Huber Korinna, Zeller Ellen, Rodehutscord Markus
Physiologisches Institut, Tierärztliche Hochschule, 30173 Hannover, Germany
Institut für Tierernährung, Universität Hohenheim, 70599 Stuttgart, Germany.
Poult Sci. 2015 May;94(5):1009-17. doi: 10.3382/ps/pev065. Epub 2015 Mar 31.
Dietary phosphorus (P) is known as a main modulator of phosphate (Pi) transporter expression. The effect of supplemented mineral P with or without phytase on protein expression of two sodium-dependent Pi (NaPi) transporters and a calcium channel was studied in the small intestine of broilers. Thirty-six broilers were randomly assigned to six different diets at 15 days of age. Two levels of total P (tP, adjusted by monocalcium phosphate (MCP) supplementation), 0.39% (BD-) and 0.47% (BD+) were fed until day 25; and at each tP level, three levels of phytase were used with 0, 500, and 12,500 FTU/kg of an E. coli phytase. Mucosa samples from jejunum and ileum were taken and apical membranes were isolated by MgCl2 precipitation. Protein expression of NaPi IIb, NaPi type III (PiT1) and the calcium channel TRPV6 were semiquantitatively measured by Western blotting and jejunal mucosal phytase activity by measurement of Pi release. The jejunal NaPi IIb transporter was expressed with two distinct bands, which were modulated differently by diet. NaPi IIb Band1 increased (P < 0.05) and Band2 decreased (P < 0.05) with phytase supplementation but was not affected by MCP supplementation. This inverse modulation of Band1 and Band2 was significantly related to the amount of net absorbed P with higher expression of Band1 at higher amounts of net absorbed P. In addition, a second Pi transporter, PiT1, was detected in which ileal expression decreased (P < 0.05) in response to higher phytase supplementation. The expression of the calcium channel TRPV6 was increased in BD+ groups. A trend for an interaction between MCP and phytase supplementation on mucosal phytase activity was observed (P = 0.079) with a decrease in activity when BD+ with 12,500 FTU/kg phytase was fed. Chicken intestinal epithelial cells responded to dietary supplemented phytase and MCP by changing the Pi transporter expression in apical membranes. In conclusion, availability of Pi is most likely the key modulator of transporter protein expression. However, a contribution of lower inositol phosphates generated by phytases and other phosphatases may also be relevant.
膳食磷（P）是已知的磷酸盐（Pi）转运蛋白表达的主要调节因子。研究了在添加或不添加植酸酶的情况下，补充矿物质磷对肉鸡小肠中两种钠依赖性Pi（NaPi）转运蛋白和一种钙通道蛋白表达的影响。36只肉鸡在15日龄时被随机分配到六种不同的日粮中。两种总磷（tP，通过补充磷酸二氢钙（MCP）进行调整）水平，0.39%（BD-）和0.47%（BD+），饲喂至25日龄；在每个tP水平下，使用三种植酸酶水平，分别为0、500和12,500 FTU/kg的大肠杆菌植酸酶。采集空肠和回肠的黏膜样本，通过MgCl2沉淀分离顶端膜。通过蛋白质印迹法半定量测定NaPi IIb、III型NaPi（PiT1）和钙通道TRPV6的蛋白质表达，并通过测量Pi释放来测定空肠黏膜植酸酶活性。空肠NaPi IIb转运蛋白以两条不同的条带表达，日粮对其调节方式不同。添加植酸酶后，NaPi IIb条带1增加（P < 0.05），条带2减少（P < 0.05），但不受MCP添加的影响。条带1和条带2的这种反向调节与净吸收磷的量显著相关，净吸收磷量越高，条带1的表达越高。此外，还检测到第二种Pi转运蛋白PiT1，随着植酸酶添加量增加，回肠中其表达降低（P < 0.05）。BD+组中钙通道TRPV6的表达增加。观察到MCP和植酸酶添加对黏膜植酸酶活性存在相互作用趋势（P = 0.079），当饲喂含12,500 FTU/kg植酸酶的BD+日粮时，活性降低。鸡肠上皮细胞通过改变顶端膜中Pi转运蛋白表达来响应日粮中添加的植酸酶和MCP。总之，Pi的可利用性很可能是转运蛋白表达的关键调节因子。然而，植酸酶和其他磷酸酶产生的低肌醇磷酸的作用也可能有关。
