Protein deprivation attenuates Hsp expression in fat tissue

Abstract

For ruminants, dietary protein is the first limiting component to the utilization of low-quality forage. Throughout gestation, low-protein intake may result in prenatal programming that causes various metabolic disturbances and physiological modulations to dams and their developing embryos. We studied the effect of long-term low-protein diet (LPD) on physiological, biochemical, and molecular parameters of the energy status in gestating beef cows. LPD resulted in significant reductions in feed intake and heart rate and promoted a negative retained energy status already after 3 weeks. Elevated levels of plasma creatinine and non-esterified fatty acids indicate endogenous degradation of fat and protein as a response to the demands in energy and nitrogen. Increasing levels of β-hydroxybutyrate confirmed the negative energy status obtained by the physiological measurements. At the molecular level, subcutaneous fat, Hsp90, Hsp70, and proteasome subunits decreased significantly after 3 months on LPD, in parallel with an increase of adipocyte fatty acidbinding protein. These results may indicate a decrease in turn-over of proteins, at the cost of induced lipolysis, and suggest that the response to protein deprivation, when examined in an energy-storing tissue, includes downregulation of the constitutive heat shock proteins involved in the protein degradation pathway of energy production and upregulation of tissue-specific genes such as those involved in energy production from fat degradation.

Effect of Dietary Urea in Gestating Beef Cows: Circulating Metabolites, Morphometrics, and Mammary Secretions

“…Greenfield et al [13] demonstrated that inclusion of dietary urea to dairy cows during late gestation (last 28 d of gestation) does not influence circulating concentrations of BHB, similar to what was observed in the current experiment. Eitam et al [14] reported an increase in circulating concentrations of BHB when protein is restricted in beef cows during mid gestation. While there was no influence of dietary treatment on concentration of BHB in the current experiment, we did observe an influence of day of gestation on BHB and increase in circulating concentrations of BHB on day 168 of gestation-one potentially attributed to fetal secondary myogenesis [15].…”

Adaptive traits of indigenous cattle breeds: The Mediterranean Baladi as a case study

“…At the mammary gland level, these results may indicate a decrease in turnover of proteins and a shift to an exclusive expression of milk component producing factors (Eitam, Brosh, Orlov, Izhaki, & Shabtay, 2009). In a more recent study, Eitam et al (2012) studied the effect of long-term protein deprivation in the diet on physiological, biochemical, and molecular parameters of the energy status in gestating Simmental cows. In this case, the expression of Hsp90, Hsp70, and proteasome subunits in subcutaneous fat decreased significantly in parallel with an increase of adipocyte fatty acid binding protein (FABP4).…”