biostudies-literatureVoelzmann ALeverhulme Trust (The Leverhulme Trust)UKRI | Biotechnology and Biological Sciences Research CouncilLeverhulme TrustHHS | NIHAcademy of Medical Sciences (The Academy of Medical Sciences)Royal SocietyRoyal Society (The Royal Society)Wellcome TrustBiotechnology and Biological Sciences Research CouncilAcademy of Medical SciencesHHS | NIH (NIH)e2516746123https://www.ebi.ac.uk/biostudies/studies/S-EPMC12933142biostudies-literatureUnknown123(8)Glycogen Synthase Kinase 3β (GSK-3β) is a key coordinator of neuronal development and maintenance; hyperactive GSK-3β is linked to neurodevelopmental and -degenerative diseases and therefore a promising therapeutic target. In neurons, GSK-3β coordinates the cytoskeleton by phosphorylating microtubule-binding proteins. In this study, we found that tight regulation of GSK-3β kinase activity is required for the maintenance of parallel microtubule bundles in <i>Drosophila</i> and rat axons. Up- or downregulation of GSK-3β led to axons forming pathological swellings in which microtubule bundles disintegrated into disorganized, curled microtubules. We identified the microtubule bundling proteins Shot and Tau as key GSK-3β targets and found that GSK-3β exerted its regulatory effect on microtubuleProceedings of the National Academy of Sciences of the United States of AmericaGSK-3β coordinates axonal microtubule organization through Shot and Tau.PMC12933142R35GM153259SBF008\1140BB/P020151/1ECF-2017-247RGS\R2\222151UKRI1894BB/I002448/1087742/Z/08/ZVoelzmann ARoof AEEvans GJOPatel SBentley MBennett HHahn INuhu-Soso LAdamson AfalseGSK-3β coordinates axonal microtubule organization through Shot and Tau.Glycogen Synthase Kinase 3β (GSK-3β) is a key coordinator of neuronal development and maintenance; hyperactive GSK-3β is linked to neurodevelopmental and -degenerative diseases and therefore a promising therapeutic target. In neurons, GSK-3β coordinates the cytoskeleton by phosphorylating microtubule-binding proteins. In this study, we found that tight regulation of GSK-3β kinase activity is required for the maintenance of parallel microtubule bundles in <i>Drosophila</i> and rat axons. Up- or downregulation of GSK-3β led to axons forming pathological swellings in which microtubule bundles disintegrated into disorganized, curled microtubules. We identified the microtubule bundling proteins Shot and Tau as key GSK-3β targets and found that GSK-3β exerted its regulatory effect on microtubule2026-01-01T00:00:00Z2026 Feb2026-07-16T20:47:40.151Z2026-07-10T03:12:51.313ZS-EPMC129331424170183110.1073/pnas.2516746123