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)

Insulin-like growth factor-I (IGF-I) has been shown to stimulate biosynthesis of progesterone and other differentiated functions of granulosa cells. The presence of the IGF-I receptor messenger RNA and IGF-I receptor as well as the role of IGF-I in the amplification of gonadotropin action in luteinized rat ovarian cells were assessed in the present study. Rat ovarian luteal tissue were obtained on day 6 of pseudopregnancy. After collagenase dispersion, luteal cells were cultured with or without IGF-I for 72 h in a serum-free medium in the absence or presence of human CG (100 ng/ml), 8-bromo-cAMP (1 mM), and 25-OH cholesterol (30 micrograms/ml). IGF-I alone increased (P less than 0.01) progesterone secretion 47% over controls. When combined with hCG the increase in progesterone secretion was enhanced 6-fold (P less than 0.001) over controls. The effects of 8 bromo-cAMP on progesterone secretion also was amplified (P less than 0.001) when IGF-I was present in the medium. When 25-OH cholesterol, a diffusable substrate for steroidogenesis, was included in the incubation medium along with IGF-I, progesterone secretion was enhanced significantly (P less than 0.01) over controls and either treatment alone. Binding studies performed with ovarian luteal cell membranes in the ovary revealed a dissociation constant of 0.94 nM for the IGF-I receptor. Autoradiograms from affinity labeling studies revealed a band corresponding to 132 Kd which is characteristic for the alpha-subunit of the type I IGF receptor. Northern blot analysis showed the presence of a major transcript at approximately 11 kilobases, which agrees with the size of the IGF-I receptor messenger RNA. In conclusion, we provide evidence for the fact that IGF-I regulates differentiated functions of the corpus luteum through interaction with specific high affinity IGF-I receptors.
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PMID:Studies on rat luteal cell response to insulin-like growth factor I (IGF-I): identification of a specific cell membrane receptor for IGF-I in the luteinized rat ovary. 165 48

Diabetes mellitus is associated with a generalized defect in connective tissue metabolism. Since collagen is the major protein of connective tissues, we used collagen as a probe to examine the role of factors in diabetic rat serum (DRS) in the etiology of these defects. Serum and skin fibroblasts were isolated from nondiabetic rats, and serum was taken from rats 48 h after injection of 200 mg/kg streptozotocin. Within 24 h of confluency, the fibroblast medium was changed to experimental serum for 24 h, with 5 microCi [3H]proline added for the final 6 h. Collagen and noncollagen proteins were quantitated using purified collagenase. Compared to cells incubated in medium without serum, collagen fell to 58% with 0.5% DRS (P less than 0.05) and continued to decrease with increasing concentrations of DRS. Noncollagen protein decreased below levels in cells incubated in medium without serum only when concentrations of diabetic serum were 1% or greater and did not decrease further with higher concentrations of diabetic serum. Collagen was decreased to a greater degree than noncollagen protein at each concentration of DRS, such that collagen relative to total protein production was significantly reduced at 0.5% or more DRS. Addition of 10(-7)-10(-9) M insulin or insulin-like growth factor-I (0.1-1000 ng/ml) to DRS did not return collagen production to the level seen in cells incubated in medium with no added serum (basal production). After separation of serum components based on size, incubation of cells with the low mol wt fraction (less than 5000 daltons) of normal and diabetic rat serum resulted in equivalent collagen production, while incubation with the high mol wt fraction of DRS resulted in 200-fold less collagen compared to the similar fraction of normal serum. This decrease in collagen production appeared due to the presence of a high mol wt factor(s) in diabetic serum which had a direct inhibitory effect on collagen and was not due to deficiency of growth peptides. The degree and specificity of these changes in collagen production probably contribute to long term complications in diabetes through altered connective tissue metabolism.
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PMID:Inhibition of collagen production by diabetic rat serum: response to insulin and insulin-like growth factor-I added in vitro. 195 85

Malnutrition is associated with defects in connective tissue metabolism such as altered growth and wound healing. Because collagen is the major protein in most tissues, we determined the threshold for induction of altered collagen production by partial food restriction in rats. Groups of animals were fasted 2 or 4 d or were fed 20-100% of a predetermined food intake for 4 to 8 d. Collagen and noncollagen protein production in articular cartilage were determined using purified collagenase digestion of collagen labeled for 2 h in vitro with [3H]proline. Significant decreases in collagen (P less than 0.01) were seen in rats after 4 d of 40% (weight-losing rats) or after 8 days of 80% (weight-gaining rats) ad libitum intake. Collagen production decreased with both duration and degree of food deprivation; after 8 d of 20% intake, collagen was less than 10% that of controls fed ad libitum (P less than 0.001). In contrast, noncollagen protein production was significantly decreased only after 4 or 8 d of less than 40% intake (weight-losing rats). Maximum suppression of noncollagen protein was to approximately 65% of levels in controls fed ad libitum (P less than 0.01) and was not further reduced in fasted rats. Insulin-like growth factor-I levels were significantly decreased with duration and severity of diet in parallel with changes in collagen. The degree and sensitivity of altered collagen production to small changes in food intake suggest close regulation of this peptide and a potential role for decreased collagen synthesis in connective tissues during mild states of undernutrition.
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PMID:Collagen production in fasted and food-restricted rats: response to duration and severity of food deprivation. 200 4

We examined the ability of cortisol to modulate the stimulatory effects of recombinant human insulin-like growth factor-I (IGF-I) on collagen synthesis, procollagen messenger RNA (mRNA) levels and DNA synthesis in 21-day fetal rat calvariae maintained in serum-free organ culture for 24-96 h. Collagen synthesis was quantitated by measuring the incorporation of [3H]proline into collagenase-digestible protein (CDP) and alpha-1(I) procollagen mRNA transcripts were assessed by Northern blot analysis. Cell replication was quantitated by measuring the incorporation of [3H]thymidine into bone. As described previously, 100 nM cortisol had a biphasic effect on CDP labeling, increasing CDP after 24 h and decreasing CDP after 48, 72, and 96 h of culture. IGF-I alone increased CDP labeling by 1.6-fold after 24 h and by 2-fold after 48 or 72 h of culture, and cortisol potentiated this anabolic effect. In the presence of 100 nM cortisol, IGF-I increased CDP labeling by 2.6-fold after 24 h, by 5-fold after 48 h, and by 8-fold after 72 h of culture. A higher concentration of cortisol (1000 nM) also potentiated the IGF-I response on CDP labeling after 96 h of culture. In the presence of 100 nM cortisol, concentrations of IGF-I lower than 10 nM consistently increased CDP labeling and the percent collagen synthesized whereas these concentrations were not always effective without cortisol. PTH, which like cortisol decreased basal CDP labeling, did not enhance the stimulatory effects of IGF-I. Cortisol also enhance the stimulatory effects of IGF-I on alpha-1(I) procollagen mRNA levels indicating that the potentiation of CDP labeling occurs via a pretranslational mechanism. IGF-I had little effect on the incorporation of [3H]thymidine into bone except in the presence of cortisol. Nevertheless, the ability of cortisol to potentiate the stimulatory effect of IGF-I on CDP labeling was independent of cell replication since the enhancement persisted in the presence of aphidicolin, a DNA synthesis inhibitor. Our findings show that physiological concentrations of cortisol can modulate the responsiveness of cells within cultured fetal rat calvariae to the anabolic effects of exogenous IGF-I.
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PMID:Cortisol enhances the anabolic effects of insulin-like growth factor I on collagen synthesis and procollagen messenger ribonucleic acid levels in cultured 21-day fetal rat calvariae. 230 19

The effect of human TNF on cultured human microvascular endothelial (HME) cells was examined. Incubation with TNF alone transformed the morphology of HME cells from a cobblestone-like appearance into a disordered array of criss-crossed, elongated, spindle-shaped cells. Coadministration of epidermal growth factor (EGF) and TNF caused even more dramatic morphologic changes than TNF alone. Addition of basic fibroblast growth factor or insulin-like growth factor-I showed rather weak effects on cell morphology than EGF. Cell growth of HME cells was stimulated up to two-fold by TNF whereas addition of EGF additively enhanced the growth rate. Treatment of HME cells with 10 ng/ml EGF increased the binding of 125I-TNF, and Scatchard analysis showed increased TNF-R number by EGF treatment. Cellular response to TNF in the absence or presence of EGF was assessed by analyzing SDS-PAGE patterns of secreted proteins from HME cells. TNF enhanced the secretion of a protein of molecular weight 25,000 Da (25 kDa) which was found to be IL-6. In contrast, secretion of a polypeptide of 29 kDa was significantly increased when HME cells were treated with EGF, but not with TNF. Coadministration of TNF and EGF synergistically increased the secretion of the 29-kDa protein. This 29-kDa protein was found to be tissue inhibitor of metalloproteinases when assayed with antitissue inhibitor of metalloproteinases antibody. TNF and EGF also enhanced secretion of collagenase with Mr of approximately 55 kDa. Increased steady state levels of the inhibitor mRNA were observed when HME cells were treated with EGF, and coadministration of TNF further increased the levels. The morphologic transformation of HME cells by TNF and/or EGF is discussed in relation to their expression of the secreted proteins.
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PMID:Effects of tumor necrosis factor and epidermal growth factor on cell morphology, cell surface receptors, and the production of tissue inhibitor of metalloproteinases and IL-6 in human microvascular endothelial cells. 254 71

The effects of insulin-like growth factor-I (IGF-I) and insulin on bone matrix synthesis and bone cell replication were studied in cultured 21-day-old fetal rat calvariae. Histomorphometry techniques were developed to measure the incorporation of [2,3-3H]proline and [methyl-3H]thymidine into bone matrix and bone cell nuclei, respectively, using autoradiographs of sagittal sections of calvariae cultured with IGF-I, insulin, or vehicle for up to 96 h. To confirm an effect on bone formation, IGF-I was also studied for its effects on [3H]proline incorporation into collagenase-digestible protein (CDP) and noncollagen protein and on [3H]thymidine incorporation into acid-precipitable material (DNA). IGF-I at 10(-9)-10(-7) M significantly increased the rate of bone matrix apposition and CDP after 24 h by 45-50% and increased cell labeling by 8-fold in the osteoprogenitor cell zone, by 4-fold in the osteoblast cell zone, and by 2-fold in the periosteal fibroblast zone. Insulin at 10(-9)-10(-6) M also increased matrix apposition rate and CDP by 40-50%, but increased cell labeling by 2-fold only at a concentration of 10(-7) M or higher and then only in the osteoprogenitor cell zone. When hydroxyurea was added to IGF-I-treated bones, the effects of IGF-I on DNA synthesis were abolished, but the increase in bone matrix apposition induced by IGF-I was only partly diminished. In conclusion, IGF-I stimulates matrix synthesis in calvariae, an effect that is partly, although not completely, dependent on its stimulatory effect on DNA synthesis.
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PMID:Insulin-like growth factor I has independent effects on bone matrix formation and cell replication. 333 7

The effect of human GH (hGH) and insulin-like growth factor-I (IGF-I) on colony formation of rabbit epiphyseal tibial chondrocytes at different stages of maturation was studied in suspension culture. The epiphyseal growth plate from the proximal tibia of 8-week-old male rabbits was dissected and divided into three different (proximal, intermediate and distal) zones, each zone representing an enrichment of chondrocytes from the germinative, proliferative and hypertrophic cell layers respectively. Chondrocytes from these three zones were isolated by collagenase digestion and cultured in the presence of 10% (v/v) newborn calf serum in suspension stabilized with 0.5% (w/v) agarose for 14 days. The colonies were classified according to diameter and the number of colonies was estimated as a function of colony size (distribution of cloning efficiency). Cell clusters with a diameter of 56 micron or more were classified as colonies. The cloning efficiency (number of colonies formed per 1000 seeded cells) was 10.1 +/- 0.7 and 6.0 +/- 0.8 for chondrocytes isolated from the proximal and intermediate zones respectively. Insulin-like growth factor-I (25-200 ng/ml) increased the number of colonies in chondrocytes isolated from the proximal zone (122 +/- 9.0-156 +/- 8.4%; control value, 100%) and from the intermediate zone (136 +/- 14.0-191 +/- 29%). Low concentrations of hGH (10-40 ng/ml) stimulated colony formation in chondrocytes isolated from the proximal zone (125 +/- 6.4-137 +/- 7.9%) whereas a high concentration of hGH (160 ng/ml) was ineffective. Chondrocytes isolated from the intermediate zone showed no response to low concentrations of hGH (10-20 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of growth hormone and insulin-like growth factor-I on colony formation of rabbit epiphyseal chondrocytes at different stages of maturation. 343 49

Insulin-like growth factor-I (IGF-I) and IGF-II are among the most prevalent growth factors secreted by bone cells and are presumed to act as autocrine regulators of bone formation. We recently demonstrated that IGFs inhibit bone collagen degradation, and we postulated that they may either inhibit the expression of interstitial collagenase or stimulate the synthesis of tissue inhibitors of metalloproteinase-1 (TIMP-1), -2, or -3. We tested the effects of IGF-I and -II on collagenase and TIMP-1, -2, and -3 expression in cultures of osteoblast-enriched cells from 22-day-old fetal rat calvariae (Ob cells). Steady state messenger RNA (mRNA) levels were determined by Northern blot analysis, and collagenase concentrations were determined in the culture medium by a specific immunoassay. After 2-6 h of treatment, IGF-I and -II decreased collagenase transcripts by up to 80%. IGF-I was a more potent inhibitor than IGF-II, because it was active at doses as low as 10 nM, whereas a dose of 100 nM was required to observe the IGF-II effect. In addition, IGF-I and -II opposed the stimulatory effect of retinoic acid on collagenase transcripts. Immunoreactive collagenase levels were not detectable in control or IGF-treated cultures, but IGF-I and -II decreased the levels induced by retinoic acid by 70-90%. The protein synthesis inhibitor cycloheximide superinduced collagenase transcripts, and IGF-I or -II decreased this mRNA induction to levels similar to, but not lower than, those observed in control cultures. The effects of IGF-I and -II on collagenase transcripts were not modified by the DNA synthesis inhibitor hydroxyurea at 1 mM. Neither IGF-I nor IGF-II modified the expression of TIMP-1, -2, or -3 mRNA in Ob cells. TIMP protein levels were not determined, and our study does not exclude a translational or posttranslational effect of IGF. In conclusion, IGF-I and -II decrease interstitial collagenase transcripts as well as induced protease levels in Ob cells, and this effect may contribute to their inhibitory actions on bone collagen degradation.
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PMID:Insulin-like growth factors inhibit interstitial collagenase synthesis in bone cell cultures. 789 45

We recently showed that structural regression is marked by an endocrine-induced increase in matrix metalloproteinase activity specific for basement membrane, which suggests that extracellular matrix (ECM) may play an important role in sustaining luteal cell function. Such a role for ECM has been demonstrated for cultured mammary epithelial cells, hepatocytes, and keratinocytes. To test this hypothesis, granulosa cells from preovulatory follicles that were induced to luteinize by gonadotropin stimulation in vivo were examined. Initial studies established that cells cultured on plastic in medium supplemented with 1% fetal bovine serum, LH (100 pg/ml), PRL (1 microgram/ml), and insulin-like growth factor-I (5 ng/ml) showed a time-dependent increase in the secretion of progesterone (P4) and total progestin (P4 plus 20 alpha-dihydroprogesterone) for at least 10 days and that replacement of fetal bovine serum with 0.1% BSA stimulated P4 secretion and reduced the 20 alpha-dihydroprogesterone to P4 ratio from 10:1 to as low as 3:1. The inclusion of an anticell adhesion receptor subunit sera (Lenny IV, against the integrin beta 1-subunit) in the culture medium for the first 2 days resulted in an irreversible loss of progestin secretion by the cultured granulosa cells, but the inclusion of a bacterial collagenase (form III) had no effect. Granulosa cells from preovulatory follicles cultured on ECM (Matrigel matrix) formed cell aggregates and projected cellular sprouts, but secreted less P4 than those cultured on plastic. The inclusion of laminin in the culture medium or laminin coating the culture wells stimulated P4 secretion by granulosa cells and promoted the enlargement of steroidogenic cells (3 beta-hydroxysteroid dehydrogenase). Fibronectin-coated, but not collagen-I-coated, wells similarly promoted P4 secretion. These results suggest that a cell adhesion receptor (an integrin), and laminin and fibronectin, major glycoprotein components of ECM, play important roles in the differentiation of granulosa cells to luteal cells.
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PMID:A cell adhesion receptor antiserum abolishes, whereas laminin and fibronectin glycoprotein components of extracellular matrix promote, luteinization of cultured rat granulosa cells. 789 87

Human growth hormone (hGH) inhibits alpha 1(I) collagen gene expression in cultured avian skin fibroblasts resulting in a decrease in the amount of collagenase-digestible proteins (CDP) in the medium. In addition, a synergism exists between GH and insulin-like growth factor-I (IGF-I) in their effect on CDP. Four N-terminal modified hGH analogs were tested for their ability to affect collagen metabolism in these cells. The truncated analog Des-7 hGH(R8M, D11A) was found to be a strong antagonist of the hGH-induced inhibition of the collagen synthesis but by itself did not inhibit collagen alpha 1(I) gene expression or modify the CDP appearance in the medium. Some synergism between Des-7 hGH and IGF-I was observed. The analog Met-hGH(R19H, L20P), in which Arg19 was replaced by histidine, and Leu20 by proline was only partially potent compared with the native hormone in causing inhibition of collagen gene expression, in attenuating CDP appearance in the medium, and in antagonizing hGH. However, this analog was as potent as hGH in its ability to synergize with IGF-I. The importance of His18 was assessed by testing the response to Met-hGH(H18D), in which His18 was replaced by Asp, and to Met-hGH(H18Q), in which His18 was replaced by glutamine (as in chicken GH sequence). Substitution of His18 by a negatively charged amino acid abolished all the hormone activities tested whereas substitution with glutamine restored only part of the activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of N-terminal modified analogs of growth hormone on collagen synthesis in avian skin fibroblasts. 831 27


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