Lamin B1 Accumulation's Effects on Autosomal Dominant Leukodystrophy (ADLD): Induction of Reactivity in the Astrocytes

Abstract

Autosomal dominant leukodystrophy (ADLD) is an extremely rare and fatal neurodegenerative disease due to the overexpression of the nuclear lamina component Lamin B1. Many aspects of the pathology still remain unrevealed. This work highlights the effect of Lamin B1 accumulation on different cellular functions in an ADLD astrocytic in vitro model. Lamin B1 overexpression induces alterations in cell survival signaling pathways with GSK3 beta inactivation, but not the upregulation of beta-catenin targets, therefore resulting in a reduction in astrocyte survival. Moreover, Lamin B1 build up affects proliferation and cell cycle progression with an increase of PPAR gamma and p27 and a decrease of Cyclin D1. These events are also associated to a reduction in cell viability and an induction of apoptosis. Interestingly, ADLD astrocytes trigger a tentative activation of survival pathways that are ineffective. Finally, astrocytes overexpressing Lamin B1 show increased immunoreactivity for both GFAP and vimentin together with NF-kB phosphorylation and c-Fos increase, suggesting astrocytes reactivity and substantial cellular activation. These data demonstrate that Lamin B1 accumulation is correlated to biochemical, metabolic, and morphologic remodeling, probably related to the induction of a reactive astrocytes phenotype that could be strictly associated to ADLD pathological mechanisms.