Coelho, P. A. | Search bioRxiv

bioRxiv2026

Functions of TIAM1 at the interface of centriole assembly and autolysosome cycling

Centrosome amplification is frequently associated with chromosomal instability and tumor progression, but how cells coordinate centriole assembly with the control of centrosome numbers and quality remains poorly understood. TIAM1 is a RAC1 guanine nucleotide exchange factor previously implicated in centrosome-associated signaling and {beta}TrCP-dependent control of PLK4 abundance. Here, we examined how Tiam1 regulates autophagy-lysosome homeostasis in mouse embryonic fibroblasts induced to overexpress PLK4. In contrast to a previous model in which Tiam1 loss promotes productive centriole overduplication, we found, by super-resolution imaging and expansion microscopy, an abnormal distribution of PLK4 on the centrioles centriole-associated structures following TIAM1 depletion, suggesting that TIAM1 may support the organization or maturation of centrioles. TIAM1 depletion also resulted in increased LC3B-positive puncta and enlarged LAMP1-positive compartments, but this was not accompanied by increased LC3B-II accumulation after bafilomycin A1 treatment. These findings suggest that TIAM1 may act at the interface between centriole assembly and endolysosomal/autolysosomal organization, linking TIAM1 to lysosome-associated centrosome quality-control pathways.

cell biology↗

bioRxiv2026

NDE1 Localizes to the Subdistal Appendages to Maintain Centrosome Integrity and Microtubule Organization

Centrosomes organize microtubules, coordinate ciliogenesis, and support accurate cell division. At the mature mother centriole, distal and subdistal appendages confer specialized functions in ciliary docking, microtubule organization, and intracellular trafficking. Nuclear distribution element 1 (NDE1) is a centrosome-associated regulator of dynein-dependent processes and ciliogenesis, but its nanoscale organization and contribution to centrosome architecture remain incompletely understood. Here, using expansion microscopy and STED super-resolution imaging, we show that endogenous NDE1 forms a ring-like structure at the subdistal appendages in mouse embryonic fibroblasts and human RPE-1 cells. NDE1 occupies an intermediate radial position between the more centriole-proximal CEP128 layer and the more peripheral ninein layer. Depletion of ODF2 or CEP128 reduces centrosomal NDE1, whereas CEP170 depletion has little effect, placing NDE1 within an ODF2- and CEP128-dependent branch of the subdistal appendage organization network. NDE1 depletion compromises centrosome integrity, reduces the centrosomal enrichment of core centriolar proteins, increases the separation between paired centrioles, and generates ectopic foci containing multiple centriolar markers. Loss of NDE1 also disrupts pericentriolar material organization and impairs the establishment of focused, centrosome-associated microtubule arrays. Furthermore, NDE1 depletion increases LC3B- and p62-positive structures and reduces autophagic flux. Together, our findings establish NDE1 as a subdistal appendage-associated factor that supports centrosome architecture and microtubule-organizing activity. More broadly, they support an emerging view of subdistal appendages as a molecularly layered platform in which distinct but cooperating components connect mother centriole maturation to microtubule organization, ciliary regulation, and intracellular trafficking.

cell biology↗