Association of LAR-like receptor protein tyrosine phosphatases with an enabled homolog in Hirudo medicinalis.

Receptor protein tyrosine phosphatases (RPTPs) are thought to play important functions in pathfinding and target recognition by growing neuronal processes. The leech RPTPs HmLAR1 and HmLAR2 are expressed selectively by central neurons, Comb cells, and peripheral muscle tissues in the Hirudo medicinalis embryo. To explore the functions of HmLARs, we have sought to determine their physiological substrates. We report here the cloning and embryonic expression of Lena, the leech homolog of Enabled, a cytosolic protein implicated in actin-based cell motility. Lena is expressed in embryonic central neurons and in the Comb cell. We present experimental evidences indicating that Lena associates selectively with the intracellular domain of HmLAR1 and HmLAR2. Additionally, RNA interference (RNAi) of HmLAR1 in intact leech embryos leads to the hyperphosphorylation of Lena. We propose, therefore, that Lena is an in vivo substrate of HmLAR1 in neurons and perhaps of HmLAR2 in the Comb cells.