SorLA, a member of the LDL receptor family, is expressed in the collecting duct of the murine kidney.

SorLA/LR11 is a recently identified member of the LDL receptor superfamily, which is broadly expressed in the nervous system, but also in some non-neuronal tissues. To investigate sorLA expression in more detail we generated sorLA-specific antibodies. The kidney-specific expression of sorLA was investigated by in situ hybridization, immunohistochemistry, and immunofluorescence of murine kidney sections. In situ hybridizations of embryonic and adult kidney sections revealed transcripts mainly in the renal medulla. This expression pattern correlated with sorLA immunostainings. By co-staining with various markers sorLA expression was found to be restricted to cortical and medullary collecting tubules. SorLA was detected in intracellular vesicular structures, but not in the plasma membrane. Vesicles were distributed throughout the cytoplasm of cortical collecting tubules, whereas a more apical localization was noted in the medullary part. This intracellular compartment partially overlapped with the trans-Golgi marker gamma-adaptin and the transferrin receptor, a marker for shuttling compartments, but not with the lysosomal marker lamp2. These results demonstrate a highly specific expression of sorLA in collecting tubules. SorLA overlaps with intracellular shuttling compartments, indicating a role of sorLA for intracellular trafficking in the kidney.