Identification of the sites of phosphorylation in insulin-like growth factor binding protein-1. Regulation of its affinity by phosphorylation of serine 101.

Jones, John I.; Busby, Walker H.; Wright, G.; Smith, Christine E.; Kimack, Nancee M.; Clemmons, David R.

doi:10.1016/s0021-9258(18)54050-3

Cited by 86 publications

(13 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Metabolic Labeling of IGFBP-6 with [ 32 P]Orthophosphate (32). To determine whether IGFBP-6 is phosphorylated, CHO cells overexpressing IGFBP-6 were grown to confluence and incubated in phosphate-free Dulbecco's MEM containing [ 32 P]orthophosphate (50 µCi/mL, Amersham) for 16 h at 37 °C.…”

Section: Methodsmentioning

confidence: 99%

Identification of O-Glycosylation Sites and Partial Characterization of Carbohydrate Structure and Disulfide Linkages of Human Insulin-like Growth Factor Binding Protein 6

1998

View full text Add to dashboard Cite

The actions of insulin-like growth factors (IGFs) are modulated by a family of high-affinity binding proteins (IGFBPs), including IGFBP-6, which preferentially binds IGF-II and is O-glycosylated. Glycosylated and nonglycosylated recombinant human IGFBP-6, expressed in Chinese hamster ovary cells and Escherichia coli, respectively, were purified using IGF-II affinity chromatography and reverse-phase medium-pressure chromatography. Electrospray ionization mass spectrometry (ESMS) of glycosylated IGFBP-6 revealed considerable heterogeneity of carbohydrate composition. Major glycoforms contained 8-16 monosaccharides, including N-acetylhexosamine, hexose, and N-acetylneuraminic acid. Glycosylation sites of IGFBP-6 were identified as Thr126, Ser144, Thr145, Thr146, and Ser152 by using a combination of ESMS and Edman sequencing of tryptic fragments separated by reverse-phase high-pressure liquid chromatography. One oligosaccharide chain contained 5-6 monosaccharides, whereas the others contained 2-4 monosaccharides. Glycosylated IGFBP-6 exhibited greater resistance to proteolysis by chymotrypsin and trypsin than nonglycosylated IGFBP-6. Native disulfide bond positions in IGFBP-6 were localized by means of observed disulfide-linked tryptic fragments, revealing that there are two disulfide-linked subdomains within each of the N- and C-terminal regions and confirming a previous suggestion that the latter regions are not interconnected. A model of IGFBP-6 is developed in which these distinct domains are separated by a central region which is O-glycosylated.

show abstract

Section: Methodsmentioning

confidence: 99%

Identification of O-Glycosylation Sites and Partial Characterization of Carbohydrate Structure and Disulfide Linkages of Human Insulin-like Growth Factor Binding Protein 6

1998

View full text Add to dashboard Cite

show abstract

“…IGFBP-1 purified from endometrial stromal cells was found to be exclusively phosphorylated on serine residues . Subsequently, the sites of phosphorylation of IGFBP-1 purified from transfected CHO cell media were identified to be Ser101, Ser119, and Ser169, where Ser101 was the major phosphorylation site. Site-directed mutagenesis of IGFBP-1 at Ser101 showed up to 3-fold reduction in affinity of IGFBP-1 for IGF-I .…”

Section: Introductionmentioning

confidence: 99%

Site-Specific IGFBP-1 Hyper-Phosphorylation in Fetal Growth Restriction: Clinical and Functional Relevance

et al. 2010

View full text Add to dashboard Cite

Phosphorylation enhances IGFBP-1 binding to IGF-I, thereby limiting the bioavailability of IGF-I that may be important in fetal growth. Our goal in this study was to determine whether changes in site-specific IGFBP-1 phosphorylation were unique to fetal growth restriction. To establish a link, we compared IGFBP-1 phosphorylation (sites and degree) in amniotic fluid from FGR (N = 10) and controls (N = 12). The concentration of serine phosphorylated IGFBP-1 showed a negative correlation with birth weight in FGR (P = 0.049). LC-MS/MS analysis revealed all four previously identified phosphorylation sites (Ser98, Ser101, Ser119, and Ser169) to be common to FGR and control groups. Relative phosphopeptide intensities (LC-MS) between FGR and controls demonstrated 4-fold higher intensity for Ser101 (P = 0.026), 7-fold for Ser98/Ser101 (P = 0.02), and 23-fold for Ser169 (P = 0.002) in the FGR group. Preliminary BIAcore data revealed 4-fold higher association and 1.7-fold lower dissociation constants for IGFBP-1/IGF-I in FGR. A structural model of IGFBP-1 bound to IGF-I indicates that all the phosphorylation sites are on relatively mobile regions of the IGFBP-1 sequence. Residues Ser98, Ser101, and Ser169 are close to structured regions that are involved in IGF-I binding and, therefore, could potentially make direct contact with IGF-I. On the other hand, residue Ser119 is in the middle of the unstructured linker that connects the N- and C-terminal domains of IGFBP-1. The model is consistent with the assumption that residues Ser98, Ser101, and Ser169 could directly interact with IGF-I, and therefore phosphorylation at these sites could change IGF-I interactions. We suggest that site-specific increase in IGFBP-1 phosphorylation limits IGF-I bioavailability, which directly contributes to the development of FGR. This study delineates the potential role of higher phosphorylation of IGFBP-1 in FGR and provides the basis to substantiate these findings with larger sample size.

show abstract

“…Phosphorylated IGFBP1 has a higher affinity for IGF1. 7 Changes in the phosphorylation state of IGFBP1 might impact IGF1 bioavailability. On the other hand, recent studies reported that IGFBP1 could modulate cellular actions via Arg-Gly-Asp (RGD) integrin-binding motifs to interact with α5-β1 integrin (ITGB1) independently of IGF/IGF receptors.…”

Section: Introductionmentioning

confidence: 99%

Insulin‐like growth factor binding protein 1 ameliorates lipid accumulation and inflammation in nonalcoholic fatty liver disease

Pan

Zhou

et al. 2021

J of Gastro and Hepatol

View full text Add to dashboard Cite

Background and Aims: Insulin-like growth factor binding protein 1 (IGFBP1) is recently proved to be associated with glucose regulation and insulin resistance. However, little is known about its direct impact on nonalcoholic fatty liver disease (NAFLD). This study aims to investigate the effect and potential mechanism of IGFBP1 in NAFLD. Methods: We first measured the expression level of IGFBP1 in NAFLD patients, mice, and cells. Then in in vivo study, C57BL/6 mice were fed with a methionine/choline-deficient (MCD) diet for 4 weeks to establish the model of NAFLD. And for the last 2 weeks, the mice were injected intraperitoneally with vehicle or recombinant mouse IGFBP1 0.015 mg/kg/d. The L02 cells were treated with free fatty acids (FFA) or palmitate acids (PA) and recombinant IGFBP1 for 48 h. Integrin-linked kinase (ILK) inhibitor and small interfering RNA were used to explore the potential interactions between IGFBP1 and integrin β1 (ITGB1). Results: The expression of IGFBP1 was increased in NAFLD patients, mice, and cells. IGFBP1 treatment significantly ameliorated lipid accumulation and hepatic injury in MCD-fed mice. IGFBP1 downregulated hepatic lipogenesis and upregulated lipid β-oxidation. In addition, IGFBP1 attenuated the nuclear factor-kappa B (NF-κB) and extracellular regulated protein kinases (ERK) signaling pathways. In vitro, we proved that IGFBP1 relieved FFA-induced lipid accumulation via interacting with ITGB1 and alleviated inflammation by inhibiting NF-κB and ERK signaling pathways. Conclusions: IGFBP1 treatment significantly ameliorated hepatic steatosis by interacting with ITGB1 and suppressed inflammation by inhibiting NF-κB and ERK signaling pathways. Therefore, IGFBP1 might be a potential therapeutic target for NAFLD.

show abstract

Identification of the sites of phosphorylation in insulin-like growth factor binding protein-1. Regulation of its affinity by phosphorylation of serine 101.

Cited by 86 publications

References 18 publications

Identification of O-Glycosylation Sites and Partial Characterization of Carbohydrate Structure and Disulfide Linkages of Human Insulin-like Growth Factor Binding Protein 6

Identification of O-Glycosylation Sites and Partial Characterization of Carbohydrate Structure and Disulfide Linkages of Human Insulin-like Growth Factor Binding Protein 6

Site-Specific IGFBP-1 Hyper-Phosphorylation in Fetal Growth Restriction: Clinical and Functional Relevance

Insulin‐like growth factor binding protein 1 ameliorates lipid accumulation and inflammation in nonalcoholic fatty liver disease

Contact Info

Product

Resources

About