help button home button Endocrine Society Endocrinology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology, doi:10.1210/en.2003-1313
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Resch, Z. T.
Right arrow Articles by Conover, C. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Resch, Z. T.
Right arrow Articles by Conover, C. A.
Endocrinology Vol. 145, No. 3 1124-1129
Copyright © 2004 by The Endocrine Society

Pregnancy-Associated Plasma Protein A Gene Expression as a Target of Inflammatory Cytokines

Zachary T. Resch, Bing-Kun Chen, Laurie K. Bale, Claus Oxvig, Michael T. Overgaard and Cheryl A. Conover

Division of Endocrinology, Metabolism, and Nutrition, Endocrine Research Unit, Mayo Clinic and Mayo Foundation (Z.T.R., B.-K.C., L.K.B., C.A.C.), Rochester, Minnesota 55905; and Department of Molecular Biology, University of Aarhus (C.O., M.T.O.), DK-8000 Aarhus C, Denmark

Address all correspondence and requests for reprints to: Cheryl A. Conover, Ph.D., Mayo Clinic, 200 First Street SW, 5-194 Joseph, Rochester, Minnesota 55905. E-mail: conover.cheryl{at}mayo.edu.


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Pregnancy-associated plasma protein A (PAPP-A) cleaves IGF-binding protein-4 (IGFBP-4) and appears to enhance local IGF bioavailability in response to injury. In this study we determined the effects of growth factors and cytokines involved in the healing process on PAPP-A expression in human dermal fibroblasts. There was no effect of platelet-derived growth factor, epidermal growth factor, or basic fibroblast growth factor on PAPP-A mRNA expression in these cells. However, treatment with the proinflammatory cytokines, TNF{alpha} and IL-1ß, resulted in time- and dose-dependent increases in PAPP-A mRNA and protein expression (3- to 4-fold maximal effects), which were prevented by actinomycin D. On the other hand, interferon-{gamma} (IFN{gamma}) treatment markedly inhibited PAPP-A expression. IGFBP-4 proteolytic activity was increased 4-fold in medium from TNF{alpha}- and IL-1ß-treated (1 nM) cells and decreased 40% in medium from IFN{gamma}-treated (1 nM) cells. IGF-I-stimulated [3H]thymidine incorporation was significantly enhanced by pretreatment with 1 nM TNF{alpha}, and this enhancement was blocked in the presence of protease-resistant IGFBP-4. In conclusion, PAPP-A expression is regulated by inflammatory cytokines in adult human fibroblasts, with functional consequences on IGFBP-4 protease activity and IGF-I bioavailability. These data provide a mechanism for the regulation of PAPP-A in response to injury and further implicate PAPP-A in the wound-healing processes.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
THE PROCESS OF wound healing requires a variety of growth factors to regulate the normal biological response to injury (1, 2). A great deal of evidence suggests that the IGF system is of particular importance in this process (3, 4, 5). IGF’s biological actions are modulated by a family of six binding proteins (IGFBPs) (6, 7). Pregnancy-associated plasma protein-A (PAPP-A) is a metalloproteinase in the metzincin superfamily that cleaves specific IGFBPs, thereby regulating local IGF bioavailability (8, 9, 10, 11, 12).

Several studies in vitro as well as in vivo have implicated this function of PAPP-A as a key determinant of the cellular proliferation that occurs in response to injury and subsequent inflammatory processes. PAPP-A was isolated from the conditioned medium of normal human fibroblasts (HF) (8), and in these cells, PAPP-A-induced proteolysis of IGFBP-4 potentiated IGF-stimulated growth (9). An in vivo study of healing human skin demonstrated increased PAPP-A within the dermal layer after a first intention wound and was associated with activated fibroblasts and macrophages (13). IGFBP-4 was also present in normal and injured human skin, implicating PAPP-A-regulated IGFBP-4 proteolysis in the control of IGF bioavailability at the site of injury.

Little is known about the molecular regulation of PAPP-A expression in response to injury. After various types of injury, a series of events, including inflammation and tissue regeneration, lead to the normal repair of the damaged area. These specific events are mediated by various growth factors and inflammatory cytokines (reviewed in Ref. 14). Therefore, we tested the hypothesis that growth factors and inflammatory cytokines that are known to be involved in normal wound-healing processes regulate PAPP-A gene expression.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Materials
TNF{alpha}, IL-1ß, and interferon (IFN{gamma}) were purchased from Research Diagnostics, Inc. (Flanders, NJ). Recombinant wild-type and protease-resistant IGFBP-4 were expressed and purified as previously described (15). IGF-II and [Leu27]IGF-II were purchased from Bachem, Inc. (Torrance, CA), and GroPep Ltd. (Adelaide, Australia), respectively. IGF-I was provided by Dr. Martin Spencer (San Francisco, CA). Actinomycin D, RIA grade BSA, platelet-derived growth factor, epidermal growth factor, and basic fibroblast growth factor were obtained from Sigma-Aldrich Corp. (St. Louis, MO). Tissue culture supplements and fetal bovine serum were obtained from Life Technologies, Inc. (Grand Island, NY). Reagents for SDS-PAGE were purchased from Bio-Rad Laboratories (Richmond, CA).

Cell cultures
Primary cultures of human dermal fibroblasts were purchased from the Human Genetic Mutant Cell Repository (Coriell Institute, Camden, NJ) and cultured as reported previously (8, 9, 16). For all experiments, cells were washed twice and incubated in serum-free medium (containing 0.1% BSA) overnight before experimental treatment. The cells were again washed and changed to serum-free medium plus experimental additions for the indicated times. At the end of the incubation, conditioned medium was collected, centrifuged to remove debris, and stored at -70 C. Cell numbers were determined at the time of medium collection using a Coulter counter (Coulter Electronics, Hialeah, FL). For gene expression experiments, RNA was isolated at the end of the incubation.

RNA isolation and cDNA synthesis
Total RNA was extracted from cells using the RNeasy Mini Kit (Qiagen, Valencia, CA) and was treated with deoxyribonuclease (DNA-free, Ambion, Inc., Austin TX). Four hundred nanograms of RNA were reversed transcribed using TaqMan RT reagents (PE Applied Biosystems, Foster City, CA) according to the manufacturer’s instructions.

Real-time PCR
Real-time quantitative PCR analyses were performed using the ABI PRISM 7700 Sequence Detection System and software (PE Applied Biosystems). Primer and probe sequences for specific detection and amplification of PAPP-A, the precursor form of major basic protein (pro-MBP), and 28S as well as assay validations were described previously (17).

PAPP-A ELISA
PAPP-A levels in cell-conditioned medium were measured using an ultrasensitive ELISA kit provided by Diagnostic Systems Laboratories, Inc. (Webster, TX). Minimum sensitivity is 0.24 mIU/liter, with intra- and interassay coefficients of variation of 4.7% and 4.2%, respectively.

IGFBP-4 protease assay
Cell-free IGFBP-4 proteolysis was assayed as previously described (8, 9, 11, 18, 19). Conditioned medium (25 µl) was incubated at 37 C for 6 h with [125I]IGFBP-4 (10,000 cpm) in the absence or presence of 5 nM IGF-II. Reaction products were separated by SDS-PAGE and visualized by autoradiography. Band intensities were quantified using an Ultro Scan XL laser densitometer (Pharmacia LKB Biotechnology, Piscataway, NJ).

Thymidine incorporation
HF monolayers were washed twice, preincubated in serum-free medium (0.1% BSA) for 24 h, washed, and changed to serum-free medium without and with TNF{alpha} (1 nM) for 24 h. After the 24-h incubation period, recombinant wild-type or protease-resistant IGFBP-4 (10 nM) with or without [Leu27]IGF-II (5 nM) was added to the culture medium for 6 h. Without changing the medium, IGF-I (5 nM) was added, and [3H]thymidine incorporation was measured at 22–26 h, as previously described (9, 11). Media from parallel cultures were collected after the 6-h incubation with IGFBP-4 and [Leu27]IGF-II for Western ligand blot (9, 11, 16).

Statistical analysis
Results are expressed as the mean ± SEM for the indicated number of experiments unless otherwise stated. Statistical comparisons were performed using ANOVA, followed by multiple comparisons. Results were considered statistically significant at P < 0.05. Where representative experiments are presented, the results have been replicated.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Various cytokines and growth factors associated with wound healing were screened for their regulation of PAPP-A gene expression in HF. There was no effect of platelet-derived growth factor, epidermal growth factor, or basic fibroblast growth factor (each at 100 ng/ml) on PAPP-A mRNA expression when measured 6 and 24 h after stimulation (data not shown). On the other hand, TNF{alpha}, IL-1ß, and IFN{gamma} had marked effects on PAPP-A expression. TNF{alpha} and IL-1ß were potent stimulators of PAPP-A gene expression in HF. A time course of PAPP-A mRNA expression in HF indicated a rapid increase (10- to 12-fold) 2 h after stimulation with TNF{alpha} (100 ng/ml; ~6 nM) and IL-1ß (100 ng/ml; ~6 nM). PAPP-A mRNA levels remained elevated (3- to 4-fold) up to 48 h after TNF{alpha} stimulation, but returned to baseline by 48 h after IL-1ß stimulation (Fig. 1AGo). PAPP-A protein levels in HF-conditioned medium reflected the changes in PAPP-A mRNA expression (Fig. 1BGo). At 48 h, PAPP-A levels in medium from TNF{alpha}-stimulated cells was approximately 1.7-fold greater than that in medium from IL-1ß-stimulated cells, paralleling the sustained elevated mRNA levels in TNF{alpha}-treated cells at this time. Dose-response experiments for TNF{alpha} showed half-maximal effectiveness at about 0.05 nM, with maximal effectiveness at approximately 1 nM (Fig. 2Go). IL-1ß showed half-maximal effectiveness at about 0.1 pM, with maximal effectiveness at approximately 30 pM. The effect of these proinflammatory cytokines appears to be at the level of transcription, as the DNA-directed RNA polymerase inhibitor, actinomycin D, completely prevented TNF{alpha} and IL-1ß induction of PAPP-A expression (Fig. 3Go).



View larger version (18K):
[in this window]
[in a new window]
  		FIG. 1. Regulation of PAPP-A expression: time-course effects of TNF{alpha} and IL-1ß. A, Real-time RT-PCR was performed on RNA isolated from cultured HF after 1, 2, 4, 8, 24, and 48 h of incubation in serum-free medium without (Control) and with 100 ng/ml TNF{alpha} ({circ}) or IL-1ß ({bullet}). PAPP-A mRNA abundance is expressed relative to control at each time point. Results are the average of two values. B, Conditioned medium from HF treated without () and with TNF{alpha} ({square}) or IL-1ß ({blacksquare}) for 1, 2, 4, 8, 24, and 48 h were assayed for PAPP-A protein by ELISA. Results are the mean ± SEM of triplicate dishes. PAPP-A levels were below assay detection at 1, 2, and 4 h. *, P < 0.05 vs. control; #, P < 0.05, IL-1ß vs. TNF{alpha}.

 


View larger version (15K):
[in this window]
[in a new window]
  		FIG. 2. Regulation of PAPP-A protein accumulation: dose-response effects of TNF{alpha} and IL-1ß. HF were treated with the indicated concentrations of TNF{alpha} ({square}) and IL-1ß ({blacksquare}) for 24 h, and medium was collected for PAPP-A ELISA. Results, expressed relative to control for each experiment, are the mean ± SEM of three experiments. *, P < 0.05 vs. control.

 


View larger version (14K):
[in this window]
[in a new window]
  		FIG. 3. Regulation of PAPP-A expression: effect of actinomycin D. HF were treated without (Control) or with 10 nM TNF{alpha} or 1 nM IL-1ß in the absence ({square}) or presence ({blacksquare}) of actinomycin D (1 µg/ml). Real-time RT-PCR was performed on RNA (A), and PAPP-A ELISA was performed on conditioned medium (B) after 8 h of treatment. Results are the average of two values.

 
Compared with the potent stimulatory effect of TNF{alpha} and IL-1ß on PAPP-A expression, IFN{gamma} treatment decreased PAPP-A expression in HF half-maximally at about 0.5 nM (Fig. 4Go). Interestingly, cotreatment of HF with IFN{gamma} inhibited the IL-1ß-induced increase in PAPP-A expression, but had no significant effect on TNF{alpha}-induced PAPP-A expression (Fig. 5Go). The expression of pro-MBP, a physiological inhibitor of PAPP-A (15, 17), was not significantly altered by any of the tested cytokines or growth factors (100 ng/ml) at 6 and 24 h after stimulation (data not shown).



View larger version (12K):
[in this window]
[in a new window]
  		FIG. 4. Regulation of PAPP-A expression: dose-response effect of INF-{gamma}. HF were treated with the indicated concentrations of IFN{gamma} for 48 h, and medium was collected for PAPP-A ELISA. Results, expressed as a percentage of the control value, i.e. no IFN{gamma}, are the mean ± SEM of three experiments. *, P < 0.05 vs. control.

 


View larger version (10K):
[in this window]
[in a new window]
  		FIG. 5. Effect of IFN{gamma} on TNF{alpha}- and IL-1ß-stimulated PAPP-A secretion. HF were treated with 1 nM TNF{alpha} or IL-1ß for 24 h in the absence or presence of 1 nM IFN{gamma}, and medium was collected for PAPP-A ELISA. Results, expressed as a percentage of the control value, are the mean ± SEM of three experiments. *, P < 0.05 IFN{gamma} vs. control and IL-1ß plus IFN{gamma} vs. IL-1ß alone.

 
To determine whether the changes in PAPP-A expression induced by cytokine treatment translated into functional protein, we assessed IGFBP-4 proteolysis in HF-conditioned medium (Fig. 6Go). Conditioned medium from HF exhibited IGF-II-dependent IGFBP-4 protease activity in cell-free assay, as reported previously (8, 9, 11, 15, 18, 19). IGF-II appears to bind to IGFBP-4 and increase its susceptibility to cleavage by PAPP-A (20, 21). As shown in Fig. 6Go, radiolabeled IGFBP-4 remained intact during incubation in medium from both control and treated cells in the absence of exogenous IGF-II. The addition of IGF-II revealed IGFBP-4 proteolytic activity in the control conditioned medium. In comparison, medium from cells treated with TNF{alpha} and IL-1ß showed 4- to 5-fold enhanced IGF-dependent IGFBP-4 protease activity, whereas medium from cells treated with INF-{gamma} showed diminished activity, only 60% of control. Direct addition of TNF{alpha}, IL-1ß, or IFN{gamma} to the assay had no effect on IGFBP-4 proteolysis.



View larger version (22K):
[in this window]
[in a new window]
  		FIG. 6. Cytokine regulation of PAPP-A proteolytic activity. HF-conditioned medium from control (C) or treated (1 nM TNF{alpha}, IL-1ß, or IFN{gamma}) cells were incubated with [125I]IGFBP-4 without (-) and with (+) 5 nM IGF-II at 37 C for 6 h. Reaction products were separated by SDS-PAGE, and the gel was dried and exposed to film. Arrows indicate intact and cleaved IGFBP-4. SFM, Unconditioned serum-free medium.

 
To assess the biological significance of cytokine-induced PAPP-A expression, HF were incubated in serum-free medium with 1 nM TNF{alpha} to increase the amount of PAPP-A that accumulated in the medium. To these cells, we added recombinant IGFBP-4 (10 nM) and [Leu27]IGF-II (5 nM) for 6 h. [Leu27]IGF-II was used in these experiments because it has normal affinity for IGFBP-4 and thus can serve as a cofactor for proteolysis, but does not bind to or activate the type I IGF receptor signaling (16, 22, 23, 24). After the 6-h preincubation, IGF-I (5 nM) was added, and [3H]thymidine incorporation was measured 22–26 h after IGF-I stimulation. After TNF{alpha} treatment, IGF-I stimulated a 5-fold increase in [3H]thymidine incorporation. This stimulation was enhanced further by a 6-h preincubation with [Leu27]IGF-II. [Leu27]IGF-II alone did not stimulate [3H]thymidine incorporation. The status of the proteolysis of IGFBP-4 was determined by Western ligand blotting of the medium after the 6-h addition of [Leu27]IGF-II (data not shown). To confirm that the enhanced response was due to IGFBP-4 proteolysis, we repeated the experiment using protease-resistant IGFBP-4 (19). In these experiments there was no degradation of exogenous IGFBP-4 and no potentiation of IGF-I responsiveness in TNF{alpha}-treated cells (Fig. 7Go).



View larger version (9K):
[in this window]
[in a new window]
  		FIG. 7. Effect of TNF{alpha} regulation of IGFBP-4 proteolysis on HF proliferation. HF were incubated in serum-free medium with 1 nM TNF{alpha} for 24 h. To this conditioned medium, IGFBP-4 (wild-type or protease-resistant) and [Leu27]IGF-II ({blacksquare}) were added for 6 h, and then IGF-I was added. [3H]Thymidine incorporation was measured 22–26 h after IGF-I stimulation. Results (mean ± SEM of three experiments) are presented as a percentage of the control value, i.e. no IGF treatment. [3H]Thymidine incorporation for wild-type IGFBP-4 and the protease-resistant IGFBP-4 control group was 391 ± 90.7 and 303.7 ± 50.3 cpm, respectively. *, P < 0.05 vs. no [Leu27]IGF-II.

 

   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
These data demonstrate that PAPP-A gene expression in HF is regulated by inflammatory cytokines in vitro and suggest a mechanism for the regulation of PAPP-A in response to injury that may contribute to enhanced IGF-I bioactivity during the healing process.

Dermal fibroblasts are essential for the repair of cutaneous wounds. During the wound-healing process, these cells are exposed to local cytokines (14, 25, 26). A recent study showed that PAPP-A immunostaining in the dermis is markedly enhanced in human skin during wound healing (13). Our finding that TNF{alpha} and IL-1ß are potent stimulators of PAPP-A gene expression and protein secretion in human dermal fibroblasts suggests that the increase in local cytokine production and the increase in PAPP-A during cutaneous wound repair may be linked. Although our in vitro data in and of themselves do not constitute proof of an in vivo relationship, they are the first demonstration that inflammatory cytokines directly regulate PAPP-A expression. Actinomycin D completely blocked the induction of PAPP-A mRNA expression by TNF{alpha} and IL-1ß, suggesting that this regulation is at the level of transcription. The rapid increase in PAPP-A mRNA levels in response to these cytokines, i.e. within 2 h, further supports transcriptional regulation. Secretion of PAPP-A protein into the medium paralleled the increase in gene expression. In contrast to TNF{alpha} and IL-1ß, IFN{gamma} inhibited PAPP-A expression. The increase in PAPP-A expression and protein secretion after treatment with TNF{alpha} and IL-1ß was paralleled by enhanced IGFBP-4 protease activity in the cell-conditioned medium. Likewise, the decrease in PAPP-A expression after treatment with INF{gamma} was reflected in diminished IGFBP-4 proteolysis. The decrease in protease activity with IFN{gamma} treatment was not due to induction of pro-MBP, an inhibitor of PAPP-A, as was reported previously in HF treated with phorbol ester tumor promoters (17). Although TNF{alpha} and IL-1ß both increased PAPP-A expression, IFN{gamma} only antagonized the effect of IL-1ß, indicating that TNF{alpha} and IL-1ß may act by different mechanisms to regulate PAPP-A expression in these cells. Further evidence of this is that HF treatment with maximal concentrations of TNF{alpha} and IL-1ß for 24 h elicited less than an additive effect, suggesting both shared and unique signaling mechanisms in the regulation of PAPP-A expression. How IFN{gamma} regulates IL-1ß-stimulated, but not TNF{alpha}-stimulated, PAPP-A expression in fibroblasts is not known. However IFN{gamma} has been reported to stimulate the production of the IL-1 receptor antagonist (27, 28, 29), thus providing a plausible mechanism for the differential antiinflammatory properties of IFN{gamma} in cytokine-stimulated cells (30).

A biological consequence of TNF{alpha}-induced PAPP-A expression in HF was enhanced IGF-I bioactivity mediated by PAPP-A proteolysis of IGFBP-4. The enhancing effect of TNF{alpha} in these experiments was specific for IGFBP-4 proteolysis because it was not observed if protease-resistant, instead of wild-type, IGFBP-4 was added. It is recognized that TNF{alpha} can have effects on other components of the IGF system in these cells. Yateman et al. (31) showed that TNF{alpha} decreased fibroblast IGFBP-3 secretion, and Morales et al. (32) reported that TNF{alpha} and IL-1ß increased the expression of a specific serine protease for IGFBP-5, but other IGFBPs were not specifically studied in these experiments.

Similar stimulation of PAPP-A expression by TNF{alpha} and IL-1ß has been found in vascular smooth muscle cells (Resch, Z. T., and C. A. Conover, manuscript in preparation). Although fibroblasts and vascular smooth muscle cells are clearly sources of PAPP-A and target cells for cytokines, there may be contributions from other cellular components of the injury response, e.g. macrophages. Indeed, PAPP-A immunostaining colocalized with activated macrophages during cutaneous wound healing (13) and in vulnerable plaque (33).

The results of this study provide further evidence for a role for PAPP-A in cell response to injury and inflammation. We propose that proinflammatory cytokines released in the injured area stimulate PAPP-A expression by target cells, with subsequent cleavage of pericellular IGFBP-4 and therefore increased IGF bioavailability during the repair response. In addition, negative regulation by IFN{gamma} may be involved. This response could be controlled during normal wound healing or inappropriately exaggerated during fibrosis or hyperplasia. A better understanding of the mechanism of cytokine regulation of IGF bioavailability in general and PAPP-A expression in particular could lead to new therapeutic targets for the control of healing processes.


   Footnotes
 
This work was supported by NIH Training Grant DK-07352 and American Heart Association Grant 0225543Z (to Z.T.R.).

Abbreviations: HF, Human fibroblast; IFN{gamma}, interferon-{gamma}; IGFBP, IGF-binding protein; PAPP-A, pregnancy-associated plasma protein A; pro-MBP, precursor form of major basic protein.

Received September 30, 2003.

Accepted for publication November 24, 2003.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Martin P Hopkinson-Woolley J, McCluskey J 1992 Growth factors and cutaneous wound repair. Prog Growth Factor Res 4:25–44[CrossRef][Medline]
  2. Singer AJ, Clark RAF 1999 Cutaneous wound healing. N Engl J Med 341:738–746[Free Full Text]
  3. Brown DL, Kane CD, Chernausek SD, Greenhalgh DG 1997 Differential expression and localization of insulin-like growth factors I and II in cutaneous wounds of diabetic and nondiabetic mice. Am J Pathol 151:715–724[Abstract]
  4. Bitar MS, Labbad ZN 1996 Transforming growth factor-ß and insulin-like growth factor-I in relation to diabetes-induced impairment of wound healing. J Surg Res 61:113–119[CrossRef][Medline]
  5. Ghahary A, Shen YJ, Wang R, Scott PG, Tredget EE 1998 Expression and localization of insulin-like growth factor-1 in normal and post-burn hypertrophic scar tissue in humans. Mol Cell Biochem 183:1–9[CrossRef][Medline]
  6. Jones JJ, Clemons DR 1995 Insulin-like growth factors and their binding proteins: biological actions. Endocr Rev 16:3–34[CrossRef][Medline]
  7. Rajaram S, Baylink DJ, Mohan S 1997 Insulin-like growth factor-binding proteins in serum and other biological fluids: regulation and functions. Endocr Rev 18:801–831[Abstract/Free Full Text]
  8. Lawrence JB, Oxvig C, Overgaard MT, Sottrup-Jensen L, Gleich GJ, Hays LG, Yates III JR, Conover CA 1999 The insulin-like growth factor (IGF)-dependent IGF binding protein-4 protease secreted by human fibroblasts is pregnancy-associated plasma protein-A. Proc Natl Acad Sci USA 96:3149–153[Abstract/Free Full Text]
  9. Conover CA, Durham SK, Zapf J, Masiarz FR, Kiefer MC 1995 Cleavage analysis of insulin-like growth factor (IGF)-dependent IGF-binding protein-4 proteolysis and expression of protease-resistant IGF-binding protein-4 mutants. J Biol Chem 270:4395–4400[Abstract/Free Full Text]
  10. Byun D, Mohan S, Yoo M, Sexton C, Baylink DJ, Qin X 2001 Pregnancy-associated plasma protein-A accounts for the insulin-like growth factor (IGF)-binding protein-4 (IGFBP-4) proteolytic activity in human pregnancy serum and enhances the mitogenic activity of IGF by degrading IGFBP-4 in vitro. J Clin Endocrinol Metab 86:847–854[Abstract/Free Full Text]
  11. Ortiz CO, Chen BK, Bale LK, Overgaard MT, Oxvig C, Conover CA 2003 Transforming growth factor-beta regulation of the insulin-like growth factor binding protein-4 protease system in cultured human osteoblasts. J Bone Miner Res 18:1066–1072[CrossRef][Medline]
  12. Boldt HB, Overgaard MT, Laursen LS, Weyer K, Sottrup-Jensen L, Oxvig C 2001 Mutational analysis of the proteolytic domain of pregnancy-associated plasma protein-A (PAPP-A): classification as a metzincin. Biochem J 358:359–367[CrossRef][Medline]
  13. Chen BK, Leiferman KM, Pittelkow MR, Overgaard MT, Oxvig C, Conover CA 2003 Localization and regulation of pregnancy-associated plasma protein a expression in healing human skin. J Clin Endocrinol Metab 88:4465–4471[Abstract/Free Full Text]
  14. Werner S, Grose R 2003 Regulation of wound healing by growth factors and cytokines. Physiol Rev 83:835–870[Abstract/Free Full Text]
  15. Overgaard MT, Haaning J, Boldt HB, Olsen IM, Laursen LS, Christiansen M, Gleich GJ, Sottrup-Jensen L, Conover CA, Oxvig C 2000 Expression of recombinant human pregnancy-associated plasma protein-A and identification of the proform of eosinophil major basic protein as its physiological inhibitor. J Biol Chem 275:31128–31133[Abstract/Free Full Text]
  16. Conover CA, Clarkson JT, Bale LK 1994 Insulin-like growth factor-II enhancement of human fibroblast growth via a nonreceptor-mediated mechanism. Endocrinology 135:76–82[Abstract]
  17. Chen BK, Overgaard MT, Bale LK, Resch ZT, Christiansen M, Oxvig C, Conover CA 2002 2002 Molecular regulation of the IGF-binding protein-4 protease system in human fibroblasts: identification of a novel inducible inhibitor. Endocrinology 143:1199–1205[Abstract/Free Full Text]
  18. Bayes-Genis A, Schwartz RS, Lewis DA, Overgaard MT, Christiansen M, Oxvig C, Ashai K, Holmes Jr DR, Conover CA 2001 Insulin-like growth factor binding protein-4 protease produced by smooth muscle cells increases in the coronary artery after angioplasty. Arterioscler Thromb Vasc Biol 21:335–341[Abstract/Free Full Text]
  19. Laursen LS, Overgaard MT, Nielsen CG, Boldt HB, Hopmann KH, Conover CA, Sottrup-Jensen L, Giudice LC, Oxvig C 2002 Substrate specificity of the metalloproteinase pregnancy-associated plasma protein-A (PAPP-A) assessed by mutagenesis and analysis of synthetic peptides: substrate residues distant from the scissile bond are critical for proteolysis. Biochem J 367:31–40[CrossRef][Medline]
  20. Laursen LS, Overgaard MT, Søe R, Boldt HB, Sottrup-Jensen L, Giudice LC, Conover CA, Oxvig C 2001 Pregnancy-associated plasma protein-A (PAPP-A) cleaves insulin-like growth factor binding protein (IGFBP)-5 independent of IGF: implications for the mechanism of IGFBP-4 proteolysis by PAPP-A. FEBS Lett 504:36–40[CrossRef][Medline]
  21. Qin X, Byun D, Lau KH, Baylink DJ, Mohan S 2000 Evidence that the interaction between insulin-like growth factor (IGF)-II and IGF binding protein (IGFBP)-4 is essential for the action of the IGF-II-dependent IGFBP-4 protease. Arch Biochem Biophys 379:209–216[CrossRef][Medline]
  22. Beukers MW, Oh Y, Zhang H, Ling N, Rosenfeld RG 1991 [Leu27] insulin-like growth factor II is highly selective for the type-II IGF receptor in binding, cross-linking and thymidine incorporation experiments. Endocrinology 128:1201–1203[Abstract]
  23. Qin X, Byun D, Strong DD, Baylink DJ, Mohan S 1999 Studies on the role of human insulin-like growth factor-II (IGF-II)-dependent IGF binding protein (hIGFBP)-4 protease in human osteoblasts using protease-resistant IGFBP-4 analogs. J Bone Miner Res 14:2079–2088[CrossRef][Medline]
  24. Bach LA, Hsieh S, Sakano K-I, Fujiwara H, Perdue JF, Rechler MM 1993 Binding of mutants of human insulin-like growth factor II to insulin-like growth factor binding proteins 1–6. J Biol Chem 268:9246–9254[Abstract/Free Full Text]
  25. Price WA, Moats-Staats BM, Stiles AD 2002 Pro- and anti-inflammatory cytokines regulate insulin-like growth factor binding protein production by fetal rat lung fibroblasts. Am J Respir Cell Mol Biol 26:283–289[Abstract/Free Full Text]
  26. Gillitzer R, Goebeler M 2001 Chemokines in cutaneous wound healing. J Leukocyte Biol 69:513–521[Abstract/Free Full Text]
  27. Tilg H, Mier JW, Vogel W, Aulitzky WE, Wiedermann CJ, Vannier E, Huber C, Dinarello CA 1993 Induction of circulating IL-1 receptor antagonist by IFN treatment. J Immunol 150:4687–4692[Abstract]
  28. Kline JN, Fisher PA, Monick MM, Hunninghake GW 1995 Regulation of interleukin-1 receptor antagonist by Th1 and Th2 cytokines. Am J Physiol 269:L92–L98
  29. Gueniche A, Viac J, Charveron M, Schmitt D 1994 Effect of gamma-interferon on IL-1{alpha}, ß and receptor antagonist production by normal human keratinocytes. Exp Dermatol 3:113–118[CrossRef][Medline]
  30. Muhl H, Pfeilschifter J 2003 Anti-inflammatory properties of pro-inflammatory interferon-gamma. Int Immunopharmacol 3:1247–1255[CrossRef][Medline]
  31. Yateman ME, Claffey DC, Cwyfan Hughes SC, Frost VJ, Wass JA, Holly JM 1993 1993 Cytokines modulate the sensitivity of human fibroblasts to stimulation with insulin-like growth factor-I (IGF-I) by altering endogenous IGF-binding protein production. J Endocrinol 137:151–159[Abstract/Free Full Text]
  32. Moralez A, Busby Jr WH, Clemmons D 2003 Control of insulin-like growth factor binding protein-5 protease synthesis and secretion by human fibroblasts and porcine aortic smooth muscle cells. Endocrinology 144:2489–2495[Abstract/Free Full Text]
  33. Bayes-Genis A, Conover CA, Overgaard MT, Bailey KR, Christiansen M, Holmes Jr DR, Virmani R, Oxvig C, Schwartz RS 2001 Pregnancy-associated plasma protein A as a marker of acute coronary syndromes. N Engl J Med 345:1022–1029[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 Diabetes CareHome page
S. Pellitero, J. L. Reverter, E. Pizarro, M. C. Pastor, M. L. Granada, D. Tassies, J.-C. Reverter, I. Salinas, and A. Sanmarti
Pregnancy-Associated Plasma Protein-A Levels Are Related to Glycemic Control but Not to Lipid Profile or Hemostatic Parameters in Type 2 Diabetes
Diabetes Care, December 1, 2007; 30(12): 3083 - 3085.
[Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
E. Capoluongo, F. Ameglio, P. Lulli, A. Minucci, C. Santonocito, P. Concolino, E. Di Stasio, S. Boccacci, V. Vendettuoli, G. Giuratrabocchetta, et al.
Epithelial lining fluid free IGF-I-to-PAPP-A ratio is associated with bronchopulmonary dysplasia in preterm infants
Am J Physiol Endocrinol Metab, January 1, 2007; 292(1): E308 - E313.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
Z. T. Resch, R. D. Simari, and C. A. Conover
Targeted Disruption of the Pregnancy-Associated Plasma Protein-A Gene Is Associated with Diminished Smooth Muscle Cell Response to Insulin-like Growth Factor-I and Resistance to Neointimal Hyperplasia after Vascular Injury
Endocrinology, December 1, 2006; 147(12): 5634 - 5640.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
Z. T. Resch, C. Oxvig, L. K. Bale, and C. A. Conover
Stress-Activated Signaling Pathways Mediate the Stimulation of Pregnancy-Associated Plasma Protein-A Expression in Cultured Human Fibroblasts
Endocrinology, February 1, 2006; 147(2): 885 - 890.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
C. A. Conover, L. K. Bale, S. C. Harrington, Z. T. Resch, M. T. Overgaard, and C. Oxvig
Cytokine stimulation of pregnancy-associated plasma protein A expression in human coronary artery smooth muscle cells: inhibition by resveratrol
Am J Physiol Cell Physiol, January 1, 2006; 290(1): C183 - C188.
[Abstract] [Full Text] [PDF]

Home page
 Clin. Chem.Home page
Q.-P. Qin, S. Kokkala, J. Lund, N. Tamm, L.-M. Voipio-Pulkki, and K. Pettersson
Molecular Distinction of Circulating Pregnancy-Associated Plasma Protein A in Myocardial Infarction and Pregnancy
Clin. Chem., January 1, 2005; 51(1): 75 - 83.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Resch, Z. T.
Right arrow Articles by Conover, C. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Resch, Z. T.
Right arrow Articles by Conover, C. A.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals