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Actin, alpha skeletal muscle precursor (Alpha-actin-1) [Contains: Actin, alpha skeletal muscle, intermediate form] [ACTA]


Explaining meat quality of bulls and steers by differential proteome and phosphoproteome analysis of skeletal muscle.

The objective of this study was to evaluate the differential proteome and phosphoproteome between bulls and steers during conversion of muscle to meat, as well as after 14 days of aging. Twelve male Nellore (Bos taurus indicus) calves were used, and six calves were randomly selected for surgical castration. Calves were fed the same diet and were harvested after 230 days on feed. Longissimus muscle was sampled just after stunning (0d postmortem), at deboning (1d postmortem) and after aging (14d postmortem) for differential proteome analysis. Castration upregulated (P < 0.05) the abundance of glycolytic enzymes, while the oxidative phosphorylation protein ATP5B was downregulated (P < 0.05). In addition, abundance of troponin T fast isoform (TNNT3) was upregulated by castration (P < 0.05), while the slow isoform (TNNT1) tended to be decreased (P < 0.10). The creatine kinase M-type was markedly fragmented postmortem. Abundance of phosphorylated PGM1 increased during the first 24 h postmortem and was highly correlated with carcass pH. Further, abundance of the phosphorylated myofibrillar proteins ACTA1 and MYLPF were positively correlated with sarcomere shortening. Overall, our finds demonstrated that abundance and phosphorylation of glycolytic enzymes are associated with changes in beef tenderness and intramuscular fat. SIGNIFICANCE: The design of the present study allowed to clarify the key proteins related to changes during conversion of muscle to meat such as pH decline and sarcomere shortening. In addition, the correlation between some biomarker and meat quality traits were confirmed.

MeSH Terms

  • Animals
  • Castration
  • Cattle
  • Glycolysis
  • Male
  • Meat
  • Muscle Proteins
  • Muscle, Skeletal
  • Phosphoproteins
  • Phosphorylation
  • Proteome
  • Quality Control
  • Red Meat


  • Castration
  • Intramuscular fat
  • Meat aging
  • Phosphoprotein
  • Zebu cattle

Serum starvation of ARPE-19 changes the cellular distribution of cholesterol and Fibulin3 in patterns reminiscent of age-related macular degeneration.

Retinal pigment epithelium (RPE) has been implicated as key source of cholesterol-rich deposits at Bruch's membrane (BrM) and in drusen in aging human eye. We have shown that serum-deprivation of confluent RPE cells is associated with upregulation of cholesterol synthesis and accumulation of unesterified cholesterol (UC). Here we investigate the cellular processes involved in this response. We compared the distribution and localization of UC and esterified cholesterol (EC); the age-related macular degeneration (AMD) associated EFEMP1/Fibulin3 (Fib3); and levels of acyl-coenzyme A (CoA): cholesterol acyltransferases (ACAT) ACAT1, ACAT2 and Apolipoprotein B (ApoB) in ARPE-19 cells cultured in serum-supplemented and serum-free media. The results were compared with distributions of these lipids and proteins in human donor eyes with AMD. Serum deprivation of ARPE-19 was associated with increased formation of FM dye-positive membrane vesicles, many of which co-labeled for UC. Additionally, UC colocalized with Fib3 in distinct granules. By day 5, serum-deprived cells grown on transwells secreted Fib3 basally into the matrix. While mRNA and protein levels of ACTA1 were constant over several days of serum-deprivation, ACAT2 levels increased significantly after serum-deprivation, suggesting increased formation of EC. The lower levels of intracellular EC observed under serum-deprivation were associated with increased formation and secretion of ApoB. The responses to serum-deprivation in RPE-derived cells: accumulation and secretion of lipids, lipoproteins, and Fib3 are very similar to patterns seen in human donor eyes with AMD and suggest that this model mimics processes relevant to disease progression.

MeSH Terms

  • Acetyl-CoA C-Acetyltransferase
  • Acyl Coenzyme A
  • Apolipoproteins B
  • Cell Line
  • Cholesterol
  • Cholesterol Esters
  • Culture Media, Serum-Free
  • Diffusion Chambers, Culture
  • Extracellular Matrix Proteins
  • Gene Expression Regulation
  • Humans
  • Macular Degeneration
  • Models, Biological
  • Retinal Pigment Epithelium
  • Signal Transduction
  • Sterol O-Acyltransferase


  • Age-related macular degeneration
  • Aging
  • Cholesterol
  • Fibulin 3
  • Retinal pigment epithelium
  • Serum deprivation