Biology subjects

Buchanan, C.

Publications and source records attributed to Buchanan, C..

3 recordsLinked to original sources

bioRxiv2021

Newly identified parasitic nematode beta-tubulin alleles confer resistance to benzimidazoles

Infections by parasitic nematodes cause large health and economic burdens worldwide. We use anthelmintic drugs to reduce these infections. However, resistance to anthelmintic drugs is extremely common and increasing worldwide. It is essential to understand the mechanisms of resistance to slow its spread. Recently, four new parasitic nematode beta-tubulin alleles have been identified in benzimidazole (BZ) resistant parasite populations: E198I, E198K, E198T, and E198stop. These alleles have not been tested for the ability to confer resistance or for any effects that they might have on organismal fitness. We introduced these four new alleles into the sensitive C. elegans laboratory-adapted N2 strain and exposed these genome-edited strains to both albendazole and fenbendazole. We found that all four alleles conferred resistance to both BZ drugs. Additionally, we tested for fitness consequences in both control and albendazole conditions over seven generations in competitive fitness assays. We found that none of the edited alleles had deleterious effects on fitness in control conditions and that all four alleles conferred strong and equivalent fitness benefits in BZ drug conditions. Because it is unknown if previously validated alleles confer a dominant or recessive BZ resistance phenotype, we tested the phenotypes caused by five of these alleles and found that none of them conferred a dominant BZ resistance phenotype. Accurate measurements of resistance, fitness effects, and dominance caused by the resistance alleles allow for the generation of better models of population dynamics and facilitate control practices that maximize the efficacy of this critical anthelmintic drug class. HighlightsO_LIFour newly identified parasitic nematode beta-tubulin alleles confer benzimidazole resistance C_LIO_LIThe four newly identified alleles do not confer deleterious fitness consequences C_LIO_LIFive beta-tubulin alleles confer recessive benzimidazole resistance C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/453836v2_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@170b0baorg.highwire.dtl.DTLVardef@162a901org.highwire.dtl.DTLVardef@45836aorg.highwire.dtl.DTLVardef@1b6ac7e_HPS_FORMAT_FIGEXP M_FIG C_FIG

genetics↗

bioRxiv2020

Intra-axonal translation of Khsrp mRNA slows axon regeneration by destabilizing localized mRNAs

Proteins generated by localized mRNA translation in axons support nerve regeneration through retrograde injury signaling and localized axon growth mechanisms. RNA binding proteins (RBP) are needed for this and other aspects of post-transcriptional control of localized mRNAs, but only a limited number of axonal RBPs have been reported. We used a targeted mass spectrometry approach to profile the axonal RBPs in naive, injured and regenerating PNS axons. We detected 76 axonal proteins that are reported to have RNA binding activity, with the levels of several of these axonal RBPs changing with axonal injury and regeneration. These axonal RBPs with altered axoplasm levels include KHSRP that we previously reported decreases neurite outgrowth in developing CNS neurons. We show that KHSRP levels rapidly increase in sciatic nerve axons after crush injury and remain elevated increasing in levels out to 28 days post-sciatic nerve crush injury. Khsrp mRNA localizes into axons and the rapid increase in axonal KHSRP after axotomy is mediated by the local translation of its mRNA. KHSRP binds to mRNAs with a 3UTR AU-rich element and targets those mRNAs to the cytoplasmic exosome for degradation. KHSRP knockout mice show increased axonal levels of defined KHSRP target mRNAs, Gap43 and Snap25 mRNAs, following sciatic nerve injury and accelerated nerve regeneration in vivo. These data indicate that axonal translation of Khsrp mRNA following nerve injury serves to destabilize other axonal mRNAs and slow axon regeneration.

neuroscience↗

bioRxiv2020

Loss of KHSRP Increases Neuronal Growth and Synaptic Transmission and Alters Memory Consolidation Through RNA Stabilization

The KH-type splicing regulatory protein (KHSRP) is an RNA-binding protein linked to decay of AU-rich element containing mRNAs. We have previously shown that KHSRP destabilizes the mRNA encoding the growth-associated protein GAP-43 and decreases neurite growth in cultured embryonic neurons. In contrast, loss of KHSRP stabilizes Gap43 mRNA and increases neurite growth. Here, we have tested functions of neural KHSRP in vivo. We find upregulation of 1460 mRNAs in the neocortex of adult Khsrp-/- mice, of which 527 bind to KHSRP with high specificity. These KHSRP targets are involved in pathways for neuronal morphology, axon guidance, neurotransmission and long-term memory. Neocortical neurons show increased axon growth and dendritic spine density in Khsrp-/- mice. Analyses of neuronal cultures from embryonic Khsrp-/- mice point to a neuron-intrinsic alteration in axonal and dendritic growth and elevations in KHSRP-target mRNAs, including subcellularly localized mRNAs. Hippocampus and infralimbic cortex of Khsrp-/- mice show presynaptic elevations in neurotransmission. The Khsrp-/- mice have significant deficits in both trace conditioning and attention set-shifting tasks compared Khsrp+/+ mice, indicating impaired prefrontal- and hippocampal-dependent memory consolidation with loss of KHSRP. Overall, our results indicate that prenatal deletion of KHSRP impairs neuronal development resulting in alterations in neuronal morphology and function by changing post-transcriptional control of neuronal gene expression.

neuroscience↗