The centrosome is a major microtubule-organizing center in animal cells. It consists of a pair of centrioles and the associated protein-dense pericentriolar material (PCM). The centrosome is not a static organelle. As the cell enters mitosis, the centrosome drastically increases in size through the expansion of the PCM (a process known as centrosome maturation). The expanded PCM enables the centrosome to become a robust microtubule-organizing center during mitosis. Outside of mitosis, the PCM also plays critical roles in centriole duplication and cilium formation. However, because of its complexity and dynamic rearrangement through the cell cycle, the precise composition, organization, and function of the PCM remain poorly defined.
We use in vivo region-specific protein labeling in cultured cells, quantitative mass spectrometry, and advanced microscopy, to determine the PCM composition at different cell cycle stages. We aim to elucidate the spatiotemporal organization of the PCM and the mechanisms underlying the assembly of this supermolecular structure. In-depth understanding of the PCM composition and its dynamic organization is a crucial step to decipher how the centrosome functions.
Mutations in Pericentrin (PCNT), a major PCM component, cause microcephalic osteodysplastic primordial dwarfism type II (MOPD II), a disorder characterized by prenatal onset proportionate short stature, skeletal abnormalities, and microcephaly. Notably MOPD II has an extensive phenotypic overlap with primary microcephaly (MCPH); both syndromes show a small but structurally normal brain and are autosomal recessive. Strikingly, most of the causative genes identified to date in both conditions encode centrosomal proteins. However, a central unanswered question is how centrosomal dysfunction at the cellular level is translated into developmental defects at the organismal level, such as dwarfism and microcephaly.
We use the zebrafish as a vertebrate model system to elucidate the role of centrosomes in asymmetric cell division, cell polarization, and cell migration. Our goal is to bridge the knowledge gap between centrosomal dysfunction and manifestation of disease phenotypes. Examining the gene-phenotype relationship will help understand the pathogenesis of centrosome-related disorders.
As one of the first groups of scientists who adapted the CRISPR/Cas technology, we developed a highly efficient CRISPR/Cas genome editing pipeline and reported the first multiplex biallelic gene knockouts in zebrafish. In many cases, the high efficiency of biallelic conversions makes it possible to study the loss-of-function phenotypes in the injected animals. We continue to refine and apply this technology in our research. Current projects include developing novel delivery strategies and devising high-throughput phenotypic analyses in both zebrafish and cell culture systems.