Washc5, also known as Strumpellin, is a core component of the WASH complex. The WASH complex activates actin-related protein-2/3-mediated actin polymerization and is pivotal in intracellular membrane trafficking in endosomes [1].

In a study, administration of a lentivirus containing a strumpellin-targeting short hairpin RNA (shRNA) to cortical motor neurons led to abnormal motor coordination in mice. Strumpellin knockdown using shRNA attenuated dendritic arborization and synapse formation in cultured cortical neurons, and this effect was rescued by wild-type strumpellin expression. The number of F-actin clusters in neuronal dendrites was decreased by strumpellin knockdown and rescued by strumpellin expression, indicating that strumpellin regulates the structural plasticity of cortical neurons via actin polymerization [1].

Mutations in the Washc5 gene are associated with autosomal dominant hereditary spastic paraplegia (HSP), spastic paraplegia 8 (SPG8). A novel splice-altering variant (c.712-2A>G) in the Washc5 gene was detected in a Chinese family with HSP, and real-time qPCR analysis showed that the expression of genes involved in the WASH complex and endosomal and lysosomal systems was altered due to this variant [2]. In a retrospective review of patients with childhood-onset HSP, a novel variant in Washc5 (SPG8) was described, and the variant was classified as a variant of uncertain significance (VUS) [3]. Additionally, Washc5 is associated with Ritscher-Schinzel syndrome 1 (RTSCS1), an autosomal recessive condition. Four siblings carried compound heterozygous variants in Washc5, and common findings included craniofacial dysmorphism, developmental delay, intellectual disability, and ataxic gait [4].

In conclusion, Washc5, as a part of the WASH complex, is crucial for actin-mediated processes in neurons. Studies, especially those using gene-knockdown models in mice, have revealed its role in the structural plasticity of cortical neurons, which is relevant to understanding diseases like HSP and Ritscher-Schinzel syndrome.