The Iron-Binding Protein Lactoferrin Protects Vulnerable Dopamine Neurons from Degeneration by Preserving Mitochondrial Calcium Homeostasis

Abstract

Previous studies on postmortem human brain tissue have shown that the iron-binding glycoprotein lactoferrin is upregulated in dopamine (DA) neurons resistant to degeneration in Parkinson disease (PD). To study how this could possibly relate to disease progression, we used midbrain cultures and experimental settings that model the progressive loss of DA neurons in this disorder. Human lactoferrin of either recombinant or natural origin provided robust protection to vulnerable DA neurons in a culture paradigm in which these neurons die spontaneously and selectively as they mature. The efficacy of lactoferrin was comparable to that of glial cell line-derived neurotrophic factor, a prototypical neurotrophic factor for DA neurons. Neuroprotection by lactoferrin was attributable to its binding to heparan sulfate proteoglycans on the cell surface of DA neurons and subsequently to partial inactivation of focal adhesion kinase (FAK), a major effector kinase of integrins. We established that FAK inactivation served to unmask a prosurvival phosphoinositide 3-kinase/AKT-dependent signaling pathway that stimulates calcium shuttling from endoplasmic reticulum to mitochondria. DA neurons exposed to the mitochondrial toxin 1-methyl-4-phenylpyridinium were also partially protected by lactoferrin, further supporting the view that mitochondria may represent a downstream target for lactoferrin protective actions. Finally, we found that the iron binding capability of lactoferrin intervened in DA cell rescue only when neurodegeneration was consecutive to iron-catalyzed oxidative stress. Overall, our data suggest that the accumulation of lactoferrin in PD brains might be evidence of an attempt by the brain to minimize the consequences of neurodegeneration.

Lactoferrin and ovotransferrin contribute toward antioxidative effects of Edible Bird’s Nest against hydrogen peroxide-induced oxidative stress in human SH-SY5Y cells

“…Different studies have also shown that LF and OVF serve neuroprotective and antioxidant functions 9,10) and may therefore be good sources of functional food ingredients. EBN is reported to have antioxidative properties, 11,12) and in view of the properties of LF and OVF, we hypothesize that they may be contributing towards the overall antioxidant properties of EBN.…”

Primary Culture of Mouse Dopaminergic Neurons

“…Primary cultures are especially relevant to study DA neuron properties [16][17][18][19] and to challenge these neurons to various stresses for evaluation of neuroprotective agents [20][21][22][23][24] . Rat culture models are most often used, as the dissection of rat embryo mesencephalon is easier, compared with the mouse, and higher amounts of neurons can be obtained in the rat.…”

Identification of a Novel 1,4,8-Triazaphenanthrene Derivative as a Neuroprotectant for Dopamine Neurons Vulnerable in Parkinson’s Disease

“…The newly synthesized compounds were evaluated using a cell culture system that models DA cell death in PD. 16,25 A number of molecules provided efficient protection to DA neurons. Note, however, that among 1,4,8-triazaphenanthrenes, the presence of a methyl group at position 2 of the heterocyclic scaffold gave rise to compounds that were much less active, compared to the unsubstituted ones.…”

“…then assessed for neuroprotection using a PD culture model that we used before and in which DA neurons degenerate selectively and spontaneously as a consequence of a mechanism involving proliferating astrocytes and calcium dyshomeostasis. 14,16,17 Briefly, cultures were exposed or not for 10 days to various test molecules and neuronal rescue was assessed by counting the number of tyrosine hydroxylase (TH) positive neurons surviving at that time.…”