JCI - Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfusion injury

Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfusion injury

Kiyoshi Mori, H. Thomas Lee, Dana Rapoport, Ian R. Drexler, Kirk Foster, Jun Yang, Kai M. Schmidt-Ott, Xia Chen, Jau Yi Li, Stacey Weiss, Jaya Mishra, Faisal H. Cheema, Glenn Markowitz, Takayoshi Suganami, Kazutomo Sawai, Masashi Mukoyama, Cheryl Kunis, Vivette D’Agati, Prasad Devarajan, Jonathan Barasch

Published in Volume 115, Issue 3

J Clin Invest. 2005; 115(3):610–621 doi:10.1172/JCI23056

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Figure 8

Iron-binding cofactor in urine. (A) Buffer was mixed with ⁵⁵Fe (No protein, light blue) and with apo-Ngal (dark blue), apo-Ngal plus siderophore (yellow), or apo-Ngal plus siderophore plus unlabeled iron (pink). The samples were then washed 3 times on a 10-kDa filter, and small aliquots were measured for retention of radioactivity (Washes 1–3). After 48 hours at 4°C the samples were washed again (Wash 4 + 48 h). Note the retention of ⁵⁵Fe by apo-Ngal plus siderophore but not by apo-Ngal alone or apo-Ngal ligated by the iron-saturated siderophore, which demonstrates that an unsaturated siderophore is required for retention of ⁵⁵Fe by Ngal. ⁵⁵Fe binding to apo-Ngal plus siderophore was stable for 48 hours. (B) Urine (<3,000 Da) was mixed with ⁵⁵Fe and with apo-Ngal, as indicated, and then washed 3 times on a 10-kDa filter. While urine (<3,000 Da) or apo-Ngal in buffer did not retain ⁵⁵Fe on a 10-kDa filter, apo-Ngal plus urine retained ⁵⁵Fe. ⁵⁵Fe retention was blocked by the addition of excess iron citrate (Fe) or of iron-saturated enterochelin (Sid:Fe).