Fyn Kinase Regulates Microglial Neuroinflammatory Responses in Cell Culture and Animal Models of Parkinson's Disease

Abstract

Sustained neuroinflammation mediated by resident microglia is recognized as a key pathophysiological contributor to many neurodegenerative diseases, including Parkinson's disease (PD), but the key molecular signaling events regulating persistent microglial activation have yet to be clearly defined. In the present study, we examined the role of Fyn, a non-receptor tyrosine kinase, in microglial activation and neuroinflammatory mechanisms in cell culture and animal models of PD. The well-characterized inflammogens LPS and TNF␣ rapidly activated Fyn kinase in microglia. Immunocytochemical studies revealed that activated Fyn preferentially localized to the microglial plasma membrane periphery and the nucleus. Furthermore, activated Fyn phosphorylated PKC␦ at tyrosine residue 311, contributing to an inflammogen-induced increase in its kinase activity. Notably, the Fyn-PKC␦ signaling axis further activated the LPSand TNF␣-induced MAP kinase phosphorylation and activation of the NFB pathway, implying that Fyn is a major upstream regulator of proinflammatory signaling. Functional studies in microglia isolated from wild-type (Fyn ϩ/ϩ ) and Fyn knock-out (Fyn Ϫ/Ϫ ) mice revealed that Fyn is required for proinflammatory responses, including cytokine release as well as iNOS activation. Interestingly, a prolonged inflammatory insult induced Fyn transcript and protein expression, indicating that Fyn is upregulated during chronic inflammatory conditions. Importantly, in vivo studies using MPTP, LPS, or 6-OHDA models revealed a greater attenuation of neuroinflammatory responses in Fyn Ϫ/Ϫ and PKC␦ Ϫ/Ϫ mice compared with wild-type mice. Collectively, our data demonstrate that Fyn is a major upstream signaling mediator of microglial neuroinflammatory processes in PD.

Involvement of c-Abl Kinase in Microglial Activation of NLRP3 Inflammasome and Impairment in Autolysosomal System

“…The cells were then transfected by electroporation using A-23 program of Lonza Nucleofector™ 2b devise. Detailed protocol can be found in our previous publication (Panicker et al, 2015). Post transfection, the cells were incubated for 48h followed by various treatment.…”

“…The whole cell lysates were prepared using modified RIPA buffer as described previously (Panicker et al, 2015). To analyze the intracellular translocation, nuclear and cytosolic fractions were collected using NE/PER kit (Thermo Fisher).…”

“…Immunostaining was done with both BV2 cells and primary microglia (Panicker et al, 2015). In brief, cells were plated on glass cover-slips and were exposed to desired treatments.…”

The Kinase Fyn As a Novel Intermediate in l-DOPA-Induced Dyskinesia in Parkinson’s Disease

“…Yet, they did not explore the behavioural correlations of these findings arguing that Fyn-KO mice "were resistant to a neurotoxic lesion with 6-OHDA". Similarly, Panicker et al [40] reported attenuated DA loss in the Fyn-KO mice intrastriatally injected with 6-OHDA. The authors attributed that result to a reduced inflammatory response in Fyn-KO that may be neuroprotective.…”

Rodent Model of Parkinson’s Disease: Unilateral or Bilateral?

“…The striatum is another location to prefer [24]. Anti-inflammation treatment based on this model is investigated for neural protection in PD process [25].…”