The RhoG-Binding Domain of ELMO1 Rescues the PTENopathy-like Phenotype in Oligodendroglial FBD-102b Cells.

Oligodendroglial cells are the myelinating glial cells of the central nervous system (CNS), and their morphological differentiation is a prerequisite for efficient myelin formation, which is essential for proper neuronal function. While oligodendroglial morphological changes normally proceed through tightly regulated developmental transitions, disruption of the underlying molecular mechanisms can lead to aberrant cellular phenotypes characterized by either premature, insufficient, or excessive differentiation. Although the phosphatidylinositol 3-kinase (PI3K) and its downstream Akt kinase signaling are well established as major drivers of oligodendrocyte morphological differentiation, myelination, and CNS white matter formation, how its negative regulator, phosphatase and tensin homolog (PTEN), is involved in the regulation of oligodendroglial morphogenesis remains incompletely understood. Recent genetic studies have highlighted a spectrum of disorders caused by PTEN dysfunction, conceptually established but currently evolving as PTENopathy, which has been partially associated with white matter abnormalities. Here, we report that, in an experimental model using the FBD-102b cell line, a well-established model of oligodendroglial cell differentiation, chemical inhibition of PTEN enhances pronounced morphological changes characterized by widespread membranes, accompanied by increased expression of differentiation and/or myelin marker proteins. We then focused on Rho family small GTPases, central regulators of cell morphogenesis, and examined their potential involvement downstream of this signaling. Expression of the RhoG-binding domain (RBD) of engulfment and cell motility 1 (ELMO1) attenuated the increased morphological changes. Similarly, inhibition of downstream Akt signaling also reversed these changes. Taken together, these results provide insight into how balanced regulation between PTEN and downstream signaling molecules governs oligodendroglial cell differentiation and suggest that dysregulation of this signaling equilibrium may contribute to cellular phenotypes relevant to disease-associated cellular alterations.