Cloning of oligopeptide transport carrier PepT1 and comparative analysis of PepT1 messenger ribonucleic acid expression in response to dietary nitrogen levels in yak (Bos grunniens) and indigenous cattle (Bos taurus) on the Qinghai–Tibetan plateau1

Abstract

The gastrointestinal lumen can directly absorb all di- and tripeptide protein degradation products, and oligopeptide absorption depends on the specific peptide transport carriers, which are located in gastrointestinal epithelial cells on the brush border membrane. Yak () use N more efficiently than cattle do, which implies that yak have a specific mechanism of nonprotein utilization including a peptide absorption mechanism. However, this mechanism has not been clarified. Our objective was to explore whether yak possess any adaptive mechanisms of peptide absorption to survive in the harsh foraging environment of the Qinghai-Tibetan plateau. Twelve castrated males of each of 2 genotypes, yak () and indigenous cattle (), were fed diets of various N levels. The yak PepT1 (yPepT1) cDNA was cloned in omasum epithelial tissue. Our results showed that the full-length yPepT1 cDNA contains 2,805 bp, and a 2,121-bp open reading frame encodes a putative protein of 707 AA residues. The yPepT1 AA sequence identified 5 putative extracellular N-glycosylation sites (Asn, Asn, Asn, Asn, and Asn), 2 putative intracellular protein kinase A sites (Ser and Thr), and 3 intracellular putative protein kinase C sites (Ser, Ser, and Ser). The yPepT1 AA sequence was 99, 95, 86, and 83% identical to PepT1 from cattle (), sheep (), pigs (), and humans (), respectively. The relative PepT1 mRNA expression for indigenous cattle was greater than yak in the rumen, omasum, duodenum, ileum, and liver ( < 0.001); however, it was lower in jejunum tissue ( < 0.01). The relative PepT1 mRNA expression in response to increasing dietary N for both genotypes were linear in the rumen and jejunum ( < 0.10); quadratic or cubic in the reticulum ( < 0.01); linear or quadratic in the duodenum, ileum, and liver ( ≤ 0.01); and linear, quadratic, or cubic in the omasum ( < 0.001). Moreover, there were significant interactions between genotype and dietary N in rumen, reticulum, omasum, duodenum, jejunum, ileum, and liver tissues. In conclusion, the PepT1 profile and expression in gastrointestinal epithelial cells of yak varied from those of cattle, implying that yak have evolved a peptide transport mechanism to adapt the environment of the Qinghai-Tibetan plateau.

Rumen parameters of yaks (Bos grunniens) and indigenous cattle (Bos taurus) grazing on the Qinghai‐Tibetan Plateau

“…Ammonia concentration was greater in yaks than in cattle and C × Y in summer and winter, which would suggest greater microbial protein yield. Previous studies reported that yaks possess a unique rumen microbial ecosystem and nitrogen utilization that is more efficient than that of cattle (Huang et al,; Long et al, ; Wang et al, ,; Wang et al,; Zhang et al, ).…”

Signature of high altitude adaptation in the gluteus proteome of the yak

“…Moreover, metabolic changes beneficial to high‐altitude adaptation were also reported in yak. Yak increases the utilization rate of nitrogen, decreases urine, nitrogen excretion, and daily glomerular filtration (H. C. Wang, Shi, Hou, Fu, & Long, 2016; H. Wang et al, 2009; J. W. Zhou et al, 2017).…”

Functional characterization of oligopeptide transporter 1 of dairy cows

“…PepT1 has been cloned and characterized in various species, including rabbit [ 11 ], human [ 12 ], sheep [ 13 , 14 ], chickens [ 15 ], zebrafish [ 16 ], pig [ 17 ], turkey [ 18 ], cattle [ 19 ], Atlantic salmon [ 20 ], grass carp [ 21 ], and yak [ 22 ]. Most of the functional analysis of PepT1 has focused on the model peptides or pharmacological substrates, however, fewer reports have focused on the nutritional aspects of PepT1.…”