PROJECT SUMMARY Centrosome deregulation is associated with developmental disorders, such as microcephaly, ciliopathy, and cardiovascular disease. Despite their fundamental importance to human health, relatively little is known about the regulation of genes encoding core centrosome components, such as Pericentrin (Pcnt)-like protein (PLP), a conserved centrosome scaffold also required for ciliary function. Completion of this proposal will advance our understanding of the post- transcriptional regulation of plp mRNA. In humans, deregulation of the homologous PCNT gene results in congenital diseases, such as microcephalic osteodysplastic primordial dwarfism type II (MOPD II) and Trisomy 21. Similarly, in Drosophila, plp deregulation leads to diverse defects, including embryonic lethality, neuron dysfunction, and male sterility. The mechanisms underlying the pleiotropic phenotypes associated with plp loss are incompletely understood. plp is predicted to encode 12 mRNA variants, but what mechanisms give rise to these distinct RNA species and how their expression is spatiotemporally regulated are completely unknown. In this K99/R00 proposal, I will test the hypothesis that the PLP protein isoform expression, coupled with the post- transcriptional regulation of plp mRNA, modulates its diverse functions within different tissues. Three aims are proposed to test this hypothesis. In Aim 1, I will identify mechanisms of embryonic plp mRNA localization and translation. In Aim 2, I will explore the contribution of alternative promoter and 3’UTR usage for the generation of different plp RNA variants. In Aim 3, I will determine the expression profile of PLP protein isoforms and examine the biological function of PLP isoforms, including PLPPM, in Drosophila neuroblasts versus early embryos. The completion of this work will reveal the mechanisms of spatially and temporally distinct expression patterns of functional PLP protein isoforms in different Drosophila tissues and will improve our understanding of plp mRNA regulation, aspects of which may be deregulated in human diseases, such as neurodegenerative disorders and cardiovascular disease. Moreover, this award will provide technical and professional training in RNA- sequencing and bioinformatics, CRISPR genome editing, and advanced imaging approaches under the guidance of my expert mentors. I will follow a structured training program to enhance my professional abilities to establish and run my own successful independent laboratory.