Neuronal Gtf2i deletion alters mitochondrial and autophagic properties.

Gtf2i encodes the general transcription factor II-I (TFII-I), with peak expression during pre-natal and early post-natal brain development stages. Because these stages are critical for proper brain development, we studied at the single-cell level the consequences of Gtf2i's deletion from excitatory neurons, specifically on mitochondria. Here we show that Gtf2i's deletion resulted in abnormal morphology, disrupted mRNA related to mitochondrial fission and fusion, and altered autophagy/mitophagy protein expression. These changes align with elevated reactive oxygen species levels, illuminating Gtf2i's importance in neurons mitochondrial function. Similar mitochondrial issues were demonstrated by Gtf2i heterozygous model, mirroring the human condition in Williams syndrome (WS), and by hemizygous neuronal Gtf2i deletion model, indicating Gtf2i's dosage-sensitive role in mitochondrial regulation. Clinically relevant, we observed altered transcript levels related to mitochondria, hypoxia, and autophagy in frontal cortex tissue from WS individuals. Our study reveals mitochondrial and autophagy-related deficits shedding light on WS and other Gtf2i-related disorders.

Nucleolin inhibitor GroA triggers reduction in epidermal growth factor receptor activation: Pharmacological implication for glial scarring after spinal cord injury.

Glial scarring, formed by reactive astrocytes, is one of the major impediments for regeneration after spinal cord injury (SCI). Reactive astrocytes become hypertrophic, proliferate and secrete chondroitin sulphate proteoglycans into the extracellular matrix (ECM). Many studies have demonstrated that epidermal growth factor receptors (EGFR) can mediate astrocyte reactivity after neurotrauma. Previously we showed that there is crosstalk between nucleolin and EGFR that leads to increased EGFR activation followed by increased cell proliferation. Treatment with the nucleolin inhibitor GroA (AS1411) prevented these effects in vitro and in vivo. In this study, we hypothesized that similar interactions may mediate astrogliosis after SCI. Our results demonstrate that nucleolin and EGFR interaction may play a pivotal role in mediating astrocyte proliferation and reactivity after SCI. Moreover, we demonstrate that treatment with GroA reduces EGFR activation, astrocyte proliferation and chondroitin sulphate proteoglycans secretion, therefore promoting axonal regeneration and sprouting into the lesion site. Our results identify, for the first time, a role for the interaction between nucleolin and EGFR in astrocytes after SCI, indicating that nucleolin inhibitor GroA may be used as a novel treatment after neurotrauma. A major barrier for axonal regeneration after spinal cord injury is glial scar created by reactive and proliferating astrocytes. EGFR mediate astrocyte reactivity. We showed that inhibition of nucleolin by GroA, reduces EGFR activation, which results in attenuation of astrocyte reactivity and proliferation in vivo and in vitro. EGFR, epidermal growth factor receptor.