| Background: Hypocalcemia is a metabolic disorder that occurs around parturition, which ischaracterized by the negative calcium balance. It is classified as the clinical type, named as milkfever, and the subclinical type. Many factors are involved in the calcium homeostasis regulationmechanism. It was unable to understand panoramically the etiology of hypocalcemia only underan reason or factor in the previous studies. Therefore, in this study some valuable and potentialproteins from cows affected hypocalcemia were screened and identified using the iTRAQtechnique to investigate their role in hypocalcemia development. It will play an importantsignificance in enriching and developing etiology of hypocalcemia.Objective: To screen and determine differences of plasma proteomic profiles among the milkfever cows (MF), subclinical hypocalcemia (SH) cows and healthy (C) cows by isobaric tags forrelative and absolute quantitation (iTRAQ) combined with liquid chromatography-tandem massspectrometry (LC-MS/MS), and thereby exploring the biological action of the different proteinson hypocalcemia in dairy cows.Methods: Boold samples from30cows with MF, SH and Healthy were collected from tailvein, ten samples each group, and EDTA was added to each sample as an anticoagulant. Fiveplasmas from the same group were randomly pooled as a mixed sample, and then were labeledwith iTRAQ reagents after depletion of plasma high abundance proteins and digestive peptides.The iTRAQ labeled samples were separated by LC-MS/MS, proteins quantification andidentification for the iTRAQ experiment were performed using Proteome Discoverer l.3and thesearch of NCBI database. The different proteins were obtained by the cutoff point of1.33for theup-regulation and0.75for down-regulation, and then were analyzed online throughbioinformatics.Results: In proteomic experiment146overlapped proteins obtained from biological duplicatesamples were used for quantification.42different proteins were found according to the cutoffpoint of1.33for the up-regulation and and0.75for the down-regulation. The majority ofdifferent proteins were involved in biological functions of life activities, metabolic pathways, signal transduction, enzyme regulation and so on, and compared with the C group, there were12up-regulated proteins and10down-regulated proteins in MF group,29up-regulated proteins and7down-regulated proteins in SH group.15of the42proteins showed the same change, whichmight be mainly associated with blood coagulation, complement activation, enzyme regulatoractivity, inflammatory response, hormone secretion, response to stress, immune response, bonemetabolic process and so on.Conclusions: We first studied plasma proteomic profile of dairy cow with hypocalcemia usingthe iTRAQ in conjunction with LC-MS/MS, which contained146proteins, in particular42eligible different proteins. They were used to elucidate the relationship between these proteinsand hypocalcemia. However, their roles need to be verified in the development of hypocalcemiain the future. Our study will provide a new idea to further reveal mechanism, prevention andtreatment of hypocalcemia in future. |
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