Regulatory mechanisms underlying the differential growth of dendrites and axons

Abstract

A typical neuron is comprised of an information input compartment, or the dendrites, and an output compartment, known as the axon. These two compartments are the structural basis for functional neural circuits. However, little is known about how dendritic and axonal growth are differentially regulated. Recent studies have uncovered two distinct types of regulatory mechanisms that differentiate dendritic and axonal growth: dedicated mechanisms and bimodal mechanisms. Dedicated mechanisms regulate either dendritespecific or axon-specific growth; in contrast, bimodal mechanisms direct dendritic and axonal development in opposite manners. Here, we review the dedicated and bimodal regulators identified by recent Drosophila and mammalian studies. The knowledge of these underlying molecular mechanisms not only expands our understanding about how neural circuits are wired, but also provides insights that will aid in the rational design of therapies for neurological diseases.

Dendrobium nobile Lindl alkaloid, a novel autophagy inducer, protects against axonal degeneration induced by Aβ25‐35 in hippocampus neurons in vitro

“…We chose the dosage of 10 −7 mol/L for next experiment because at this dose level, axonal degeneration was more serious than reduction in cell viability, which was closely similar to “dying‐back” pattern of neurons degeneration. The communication of signaling events between synapses or axon terminals and soma is dependent on axonal intact; in adult, damaged axon can hardly regenerate due to the development of an inhibitory CNS environment . Thus, DNLA was added into medium prior to Aβ 25‐35 peptide in order to prevent axonal degeneration.…”

“…Total protein was extracted from cultured neurons using a total protein extraction kit (Applygen, Beijing, China; P1250) and quan- SYNproteinlevelsvscotreatmentofAβ [23][24][25][26][27][28][29][30][31][32][33][34][35] withDNLA,suggesting thattheprotectiveeffectofDNLAonaxonaldegenerationstimulated byAβ [23][24][25][26][27][28][29][30][31][32][33][34][35] wasmarkedlyantagonizedbyBAFA.Toexcludepossible effectofotherpharmacologicalactionofBAFA,weusedanotherautophagy inhibitor HCQ to repeat above measurements. The results demonstrated that inhibitory effects of HCQ and BAFA on neuro-protectionofDNLAwerefullyidentical( Fig.S3).…”

Intrinsic mechanisms for axon regeneration: insights from injured axons in Drosophila

“…Since mixed polarity microtubules form at the tips of injured dendrites [10], kinesin-driven microtubule sliding is another candidate mediator of renewed dendrite growth, particularly since microtubules also have mixed (opposing) polarity in dendrites during their original developmental outgrowth [16]. However, the molecular distinctions between mechanisms that promote dendrite growth verses axonal growth after injury are thus far poorly understood [51]. …”

Neurodevelopment and degeneration

“…Ye et al, using both mammals and fl ies as models, discuss the underlying mechanisms regulating axon and dendrite growth [2] . Two models, dedicated and bimodal mechanisms, have been proposed and are reviewed.…”

“…Two models, dedicated and bimodal mechanisms, have been proposed and are reviewed. Whereas the dedicated regulators like BMP7 or Rac1 affect only the growth of either axons or dendrites, bimodal regulators like Sema3A execute binary functions that promote axon or dendrite growth while inhibiting the other [2] . Accompanying growth, differentiated axons exhibit guidance properties that Liu et al review in great detail [3] .…”