Mass spectrometry data analysis of proteome in Jingyuan chicken Leg muscle and Breast muscle
Label-free quantitative proteomics was used to analyze the Jingyuan chicken leg muscle and Breast muscle tissues. 265,391.0 secondary protein spectrograms were identified by LC-MS/MS mass spectrometry, and 85811.0 effective spectrograms were obtained after data search, with the utilization rate of 32.3%. After spectrum analysis, 15,139.0 peptides were identified, among which 12,819.0 specific peptides were identified. After examination and comparison, 1940.0 proteins were identified, among which 1317.0 proteins could be quantified (Figure 1A). The results showed that the sequence length of detected peptides was mainly distributed between 8 and 32 (Figure 1B). The error between the actual and theoretical values of the identified protein-peptide relative molecular weight was concentrated around 0, less than 20 ppm (Figure 1C). The analysis found that most peptides were less than 200 kDa, and these proteins covered 80% of the identified protein sequences (Figure 1D). The above data indicated that protein identification results were relatively ideal, and the subsequent data analysis could be continued.
Screening and principal component analysis of differential proteins in leg and Breast muscles of Jingyuan chicken
By using mass spectrometry, in each protein, the signal abundance was analyzed, and the LFQ intensity value of that protein was obtained using a non-standard quantitative calculation method. Then the calculation of the relative quantitative value of each sample was done according to the protein LFQ intensity value between different samples. The calculation principle of differential protein expression is to screen for differential proteins with a p-value of < 0.05. When the differential protein expression changes by more than 2, it indicates that the differential protein is upregulated during life-long activities. When the differential protein expression varies less than 1/2, it shows that protein is downregulated during life activities. According to the principle of protein differential expression screening, a total of 190 differentially expressed proteins were found in the muscles of the leg and breasts. Compared to the breast muscles, 121 proteins in the leg muscles were upregulated, and 69 types of proteins were downregulated (Figure 2A, B ). The principal component analysis was carried out on 190 differential proteins identified in Jingyuan chicken leg muscle and breast muscle, as shown in Figure 2C. The variance contribution rate of the first principal component PC1 was 53.8%, the variance contribution rate of the second principal component PC2 was 17.4%. The contribution rate of PC1 and PC2 reached 71.2%, reflecting most of the information on the change of differential proteins, and the proteome of the two parts was significantly different.
Functional classification and GO enrichment analysis of differentially expressed proteins in Jingyuan chicken leg muscle and breast muscle
To further study the biological functions performed by differentially expressed proteins in Jingyuan chicken leg and breast muscles, we performed Gene Ontology (GO) function annotation and enrichment analysis of 190 differential proteins. Mainly through the biological process (BP), cellular component (CC), and molecular function (MF) are three aspects of the differentially expressed proteins that have been elaborated. Figure 3 shows that differential proteins are mainly involved in cellular processes (116 proteins, 22%), single-organism process (112 proteins, 21%), metabolic processes (93 proteins, 18%) ), biological regulation (47 proteins, accounting for 9%), cellular component organization or biogenesis (33 proteins, accounting for 6%) and other biological processes. In CCs, differential proteins are mainly involved in the cell (114 differential proteins, accounting for 30%), organelle (87 proteins, accounting for 23%), macromolecular complex (51 proteins, accounting for 14%), membrane (49 proteins, accounting for 13%), extractor region (38 proteins, accounting for 10%) and other cell components. In MFs, differential proteins mainly participate in binding (123 proteins, accounting for 45%), catalytical activity (104 proteins, accounting for 38%), transportation activity (16 proteins, accounting for 6%), structural molecular activity (11 proteins, accounting for 4%) and other molecular functions.
Further, the subcellular localization of 190 differentially expressed proteins found in leg muscle and breast muscle of Jingyuan chicken. The differential proteins were mainly located in the cytoplasm (92 proteins, 48.42%), mitochondria (28 proteins, 14.74%), nucleus (24 proteins, 12.63%), extracellular (21 protein, 11.05%), cytoplasm nucleus (12 proteins, 6.32%), plasma membrane (9 proteins, 4.74%), other (4 proteins, 2.11%) organelles, as shown in Fig. 4. For systematically analyzing the differential protein functions identified in Jingyuan chicken leg and breast muscles, COG (Cluster of Orthologous Groups of proteins) was used to perform gene function annotation and genome evolution analysis on 190 differential proteins. Figure 5 shows the results obtained from the study. The Histogram shows participation in energy production and conversion (15 proteins), carbohydrate transportation and metabolism (15 proteins), lipid transportation and metabolism (13 proteins), cytoskeleton (12 proteins), general function prediction (9 proteins), translation, ribosomal structure and biogenesis (5 proteins), intracellular trafficking, secretion and vesicular transport (5 proteins), etc. The biological processes with the highest frequency of proteins are primarily energy production and conversion (15 proteins), carbohydrate transport, and metabolism (15 proteins), lipid transport, and metabolism (13 proteins). The biological processes with the lowest frequency of occurrence mainly include post-translational modification, protein turnover, chaperones, coenzyme transport and metabolism, Inorganic ion transport and metabolism, secondary metabolites biosynthesis, transport, and catalyst, etc. However, in the annotation of gene function and genome evolution analysis, 90 different protein functions have not been determined.
KEGG pathway analysis of differentially expressed protein in Jingyuan chicken leg muscle and breast muscle
Research shows that many types of proteins in the body perform their biological functions through interaction, and a single protein cannot independently perform its biological functions as the interaction of these proteins is connected by signal pathways. Therefore, the analysis of different pathways of proteins can help us to understand the biological functions more systematically and comprehensively. The regulatory mechanism of protein-protein interaction involves a change of character or occurrence of diseases. The KEGG analysis method may well classify proteins, identify the metabolic or signaling pathways in which these proteins may participate, and obtain information about the proteins involved in a series of biological processes from the cell surface to the nucleus, which ultimately helps us understand the entire organism. KEGG pathway enrichment analysis of 190 proteins differentially expressed in Jingyuan chicken leg muscles and breast muscles showed that 190 differential proteins involved a total of 286 signaling pathways, of which these differential proteins involved more than 20 significant pathways: gga01100 Metabolic pathways, gga00500 Starch and sucrose metabolism, Figure 6 depicts gga00010 Glycolysis/Gluconeogenesis, gga00071 Fatty acid degradation, gga01212 Fatty acid metabolism, gga01200 Carbon metabolism, gga00280 Valine, leucine and isoleucine degradation, gga03320 PPAR signaling pathway, etc. Thus, proteins with a significant difference between Jingyuan chicken leg muscle and breast muscle are mainly enriched by gga000500 starch and sucrose metabolism, gga00071 Fatty acid degradation, gga01212 fatty acid metabolism, gga03320 PPAR signaling pathway, etc.
Parallel reaction monitoring (PRM) validation of the differential expression protein between leg muscle and breast muscle of Jingyuan chicken
According to the information on the differential protein peptides in combination with GO analysis and KEGG pathway analysis, 23 target proteins were selected for PRM quantification. Due to the characteristics of some proteins and the abundance of their expression, only 21 of them have been quantified. It was found that 10 of the 21 quantified proteins were related to fat deposition, namely E1BTT4, E1C0Q5 (ACAT1), F1NC38 (ACADL), Q5F420 (ACSL1), A0A1D5P3S9 (ECI1), Q5ZL56 (ACADS), F1NUQ3 (FABP3), A0A1D5PL36 (ACAA2), F1NR44 (ECHS1), Q5ZIR7 (FABP5) and other ten proteins. These proteins were enriched in "gga00071Fattyaciddegradation, gga01212Fattyacidmetabolis, gga03320PPARsignalingpathway" network pathways that regulate fat deposition, as shown in Table1. The activity of related proteins that regulate fat deposition in Jingyuan chicken leg muscles was found to be significantly more potent than that of breast muscles, further explaining the critical reason why the IMF content of leg muscles was higher than that of breast muscles.
Network Interaction Analysis of IMF-specific Deposited Key Proteins in Jingyuan Chicken Leg and breast Muscles
Protein is the primary executor of life activities, and the interaction between proteins plays a vital role in regulating life activities. Both STRING and Cytoscape software were used to analyze the network interactions of IMF specific deposition proteins that regulated the leg and breast muscles of Jingyuan chicken to obtain a protein-protein interaction network map. Figure 7 depicts that there are eight proteins involved in the protein-protein interaction network, and these eight proteins form 19 network interaction paths, indicating that IMF deposition is a very complex and ordered biological process.