Mitofusin-2 regulates inflammation-mediated mouse neuroblastoma N2a cells dysfunction and endoplasmic reticulum stress via the Yap-Hippo pathway

Abstract

Endoplasmic reticulum (ER) stress is involved in inflammation-induced neurotoxicity. Mitofusin 2 (Mfn2), a member of the GTPase family of proteins, resides in the ER membrane and is known to regulate ER stress. However, the potential role and underlying mechanism of Mfn2 in inflammation-induced neuronal dysfunction is unknown. In our study, we explored the potential of Mfn2 to attenuate inflammation-mediated neuronal dysfunction by inhibiting ER stress. Our data show that Mfn2 overexpression significantly ameliorated tumor necrosis factor alpha (TNFα)-induced ER stress, as indicated by the downregulation of the ER stress proteins PERK, GRP78 and CHOP. Mfn2 overexpression also prevented the TNFα-mediated activation of caspase-3, caspase-12 and cleaved poly (ADP-ribose) polymerase (PARP). Cellular antioxidant dysfunction and reactive oxygen species overproduction were also improved by Mfn2 in the setting of TNFα in mouse neuroblastoma N2a cells in vitro. Similarly, disordered calcium homeostasis, indicated by disturbed levels of calcium-related proteins and calcium overloading, was corrected by Mfn2, as evidenced by the increased expression of store-operated calcium entry (SERCA), decreased levels of inositol trisphosphate receptor (IP3R), and normalized calcium content in TNFα-treated N2a cells. Mfn2 overexpression was found to elevate Yes-associated protein (Yap) expression; knockdown of Yap abolished the regulatory effects of Mfn2 on ER stress, oxidative stress, calcium balance, neural death and inflammatory injury. These results lead us to conclude that re-activation of the Mfn2-Yap signaling pathway alleviates TNFα-induced ER stress and dysfunction of mouse neuroblastoma N2a cells. Our findings provide a better understanding of the regulatory role of Mfn2-Yap-ER stress in neuroinflammation and indicate that the Mfn2-Yap axis may be a focus of research in terms of having therapeutic value for the treatment of neurodegenerative diseases.

Mfn2 Regulates High Glucose-Induced MAMs Dysfunction and Apoptosis in Podocytes via PERK Pathway

“…Moreover, Mfn2-UPR interaction plays an important regulatory role in inflammation response. For instance, overexpression of Mfn2 alleviated TNFα-mediated ER stress in N2a cells by suppressing the expression of CHOP, caspase3, and caspase12 ( Hou et al, 2019 ).…”

Neuronal Hippo signaling: From development to diseases

“…Another study has found that melatonin reduces reperfusion‐mediated cerebral injury and sustains mitochondrial function by suppressing MST1‐Hippo pathway, indicating a neuroprotective potential of Hippo pathway via regulating mitochondrial fusion (Lan et al., 2019). Moreover, elevating YAP activity by overexpressing mitofusion 2 ( Mfn2 ), an upstream negative regulator of Hippo pathway was also found to have a neuroprotective effect, as Mfn2‐YAP axis helps in reducing ER stress, oxidative stress, inflammatory injury, calcium dysregulation, and neuronal death (Hou et al., 2019). Therapeutic intervention of Hippo pathway by pharmacological inhibitor of MST1, Xmu‐mp‐1, has served a neuroprotective role in subarachnoid hemorrhage (Qu et al., 2018), thus highlighting the emerging potential of this pathway in restricting the progression of neurodegeneration.…”

Mitochondrial Dysfunction in Polycystic Ovary Syndrome

“…(Xin et al, 2019). Moreover, in mouse neuroblastoma N2a cells, mfn2 can affect ER stress through Yap-Hippo pathway (Hou et al, 2019). These evidences suggest that mfn2 is involved in regulating the function of the ER.…”