טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentInbar Haya Magid Gold
SubjectRegulation of iron uptake and metabolism in renal
epithelia
DepartmentDepartment of Biotechnology and Food Engineering
Supervisor Dr. Meyron Holtz Esther
Full Thesis textFull thesis text - English Version


Abstract

The kidneys are located near the middle of the back, just below the rib cage. 
They are a small but very important organ in the human body. Among their functions are: excretion of waste from the body.

The protein- and nutrient-reabsorption from the primary urine takes place in the nephron, the basic unit of the kidney, which is composed of four main areas: glomerular capsule, proximal convoluted tubule (PCT), loop of Henle, and the distal convoluted tubule (DCT). Most reabsorption occurs in the PCT where epithelial cells apically express microvilli. In patients suffering from proteinuria, transferrin is abundant in the urine, indicating that transferrin (in the plasma, ferric iron is bound to transferrin) passes the glomerulus into the primary filtrate.

In this research we tried to decipher how iron is absorbed from the primary urine.
Renal epithelial cells absorb all iron from the primary urine, in contrast to other cells which take up iron according to their needs. What mechanism and which protein/s allow the kidneys to do it?  
We analyzed 3 proteins that might have a role in renal iron metabolism.

TfR1: Which is responsible for taking up iron according to the cell's needs in most cell in our body.  

Cubilin: A receptor that is associate with renal iron metabolism In addition to that, Previous results in our lab showed an increase cubilin protein levels during iron overload.

Megalin: Because cubilin lacks a transmembrane domain, and it forms a complex with megalin (depending on megalin for localization and internalization); we analyzed megalin contribution to renal iron metabolism as well.

We found that TfR1 mRNA decreased during iron overload, cubilin mRNA remains the same but mRNA levels of megalin increased during iron overload. We suggest that the elevation in megalin levels stabilizes cubilin into the apical membrane and allows it to scavenge all iron from the primary urine.
Nevertheless, TfR1 probably located along the nephron and might absorb the Tf-iron complex as well.


Kidney epithelial cells are protected from iron, probably by excretion of iron through the basolateral membrane back to the body. In the second part of this research, we have done
characterization of tagged ferritin in order to tract it in renal cell. We suggest that ferritin might be responsible for secretion of iron through the basolateral membrane. Tagged ferritin will be a very useful research toll to rest our hypothesis.