Defining the Adipose Tissue Proteome of Dairy Cows to Reveal Biomarkers Related to Peripartum Insulin Resistance and Metabolic Status

Adipose
tissue is a central regulator of metabolism in dairy cows;
however, little is known about the association between various proteins
in adipose tissue and the metabolic status of peripartum cows. Therefore,
the objectives were to (1) examine total protein expression in adipose
tissue of dairy cows and (2) identify biomarkers in adipose that are
linked to insulin resistance and to cows’ metabolic status.
Adipose tissue biopsies were obtained from eight multiparous cows
at −17 and +4 days relative to parturition. Proteins were analyzed
by intensity-based, label-free, quantitative shotgun proteomics (nanoLC–MS/MS).
Cows were divided into groups with insulin-resistant (IR) and insulin-sensitive
(IS) adipose according to protein kinase B phosphorylation following
insulin stimulation. Cows with IR adipose lost more body weight postpartum
compared with IS cows. Differential expression of 143 out of 586 proteins
was detected in prepartum versus postpartum adipose. Comparing IR
to IS adipose revealed differential expression of 18.9% of the proteins;
those related to lipolysis (hormone-sensitive lipase, perilipin, monoglycerol
lipase) were increased in IR adipose. In conclusion, we found novel
biomarkers related to IR in adipose and to metabolic status that could
be used to characterize high-yielding dairy cows that are better adapted
to peripartum metabolic stress.