Investigating LIM (Lin-11, Isl-1, and Mec-3) Kinases and Their Correlation with Pathological Events and Microtubule Dynamics in an Experimental Model of Spinal Cord Injury in Rats.

Abstract

The spinal cord injury (SCI) and the neurodegenerative processes accompanying it follow an intricate pathway with very limited options for treatment strategies until now. Microtubules, essential for the growth and maintenance of neurons, are mostly disorganized and destabilized due to neurodegeneration. Regeneration or plasticity is restricted to the adult central nervous system (CNS) due to several intrinsic and extrinsic mechanisms. Some fundamental or injury-induced expressions of specific molecules can be inhibited or antagonized pharmacologically to protect neurons to a certain extent after neurodegeneration. Accordingly, these molecules offer an excellent target as a therapeutic approach to promote neuroprotection. LIM kinases (LIMKs) are one of these molecules that phosphorylates members of the actin-depolymerizing factor (ADF)/cofilin family of actin-binding and filament-severing proteins. The individual role of LIMKs has not yet been studied in the pathology of SCI. In this study, we targeted LIMK and checked its role in microtubule destabilization in vitro. LIMK1 was found to be upregulated after microtubule depolymerization and inhibition of LIMK with specific inhibitor-protected neurons. Then, we checked the expressions of individual LIMKs throughout different time points across SCI in a rat contusion model, correlating with established pathophysiological markers. The phosphorylated form of LIMK1 was found to be elevated at chronic time points after injury, where scar formation and diminution of neurons prevail. Finally, we targeted the LIMK pathway with its specific inhibitor BMS-5, which showed neuroprotection after SCI. Overall, our results provided a concept concerning how a small-molecule inhibitor of LIMK may offer a strategy to treat SCI-associated neurodegeneration.