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Elias Castanas - One of the best experts on this subject based on the ideXlab platform.
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opioid alkaloids and casomorphin peptides decrease the proliferation of prostatic cancer cell lines lncap pc3 and du145 through a partial interaction with opioid receptors
European Journal of Pharmacology, 1997Co-Authors: Marilena Kampa, Anastassia Hatzoglou, Pierremarie Martin, Elias Castanas, Efstathia Bakogeorgou, Athina DamianakiAbstract:Opioid agonists (ethylketocyclazocine, etorphine, [d-Ala2,d-Leu5]enkephalin (DADLE), [[d-Ala2,N-Me–Phe4–Gly-ol]enkephalin (DAGO), [d-Ser2,Leu5]enkephalin–Thr6 (DSLET) and morphine were found to inhibit the proliferation of human prostate cancer cell lines (LNCaP, DU145, and PC3), in a dose-dependent manner. The 50% inhibitory concentrations (IC50) were in the picomolar range. In many cases, this effect was antagonized by the general opioid antagonist, diprenorphine, indicating the existence of specific opioid binding sites. Saturation binding experiments with selective ligands and effectors showed no opioid sites on the LNCaP cell line κ1 and μ sites on the PC3 cell line, and κ1, κ3 and μ sites on the DU145 cell line. In other cases, the opioid effect was not antagonized by diprenorphine, indicating that the action of opioids might be mediated through other membrane receptors. Furthermore, casomorphin peptides, issued from bovine alpha- (Alpha-Casein-90-95 and Alpha-Casein-90-96) and beta-caseins (beta-casomorphin and beta-casomorphin-1-5), and human alphaS1-casein (alphaS1-casomorphin and alphaS1-casomorphin amide) inhibited cell proliferation of human prostate cell lines, also by a mechanism partly involving opioid receptors. As opioid neurons can be found in the prostate gland, and casomorphin peptides might reach the gland through the general circulation, the above findings indicate a putative role of opioids in prostate cancer cell growth.
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identification of a novel opioid peptide tyr val pro phe pro derived from human alpha s1 casein alpha s1 casomorphin and alpha s1 casomorphin amide
Biochemical Journal, 1996Co-Authors: Marilena Kampa, Spyros Loukas, Anastassia Hatzoglou, Patrice Martin, Pierremarie Martin, Elias CastanasAbstract:: A new casomorphin pentapeptide (alpha S1-casomorphin) has been isolated from the sequence of human alpha S1-casein [alpha S1-casein-(158-162)], with the sequence Tyr-Val-Pro-Phe-Pro. This peptide was found to bind with high affinity to all three subtypes of the kappa-opioid receptor (kappa 1-kappa 2). When amidated at the C-terminus, alpha S1-casomorphin amide binds to the delta- and kappa 3-opioid sites. Both alpha S1-casomorphin and its amide inhibit in a dose-dependent and reversible manner the proliferation of T47D human breast cancer cells. This anti-proliferative activity was greater for alpha S1-casomorphin, which was the most potent opioid in inhibiting T47D cell proliferation. In T47D breast cancer cells, other casomorphins have been found to bind to somatostatin receptors in addition to opioid sites. In contrast, alpha S1-casomorphin and its amide do not interact with somatostatin receptors in our system.
Patrice Martin - One of the best experts on this subject based on the ideXlab platform.
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Translational efficiency of casein transcripts in the mammary tissue of lactating ruminants
Reproduction Nutrition Development, 2006Co-Authors: Claudia Bevilacqua, Jean Helbling, Guy Miranda, Patrice MartinAbstract:Caseins are essentially concentrated in the colloidal fraction of ruminant milks as highly hydrated and mineralized spherical particles, termed casein micelles. They form a group of four peptide chains ($\alpha_{\rm s1}$, $\beta$, $\alpha_{\rm s2}$ and $\kappa$), encoded by four structural genes (CSN1S1, CSN2, CSN1S2 and CSN3, respectively) of which the expression is regulated by lactogenic hormones. These phosphoproteins are synthesized, essentially during lactation, in the mammary epithelial cells and we show, for the first time, that their regulation is also controlled at the translational level. Apparently, the four casein messenger are not translated with the same efficiency. Specific amplification systems have been developed and optimized to quantify, by real time quantitative PCR (qPCR), transcripts encoding the four caseins starting from total RNA extracted from mammary tissues taken on goats ($n$ = 4), ewes ($n$ = 3) and cows ($n$ = 3), in lactation. The relative proportions of each specific messenger (% of casein mRNA) were compared to the relative amounts of the corresponding caseins (% of whole casein) in milks sampled from the same animals, determined after fractionation by reverse phase HPLC and integration of the corresponding peak areas. From qPCR data, the four casein transcripts appeared to be present approximately at the same level of abundance (ca. 25%, except for defective genotypes at the CSN1S1 locus, in the goat) whereas the amounts of the corresponding proteins in milk were ranging between 9 and 38% of the whole casein fraction. A comparison of specific translational efficiencies (% of protein in milk/% of transcript in the mammary tissue), showed that $\alpha_{\rm s1}$- and $\beta $-casein transcripts are translated ca. 3- to 4-fold more efficiently than $\alpha_{\rm s2}$- and $\kappa $-casein transcripts. This seems to be the rule in the three ruminant species studied. More or less optimal contexts for initiation of translation (Kozak recognition sequence of the start codon) as well as 3' untranslated region (UTR) sequences and length might explain, at least in part, our results. These preliminary results which have now to be confirmed with a larger number of individuals to strengthen our findings and conclusions, provides, however, a rational explanation to the unbalanced casein distribution (approximate proportions 4:1:4:1 for $\alpha_{\rm s1}$:$\alpha _{\rm s2}$:$\beta $:$\kappa$, respectively) reported for ruminant milks. The possible effects of specific secondary structures in the 5' and 3' UTRs of casein messengers still have to be considered.
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The impact of genetic polymorphisms on the protein composition of ruminant milks
Reproduction Nutrition Development, 2002Co-Authors: Patrice Martin, Małgorzata Szymanowska, Lech Zwierzchowski, Christine LerouxAbstract:The purpose of this review is to give an overview of our current knowledge on the polymorphisms occurring in genes coding for milk proteins and responsible for quantitative variability in their expression, thus influencing the protein composition of livestock ruminant milk. The overall genomic organisation of the 6 main ruminant milk protein genes: $\alpha$-lactalbumin, $\beta$-lactoglobulin and the four caseins ($\alpha_{{\rm s}1}$, $\alpha_{{\rm s}2}$, $\beta$ and $\kappa$), their chromosomal location and their expression pattern are first summarised before presenting general mechanisms controlling gene expression both at the transcriptional and the post-transcriptional levels. Polymorphisms found in cis-regulatory elements, mainly within the 5'-flanking region of the genes encoding $\beta$-lactoglobulin and $\alpha_{{\rm s}1}$- and $\alpha_{{\rm s}2}$-caseins, have been found, in cattle, to influence their transcription rate. In addition, polymorphisms found in the transcription unit, within intron as well as exon sequences, have been shown to be responsible for defects in the processing of primary transcripts and/or the export of messenger RNA to the cytoplasm. Mutations responsible for the occurrence of premature stop codons in $\alpha_{{\rm s}1}$- and $\beta$-casein mRNAs have been shown to be associated both with a decrease in the level of the relevant transcripts and the existence of multiple forms of messengers due to alternative splicing (exon skipping, usage of cryptic splice sites). Such a situation, well-exemplified by the gene encoding $\alpha_{{\rm s}1}$-casein in the goat, may have dramatic biological consequences (secretion pathway, casein micelle structure, fat content, etc.) by modifying the message and accordingly the primary structure of the protein as well as its expression. Since some of these polymorphisms dramatically affect technological properties of milk, including cheese yields and organoleptic characteristics, methods mainly based on the PCR technique have been designed and applied in selection and breeding programmes to improve milk protein quality.
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alpha s1 casein is required for the efficient transport of beta and kappa casein from the endoplasmic reticulum to the golgi apparatus of mammary epithelial cells
Journal of Cell Science, 1999Co-Authors: Eric Chanat, Patrice Martin, Michele OllivierbousquetAbstract:In lactating mammary epithelial cells, interaction between caseins is believed to occur after their transport out of the endoplasmic reticulum. We show here that, in alpha(S1)-casein-deficient goats, the rate of transport of the other caseins to the Golgi apparatus is highly reduced whereas secretion of whey proteins is not significantly affected. This leads to accumulation of immature caseins in distended rough endoplasmic reticulum cisternae. Casein micelles, nevertheless, were still observed in secretory vesicles. In contrast, no accumulation was found in mammary epithelial cells which lack beta-casein. In mammary epithelial cells secreting an intermediate amount of alpha(S1)-casein, less casein accumulated in the rough endoplasmic reticulum, and the transport of alpha(S1)-casein to the Golgi occurred with kinetics similar to that of control cells. In prolactin-treated mouse mammary epithelial HC11 cells, which do not express alpha(S)-caseins, endoplasmic reticulum accumulation of beta-casein was also observed. The amount of several endoplasmic reticulum-resident proteins increased in conjunction with casein accumulation. Finally, the permeabilization of rough endoplasmic reticulum vesicles allowed the recovery of the accumulated caseins in soluble form. We conclude that optimal export of the caseins out of the endoplasmic reticulum is dependent upon alpha(S1)-casein. Our data suggest that alpha(S1)-casein interacts with the other caseins in the rough endoplasmic reticulum and that the formation of this complex is required for their efficient export to the Golgi.
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differential splicing of pre messenger rna produces multiple forms of mature caprine alpha s1 casein
FEBS Journal, 1997Co-Authors: Pasquale Ferranti, Christine Leroux, Lina Chianese, Francesco Addeo, Antonio Malorni, Patrice MartinAbstract:The identity of multiple forms of caprine alpha(s1)-casein in variants A, B, and C has been determined by structural characterisation using mass spectrometry, automated Edman degradation and peptide mapping. Mature goat alpha(s1)-casein exists as a mixture of at least four molecular species which differ in peptide chain length. The main component corresponds to the 199-residues form already described. The other three, in lesser amounts, were shorter forms of alpha(s1)-casein and differed for the deleted peptides 141-148, as shown previously for ovine alpha(s1)-casein, peptide 110-117, or Gln78. Analysis of alpha(s1)-casein mRNA from milk somatic cells demonstrated that these forms originated from skipping events at the level of exon 13 (codifying for peptide 110-117) and 16 (codifying for peptide 141-148) and from the presence of a cryptic splice site within exon 11 (whose first CAG triplet encodes Gln78) during primary transcript processing. The finding of these splicing abnormalities in the three common variants A, B, and C suggests that this is a general feature of alpha(s1)-casein in goat. A further source of heterogeneity of caprine alpha(s1)-casein was identified in the discrete phosphorylation of seryl residues. Eight serine residues (at positions 44, 46, 64 to 68 and 75) are fully phosphorylated (except in variant A because of the replacement Glu77-->Gln which prevents phosphorylation of Ser75). Conversely, Ser115 and Ser41 are phosphorylated only to about 50% and 20%, respectively. Ser12, although located in a consensus triplet, is never phosphorylated, similarly to the ovine alpha(s1)-casein variants. These results confirm that there are stabilised mechanisms of simultaneous synthesis of alpha(s1)-casein at different length and of post-translational modification in both caprine and ovine species.
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identification of a novel opioid peptide tyr val pro phe pro derived from human alpha s1 casein alpha s1 casomorphin and alpha s1 casomorphin amide
Biochemical Journal, 1996Co-Authors: Marilena Kampa, Spyros Loukas, Anastassia Hatzoglou, Patrice Martin, Pierremarie Martin, Elias CastanasAbstract:: A new casomorphin pentapeptide (alpha S1-casomorphin) has been isolated from the sequence of human alpha S1-casein [alpha S1-casein-(158-162)], with the sequence Tyr-Val-Pro-Phe-Pro. This peptide was found to bind with high affinity to all three subtypes of the kappa-opioid receptor (kappa 1-kappa 2). When amidated at the C-terminus, alpha S1-casomorphin amide binds to the delta- and kappa 3-opioid sites. Both alpha S1-casomorphin and its amide inhibit in a dose-dependent and reversible manner the proliferation of T47D human breast cancer cells. This anti-proliferative activity was greater for alpha S1-casomorphin, which was the most potent opioid in inhibiting T47D cell proliferation. In T47D breast cancer cells, other casomorphins have been found to bind to somatostatin receptors in addition to opioid sites. In contrast, alpha S1-casomorphin and its amide do not interact with somatostatin receptors in our system.
Richard A Anderson - One of the best experts on this subject based on the ideXlab platform.
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a casein kinase i isoform is required for proper cell cycle progression in the fertilized mouse oocyte
Journal of Cell Science, 1997Co-Authors: Stefan D Gross, Gerald Schatten, Calvin Simerly, Richard A AndersonAbstract:Casein kinase I is a family of serine/threonine protein kinases common to all eukaryotes. In yeast, casein kinase I homologues have been linked to the regulation of growth, DNA repair and cell division. In addition, their subcellular localization to membraneous structures and the nucleus is essential for function. In higher eukaryotes, there exist seven genetically distinct isoforms: (alpha), ss, (gamma)1, (gamma)2, (gamma)3, (delta) and (epsilon). Casein kinase I(alpha) exhibits a cell cycle-dependent subcellular localization including an association with cytosolic vesicular structures and the nucleus during interphase, and the spindle during mitosis. casein kinase I has also been shown to modulate critical regulators of growth and DNA synthesis/repair in mammalian cells such as SV40 large T antigen and p53. These results suggest that casein kinase I may be involved in processes similar to those ascribed to the yeast casein kinase I homologues. To define a role for casein kinase I(alpha) in cell cycle regulation, the mouse oocyte was utilized because of its well-defined cell cycle and ease of micromanipulation. Immunofluorescence studies from meiosis I of maturation to the first zygotic cleavage demonstrated that the kinase was associated with structures similar to those previously reported. Microinjection of casein kinase I(alpha) antibodies at metaphase II-arrest and G2 phase, had no effect on the completion of second meiosis or first division. However, microinjection of these antibodies during the early pronucleate phase prior to S-phase onset blocked uptake of the kinase into pronuclei and interfered with proper and timely cell cycle progression to first cleavage. These results suggest that the kinase regulates the progression from interphase to mitosis during the first cell cycle.
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casein kinase i alpha and alpha l alternative splicing generated kinases exhibit different catalytic properties
Biochemistry, 1996Co-Authors: Jiren Zhang, Stefan Gross, Matthew D Schroeder, Richard A AndersonAbstract:Casein kinase I (CKI) is a family of serine/threonine protein kinases found in all eukaryotes examined to date. Here, the rat CKI isoforms alpha and alpha L were cloned and expressed in both eukaryotic and prokaryotic systems. Characterization of the genomic DNA flanking the exon unique to CKI alpha L demonstrated that CKI alpha and CKI alpha L arise by the alternative splicing of a common pre-mRNA molecule. To the best of our knowledge, the alpha L isoform is the only known active serine/threonine kinase to contain an insert within its catalytic domain. Tissue distribution of each splicing isoform was examined by RT-PCR, immunoprecipitation, and Western blotting. Both isoforms were expressed in all tissues tested but at different levels. Bacterially expressed CKI alpha isoforms were active and therefore biochemically characterized. CKI alpha and CKI alpha L proteins were demonstrated to have casein kinase I catalytic properties. More importantly, the recombinant isoform proteins exhibited differences in binding and activity toward common CKI substrates. These observations demonstrate that the alpha L insert within the kinase domain modulates substrate kinetics. These kinetic differences suggest that CKI alpha and CKI alpha L may perform different biological roles.
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a phosphatidylinositol 4 5 bisphosphate sensitive casein kinase i alpha associates with synaptic vesicles and phosphorylates a subset of vesicle proteins
Journal of Cell Biology, 1995Co-Authors: S D Gross, D P Hoffman, P L Fisette, Peter W. Baas, Richard A AndersonAbstract:In interphase cells, Alpha-Casein kinase I (alpha-CKI) is found associated with cytosolic vesicular structures, the centrosome, and within the nucleus. To identify the specific vesicular structures with which alpha-CKI is associated, established cell lines and primary rat neurons were immunofluorescently labeled with an antibody raised to alpha-CKI. In nonneuronal cells, alpha-CKI colocalizes with vesicular structures which align with microtubules and are partially coincident with both Golgi and endoplasmic reticulum markers. In neurons, alpha-CKI colocalizes with synaptic vesicle markers. When synaptic vesicles were purified from rat brain, they were highly enriched in a CKI, based on activity and immunoreactivity. The synaptic vesicle-associated CKI is an extrinsic kinase and was eluted from synaptic vesicles and purified. This purified CKI has properties most similar to alpha-CKI. When the activities of casein kinase I or II were specifically inhibited on isolated synaptic vesicles, CKI was shown to phosphorylate a specific subset of vesicle proteins, one of which was identified as the synaptic vesicle-specific protein SV2. As with alpha-CKI, the synaptic vesicle CKI is inhibited by phosphatidylinositol 4,5-bisphosphate (PIP2). However, synthesis of PIP2 was detected only in plasma membrane-containing fractions. Therefore, PIP2 may spatially regulate CKI. Since PIP2 synthesis is required for secretion, this inhibition of CKI may be important for the regulation of secretion.
Anastassia Hatzoglou - One of the best experts on this subject based on the ideXlab platform.
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opioid alkaloids and casomorphin peptides decrease the proliferation of prostatic cancer cell lines lncap pc3 and du145 through a partial interaction with opioid receptors
European Journal of Pharmacology, 1997Co-Authors: Marilena Kampa, Anastassia Hatzoglou, Pierremarie Martin, Elias Castanas, Efstathia Bakogeorgou, Athina DamianakiAbstract:Opioid agonists (ethylketocyclazocine, etorphine, [d-Ala2,d-Leu5]enkephalin (DADLE), [[d-Ala2,N-Me–Phe4–Gly-ol]enkephalin (DAGO), [d-Ser2,Leu5]enkephalin–Thr6 (DSLET) and morphine were found to inhibit the proliferation of human prostate cancer cell lines (LNCaP, DU145, and PC3), in a dose-dependent manner. The 50% inhibitory concentrations (IC50) were in the picomolar range. In many cases, this effect was antagonized by the general opioid antagonist, diprenorphine, indicating the existence of specific opioid binding sites. Saturation binding experiments with selective ligands and effectors showed no opioid sites on the LNCaP cell line κ1 and μ sites on the PC3 cell line, and κ1, κ3 and μ sites on the DU145 cell line. In other cases, the opioid effect was not antagonized by diprenorphine, indicating that the action of opioids might be mediated through other membrane receptors. Furthermore, casomorphin peptides, issued from bovine alpha- (Alpha-Casein-90-95 and Alpha-Casein-90-96) and beta-caseins (beta-casomorphin and beta-casomorphin-1-5), and human alphaS1-casein (alphaS1-casomorphin and alphaS1-casomorphin amide) inhibited cell proliferation of human prostate cell lines, also by a mechanism partly involving opioid receptors. As opioid neurons can be found in the prostate gland, and casomorphin peptides might reach the gland through the general circulation, the above findings indicate a putative role of opioids in prostate cancer cell growth.
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identification of a novel opioid peptide tyr val pro phe pro derived from human alpha s1 casein alpha s1 casomorphin and alpha s1 casomorphin amide
Biochemical Journal, 1996Co-Authors: Marilena Kampa, Spyros Loukas, Anastassia Hatzoglou, Patrice Martin, Pierremarie Martin, Elias CastanasAbstract:: A new casomorphin pentapeptide (alpha S1-casomorphin) has been isolated from the sequence of human alpha S1-casein [alpha S1-casein-(158-162)], with the sequence Tyr-Val-Pro-Phe-Pro. This peptide was found to bind with high affinity to all three subtypes of the kappa-opioid receptor (kappa 1-kappa 2). When amidated at the C-terminus, alpha S1-casomorphin amide binds to the delta- and kappa 3-opioid sites. Both alpha S1-casomorphin and its amide inhibit in a dose-dependent and reversible manner the proliferation of T47D human breast cancer cells. This anti-proliferative activity was greater for alpha S1-casomorphin, which was the most potent opioid in inhibiting T47D cell proliferation. In T47D breast cancer cells, other casomorphins have been found to bind to somatostatin receptors in addition to opioid sites. In contrast, alpha S1-casomorphin and its amide do not interact with somatostatin receptors in our system.
T. Huppertz - One of the best experts on this subject based on the ideXlab platform.
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chymosin induced hydrolysis of caseins influence of degree of phosphorylation of alpha s1 casein and genetic variants of beta casein
International Dairy Journal, 2014Co-Authors: Etske Bijl, Hein J F Van Valenberg, Sybren Sikkes, Stijn Jumelet, Guido Sala, Kees Olieman, Toon Van Hooijdonk, T. HuppertzAbstract:The objective of this study was to investigate the impact of natural variations in αS1-casein and β-casein composition of milk on chymosin-induced hydrolysis of these caseins in milk gels and in sodium caseinate solutions. At 50% casein degradation, 15% more of αS1-casein with eight phosphate groups was hydrolysed compared with αS1-casein with nine phosphate groups in chymosin-induced milk gels. Furthermore, in sodium caseinate solutions, >10% more β-casein A2 was degraded compared with β-casein A1 and B at 50% casein degradation. Proteolysis by chymosin was not impacted by natural variation in the αS1-casein/β-casein ratio. Natural variation in αS1-casein/β-casein ratio did not impact upon firmness and gel strength in milk gels. Overall, comparison of sodium caseinate solutions to milk gels showed that differences in either phosphorylation of αS1-casein or amino acid composition of β-casein caused significant differences in degradation by chymosin, possibly due to changes in physical conformation of caseins.
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dissociation of caseins in high pressure treated bovine milk
International Dairy Journal, 2004Co-Authors: T. Huppertz, P F Fox, Alan L. KellyAbstract:In this study, reversibility of high pressure (HP)-induced solubilisation of alpha(s1)- and beta-casein and HP-induced changes in micellar hydration and levels of ultracentrifugally-sedimentable solids in raw skim milk were examined. HP treatment of milk at 100-600MPa resulted in considerable solubilisation of alpha(s1)- and beta-caseins, with the extent of solubilisation reaching a maximum around 250 MPa. HP-induced solubilisation of caseins was probably a result of solubilisation of colloidal calcium phosphate and disruption of hydrophobic interactions. On storage of HP-treated milk at 5degreesC, dissociation of caseins was largely irreversible but at 20degreesC, considerable reassociation of caseins was observed. Hydration of the casein micelles was increased by HP treatment at 100600 MPa, possibly due to HP-induced interactions between caseins and whey proteins; these changes were more extensive at higher pressures. The level of ultracentrifugally sedimentable solids was reduced by HP treatment, with a minimum occurring at 250 MPa; Changes in micellar hydration and the level of ultracentrifugally sedimentable solids were largely irreversible at 5degreesC, but partially reversible at 20degreesC. These results indicate that HP treatment increases levels of alpha(s1)- and beta-caseins in the soluble phase of milk and produces casein micelles with different properties compared to those in untreated milk; therefore, HP treatment may have a considerable influence on the processing characteristics of milk. (C) 2004 Elsevier Ltd. All rights reserved.
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high pressure treatment of bovine milk effects on casein micelles and whey proteins
Journal of Dairy Research, 2004Co-Authors: T. Huppertz, P F Fox, Alan L. KellyAbstract:Effects of high pressure (HP) on average casein micelle size and denaturation of alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-lg) in raw skim bovine milk were studied over a range of conditions. Micelle size was not influenced by treatment at pressures 100 MPa. Denaturation of alpha-la and beta-lg increased with increasing pressure, treatment time and temperature and milk pH. The majority of denatured beta-lg was apparently associated with casein micelles. These effects of HP on casein micelles and whey proteins in milk may have significant implications for properties of products made from HP-treated milk.