Differences in skeletal muscle proteolysis in Nellore and Angus cattle might be driven by Calpastatin activity and not the abundance of Calpain/Calpastatin

Abstract

SUMMARYThe present study aimed to explore the molecular factors underlying differences in Calpain/Calpastatin proteolytic system in Nellore and Angus cattle. Longissimus muscle samples were collected in Nellore (n = 6; body weight (BW) = 373 ± 37·3 kg) and Angus (n = 6; BW = 383 ± 23·9 kg) cattle at slaughter for analysis of gene and protein expression, and Calpastatin enzyme activity. Additionally, the myofibrillar fragmentation index was used to quantify the extension of proteolysis in longissimus muscle samples. A greater myofibrillar fragmentation was observed in skeletal muscle of Angus compared with Nellore cattle. Conversely, no differences were found between breeds for mRNA expression of Calpain 1 (CAPN1) and Calpastatin (CAST). Similarly, no differences were observed for the abundance of Calpain and Calpastatin proteins between skeletal muscles of Nellore and Angus cattle. Despite the lack of differences in mRNA and protein abundance, a greater activity of Calpastatin was observed in skeletal muscle of Nellore compared with Angus cattle. These data indicate that the greater proteolysis in skeletal muscle of Angus compared with Nellore cattle is mainly driven by a greater Calpastatin activity rather than Calpain or Calpastatin mRNA and protein expression.

Expressão de genes envolvidos no perfil de ácidos graxos e proteólise >i<post mortem>/i< de bovinos Nelore e Rubia Gallega x Nelore

“…In addition, Moloto et al (2017) emphasized that the complexity of the tenderness process and the different metabolic pathways involved in muscle-to-meat transformation lead to the difficulty of identifying markers for meat tenderness. Moreover, Martins et al (2017) assessing the proteolysis of Angus and Nelore cattle, observed that the higher proteolysis in longissimus muscle of Angus compared to Nelore cattle was not caused by differences in the expression of genes that encoding calpastatin or calpain, nor due to the abundance of these enzymes, but due to the higher calpastatin activity in skeletal muscle of Nelore compared to Angus animals. Therefore, our study indicate that differences found in shear force values between genetic groups involve others complex systems and only the gene expression from calpain-calpastatin proteolytic system is not able to reply our results.…”

“…Sabe-se que Bos indicus apresentam maior atividade de calpastatina quando comparados aos Bos taurus. Essa atividade elevada de calpastatina em bovinos Bos indicus diminui a proteólise post mortem, afetando negativamente a maciez KOOHMARAIE, 1994;PRINGLE et al, , 1999MARTINS et al, 2017;. No entanto, a diferença na proteólise post mortem entre essas subespécies não tem sido associada apenas ao sistema calpaína-calpastatina, como também a outros sistemas proteolíticos e até mesmo a expressão gênica e abundância proteica de marcadores de maciez da carne (OUALI et al, 2006).…”

“…No entanto, a diferença na proteólise post mortem entre essas subespécies não tem sido associada apenas ao sistema calpaína-calpastatina, como também a outros sistemas proteolíticos e até mesmo a expressão gênica e abundância proteica de marcadores de maciez da carne (OUALI et al, 2006). Martins et al (2017), ao compararem animais zebuínos e taurinos britânicos, observaram que bovinos Nelore apresentam menor índice de fragmentação miofibrilar, comparados à raça britânica Angus (47,6 ± 4,28% vs. 69,2 ± 4,28%). Esse mesmo estudo avaliou a atividade da calpastatina, bem como a expressão gênica e abundância de proteínas envolvidas no amaciamento da carne.…”

“…Esse mesmo estudo avaliou a atividade da calpastatina, bem como a expressão gênica e abundância de proteínas envolvidas no amaciamento da carne. Os autores sugeriram que a maior proteólise post mortem no músculo esquelético de bovinos Angus, em comparação ao Nelore, não é causada por diferenças na expressão dos genes que codificam calpastatina ou calpaína, ou pela abundância dessas enzimas, mas sim devido à maior atividade da calpastatina no músculo esquelético de bovinos Nelore (MARTINS et al, 2017).…”

“…This variability found within subspecies has been attributed to different levels of proteolytic enzymes found in animal muscles , especially calpaincalpastatin system enzymes. Bos indicus cattle have higher calpastatin activity when compared to Bos taurus, resulting in decreased post mortem proteolysis and lower meat tenderness KOOHMARAIE, 1994;, MARTINS et al 2017.…”