Neuroprotection by Neurotropin through Crosstalk of Neurotrophic and Innate Immune Receptors in PC12 Cells

Abstract

Infected or damaged tissues release multiple “alert” molecules such as alarmins and damage-associated molecular patterns (DAMPs) that are recognized by innate immune receptors, and induce tissue inflammation, regeneration, and repair. Recently, an extract from inflamed rabbit skin inoculated with vaccinia virus (Neurotropin®, NTP) was found to induce infarct tolerance in mice receiving permanent ischemic attack to the middle cerebral artery. Likewise, we report herein that NTP prevented the neurite retraction in PC12 cells by nerve growth factor (NGF) deprivation. This effect was accompanied by interaction of Fyn with high-affinity NGF receptor TrkA. Sucrose density gradient subcellular fractionation of NTP-treated cells showed heretofore unidentified membrane fractions with a high-buoyant density containing Trk, B subunit of cholera toxin-bound ganglioside, flotillin-1 and Fyn. Additionally, these new membrane fractions also contained Toll-like receptor 4 (TLR4). Inhibition of TLR4 function by TAK-242 prevented the formation of these unidentified membrane fractions and suppressed neuroprotection by NTP. These observations indicate that NTP controls TrkA-mediated signaling through the formation of clusters of new membrane microdomains, thus providing a platform for crosstalk between neurotrophic and innate immune receptors. Neuroprotective mechanisms through the interaction with innate immune systems may provide novel mechanism for neuroprotection.

Multiplicity of Glycosphingolipid-Enriched Microdomain-Driven Immune Signaling

“…Thus, additional investigations are required to elucidate the mechanisms underlying the cis-interactions of TLR4 with membrane microdomain components. Cross-talk between neurotrophic receptors and TLR4 is also thought to be involved in neuroprotection mechanisms [48]. An extract from inflamed rabbit skin inoculated with vaccinia virus (Neurotropin ® , NTP) was shown to control nerve growth factor (NGF) receptor TrkA-mediated TLR4-associated signaling through clusters of newly formed membrane microdomains in PC12 cells.…”

The Heterogeneity of Response of PC12 Cells from Different Laboratories to Nerve Growth Factor and Pituitary Adenylate Cyclase-Activating Polypeptide Questions the Reproducibility of Studies Carried Out with Tumor Cell Lines

“…For more information regarding PACAP and its mechanisms of action, refer to the following review [5]. Because PC12 cells are easy to grow and exhibit obvious morphological modifications, they have been used over the last 40 years in >20,000 studies referenced in PubMed to decipher the intracellular signaling cascades involved in the effects of some growth factors and neurotransmitters on proliferation and differentiation of neuroendocrine cells [6][7][8][9][10]. Other researchers have used PC12 cells to address the ability of some molecules to act as anticancer drugs [11].…”