Developmental analysis of Lingo-1/Lern1 protein expression in the mouse brain: interaction of its intracellular domain with Myt1l.

Lingo-1 (also known as Lern1) is a component of the Nogo receptor complex that mediates intracellular signaling in response to myelin associated inhibitors (MAIs): NogoA, MAG, and Omgp. Signaling through Nogo receptor extends to more than its well known role in preventing axon regeneration after lesion in the CNS, being implicated in neuronal functional maturation. Using Lingo-1-deficient mice, it has been demonstrated that Lingo-1 plays relevant roles in oligodendrocyte differentiation during brain development, and that treatment with Lingo-1 antagonists can improve axon regeneration after lesion in adult mice by decreasing MAI mediated signaling. However, a detailed description of the pattern of expression of Lingo-1 protein in correlation with the other partners of Nogo receptor is missing. Here, we show that components of the Nogo receptor complex, Lingo-1, NgR1, p75, and TROY coexist in mouse brain in a defined time window only at later postnatal stages. We have also determined the Lingo-1 distribution showing expression in particular subsets of neurons, but not in myelinating mature oligodendrocytes. Surprisingly, Lingo-1 is expressed at early developmental stages without NgR1, which supports the notion that Lingo-1 may participate in other activities in developing neurons different from oligodendrocyte maturation or axon extension inhibition in the adult. Finally, we propose that the intracellular domain of Lingo-1 contributes to signaling and show that it interacts with the postmitotic neuronal specific zinc finger protein Myt1l, suggesting that Lingo-1 may regulate Myt1l transcription factor activity by affecting its subcellular localization.