China
Africa
Explore chapters and articles related to this topic
Insulin/IGF Signaling in Early Brain Development
Published in André Kleinridders, Physiological Consequences of Brain Insulin Action, 2023
Selma Yagoub, Rachel N. Lippert
The growth cone is the actively extending portion of the developing neuron, providing a leading point for emerging neurites searching for the proper synaptic targets. While this is an extremely complex system, utilizing gradients of molecular cues and both presynaptic and postsynaptic signaling, the expression and activity of receptor tyrosine kinases in the developing extension are critical for this process. The IGF-1R is found localized in the developing growth cone, underscoring the necessary balance of insulin and IGF-1 hormones in development (36, 37). Enrichment specifically of the beta subunit of the IGF-1R is found at the developing growth cone in cultured hippocampal pyramidal neurons (38, 39). Additionally, this region within the developing growth cone is critical for glial cell interactions, necessary for proper brain structure organization (40). Studies using cell culture of PC12 cells overexpressing the insulin receptor also indicate that insulin itself plays a role in neurite outgrowth of cultured neuronal cells (41, 42). This action is via MAP kinase activation, where translocation of MAP kinase to the nucleus is correlated with increased expression of insulin receptors on the cell surface. Insulin acts on the cone growth also by activating the Shc/Grb-2/MAPK signaling pathways (43).
ENTRIES A–Z
Published in Philip Winn, Dictionary of Biological Psychology, 2003
A growth cone is found at the end of a developing AXON. Projecting from the growth cone are whisker-like filaments called FILOPODIA, (interconnected by membranes called LAMELLIPODIA). The filopodia extend and retract, guiding axons forward as they grow. Axonal growth is actually generated by the growth cone. ADHESION MOLECULES on the growth cone appear to act, in a sense, to drag the axon forward towards targets that are chemically identified.
Efficient simulations of stretch growth axon based on improved HH model
Published in Neurological Research, 2023
Xiao Li, Xianxin Dong, Xikai Tu, Hailong Huang
The axon starts the second stage of growth when the growth cone reaches the target cell and creates a synaptic connection with it. During this stage, integrated axons crossing increasingly distant body regions are subjected to continuous mechanical tension [24]. The modified HH axon model simulates the generation and propagation of action potentials evoked by mechanical stimuli successfully. Traction stimulation is administered rapidly in the center of the axon, and the resulting action potential propagates in two directions. After mechanical traction stimulation, the axon grows in length, diameter, and area of the membrane. Due to the fact that the number of ion channels on the membrane is directly proportional to its area, the ion transport speed of the cell membrane rises, resulting in a decrease in membrane resistance. The shift in membrane capacitance is illustrated in Figure 5, when stretch growth axons are triggered again by mechanical strain. Within 1 ms, the membrane capacitance rapidly increases from the constant value.
Down regulation of DNA topoisomerase IIβ exerts neurodegeneration like effect through Rho GTPases in cellular model of Parkinson’s disease by Down regulating tyrosine hydroxylase
Published in Neurological Research, 2021
Kiyak Bercem Yeman, Sevim Isik
Rho family of GTPases are known to regulate the actin cytoskeleton, transcriptional activation, membrane trafficking, and microtubule dynamics [13]. These proteins can therefore regulate the morphology of neurites and growth cones during neural development. The best-characterized members of this family are RhoA, Rac1, and Cdc42 [9,13]. Rac1/Cdc42 and RhoA typically show an antagonistic association with neuronal morphology. While Rac1 and Cdc42 enhance growth cone development and neurite outgrowth, RhoA regulates neurite outgrowth negatively inducing growth cone collapse and neurite retraction during neural development [14]. Therefore, Rho GTPases have been proposed to be involved in PD [15–17]. It is believed that these proteins can be used to reverse the long-standing damage of the nigrostriatal degeneration and can potentially be modulated in PD therapy [12].
RVG29-modified microRNA-loaded nanoparticles improve ischemic brain injury by nasal delivery
Published in Drug Delivery, 2020
Rubin Hao, Bixi Sun, Lihua Yang, Chun Ma, Shuling Li
After cerebral ischemia, RhoA expression increases in the brain, strengthening the polymerization of actin in the growth cone and driving axial stretch to cause synaptic contraction of dendritic and spinous processes in nerve cells (Mulherkar et al., 2017). These changes result in a functional synaptic reduction, growth cone collapse, and accelerated nerve necrosis (Park et al., 2017). Therefore, inhibition of the RhoA signaling pathway can quickly prevent further destruction of nerve cell polarity and further decreases in the ability of nerves to transmit electrical impulses and neuronal information (Kim et al., 2017). This study showed that the miRNA group treated with nasal aspiration could more effectively reduce the expression of RhoA and maintain the damaged nerve cytoskeleton than the other groups.