CNF1 Enhances Brain Energy Content and Counteracts Spontaneous Epileptiform Phenomena in Aged DBA/2J Mice

Abstract

Epilepsy, one of the most common conditions affecting the brain, is characterized by neuroplasticity and brain cell energy defects. In this work, we demonstrate the ability of the Escherichia coli protein toxin cytotoxic necrotizing factor 1 (CNF1) to counteract epileptiform phenomena in inbred DBA/2J mice, an animal model displaying genetic background with an high susceptibility to induced- and spontaneous seizures. Via modulation of the Rho GTPases, CNF1 regulates actin dynamics with a consequent increase in spine density and length in pyramidal neurons of rat visual cortex, and influences the mitochondrial homeostasis with remarkable changes in the mitochondrial network architecture. In addition, CNF1 improves cognitive performances and increases ATP brain content in mouse models of Rett syndrome and Alzheimer's disease. The results herein reported show that a single dose of CNF1 induces a remarkable amelioration of the seizure phenotype, with a significant augmentation in neuroplasticity markers and in cortex mitochondrial ATP content. This latter effect is accompanied by a decrease in the expression of mitochondrial fission proteins, suggesting a role of mitochondrial dynamics in the CNF1-induced beneficial effects on this epileptiform phenotype. Our results strongly support the crucial role of brain energy homeostasis in the pathogenesis of certain neurological diseases, and suggest that CNF1 could represent a putative new therapeutic tool for epilepsy.

Bacterial Toxins and Targeted Brain Therapy: New Insights from Cytotoxic Necrotizing Factor 1 (CNF1)

“…It has also been demonstrated that a single injection of CNF1 in tDBA/2J mice (an animal model with high susceptibility to induced- and spontaneous epileptic seizures) is able to induce a remarkable amelioration of the seizure phenotype, increasing markers of neuroplasticity and mitochondrial ATP, necessary to decrease seizure generation [ 46 ]. Altogether, these findings highlight the great potential of CNF1 as therapeutic tool for a broad range of brain pathologies.…”

The Bacterial Toxin CNF1 Protects Human Neuroblastoma SH-SY5Y Cells against 6-Hydroxydopamine-Induced Cell Damage: The Hypothesis of CNF1-Promoted Autophagy as an Antioxidant Strategy

“…In the brain, they can affect neuronal development and survival as well as neurodegeneration [42]. Previous in vivo studies on mouse models of different neuroinflammatory diseases characterized by brain mitochondria impairment, showed a beneficial effect of CNF1, a Rho GTPases' modulator protein, on different pathological markers, including mitochondrial free radical overproduction and synaptic plasticity [20,22,[28][29][30].…”

“…In this context, the Escherichia coli protein toxin cytotoxic necrotizing factor 1 (CNF1) may represent a promising potential agent against several neurological diseases characterized by alterations in mitochondrial functionality and pathological ROS production [18][19][20][21][22]. CNF1 acts by deamidating Rho GTPases (Rho, Rac and Cdc42) on a specific glutamine residue inside the GTP-binding domain, thus blocking the molecules in their activated, GTP-bound state [23,24].…”

“…Such an increase is accompanied by phosphorylation/inactivation of dynamin-related protein 1 (Drp1) that causes a profound modification of the mitochondrial architecture, consisting of the formation of a complex network of elongated mitochondria [18]. Interestingly, the CNF1 ability to trigger an increment of cell energy production has been confirmed in vivo in mouse models of PD [22], as well as of other neuroinflammatory diseases characterized by brain mitochondria impairment, such as Alzheimer's disease [28], epilepsy [20] and Rett syndrome [29,30].…”

The Bacterial Protein CNF1 as a Potential Therapeutic Strategy against Mitochondrial Diseases: A Pilot Study

“…Moreover, the recruitment of Drp1 to mitochondria is eased by the actin cytoskeleton activity [ 24 , 25 ]. Specifically, intracerebroventricular injection of a single purified CNF1 dose induces a notable amelioration of the seizure phenotype in an absence seizure mouse model, with a significant augmentation in neuroplasticity markers, in mitochondrial ATP content, and in mitochondrial complex IV activity in mouse brain cortices [ 26 ]. These results are accompanied by an increase in phospho-Drp1 and a decrease in mitochondrial fission proteins (Drp1 and hFis) expressions.…”