Taylor, R.W., Qi, J.Y., Talaga, A.K., Ma, T.P., Pan, L., Bartholomew, C.R., Klionsky, D.J., Moens, C.B., and Gamse, J.T. (2011) Asymmetric inhibition of ulk2 causes left-right differences in habenular neuropil formation. The Journal of neuroscience : the official journal of the Society for Neuroscience. 31(27):9869-9878.
Studies of the zebrafish epithalamus have provided recent insights into the development of left–right brain asymmetry, which
is crucial to normal human brain function. The habenular nuclei of zebrafish are robustly asymmetric, with dense elaboration
of neuropil only in the left lateral subnucleus. Because this feature is tightly correlated with asymmetric expression of
K+ channel tetramerization domain-containing proteins 12.1 and 12.2 (Kctd12.1/12.2), we screened for Kctd12.1-interacting proteins
to identify molecular mechanisms leading to neuropil asymmetry, and uncovered a novel interaction between Kctd12.1 and Unc-51-like
kinase 2 (Ulk2). We show here that knockdown of Ulk2 or overexpression of Kctd12 proteins reduces asymmetric neuropil elaboration.
Conversely, overexpression of Ulk2 or mutation of kctd12 genes causes excess neuropil elaboration. We conclude that Ulk2 activity promotes neuropil elaboration while Kctd12 proteins
limit Ulk2 activity asymmetrically. This work describes a regulatory mechanism for neuronal process extension that may be
conserved in other developmental contexts in addition to the epithalamus.