Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bone cells isolated from mouse calvariae by a sequential digestion procedure have many osteoblast characteristics: they respond to PTH and prostaglandin E2 by activation of adenylate cyclase but not to calcitonin, they stain for alkaline phosphatase and they make only type I collagen. In confluent monolayer culture, they do not secrete collagenase in appreciable quantities, unless stimulated with resorptive substances such as PTH, prostaglandin E2, 1,25(OH)2 vitamin D-3 and monocyte-conditioned medium. This suggests they play a direct role in bone resorption.
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PMID:Mouse osteoblasts synthesize collagenase in response to bone resorbing agents. 609 72

Connective tissue destruction is a major characteristic of chronic rheumatoid arthritis (RA). Attempts at repair and fibrosis are also seen. This process is accompanied by local cellular and humoral inflammatory reactions. Production of large amount of collagenase and prostaglandin (PGE2) are demonstrated in vivo and can account for the pathogenesis. Long term cultures of adherent synovial cells from patient with RA produce also large amounts of collagenase and PGE2. Collagenase and PGE2 levels can be stimulated with a soluble factor (MCF), a monokine produced by monocyte-macrophages in culture. MCF production is modulated by cellular elements (T lymphocytes), by humoral elements (Fc fragments of immunoglobulin, immune complexes, antigens, lectins), by elements of the matrix (collagen). MCF appears to belong to the category of the interleukin 1. This factor also affects cell replication, collagen synthesis, hormonal response (to PGE2 and PTH). The monocyte-macrophages in this system appear to be the key between the immune and non-immune systems. Studies of MCF (one of the monocyte-macrophage products) will help the understanding of the pathogenesis of chronic inflammation such as RA and the designing and screening of new drugs potentially useful in destructive diseases.
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PMID:Aspects of resorption and formation of connective tissue during chronic inflammation in rheumatoid arthritis. 629 70

Several studies have revealed a variety of interactions between PTH and ACTH. The existence of a significant area of homology in the bioactive regions of the two molecules has been proposed as a possible reason for such interactions. To clarify the relationship, corticosteroidogenic and cAMP accumulative effects of bovine PTH (bPTH 1-84), its amino-terminal fragment (bPTH 1-34), and the amino terminal fragment of human PTH (hPTH 1-34) were compared with ACTH 1-39 by determining their dose-response characteristics in collagenase-dissociated adrenocortical cells from rats. bPTH 1-84 and bPTH 1-34 (10(-8)-10(-5)M) did not alter steroid production of the cells nor did 10(-6)M bPTH 1-34 affect the steroid response curve to ACTH 1-39. However, the degree of steroidogenesis elicited by hPTH 1-34 over the dose range 3.3 X 10(-7)-3.3 X 10(-5)M was the same as that elicited by ACTH 1-39 over the range 10(-11)-10(-9) M. cAMP generation with hPTH 1-34 was maximal at 10(-4) M but the correlation between the steroid and cAMP responses with ACTH 1-39 was noticeably different from that with hPTH 1-34. In experiments with ACTH 6-24 (a competitive inhibitor of ACTH 1-39), both steroid and cAMP responses to hPTH 1-34 were greatly reduced. Oxidized hPTH 1-34 did not elicit any steroid production nor did several other peptide hormones (arginine vasopressin, angiotensin II, calcitonin, insulin, GH) at 10(-5) M. These observations indicate that hPTH 1-34 can exert a direct and specific effect on rat adrenocortical cells revealing the peptide as a full agonist for steroid production in this system. We suggest that it is a combination of sequence homology and conformational structure which permits hPTH 1-34 to interact with, and elicit its response through, the receptor for ACTH 1-39.
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PMID:Corticosteroidogenesis and adenosine 3', 5'- monophosphate production by the amino-terminal (1-34) fragment of human parathyroid hormone in rat adrenocortical cells. 630 60

During bone remodeling, activation of resorption is followed by a cycle of formation and this ordered sequence of events has long suggested that local interactions between osteoclasts and osteoblasts are an important regulatory mechanism in bone metabolism. To study this phenomenon, we have prepared bone cells containing primarily osteoclasts by brief digestion of mice calvariae in collagenase, overnight attachment to polystyrene tissue culture flasks in serumless medium supplemented with OB (osteoblast) cell conditioned medium and subsequent growth in low serum. These OC (osteoclast) cells were found to be highly enriched in acid phosphatase activity and expressed cAMP responses to PTH (parathyroid hormone) and prostaglandin E2 but exhibited no PTH-stimulated hyaluronate synthesis in contrast to prostaglandin E2. PTH effects on hyaluronate, however, could be restored upon coculture of OC cells with OB cells (noncontact) or with OB cell conditioned medium, thereby suggesting that OB cells regulate OC cell PTH responsiveness and/or differentiation by soluble cell products secreted into the medium.
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PMID:Paracrine interactions in bone-secreted products of osteoblasts permit osteoclasts to respond to parathyroid hormone. 632 52

The purpose of the present study was to investigate the mechanism of action on bone of Benzo(B)Thiophene-2-Carboxylic Acid (BL-5583). BL-5583, at a dose range of 0.01-100 micrograms/ml, inhibited spontaneous as well as A23187 and PTH-induced bone resorption in tissue culture. This compound also decreased calcium uptake in both osteoclastic and osteoblastic enriched bone cell populations obtained by sequential collagenase digestion of 1-2 day newborn rat calvariae. The decrease occurred after a 5 min. incubation with 45Ca and BL-5583. The effective dose range was 0.01-100 micrograms/ml. No effect on leucine incorporation or lactic acid production by bone cells was observed. BL-5583 also induced a transient decrease in calcium uptake in skin cells isolated from fetal rats by collagenase digestion, suggesting a lack of tissue specificity for this compound. No effect on cyclic AMP in isolated bone cells was observed with the same dose range that produced a calcium effect.
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PMID:Benzo(B)thiophene-2-carboxylic acid: calcium uptake and cyclic AMP production in isolated bone cells. 633 14

An isolated osteoblast-like cell line (MMB-1) was used to study the hormonal regulation of collagen synthesis in bone cells. Collagen synthesis was measured by incorporation of [3H]proline into collagenase-digestible and collagenase-non-digestible proteins after exposure of the cells in culture to varying concentrations of PTH, 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3], osteoclast-activating factor, and insulin. Collagen synthesis was inhibited by 10(-10) M 1,25-(OH)2D3 and 3 X 10(-10) M PTH after 9-12 h of treatment. Osteoclast-activating factor at 10(-10) M also inhibited collagen synthesis. Insulin at 10(-8) M increased collagen synthesis without stimulating proline incorporation into noncollagen proteins. No effect on collagen synthesis was observed with 24,25-(OH)2D3. Inhibition of collagen synthesis was also observed when cells were treated with either 3 X 10(-5) M 8-bromo-cAMP or 3 X 10(-5) M (Bu)2cAMP. For all agents tested, the onset of the effects was gradual, with differences from controls beginning at 4-8 h, and maximal effects occurring only after 24 h or more of treatment. The collagen synthesized by these cells remained associated primarily with the cell monolayer and was estimated to be greater than 90% type I collagen. No detectable changes in the type or composition of collagen synthesized were found with any of the hormonal treatments. These studies indicate that the synthesis of collagen in bone cells is under multihormonal control, with both cAMP-dependent and cAMP-independent mechanisms involved. The MMB-1 cell line offers a suitable model system for studies of the interactions of hormones in the control of bone turnover.
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PMID:Multiple hormonal mechanisms for the control of collagen synthesis in an osteoblast-like cell line, MMB-1. 633 52

Stimulators of bone resorption, such as PTH, 1,25-dihydroxycholecalciferol [1,25-(OH)2D3], or prostaglandin E2 (PGE2), do not cause calcium release from cultured calvaria of the genetically determined osteopetrotic microphthalmic (mi/ mi) mouse, due to a defect in the function of osteoclasts. To investigate the capacity of cells of mi/mi bone to degrade collagen, calvaria of 1- to 3-day-old normal and mi/mi littermates were labeled in vivo with [3H]proline 16 h before removal, followed by culture in resorption medium. PTH, 1,25-(OH)2D3, and PGE2 stimulated the release of 3H-labeled material into the culture medium from both normal and mi/mi calvaria. The labeled substance released was of collagenous origin, as indicated by its content of hydroxyproline and susceptibility to collagenase. PTH also stimulated the release of 3H-labeled materials from normal calvaria labeled in vivo 112 h before the mice were killed, but had little or no effect on 3H release from the mi/mi bone, indicating that only noncalcified collagen is susceptible to hormone-stimulated degradation in osteopetrotic bone. We conclude that a portion of the hormone-stimulated resorptive mechanism, namely collagenolysis, is functional in bone of mi/mi mice. This result helps to pinpoint the resorptive defect in mi/ mi bone to a failure to dissolve mineral, rather than a more general phenomenon of failure to remove both mineral and matrix.
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PMID:A collagenolytic response to parathormone, 1,25-dihydroxycholecalciferol D3, and prostaglandin E2 in bone of osteopetrotic (mi/mi) mice. 657 20

Sequential collagenase digestion of mice calvariae provides populations of bone cells that express either osteoclasts (OC) or osteoblastic (OB) activities after growth for 6 days in similar culture conditions consisting of minimal essential medium supplemented with 10% fetal calf serum (FCS). The OC characteristics (acid phosphatase activity and hyaluronate synthesis, and their stimulation by PTH) were recovered in the cell populations released early from calvariae, but these also contained OB cells and numerous spindle-shaped alkaline phosphatase positive cells that resembled fibroblasts. We have attempted to select for growth of OC cells in these early populations by exploiting differences in growth requirements of OC, OB, and fibroblastic cells. We find that after growth for 6 days in low serum (2% FCS), OC cell populations demonstrated a threefold increase in OC activity/cell, and cell yield was reduced to one-third of that obtained in 10% FCS. Spindle-shaped cells were absent in 2% FCS and OB marker activities (alkaline phosphatase and citrate decarboxylation) were reduced threefold. In contrast to OC cells, high serum (10% FCS) favored the growth and phenotypic expression of OB cells (late populations). Cell yield and OB marker activities/cell were twofold higher in OB cells grown in 10% FCS vs 2% FCS, whereas growth but not phenotypic expression was retained at 5% FCS. These data suggest that differential serum dependence of OC and OB cells may provide a basis for further enrichment for each cell type following sequential digestion.
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PMID:Differential serum dependence of cultured osteoclastic and osteoblastic bone cells. 665 53

Cell aggregates of bovine parathyroid tissue were prepared by limited collagenase digestion and placed in culture in Weymouth's MB752/1 (calcium = 3.3 mg/100 ml) containing 5% fetal bovine serum and supplemented with insulin alone, or insulin, hydrocortisone, transferrin and epidermal growth factor. Only insulin was required for the maintenance of PTH secretion over a 9-day period. The cell aggregates spread to form monolayer in 3-5 days. The majority of the cells in monolayer were polygonal with well-defined borders. Nuclei were round and the cytoplasm was free of vacuoles. Cell cultures responded to secretory stimulation by low calcium or by isoproterenol with increases in the secretion of PTH and SP-1. At low calcium, about 18% of both the cellular PTH and SP-1 was secreted per hour, and up to 50% of the cell content of these proteins was released per hour upon stimulation by isoproterenol and low calcium combined. The responses to calcium and isoproterenol decreased as a function of time in culture, and calcium responses often disappeared completely by 10 days of culture. When cells were cultured in medium containing a higher (5 mg%) than standard concentration of calcium between days 3-6 of culture, the degree of secretory inhibition attainable with high calcium was greater than that of cells cultured in the standard medium. When secreted hormonal peptides were separated by SDS-gel electrophoresis prior to RIA, it was found that the secretion of intact hormone was sensitive to calcium. For every molecule of PTH secreted into the medium, 1.5-2 mole-equivalents of carboxyl fragments were also released. Calcium control of fragment release was not as stringent as that of PTH release.
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PMID:Primary monolayer cell culture of bovine parathyroids: effects of calcium, isoproterenol and growth factors. 686 97

Suppression of PTH secretion by extracellular calcium is mediated by a plasma membrane calcium receptor (CaR). However, primary cultures of bovine parathyroid cells are known to quickly lose their responsiveness to extracellular calcium. The present study was designed to determine if the loss of calcium responsiveness is due to changes in CaR expression. In primary monolayer cultures of parathyroid cells, calcium-mediated suppression of PTH was still evident after 24 hours in culture but was completely absent after 6 days. This was preceded by a 75% drop in CaR mRNA content within 24 hours. CaR mRNA levels remained low for the 6-day culture. Earlier time points, examined in parathyroid cell suspensions, showed a 70% drop in CaR mRNA by 4 hours after collagenase-dispersion of the glands and an 85% drop after 24 hours. The decreased expression of CaR mRNA was not influenced by altering medium serum, calcium, or 1,25-dihydroxyvitamin D3. Our results indicate that the loss of responsiveness of cultured parathyroid cells to calcium is due to decreased CaR mRNA and, presumably, CaR protein expression.
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PMID:Loss of calcium responsiveness in cultured bovine parathyroid cells is associated with decreased calcium receptor expression. 762 22


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