The C-Kit receptor: a stem cell marker expressed in kidney collecting duct intercalated cells
Theodoru, Andrea   (Massachusetts General Hospital)
Mentor: Brown2, Dennis (Massachusetts General Hospital)
The receptor tyrosine kinase, c-Kit, is an important stem cell marker whose expression has been described in bone marrow, liver, heart, amniotic fluid, and lungs. C-Kit has also been detected in the thick ascending limb of the kidney, which neonatal rat studies have shown to have regenerative potential (1). However, the role of c-Kit expression in kidney collecting duct intercalated cells (IC) is largely uncharacterized. In hemopoietic progenitor cells, c-Kit expression declined as erythroid progenitor cells matured into erythrocytes (2); similarly, we hypothesized that c-Kit might reflect stem cell activity in IC, and that its expression might also decline as the kidney develops. We used wild type mice and mice expressing EGFP in ICs to study the expression of c-Kit in IC via immunofluorescence and western blotting from the day of birth to adulthood. Our results show that there is a decline in basolateral membrane c-Kit expression after neonatal day 4, which continues until day 25, the age of adulthood in mice. Western blotting showed a marked decrease after day 20 and immunofluorescence confirmed this result in ICs. This was an initial study into the characterization of c-Kit receptors in the kidney. Our findings are in line with the interpretation of c-Kit expression as an indicator of the potential of ICs for regeneration and pluripotency. IC cell regeneration via a c-Kit mediated pathway could have major implications for kidney regeneration after injury, and this now requires further in depth studies to test this hypothesis.