The involvement of the novel proteins, perilipin, ATGL, and CGI-58, in lipolysis of early and mid lactation Holstein cows

Perilipin, adipose triglyceride lipase (ATGL), and comparative gene identity-58 (CGI-58) are novel proteins that greatly effect lipid catabolism in rodents and humans. During early lactation, dairy cows often enter negative energy balance when milk production requirements exceed energy intake, and must mobilize adipose tissue to meet these needs. Severe and prolonged negative energy balance can lead to reduced fitness. Perilipin, ATGL and CGI-58 protein abundance was quantified to determine the relationship of these proteins with adipose tissue mobilization of early (5-14 days in milk [DIM]; n=11) compared to mid (176-206 DIM; n=9) lactation cows. Phosphorylation of perilipin was increased in early lactation and significantly correlated with lipolytic indicators in early and mid lactation. ATGL was increased in mid lactation and CGI-58 was similar across stages of lactation. These results suggest phosphorylation of perilipin occurs during stimulated and basal lipolysis; whereas ATGL may function as a basal lipase