Differential expression of Mical2 and its activator (Sema3a) in Alzheimer’s disease mouse model

Abstract

AbstractBackgroundMicals are actin regulatory enzymes which can enhance depolymerization of actin filaments (F‐Actin). Activated Micals catalyze the selective oxidation of methionine residues, Met44 and Met47 within the D‐loop of F‐actin. The oxidation of methionine residues disrupts the interaction between G‐actin monomers, thus facilitating F‐actin depolymerization. Dendritic spines are enriched with filamentous actin (F‐actin) where it regulates the formation, elimination and structural plasticity of spines. Early stage of AD is associated with loss of dendritic spines and F‐actin from synapses, leading to memory deficits. However, the potential mechanism involved in the loss of F‐actin remains largely unknown. Therefore, we aimed to elucidate the role of Micals and semaphorins in actin depolymerization at the synapse of AD mouse model.MethodsTotal RNA was isolated from the cortex, hippocampus and entorhinal cortex of adolescent, young, and middle aged wildtype and APP/PS1 mice as well as from the synaptosomes of respective age groups. The cDNA is synthesized and qRT‐PCR is performed using SYBR green reagents with specific primers to Micals and Semaphorins. Data was analyzed using two tailed non parametric test with a p value of <0.05 signifies the result.ResultsThe mRNA expression levels of Micals and Semaphorins in entorhinal cortex, hippocampus, and cortex of wildtype and APP/PS1 as well as in the synaptosomes of age matched animals were measured by qRT‐PCR. We found that Semaphorin3a showed differential mRNA expression levels in entorhinal cortex of adolescence and young adults of APP/PS1 mice in comparison to wildtype littermate controls. Further, we detected that the synapse specific mRNA levels of Mical 2 and Semaphorin3a are significantly decreased in adolescent APP/PS1 mice in comparison to WT mice. However, we did not detect any significant alteration in the mRNA expression levels of Mical1, Mical3 and Semaphorin3f in APP/PS1 mice at different age groups in comparison to WT littermate controls.ConclusionAltered expression levels of actin regulatory proteins like Micals and Semaphorins at the dendritic spines could play critical roles in Aβ mediated F‐actin depolymerization in Alzheimer's disease pathology.