The C. Elegans Homolog Of Drosophila Lethal Giant Larvae Functions Redundantly With Par-2 To Maintain Polarity In The Early Embryo
Polarity is essential for generating cell diversity. The one-cell C. elegans embryo serves as a model for studying the establishment and maintenance of polarity. In the early embryo, a myosin II-dependent contraction of the cortical meshwork asymmetrically distributes the highly conserved PDZ proteins PAR-3 and PAR-6 as well as an atypical protein kinase C (PKC-3) to the anterior. The RING-finger protein PAR-2 becomes enriched on the posterior cortex and prevents these three proteins from returning to the posterior. In addition to the PARs, other proteins are required for polarity in many metazoans. One example is the conserved Drosophila tumorsuppressor protein Lethal (2) giant larvae (Lgl). In Drosophila and mammals, Lgl contributes to the maintenance of cell polarity and plays a role in asymmetric cell division. We have found that the C. elegans homolog of Lgl, LGL-1, has a role in polarity but is not essential. It localizes asymmetrically to the posterior of the early embryo in a PKC-3-dependent manner, and functions redundantly with PAR-2 to maintain polarity. Furthermore, over-expression of LGL-1 is sufficient to rescue loss of PAR-2 function. LGL-1 negatively regulates the accumulation of myosin (NMY-2) on the posterior cortex in an anterior PAR-dependent manner.
Polarity; Lethal Giant Larvae; par
Kemphues, Kenneth J
Lee, Siu Sylvia; Bretscher, Anthony Paul
Ph. D., Biochemistry
Doctor of Philosophy
dissertation or thesis