Spatial and proteomic profiling reveals centrosome‐independent features of centriolar satellites.

Centriolar satellites are small electron‐dense granules that cluster in the vicinity of centrosomes. Satellites have been implicated in multiple critical cellular functions including centriole duplication, centrosome maturation, and ciliogenesis, but their precise composition and assembly properties have remained poorly explored. Here, we perform in vivo proximity‐dependent biotin identification (BioID) on 22 human satellite proteins, to identify 2,113 high‐confidence interactions among 660 unique polypeptides. Mining this network, we validate six additional satellite components. Analysis of the satellite interactome, combined with subdiffraction imaging, reveals the existence of multiple unique microscopically resolvable satellite populations that display distinct protein interaction profiles. We further show that loss of satellites in PCM1‐depleted cells results in a dramatic change in the satellite interaction landscape. Finally, we demonstrate that satellite composition is largely unaffected by centriole depletion or disruption of microtubules, indicating that satellite assembly is centrosome‐independent. Together, our work offers the first systematic spatial and proteomic profiling of human centriolar satellites and paves the way for future studies aimed at better understanding the biogenesis and function(s) of these enigmatic structures. Synopsis: Centriolar satellites are implicated in cellular functions such as centriole duplication, centrosome maturation and ciliogenesis, but their precise composition and assembly properties are still poorly defined. Spatial and proteomic profiling now reveals their interactome and centrosome‐independent features. BioID of 22 centriolar satellite proteins identifies 2113 proximity interactions amongst 660 proteins.Six additional centriolar satellite proteins were identified.There are multiple microscopically‐resolvable satellite subpopulations.Satellite composition is largely unaffected by centriole depletion or disruption of the microtubule cytoskeleton.PCM1 depletion results in a dramatic change in the proximity interaction landscape of centriolar satellite components. [ABSTRACT FROM AUTHOR]