Role of microscopy in elucidating the mechanism and regulation of the osteoclast resorptive apparatus

Gay, Carol V.

doi:10.1002/(sici)1097-0029(19960201)33:2<165::aid-jemt6>3.0.co;2-s

Cited by 11 publications

(6 citation statements)

References 58 publications

(36 reference statements)

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“…Thus, it is believed that the cathepsin L-rich macrophages in the lesions may feature 2 eroding systems, that is, an acid-secreting mechanism to dissolve the inorganic or mineral component of bone and a proteinase-secreting mechanism to degrade the proteins once shielded by hydroxyapatite (42).…”

Section: Discussionmentioning

confidence: 99%

“…Besides secretion of cysteine proteinases, activated macrophages also generate an acidic microenvironment in culture, and this occurs specifically at the attachment site between the cell and the base of the culture dish (41). Thus, it is believed that the cathepsin L-rich macrophages in the lesions may feature 2 eroding systems, that is, an acid-secreting mechanism to dissolve the inorganic or mineral component of bone and a proteinase-secreting mechanism to degrade the proteins once shielded by hydroxyapatite (42).…”

Section: Discussionmentioning

confidence: 99%

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Macrophage cathepsin L, a factor in the erosion of subchondral bone in rheumatoid arthritis

Iwata

Mort

Tateishi

et al. 1997

Arthritis & Rheumatism

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Objective. To test the hypothesis that the proteinase cathepsin L is involved in the subchondral bone lesions found in chronic rheumatoid arthritis (RA).Methods. The medial tibia1 plateaus from 4 control cases and 30 patients diagnosed as having end-stage RA were examined immunochemically for cathepsin L.Results. RG lesions include large groups of mononuclear cells, many of which are rich in cathepsin L. Since these mononuclear cells contained the CD68 glycoprotein and, in the electron microscope, displayed an irregular cell surface, cytoplasmic vacuoles, lysosomes, and phagosomes, they were identified as belonging to the macrophage family. The lesions were classified into 2 main patterns, both displaying these cathepsin Grich cells, which, in at least 1 of the 2, were closely associated with bone degradation.Conclusion. The cathepsin L-rich macrophages are sufficiently numerous to be considered a major factor in producing the erosion of subchondral bone found in chronic RA lesions.Little is known of the cells involved in the resorption of subchondral bone that occurs in rheumatoid arthritis (RA), although there is some evidence that osteoclasts are responsible (1-3). There is general agreement that in healthy people, the degradation of bone is effected by osteoclasts through the secretion of cathepsin L and other proteinases into the acid-rich space that separates them from the bone (43). On the assumption Submitted for publication May 1, 1996; accepted in revised form September 30, 1996. that the same mechanism is operative in RA lesions, the expectation was that cathepsin L-producing osteoclasts would be observed in these lesions.In support of the potential role of cathepsin L in the resorption of bone and cartilage observed in RA patients, it is known that this enzyme degrades several bone components in vitro, namely, type I collagen (6) and the proteins osteonectin and osteocalcin (7), as well as components of cartilage, namely, type 11, IX, and XI collagens (6), the major proteoglycan, aggrecan (8), and link protein (9). Moreover, cathepsin L can be secreted outside the cell, as occurs in the course of antigen presentation (10) and in sperm maturation (11). Pathologic cells may also secrete large amounts of cathepsin L, as observed in cultures of malignantly transformed cells (12). Of particular interest is the evidence of cathepsin L secretion at sites of normal bone resorption (13-16), as well as elevated levels of cathepsin L in the synovial fluid of RA patients (17).The postulated role of osteoclasts in the production of RA lesions (1-3) implies that these cells synthesize and secrete cathepsin L and other proteinases for bone degradation. To find out whether osteoclasts or other cells are involved in the production of cathepsin L, we used an immunohistochemical approach. It was known that cathepsin L is synthesized as the 41-kd proteolytically inactive precursor procathepsin L, which in the acidic environment of the lysosome, gives rise to active forms of cathepsin L (18). We used an antibody raise...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Macrophage cathepsin L, a factor in the erosion of subchondral bone in rheumatoid arthritis

Iwata

Mort

Tateishi

et al. 1997

Arthritis & Rheumatism

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“…Inhibition of the isoforms of carbonic anhydrase by sulfonamides is variable, with the most research focused on isoform II (Maren and Conroy 1993;Sly and Hu 1995). The cells examined in this study, avian osteoclasts, have been shown to contain solely CA II, as reviewed earlier (Gay 1996). Sulfonamide inhibition of the isoforms varies, with CA II and V being the most sensitive, forms I, IV, and VI being somewhat sensitive, and form III being insensitive to inhibition (Sly and Hu 1995).…”

Section: Discussionmentioning

confidence: 98%

“…Staining decreased with increasing unlabeled inhibitor. Osteoclasts still adherent to bone were used to assess the effectiveness of the dye because these cells have been shown to contain carbonic anhydrase (Gay and Mueller 1974;Gay 1996) and are actively producing acid, a carbonic anhydrase-dependent process (Hunter et al 1988(Hunter et al ,1991. Staining of cultured cells was observed but with much less intensity (not shown).…”

Section: Discussionmentioning

confidence: 99%

Localization of Carbonic Anhydrase in Living Osteoclasts with Bodipy 558/568-modified Acetazolamide, a Thiadiazole Carbonic Anhydrase Inhibitor

Brubaker¹,

Mao

1999

J Histochem Cytochem.

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SUMMARYWe describe the synthesis of Bodipy 558/568-modified acetazolamide, a fluorescent inhibitor of carbonic anhydrase and its use to localize the enzyme in living cells. The modified acetazolamide, with its specific sulfonamide group intact, labeled cells at concentrations as low as 10 -9 M, with a minimal loading time of 5 min. The staining was decreased by 57.4% by preincubating cells with unaltered acetazolamide (1:100) or with trifluoromethane sulfonamide, 6-ethoxyzolamide, and 5-(3-hydroxybenzoyl)-thiophene-2-sulfonamide. The efficacy of the inhibitor was unchanged by the fluorescent label, as determined by an acridine orange assay that detects acidification of osteoclasts, the cell model used in this study. This compound should prove to be useful for studying carbonic anhydrase in many organisms because of the high degree of conservation of the active site of this enzyme. (J Histochem Cytochem 47:545-550, 1999)

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“…The cytoplasm interior to the ruffled border possesses an abundance of vesicles containing lysosomal enzymes [Baron et al, 1988] and a nuclear region surrounded by multiple Golgi complexes and numerous mitochondria [for reviews see Baron et al, 1993;Teitelbaum et al, 1996]. Acid secretion from the ruffled border region requires ion-generating and ion-transport systems to be present in the cytosol and in several distinct plasma membrane domains [Baron et al, 1993;Gay, 1996].…”

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confidence: 99%

Spectrin localization in osteoclasts: Immunocytochemistry, cloning, and partial sequencing

et al. 1998

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The presence of spectrin was demonstrated in chick osteoclasts by Western blotting and light and electron microscopic immunolocalization. Additionally, screening of a chick osteoclast cDNA library revealed the presence of alpha-spectrin. Light microscope level immunocytochemical staining of osteoclasts in situ revealed spectrin staining throughout the cytoplasm with heavier staining found at the marrow-facing cell margin and around the nuclei. Confocal microscopy of isolated osteoclasts plated onto a glass substrate showed that spectrin encircled the organelle-rich cell center. Nuclei and cytoplasmic inclusions were also stained and the plasma membrane was stained in a nonuniform, patchy distribution corresponding to regions of apparent membrane ruffling. Ultracytochemical localization showed spectrin to be found at the plasma membrane and distributed throughout the cytoplasm with especially intense staining of the nuclear membrane and filaments within the nuclear compartment.

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Role of microscopy in elucidating the mechanism and regulation of the osteoclast resorptive apparatus

Cited by 11 publications

References 58 publications

Macrophage cathepsin L, a factor in the erosion of subchondral bone in rheumatoid arthritis

Macrophage cathepsin L, a factor in the erosion of subchondral bone in rheumatoid arthritis

Localization of Carbonic Anhydrase in Living Osteoclasts with Bodipy 558/568-modified Acetazolamide, a Thiadiazole Carbonic Anhydrase Inhibitor

Spectrin localization in osteoclasts: Immunocytochemistry, cloning, and partial sequencing

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