Fbxl12 Knockout SIM-A9 Cell Line

The Fbxl12 Knockout SIM-A9 Cell Line is a CRISPR/Cas9-edited knockout cell line for loss-of-function studies of the Fbxl12 gene (encoding FBXL12). It provides a stable genetic background with disrupted FBXL12 expression, enabling dissection of SCF(FBXL12) E3 ubiquitin ligase complex roles. Supplied as a proliferating microglial population, it is suitable for functional and biochemical assays requiring sustained gene inactivation, serving as a tool for investigating ubiquitin-mediated proteasomal degradation without transient knockdown limitations in an immunologically relevant cell type.

The host cell line SIM-A9 is a spontaneously immortalized mouse microglial cell line derived from neonatal cerebral cortices. Microglia are the resident innate immune cells of the central nervous system, playing critical roles in immune surveillance, synaptic pruning, phagocytosis of debris, and neuroinflammatory responses. SIM-A9 cells retain key characteristics of primary microglia, including expression of microglial markers and phagocytic activity, making them a widely accepted model for studying neuroimmune functions in vitro. This cellular background is particularly relevant for examining how protein degradation dynamics influence microglial activation, cytokine secretion, and homeostatic maintenance in the CNS.

FBXL12 functions as the substrate recognition subunit of the SCF (SKP1-CUL1-F-box protein) E3 ubiquitin ligase complex. Within this multi-protein assembly, FBXL12 interacts directly with SKP1, CUL1, and RBX1 to mediate the transfer of ubiquitin to target proteins, marking them for proteasomal degradation. The activity of the SCF(FBXL12) complex is regulated by neddylation of CUL1 and the transcriptional control of FBXL12 expression. This ubiquitin ligase orchestrates the turnover of key substrates involved in cell cycle progression and protein homeostasis. By controlling the stability of these proteins, FBXL12 exerts a crucial influence on the ubiquitin-proteasome system, linking protein degradation to broader signaling networks.

In the microglial context, FBXL12-mediated proteasome-dependent degradation may intersect with pathways governing inflammatory responses, oxidative stress, and cellular senescence??processes implicated in neurodegenerative disorders such as Alzheimer??s and Parkinson??s disease. Disruption of Fbxl12 in SIM-A9 cells enables the investigation of how impaired ubiquitin ligase function alters microglial protein turnover, leading to changes in activation status, cytokine production, and phagocytic capacity. This model thus provides a platform to explore the molecular mechanisms by which ubiquitin system dysregulation contributes to neuroinflammation and the pathogenesis of neurodegeneration.

This cell line is well-suited for ubiquitination assays, co-immunoprecipitation to probe SCF complex assembly, Western blotting, cell cycle analysis, RT-qPCR, and cytokine profiling. It enables identification of novel FBXL12 substrates, dissection of ubiquitin-proteasome and innate immune signaling crosstalk, and screening of protein degradation modulators. For technical details and ordering, contact Ascent Research.