppressed mice, expressed very similar B-cell-related antigens and differences on the cell surface (HT 58 greater than HT 117 greater than HT 130 greater than B cells) when they were exposed to monoclonal antibodies (mAb) to cartilage proteoglycans. Anti-proteoglycan antibodies used in this study recognize complex epitopes of core protein segment associated with carbohydrate, shared by human cartilage proteoglycans and certain lymphoma cells. The binding of these antibodies was independent of cell-cycle phase. The results suggest that the anti-proteoglycan mAbs could be used as new phenotypic markers to individualize non-Hodgkin lymphomas.