Localization of serglycin in human neutrophil granulocytes and their precursors

Abstract

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.

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

“…In normal human bone marrow, serglycin is detectable only by immunohistochemistry at the promyelocyte and myelocyte stage, whereas mature neutrophils stain negative for serglycin (Figures 1g and h, 9 ). In bone marrow specimens from all 18 patients with AML, the vast majority of the abnormal leukemic blast cells showed cytoplasmic immunostaining for serglycin with a predominantly perinuclear, dot-like staining pattern, resembling that seen in promyelocytes from normal bone marrow (Figures 1a-f).…”

“…The ELISA has the same sensitivity for glycosylated and nonglycosylated serglycin. 9 Neutrophil elastase was measured by a commercially available ELISA (HyCult biotechnology, Uden, the Netherlands). MPO and Lysozyme levels were measured by ELISA as described previously.…”

“…9 The polyclonal rabbit antibody used for the ELISA was generated toward full-length, nonglycosylated, recombinant human serglycin. The ELISA has the same sensitivity for glycosylated and nonglycosylated serglycin.…”

“…[1][2][3] Serglycin mRNA expression has been demonstrated in several myeloid and lymphoid cell lines, [4][5][6][7] and serglycin immunoreactivity has been observed in myeloid cells and cell lines 8,9 as well as in cell lines of lymphoid, mast cell, plasmacytoid and myelomonocytic origin. 10 The function of serglycin in the different types of cells is slowly becoming apparent.…”

“…3 During differentiation of neutrophils in human bone marrow, serglycin mRNA expression and immunoreactivity is present only at the promyelocyte and immature myelocyte stage, whereas mature neutrophils are devoid of serglycin immunoreactivity and mRNA. 6,9 This prompted us to investigate the expression of serglycin in the malignant counterpart of immature myeloid cells, the myeloblasts, in bone marrow samples from patients with acute myeloid leukemia (AML). Furthermore, we characterize the expression of serglycin in the malignant counterparts of other hematopoietic cell types that have been reported to express serglycin, for example, anaplastic large cell lymphoma (ALCL), natural killer cell (NK cell) lymphoma and acute lymphoblastic leukemia (ALL).…”