OBJECTIVE Pleckstrin homologylike domain family A member 1(PHLDA1),also known as TDAG51,was first identified as a potential transcription factor required for Fas expression and activation-induced apoptosis in mouse T cell hybridomas.Subsequent research showed that PHILDA1 plays crucial roles in cell proliferation and apoptosis,PHLDA1 deficiency caused several phenotypic changes in macrophages that increased cytoprotection against oxidative and endoplasmic reticulum(ER) stress.However,little is known about the critical role of PHLDA1 in the neuroinflammation and neuronal apoptosis.METHODS Mouse Parkinson disease(PD) model was induced by intraperitoneal injection(ip) of MPTP for 7 d.Immunohistofluorescence staining was used to observe TH,Iba-1 and PHLDA1 in brain slides.Primary microglia and BV2 microglial cell lines were exposed to lipopolysacchrides(LPS) at different time points to determine PHLDA1 mRNA and protein level in vitro.BV2 cells with PHLDA1 knockdown using lentivirus experessing shRNA were exposed to LPS for the detection of proinflammatory genes expression by q-PCR or Western blotting.The NF-κB and MAPK pathways were detected to reveal the underlying mechanisms of PHLDA1 regulate microglia activation.Furthermore,to determine the effect of PHLDA1 deletion in the substantia nigra(SN) on motor dysfunction,the mice were previously infected with AAV-GFP(control) or AAV-shP HLDA1 in the SN in PD model,then were administered with behavior assessment.RESULTS PHLDA1 was expressed in microglia.PHLDA1 was increased in primary microglia or BV2 microglia cell lines by LPS treatment,acted as a positive regulator of TLR4 signaling.PHLDA1 deficiency suppressed LPS-induced microglia activation.The underlying mechanisms of PHLDA1 might be through directly interacting with TRAF6 to promote its auto-ubiquitination consequently enhanced neuroinflammatory.In PD model,PHLDA1 deletion in the SN limits microglial activation and protects dopaminergic neurons.PHLDA1 deficiency mice have a good behavioral score.CONCLUSION PHLDA
