近期發表在《Journal of the American Society of Nephrology》上的一篇文章報導,細胞外基質磷酸化糖蛋白(Matrix extracellular phosphoglycoprotein,MEPE)促進尿磷排出的同時,還可以抑制磷酸鹽在腸道的的吸收。
細胞外基質磷酸化糖蛋白(Matrix extracellular phosphoglycoprotein,MEPE)是調磷因子之一,可以誘發產生高磷酸鹽尿,但其是否影響到磷酸鹽的吸收,尚不可知。在此,研究人員應用原位腸絆技術,發現短期灌注 MEPE 可以抑制空腸磷酸鹽的吸收,但十二指腸吸收不受影響。同時對尿磷酸鹽測定顯示,MEPE 引起磷酸鹽尿與腎近曲小管鈉-磷共同轉運體水平減低有關。這種短期的效應對血液循環中甲狀旁腺素、1,25-二羥維生素D 或成纖維細胞生長因子23無影響。研究結果提示,MEPE 作為調磷因子之一對磷酸鹽的吸收和排洩均有影響。(生物谷Bioon.com)
生物谷推薦原始出處:
J Am Soc Nephrol 19: 2313-2320, 2008 doi: 10.1681/ASN.2008030315
Matrix Extracellular Phosphoglycoprotein Inhibits Phosphate Transport
Joanne Marks*, Linda J. Churchill*, Edward S. Debnam* and Robert J. Unwin*,
London Epithelial Group, * Department of Physiology and Centre for Nephrology, University College London (Royal Free Campus), London, United Kingdom
The role of putative humoral factors, known as phosphatonins, in phosphate homeostasis and the relationship between phosphate handling by the kidney and gastrointestinal tract are incompletely understood. Matrix extracellular phosphoglycoprotein (MEPE), one of several candidate phosphatonins, promotes phosphaturia, but whether it also affects intestinal phosphate absorption is unknown. Here, using the in situ intestinal loop technique, we demonstrated that short-term infusion of MEPE inhibits phosphate absorption in the jejunum but not the duodenum. Simultaneousmeasurement of urinary phosphate excretion suggests that the phosphaturic action of MEPE correlates with a significant reduction in the protein levels of the renal sodium-phosphate co-transporter NaPi-IIa in the proximal convoluted tubules of the outer renal cortex, assessed by Western blotting and immunohistochemistry. This short-term inhibitory effect of MEPE on renal and intestinal phosphate handling occurred without any changes in circulating levels of parathyroid hormone, 1,25-dihydroxyvitamin D3, or fibroblast growth factor 23. Taken together, these findingssuggest that MEPE is a candidate phosphatonin involved in phosphate homeostasis, acting in both the kidney and the gastrointestinal tract.