Distinct Roles of Perilipins in the Intramuscular Deposition of Lipids in Glutamine-Supplemented, Low-, and Normal-Birth-Weight Piglets

Abstract

Piglets with low birth weight (LBW) usually have reduced muscle mass and increased lipid deposition compared with their normal-birth-weight (NBW) littermates. Supplementation of piglets with amino acids during the first days of life may improve muscle growth and simultaneously alter the intramuscular lipid deposition. The aim of the current study was to investigate the influence of glutamine (Gln) supplementation during the early suckling period on lipid deposition in the longissimus muscle (MLD) and the role of different perilipin (PLIN) family members in this process. Four groups were generated consisting of 72 male LBW piglets and 72 NBW littermates. Piglets were supplemented with either 1 g Gln/kg body weight or an isonitrogenous amount of alanine (Ala) between days post natum (dpn) 1 and 12. Twelve piglets per group were slaughtered at 5, 12, and 26 dpn, and muscle tissue was collected. Perilipins were localized by immunohistochemistry in muscle sections. The mRNA and protein abundances of PLIN family members and related lipases were quantified by quantitative RT-PCR (qPCR) and western blots, respectively. While PLIN1 was localized around lipid droplets in mature and developing adipocytes, PLIN2 was localized at intramyocellular lipid droplets, PLIN3 and 4 at cell membranes of muscle fibers and adipocytes, and PLIN5 in the cytoplasm of undefined cells. The western blot results indicated higher protein abundances of PLIN2, 3, 4, and 5 in LBW piglets (p < 0.05) at 5 dpn compared with their NBW littermates independent of supplementation, while not directly reflecting the mRNA expression levels. The mRNA abundance of PLIN2 was lower while PLIN4 was higher in piglets at 26 dpn in comparison with piglets at 5 dpn (p < 0.01). Relative mRNA expression of LPL and CGI-58 was lowest in piglets at 5 dpn (p < 0.001). However, ATGL mRNA was not influenced by birth weight or supplementation, but the Spearman correlation coefficient analysis revealed close correlations with PLIN2, 4, and 5 mRNA at 5 and 26 dpn (r > 0.5, p < 0.001). The results indicated the importance of birth weight and age for intramuscular lipid deposition and different roles of PLIN family members in this process, but no clear modulating effect of Gln supplementation.

Proteomic analysis shows decreased type I fibers and ectopic fat accumulation in skeletal muscle from women with PCOS

“…Aldo-keto reductase family 1 members C1 and C3 ( AKR1C1 and AKR1C3, Figure 2B ), which have an androsterone dehydrogenase activity (GO:0047023), were also upregulated and AKR1C1 was strongly correlated to higher circulating testosterone levels (Spearman’s rho = 0.65, p=0.002), suggesting that muscle may produce testosterone via the backdoor pathway. Moreover, perilipin-1 that typically coats the surface of lipid droplets in adipocytes ( Gandolfi et al, 2011 ; Zhao et al, 2021 ), the so-called extra-myocellular adipocytes, was increased in PCOS muscle. The increased expression of perilipin-1 was confirmed by immunofluorescence staining and quantification of muscle biopsies ( Figure 2C and D ).…”

“…Perilipins act largely as a scaffold protein on lipid droplets. Perilipin-1 is localized in the periphery of intramuscular lipids, known as extracellular lipids ( Gandolfi et al, 2011 ; Zhao et al, 2021 ). In pig, muscle perilipin-1 proteins are localized around lipid droplets in mature and developing adipocytes in correspondence with extra-myocellular lipids ( Gandolfi et al, 2011 ; Zhao et al, 2021 ).…”

Proteomic analysis shows decreased Type I fibers and ectopic fat accumulation in skeletal muscle from women with PCOS

“…2B ), which have an androsterone dehydrogenase activity (GO:0047023), were also upregulated and AKR1C1 was strongly correlated to higher circulating testosterone levels (Spearman rho=0.65, P =0.002), suggesting that muscle may produce testosterone via the backdoor pathway. Moreover, perilipin-1 that typically coats the surface of lipid droplets in adipocytes (Gandolfi et al ., 2011; Zhao et al ., 2021), so-called extra-myocellular adipocytes, was increased in PCOS muscle. The increased expression of perilipin-1 was confirmed by immunofluorescence staining and quantification of muscle biopsies ( Fig.…”

Identification of microRNA Transcriptome Involved in Bovine Intramuscular Fat Deposition

“…Perilipin 1 (PLIN1) is most abundant in white adipose tissues where it is involved with hormonestimulated lipolysis; whereas perilipin 5 (PLIN5) is expressed in cardiac and skeletal muscle, and brown adipose tissues where it regulates fatty acid supply to the mitochondria (45). In pigs, immunohistochemistry was used to determine where PLIN proteins were located within the longissimus muscle of low or normal birth weight piglets at specific days (5, 12, and 26 d) postnatal (46). PLIN3 and PLIN4 were found at the periphery of muscle fibers and intramuscular adipocytes; in contrast, PLIN5 was localized within an undefined cell type located between the muscle fibers (46).…”

“…In pigs, immunohistochemistry was used to determine where PLIN proteins were located within the longissimus muscle of low or normal birth weight piglets at specific days (5, 12, and 26 d) postnatal (46). PLIN3 and PLIN4 were found at the periphery of muscle fibers and intramuscular adipocytes; in contrast, PLIN5 was localized within an undefined cell type located between the muscle fibers (46). Sterol regulatory element-binding protein (SREBP1c) cleavage-activating protein (SCAP) is required to activate all isoforms of SREBP.…”