Purification and biochemical characterization of a fibroblast growth factor-binding protein (FGF-BP) from the lactoferrin fraction of bovine milk

Biological activities of commercial bovine lactoferrin sources

Lactoferrin (Lf) samples from several manufacturers were evaluated in vitro. The purity and protein form of each Lf were examined by SDS-PAGE, Western blot, and proteomics analysis. Assays were conducted to evaluate uptake of Lfs and iron from Lfs by enterocytes as well as Lf bioactivities, including effects on intestinal cell proliferation and differentiation, IL-18 secretion, TGF-β1 transcription, and growth of enteropathogenic Escherichia coli (EPEC). Composition of the Lfs varies; some only contain a major Lf band (∼80 kDa), and some also contain minor forms. All Lfs and iron from the Lfs were absorbed by Caco-2 cells, with various efficiencies. The bioactivities of the Lfs varied considerably, but there was no consistent trend. All Lfs promoted intestinal cell proliferation, secretion of IL-18, and transcription of TGF-β1. Some Lfs exhibited pro-differentiation effects on Caco-2 cells. Effects of pasteurization (62.5 °C for 30 min, 72 °C for 15 s, or 121 °C for 5 min) on integrity, uptake, and bioactivities were examined using Dicofarm, Tatua, and native bovine Lfs. Results show that pasteurization did not affect protein integrity, but variously affected uptake of Lf and its effects on intestinal proliferation, differentiation, and EPEC growth. To choose a Lf source for a clinical trial, assessment of bioactivities is recommended.

Biochemical Characterization of Ferulic Acid and Caffeic Acid Which Effectively Inhibit Melanin Synthesis via Different Mechanisms in B16 Melanoma Cells

In this study, we examined the inhibitory effects of ferulic acid and caffeic acid on melanin production using a murine B16 melanoma cell line. The mechanisms by which the two acids inhibit melanin production were investigated by evaluating their effects on the activity of tyrosinase, which is involved is the first step of melanin biosynthesis. Ferulic acid showed no toxicity against the melanoma cells at any dose, whereas caffeic acid exerted cellular toxicity at concentrations higher than 0.35 mM. Both ferulic and caffeic acids effectively inhibited melanin production in the B16 melanoma cells. Ferulic acid reduced tyrosinase activity by directly binding to the enzyme, whereas no binding was observed between caffeic acid and tyrosinase. Both ferulic acid and caffeic acid inhibited casein kinase 2 (CK2)-induced phosphorylation of tyrosinase in a dose-dependent manner in vitro. Ferulic acid was found to be a more effective inhibitor of melanin production than caffeic acid; this difference in the inhibitory efficacy between the two substances could be attributable to the difference in their tyrosine-binding activity. Our analysis revealed that both substances also inhibited the CK2-mediated phosphorylation of tyrosinase.

Serum activities of two bone markers in captive Asian elephants (Elephas maximus) at different ages

The blood biochemical analysis of bone markers could have a role in the early diagnosis of metabolic bone disease in animals; however, there is limited information on bone markers in captive Asian elephants (Elephas maximus). Serum samples from ten captive Asian elephants were obtained to clarify the relationship between age and the blood bone markers tartrate-resistant acid phosphatase isoform 5b (TRAP5b) and bone specific alkaline phosphatase (BALP). Serum TRAP5b and BALP activities were negatively correlated with age. A positive correlation was observed between TRAP5b activity and BALP activity. These results may contribute to the health management of captive Asian elephants.

A peptidomic approach to biomarker discovery for bovine mastitis

Bovine mastitis is usually caused by either Gram positive or Gram negative bacteria, reducing the quantity and quality of milk produced. This investigation using capillary electrophoresis and mass spectroscopy, studied peptides in milk from cows with clinical mastitis in comparison to milk from healthy cows to identify biomarkers for mastitis. In addition, the milk peptidome from udders infected with Gram positive Staphylococcus aureus (S. aureus) or with Gram negative Escherichia coli (E. coli), was examined to assess differential diagnosis between the causative agent. Comparison of the peptidome between healthy (n=10) and mastitic milk (n=27) identified 154 peptides for a biomarker panel which in a model for diagnosis of mastitis showed 100% sensitivity and specificity. β-casein and α(s1) casein provided the majority of peptides identified in this model. The peptidome comparison of milk from mastitis cases caused by S. aureus (n=8) or E. coli (n=11) revealed a biomarker panel of 47 peptides which discriminated between cause of infection with a sensitivity of 75% and a specificity of 100%. β-casein fragments were the most common of the peptides in this model. Peptide biomarkers of milk could be used in the diagnosis of mastitis and can discriminate between these two bacterial causes.

BIOLOGICAL SIGNIFICANCE

The paper describes an innovative approach to the use of gel free proteomics to identify the peptides that are present in milk during clinical mastitis, which is a major cause of loss of production to dairy farmers worldwide. The use of capillary electrophoresis, liquid chromatography and mass spectrometry has been able to identify panels of peptides which can be used for disease diagnosis and for differential diagnosis of the causative bacteria of the infections of the mammary gland. As well as contributing to our knowledge of the pathophysiology of bovine mastitis the results could be the basis of improved detection and differential diagnosis of the disease.

Lactoferrin and cancer disease prevention

Lactoferrin (LF) is an iron-binding glycoprotein that is composed of the transferrin family and is predominantly found in the products of the exocrine glands located in the gateways of the digestive, respiratory, and reproductive systems, suggesting a role in the non-specific defence against invading pathogens. Additionally, several physiological roles have been attributed to LF, namely regulation of iron homeostasis, host defence against infection and inflammation, regulation of cellular growth, and differentiation and protection against cancer development and metastasis. These findings have suggested LF's great potential therapeutic use in cancer disease prevention and/or treatment, namely as a chemopreventive agent. This review looks at the recent advances in understanding the mechanisms underlying the multifunctional roles of LF and future perspectives on its potential therapeutic applications.

Biochemical characterization of tau protein and its associated syndapin 1 and protein kinase Cepsilon for their functional regulation in rat brain

BACKGROUND

We recently reported that both sulfatide and cholesterol-3-sulfate (SCS) function as potent stimulators for the GSK-3beta-mediated phosphorylation of tau protein (TP) in vitro [J. Biochem. 143 (2008) 359-367].

METHODS

By means of successive gel filtration on a Superdex 200 pg column and three distinct ion-exchange column chromatographies, TP and its associated proteins were highly purified from the extract of rat brain.

RESULTS

We found that (i) syndapin 1 and novel protein kinase Cepsilon (nPKCepsilon) were identified as the TP-associated proteins; (ii) SCS highly stimulated the phosphorylation of TP and syndapin 1 by nPKCepsilon as well as CK1; (iii) the full phosphorylation of TP and syndapin 1 by nPKCepsilon in the presence of sulfatide resulted in their dissociation; (iv) TP primed by CK1 functioned as an effective phosphate acceptor for GSK-3beta; (v) syndapin 1 highly stimulated the GSK-3beta-mediated phosphorylation of TP; and (vi) TP isoforms were highly expressed in aged brain, whereas syndapin 1 was consistently detected in adult brain, but not in newborn brain.

GENERAL SIGNIFICANCE

These results provided here suggest that (i) TP-associated nPKCepsilon suppresses the GSK-3beta-mediated phosphorylation of TP through the phosphorylation of GSK-3beta by the kinase in vitro; and (ii) SCS act as effective sole mediators to induce the GSK-3beta-mediated high phosphorylation of both TP and its associated syndapin 1 involved in the biochemical processes of neuronal diseases, including Alzheimer's disease.

Characterization of meFucoidan as a selective inhibitor for secretory phospholipase A2-IIA and the phosphorylation of meFucoidan-binding proteins by A-kinase in vitro

The direct interaction of Mekabu fucoidan (meFucoidan) with four functional basic proteins (sPLA2-IIA, bFGF, histone H2B and HBV core protein) and three synthetic FGF-BP peptides (sp5, GE13 and RS6) was characterized in vitro. It was found that (i) meFucoidan inhibited dose-dependently the activity of sPLA2-IIA, but not pPLA2, through its direct binding to the enzyme; (ii) sPLA2-IIA activity was sensitive to meFucoidan rather than heparin, but significantly stimulated by sulfatide; (iii) the A-kinase-mediated phosphorylation of these basic proteins, except sPLA2-IIA, and synthetic peptides, containing potent phosphorylation sites for A-kinase, was inhibited dose-dependently by meFucoidan; and (iv) two consensus meFucoidan-binding motifs (B-B-B-B-X and B-X-B-B-X; B, basic amino acid) in these basic proteins and synthetic peptides could be overlapping to the potent phosphorylation site (B-B-X-S/T) for the kinase in vitro. These results presented here suggest that meFucoidan functions as a selective inhibitor for sPLA2-IIA and the A-kinase-mediated phosphorylation of cellular meFucoidan-binding functional basic proteins in vitro.

A novel consensus phosphorylation motif in sulfatide- and cholesterol-3-sulfate-binding protein substrates for CK1 in vitro

A novel phosphorylation motif for casein kinase 1 (CK1) in response to two sulfated lipids [sulfatide and cholesterol-3-sulfate (SCS)] was determined, using three functional proteins [myelin basic protein (MBP), tau protein (TP) and RhoA (a small GTPase)] and five synthetic MBP peptides as phosphate acceptors for the kinase in vitro. It was found that (i) MBP, p8 (positions 38-118) cleaved from MBP, and a synthetic peptide M103 were effectively phosphorylated by CK1delta in the presence of SCS; (ii) sulfatide in comparison with CH-3S highly enhanced autophosphorylation of CK1delta; (iii) SCS had a high binding affinity with MBP and peptide M103, but not other MBP peptides lacking K-G-R; and (iv) a novel consensus phosphorylation motif (K/R-X-K/R-X-X-S/T) for CK1 was identified among several SCS-binding proteins (SCS-BPs) and three CK1 isoforms (delta, epsilon and gamma). The binding of SCS to two basic brain proteins (MBP and TP) resulted in the high stimulation of their phosphorylation by three CK1 isoforms (alpha, delta and epsilon), but not CK1gamma. In contrast, an acidic protein (RhoA) was effectively phosphorylated by CK1delta in the presence of SCS, and also highly phosphorylated by CK1gamma in the presence of sulfatide. Our results presented here suggest that (i) sulfatide may function as an effective stimulator for autophosphorylation of CK1; and (ii) cellular SCS-binding proteins, containing novel phosphorylation motifs for CK1, may be preferentially phosphorylated by CK1 with isoform specificity at the highly accumulated level of SCS in the brain.

Identification of angiogenin as the osteoclastic bone resorption-inhibitory factor in bovine milk

We identified, for the first time, the factor responsible for inhibiting osteoclast-mediated bone resorption in the basic protein fraction of bovine milk (milk basic protein, MBP). The protein was purified by a combination of ion and gel column chromatography from MBP, based on its activity to prevent unfractionated rabbit bone cells from forming pits on dentine slices. It was found to have a molecular weight of 15 kDa on SDS-PAGE, and the sequence of the N-terminal 25 amino acid residues was identical to that of bovine angiogenin. The purified bovine angiogenin inhibited the pit-forming activity of both unfractionated bone cells and purified osteoclasts in a dose-dependent manner, and the inhibitory activity was markedly suppressed by treatment with anti-bovine angiogenin antibody. The inhibitory activity was confirmed in mice both in vitro and in vivo. Treatment of osteoclasts with bovine angiogenin resulted in an impairment of the formation F-actin ring and a reduction in the mRNA levels of TRAP and cathepsin K, both known to be essential for the bone resorption activity of osteoclasts. These results suggest that bovine angiogenin is the substance mainly responsible for the inhibitory effect of bovine milk on osteoclast-mediated bone resorption, and that it exerts its activity by acting directly on the osteoclasts.

Biochemical characterization of a N-terminal fragment (p5) cleaved from fibroblast growth factor-binding protein (FGF-BP) in bovine milk in vitro

By means of successive gel filtration on a Superdex 30 pg column and Mono S column chromatography, a 5-kDa polypeptide (p5) was highly purified from the low molecular weight (LMW) fraction separated from the partially purified lactoferrin (bLF) fraction of bovine milk, and biochemically characterized as a phosphate acceptor for two protein kinases [cAMP-dependent protein kinase (PKA) and casein kinase 1delta (CK1delta)] in vitro. Purified p5 was identified as a fragment (N-terminal positions 24-51, 28 amino acid residues) cleaved from fibroblast growth factor-binding protein (FGF-BP, p37). Both purified p5 and synthetic p5 (sp5) were effectively phosphorylated by PKA, and also phosphorylated by CK1delta in the presence of two sulfated lipids [sulfatide or cholesterol-3-sulfate (CH-3S), SCS] in vitro. A novel phosphorylation site (RNRRGS) for CK1delta and a potent SCS-binding site (RNRR) on p5 were identified. The PKA-mediated phosphorylation of p5 was highly stimulated when incubated with either acidic FGF (aFGF) or bLF in vitro, but this phosphorylation was more sensitive to SCS than H-89 (a specific PKA inhibitor). Immunoprecipitate experiments revealed p5, but not the phosphorylated p5, to be directly bound to aFGF in vitro. These results show that (i) p5 has a high binding affinity with aFGF as well as bLF; (ii) the binding of SCS to p5 results in the selective inhibition of its phosphorylation by PKA; and (iii) SCS functions as an effective stimulator for the phosphorylation of p5 by CK1delta in vitro. In addition, p5 may play an important physiological role as a trafficking factor for the physiological interaction between aFGF group including endothelial cell growth factors and their binding proteins in vivo.