Casein kinase-2 inhibition promotes retinal ganglion cell survival after acute intraocular pressure elevation

Intraocular pressure elevation can induce retinal ganglion cell death and is a clinically reversible risk factor for glaucoma,the leading cause of irreversible blindness.We previously demonstrated that casein kinase-2 inhibition can promote retinal ganglion cell survival and axonal regeneration in rats after optic nerve injury.To investigate the underlying mechanism,in the current study we increased the intraocular pressure of adult rats to 75 mmHg for 2 hours and then administered a casein kinase-2 inhibitor(4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole)by intravitreal injection.We found that intravitreal injection of 4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole promoted retinal ganglion cell survival and reduced the number of infiltrating macrophages.Transcriptomic analysis showed that the mitogen activated protein kinase signaling pathway was involved in the response to intraocular pressure elevation but was not modulated by the casein kinase-2 inhibitors.Furthermore,casein kinase-2 inhibition downregulated the expression of genes(Cck,Htrsa,Nef1,Htrlb,Prph,Chat,Slc18a3,Slc5a7,Scn1b,Crybb2,Tsga10ip,and Vstm21)involved in intraocular pressure elevation.Our data indicate that inhibition of casein kinase-2 can enhance retinal ganglion cell survival in rats after acute intraocular pressure elevation via macrophage inactivation.

Colloidal nanoparticles prepared from zein and casein:interactions,characterizations and emerging food applications

Protein colloidal nanoparticles(NPs)are ubiquitous present in nature and function as building blocks with multiple functions in both food formulations and biological processes.Food scientists are inspired by naturally occurring proteins to induce self-assembly behavior of protein by manipulating environmental parameters,providing opportunities to construct special and expected NPs.Zein and casein,the main proteins derived from corn and milk,are two examples of the most prevalently studied food proteins for nanoarchitectures in recent years.In this article,the compositions,structures,and physicochemical properties of these two proteins and casein derivatives are summarized as well as their interactions and characterizations.Strategies to fabricate zein-sodium caseinate based NPs are critically highlighted and illustrated.Particularly,applications such as encapsulation and delivery of bioactive compounds,producing food packaging for enhanced antioxidative and antimicrobial effects,and stabilization of emulsions to achieve fat replacement.Due to the imperative role of food proteins in diet composition,this review not only provides cutting-edge knowledge for nanoparticle construction but also opens new avenues for efficient utilization and exploitation of food proteins.

Casein kinase 2 interacts with and phosphorylates ataxin-3

Objective Machado-Joseph disease （MJD）/Spinocerebellar ataxia type 3 （SCA3） is an autosomal dominant neurodegenerative disorder caused by an expansion of polyglutamine tract near the C-terminus of the MJD1 gene product, ataxin-3. The precise mechanism of the MJD/SCA3 pathogenesis remains unclear. A growing body of evidence demonstrates that phosphorylation plays an important role in the pathogenesis of many neurodegenerative diseases. However, few kinases are known to phosphorylate ataxin-3. The present study is to explore whether ataxin-3 is a substrate of casein kinase 2 （CK2）. Methods The interaction between ataxin-3 and CK2 was identified by glutathione S-transferase （GST） pull-down assay and co-immunoprecipition assay. The phosphorylation of ataxin-3 by CK2 was measured by in vitro phosphorylation assays. Results （1） Both wild type and expanded ataxin-3 interacted with CK2α and CK2β in vitro. （2） In 293 cells, both wild type and expanded ataxin-3 interacted with CK2β, but not CK2α. （3） CK2 phosphorylated wild type and expanded ataxin-3. Conclusion Ataxin-3 is a substrate of protein kinase CK2.

长毛兔Kappa-casein基因多态性与生产性能关系的研究

实验对176只长毛兔群体的Kappa-casein基因的基因型和基因频率进行了检测,结果表明:等位基因A和B的频率分别为0.79与0.21,基因型BB在长毛兔群体中的频率为0.09,远低于基因型AA的频率0.66。同时对Kappa-casein基因与长毛兔的生产性能进行分析,表明Kappa-casein基因AA基因型和BB基因型的长毛兔在315日龄体重、21日龄窝重上差异显著(P<0.05),AB基因型和BB基因型的长毛兔产仔数差异显著(P<0.05)。

乳源β-Casein-125肽的基本特征及促B淋巴细胞增殖作用

利用Uniprot、SABLE、ProtParam tool等在线数据库分析β-Casein-125肽生物学特征;利用质谱定量技术检测β-Casein-125肽在初乳、过渡乳和成熟乳中的含量变化;利用细胞增殖实验方法揭示β-Casein-125肽在促进B淋巴细胞增殖中的作用。结果表明:β-Casein-125肽的稳定性系数为111.43,脂肪指数和亲水性分别为111.43和0.471,属于疏水性稳定型多肽。质谱定量分析发现:β-Casein-125肽含量随泌乳时间变化含量显著降低。β-Casein-125肽不仅可以顺利进入小鼠B淋巴细胞,并且可显著促进细胞增殖。β-Casein-125肽具有高稳定性和疏水性的特征,可以促进淋巴细胞增殖,提示该肽可能在新生儿免疫系统建立中发挥重要作用。

A Novel Exponential Kinetic Model for Casein Tryptic Hydrolysis to Prepare Active Peptides

The kinetics of casein tryptic hydrolysis to prepare activepeptides was investigated. Taking into account the reaction mechanismincluding single substrate hydrolysis, irreversible enzymeinactivation, and substrate inhibition, a set of exponentialequations was established to characterize the enzymatic hydrolysiscurves. The verification was carried out by a series of experimentalresults and indicated that the average regressive error was less than5/100. According to the proposed kinetic model, the kinetic constantsand thermodynamic constants of the reaction system were alsocalculated.

Low-protein diets supplemented with casein hydrolysate favor the microbiota and enhance the mucosal humoral immunity in the colon of pigs

Background:High-protein diets can increase the colonic health risks.A moderate reduction of dietary crude-protein(CP)level can improve the colonic bacterial community and mucosal immunity of pigs.However,greatly reducing the dietary CP level,even supplemented with all amino acids(AAs),detrimentally affects the colonic health,which may be due to the lack of protein-derived peptides.Therefore,this study evaluated the effects of supplementation of casein hydrolysate(peptide source)in low-protein(LP)diets,in comparison with AAs supplementation,on the colonic microbiota,microbial metabolites and mucosal immunity in pigs,aiming to determine whether a supplementation of casein hydrolysate can improve colonic health under very LP level.Twenty-one pigs(initial BW 19.90±1.00 kg,63±1 days of age)were assigned to three groups and fed with control diet(16%CP),LP diets(13%CP)supplemented with free AAs(LPA)or casein hydrolysate(LPC)for 4 weeks.Results:Compared with control diet,LPA and LPC diet decreased the relative abundance of Streptococcus and Escherichia coli,and LPC diet further decreased the relative abundance of Proteobacteria.LPC diet also increased the relative abundance of Lactobacillus reuteri.Both LP diets decreased concentrations of ammonia and cadaverine,and LPC diet also reduced concentrations of putrescine,phenol and indole.Moreover,LPC diet increased total short-chain fatty acid concentration.In comparison with control diet,both LP diets decreased protein expressions of Toll-like receptor-4,nuclear factor-κB,interleukin-1βand tumor necrosis factor-α,and LPC diet further decreased protein expressions of nucleotide-binding oligomerization domain protein-1 and interferon-γ.LPC diet also increased protein expressions of G-protein coupled receptor-43,interleukin-4,transforming growth factor-β,immunoglobulin A and mucin-4,which are indicators for mucosal defense activity.Conclusions:The results showed that supplementing casein hydrolysate showed beneficial effects on the colonic microbiota and mucosal immunity and barrier function in comparison with supplementing free AAs in LP diets.These findings may provide new framework for future nutritional interventions for colon health in pigs.

Nutritional evaluation of caseins and whey proteins and their hydrolysates from Protamex

Whey protein concentrate (WPC 80) and sodium caseinate were hydrolyzed by Protamex to 5%, 10%, 15%, and 20% degree of hydrolysis (DH). WPC 80, sodium caseinate and their hydrolysates were then analyzed, compared and evaluated for their nutritional qualities. Their chemical composition, protein solubility, amino acid composition, essential amino acid index (EAA index), biological value (BV), nutritional index (NI), chemical score, enzymic protein efficiency ratio (E-PER) and in vitro protein digestibility (IVPD) were determined. The results indicated that the enzymatic hydrolysis of WPC 80 and sodium caseinate by Protamex improved the solubility and IVPD of their hydrolysates. WPC 80, sodium caseinate and their hydrolysates were high-quality proteins and had a surplus of essential amino acids compared with the FAO/WHO/UNU (1985) reference standard. The nutritive value of WPC 80 and its hydrolysates was superior to that of sodium caseinate and its hydrolysates as indicated by some nutritional parameters such as the amino acid composition, chemical score, EAA index and predicted BV. However, the E-PER was lower for the WPC hydrolysates as compared to unhydrolyzed WPC 80 but sodium caseinate and its hydrolysates did not differ significantly. The nutritional qualities of WPC 80, sodium caseinate and their hydrolysates were good and make them appropriate for food formulations or as nutritional supplements.

AN-g-Casein纤维的结构与性能的研究

利用扫描电镜(SEM)观察,发现AN-g-Casein纤维截面形成了皮芯型结构;芯层Casein组分相畴约20～60nm,拉断时,芯层易产生原纤化;皮层结构致密,断面平整;纤维表面形成细长条纹。AN-g-Casein纤维中二组分的结晶度基本不随酪素含量而变。AN-g-Casein纤维吸湿性、染色性优异,且能采用酸性染料、阳离子染料染色,AN-g-Casein纤维力学性能良好,是一种值得推广应用的新型改性仿真丝纤维。

AN-g-casein浓溶液在毛细管流动中的末端校正

采用气压式毛细管流变仪 ,测定了实验室自制丙烯腈 -酪素接枝共聚物 (AN- g- casein)浓溶液的流变性能。实验结果发现 :AN- g- casein浓溶液属切力变稀型非牛顿流体 ;在实验范围内 ,毛细管流动中的末端校正系数 e随切变速率的提高而增大 ,当切变速率较高时 ,AN- g- casein大分子在浓溶液中形成了束状物 ,拉伸变形受到了限制 ,e值上升趋于极限 ;当切变速率较高 ,毛细管长径比较小时 ,真实剪切应力仅占表观剪切应力的 35%左右 ,证明了毛细管流动末端校正的必要性。

In vitro and in silico analysis of dual-function peptides derived from casein hydrolysate

There is no study on food-derived peptide with both anticoagulant and angiotensin I-converting enzyme inhibitory (ACEI) activities yet. In this work, the anticoagulant and ACEI activities of the casein hydrolysates released by pepsin digestion were evaluated for the first time to the best of our knowledge. Results indicated that the casein hydrolysate exhibited potent anticoagulant activity by prolonging the thrombin time (TT) and the activated partial thromboplastin time (APTT). Compared with control samples, at 10 mg/mL, the TT and APTT of casein hydrolysate were 186.0 % ± 6.6 % and 163.5 % ± 7.4 %, respectively. The casein hydrolysate also showed a strong ACEI activity with an IC50 value of 1.775 mg/mL. The components of the bioactive casein hydrolysate were analyzed by nanoscale liquid chromatography quadrupole time-of-flight tandem mass spectrometry (NanoLC-Q-TOF-MS/MS). Total of 115 peptides were identified, among which 34, 9, 55 and 17 peptides were derived from α_(s1-), α_(s2-), β-, and κ-casein, respectively. The results of PeptideRanker and PepSite 2 analysis showed that 6 peptides (FRQFYQL, NENLLRF, NPWDQVKR, PVVVPPFLQ, PVRGPFPIIV, and ARHPHPHLSF) have both ACEI and anticoagulant activities by binding to the active sites of ACE and thrombin. This study indicated that casein is a potential functional food supplement that can be used for medical purposes.

Potential of casein kinase I in digestive cancer screening

Casein kinase I is a group of ubiquitous Serine/Threonine kinases that have been implicated in both normal cellular functions and several pathological conditions including Alzheimer's disease and cancer.Recent findings in colon and pancreatic cancer have brought tremendous attention to these molecules as potential therapeutic targets in treatment of digestive cancers.In this review,we summarize up to date what is known about this family of kinases and their involvement in carcinogenesis and other pathological conditions.Our emphasis is on their implications in digestive cancers and their potential for cancer screening and therapy.

异源β-Casein基因启动子调控下的t-PAcDNA在兔乳腺中的暂性表达

β-酪蛋白 (β-Casein)是哺乳动物乳汁中主要的蛋白质 ,其基因 5′侧翼调控区常作为乳腺定位表达的调控序列。表达载体 p SVL-βr-PA和 p SVL-βb-PA分别含有 1 .0 kb的大鼠β-Casein和 0 .6kg的牛β-Casein基因调控序列及 t-PAc DNA。采用基因直接注射方法将两种表达载体分别注入家兔乳腺中。溶圈试验结果显示 ,两种表达载体均能在兔乳腺细胞中得到表达 。

Isolation and identification of novel casein-derived bioactive peptides and potential functions in fermented casein with Lactobacillus helveticus

The present study here establishes a complete and effective method for isolating,purifying and identifying extracellular and intracellular peptides,and also describes the characters and bioactivities of peptides from fermented casein with Lactobacillus helveticus.Intracellular peptides are much larger in quantity and more complex in composition than extracellular peptides,between which the correlation reveals proteolytic and metabolic mechanisms.In addition,totally 241 different peptide sequences were identified by Nano LC–MS/MS from casein(212)and Lactobacillus helveticus proteins(29).These casein-derived peptides mostly originated from-casein,followed byS1-casein,-casein,andS2-casein,and came from extracell(69)and intracell(143),in which common peptides have a total of 27.Forty-four of the identified peptides were previously described as bioactive,including angiotensinconverting enzyme(ACE)-inhibitory,antioxidant,immunomodulating,antimicrobial,DPP-IV inhibitory,antiamnesic and anticancer effects and so on.Thirteen peptides with the potential of some biological activities are obtained,which were described in previous studies.A total of 47 novel peptides of 5 to 26 amino acids that were not disclosed were obtained.The new sources of natural bioactive peptides may have the very high application value as potential new peptide drugs for treatment human diseases.The product peptide DELQDKIHPF found in both extracell and intracell was quantitatively analyzed using the MRM mode of UPLC-U3Q,23.1 and 9.76 ng/mL,respectively.The quantitative analysis of the potential bioactive peptide may also advance the production of peptide products in the future.

山羊β-casein位点打靶载体在乳腺上皮细胞中的表达研究

以本地山羊基因组DNA为模板 ,通过长链PCR扩增出山羊 β casein上游包括启动子 ,外显子 1及部分外显子 2的 6 1kb的调控序列及下游 3 3kb的序列 ,将来自质粒pCDNA3的neo基因以及来自质粒pNEOZTK2 的tk基因 ,经克隆重组后构建了本地山羊乳腺特异性定点打靶载体 ,并在其中克隆人乳铁蛋白mini基因 ,采用脂质体法转染小鼠乳腺上皮癌化细胞系C12 7,以进行打靶载体的表达功能检测 ,双夹心ELISA测得诱导液中乳铁蛋白表达量为 0 2 μg mL ,Western blot显示重组蛋白分子量比标准品略小 ,约为 76kD ,结果说明本载体能够指导外源基因在动物乳腺细胞内正确表达。

Alginate-Casein Microspheres as Bioactive Vehicles for Nutrients

The aim of this work was to develop an alginate-casein composite microsphere as a bioaetive vehicle for oral administration of nutrients by a simple extrusion dripping method. Riboflavin was selected as a model drug, and the microencapsulation efficiency was raised to 97.94% after optimizing the preparation conditions by response surface methodology. In vitro release studies showed that riboflavin was released completely from alginate-casein microspheres in simulated intestinal fluids. Meanwhile, the morphology, structure and interaction between alginate and casein were characterized by scanning electron microscopy （SEM） and Fourier transform infrared （FTIR） spectra.

A Comparative Study of the Difference Method and the Enzyme-Hydrolyzed Casein Method for Determining True Amino Acid Digestibilities and Endogenous Amino Acid Losses in Duck Feed

In this study, we examined the varia- tions between the difference method and the enzyme- hydrolyzed casein method for determining endogenous amino acid loss and the true amino acid digestibility in ducks fed normal protein-containing diets. These methods were compared to the nitrogen-free （N-free） diet method. The difference method was based on soy- bean meal as the only protein source, with the experi- mental diets containing crude protein levels at 15% and 20%. The enzyme-hydrolyzed casein method was based on enzyme-hydrolyzed casein meal as the pro- tein source, with the experimental diet containing a crude protein level of 17.5%. The N-free diet was prepared with starches and paper fibers. In each meth- od,64 Tianfu meat drakes （7-weeks-old） with an av- erage body weight of 2.77±0.16 kg were used and divided into four groups, and fed four different diets. Each group contained four replicates of four drakes and they were force fed trial diets according to the Sirbald method for detecting their apparent amino aciddigestibility, endogenous amino acid loss and true a- mino acid digestibility. The results demonstrated that using the difference, enzyme-hydrolyzed casein and N-free diet methods, endogenous amino acid losses were 0. 9946,1. 2243 and 0. 9297 mg/g dry matter in- take （ DMI）, respectively. The true amino acid digest- ibility measured by the difference method was 88.93 %±4.43 %. Using the enzyme-hydrolyzed ca- sein method with two dietary crude protein levels of 15% and 20%, the digestibility was 91.15%±4.33% and 91.97%±4. 16%, respectively, and by the N-free diet methods with two dietary crude protein levels of 15% and 20% ,it was 88.55%±4.29% and 88.82 %±4.61%, respectively. The results suggested that when the dietary protein level was 15% to 20 %, the true amino acid digestibility and endogenous ami- no acid loss as determined by the difference method was more accurate than the values determined by the enzyme-hydrolyzed casein method.

Identification of Bovine Casein Phosphorylation Using Titanium Dioxide Enrichment in Combination with Nano Electrospray Ionization Tandem Mass Spectrometry

Protein phosphorylation is an important post-translational modification that regulates milk protein structure and function.The objective of this study was to analyze the presence of phosphorylated casein.Bovine milk proteins were first separated by SDS polyacrylamide gel electrophoresis.After in gels digestion and extraction,phosphorylated peptides were enriched by titanium dioxide and identified by ultra performance liquid chromatography coupled with nano electrospray ionization tandem mass spectrometry.This method ensured the identification of 20 phosphorylated peptides,including 7 phosphorylated forms of α_s1-casein,8 α_s2-casein,and 5 β-casein.Eight phosphorylated sites derived from 3 α_s1-caseins,3 α_s2-caseins,and 2 β-caseins were also identified,and localized on residues Ser^61,Ser^63 and Ser^130 in α_s1-casein;Thr^145,Ser^146 and Ser^158 in α_s2-casein;and Ser^50 and Thr^56 in β-casein.These findings provide valuable information for investigating casein phosphorylation of the bovine milk.

AN-g-Casein二元共聚体系的相容性

根据热力学理论计算 ,丙烯腈、酪素共聚物 (AN- g- Casein)二组分互不相容。通过动态力学热分析证实了这一结论。由于接枝共聚使二组分既分相又互相牵制 ,引起了特征界面松弛现象 ,通过扫描电镜观察 ,发现接枝共聚物二相以高聚物网络 (IPNs)共存 ,相畴分布从 0 .2 μm到 4μm。由于 IPNs的存在 ,使 AN- g- Casein共聚物序态降低 ,序态分布加宽 ,又由于 IPNs加强了纤维中原纤间的结合力 。

Flocculation of Kaolinite Suspensions in Water by Coconut Cream Casein

The flocculation of kaolinite colloidal particles was carried out at pH = 6 in suspension of initial turbidity varying between 24 NTU and 102 NTU by a casein extracted from Cocos nucifera cream. During Jar-test essays, 90% to 99% of colloids were eliminated in the sediments. The optimal doses of casein used depend on the initial colloids concentrations of the suspension and were found to be 60 mg/L and 100 mg/L respectively for suspensions having turbidity of 24 NTU and 102 NTU. The corresponding residual turbidity are respectively 2.80 NTU and 10.22 NTU for clarified water. The structural analysis of the freeze-dried sediments by FTIR shows sharp adsorption bands at 1558 cm–1 and 1653 cm–1, indicating the presence of casein in the sediment. The flocculation process between the particles of kaolinite and the coconut casein is adsorption and bridging.