NEDD1

NEDD1 Full Name

neural precursor cell expressed, developmentally down-regulated 1

NEDD1 Introduction

NEDD1, despite the name it inherited from a gene-expression screen for developmentally regulated neural transcripts, is now recognized as an essential regulator of the microtubule cytoskeleton: it functions as the targeting factor that delivers the gamma-tubulin ring complex (gamma-TuRC) to centrosomes and to other sites where microtubules are nucleated. Microtubule nucleation, the process by which new microtubules are initiated, requires the gamma-tubulin ring complex, a large assembly that templates the growth of microtubule filaments; for this template to work, it must be anchored at the right location, and NEDD1 provides that link. NEDD1 localizes to centrosomes throughout the cell cycle and to the mitotic spindle during cell division, and its phosphorylation by mitotic kinases regulates the recruitment of gamma-TuRC and hence the organization of the spindle. When NEDD1 is depleted, cells fail to assemble normal spindles, missegregate chromosomes, and arrest with mitotic defects, demonstrating that the protein is required for faithful cell division. Because the same microtubule-nucleation machinery is used to build the interphase microtubule array and primary cilia, NEDD1 influences cell shape, polarity, and signaling beyond mitosis. Overexpression of NEDD1 has been reported in some cancers, and its role in spindle assembly has made it a candidate target for antimitotic cancer therapy.

Figure 1. The structure of NEDD1.

WD40-Repeat Adaptor and Gamma-TuRC Targeting Mechanism
The NEDD1 protein consists largely of WD40 repeats, which fold into a beta-propeller domain that provides a versatile platform for protein-protein interactions.
This WD40 propeller binds the gamma-tubulin ring complex, the large multiprotein assembly that templates microtubule nucleation, while additional regions of NEDD1 contact centrosomal proteins.
The NEDD1 gene is located on human chromosome 12, and its transcript is expressed in most tissues, consistent with a general requirement for microtubule organization.
During interphase NEDD1 helps localize gamma-TuRC to the centrosome, where the majority of cytoplasmic microtubules are nucleated, and it also contributes to nucleation at the Golgi apparatus and at chromatin.
At the onset of mitosis, phosphorylation of NEDD1 by kinases such as Aurora A, CDK1, and Plk1 enhances its ability to recruit gamma-TuRC to the spindle poles and to the spindle itself.
Because microtubules of the mitotic spindle must be nucleated and organized with great precision, the regulated targeting of gamma-TuRC by NEDD1 is a critical control point in cell division.
Depletion or mutation of NEDD1 therefore compromises both interphase microtubule organization and the assembly of a functional mitotic spindle.

Spindle Assembly, Cell Division, and Implications for Cancer Therapy
Microtubules nucleated through the NEDD1-gamma-TuRC pathway form the bipolar spindle that separates chromosomes during mitosis, and loss of NEDD1 leads to multipolar or disorganized spindles and to errors in chromosome segregation.
Cells lacking NEDD1 typically activate the spindle assembly checkpoint and arrest in mitosis before undergoing apoptosis or senescence, underscoring the essential nature of the protein for proliferation.
Because dividing cells depend absolutely on spindle assembly, proteins such as NEDD1 that control microtubule nucleation are attractive targets for antimitotic chemotherapy.
Elevated NEDD1 expression has been observed in several tumor types, and high levels of the protein may help cancer cells tolerate the spindle stress imposed by their genomic instability.
Beyond mitosis, NEDD1-dependent nucleation supports the formation of primary cilia, sensory organelles whose dysfunction underlies a family of human disorders known as ciliopathies.
Research on NEDD1 therefore spans basic cell biology, cancer therapeutics, and developmental disease, illustrating how a single adaptor protein governs the assembly of the microtubule cytoskeleton in diverse contexts.

Alternate Names for NEDD1

NEDD1; neural precursor cell expressed, developmentally down-regulated 1; protein NEDD1; GCP WD; TUBGCP7; NEDD-1; neural precursor cell expressed developmentally down-regulated protein 1; GCP-WD; FLJ35902;