Biology subjects

Azimzadeh, J.

Publications and source records attributed to Azimzadeh, J..

3 recordsLinked to original sources

bioRxiv2026

Rotational asymmetry is required to position centrioles at the base of the primary cilium

The polarization of motile cilia requires that the centrioles, from which cilia are formed, display rotational asymmetry. This property is manifested in the presence of asymmetrically distributed appendages and relies on evolutionary conserved mechanisms. These mechanisms are also at play in cells that form primary cilia despite the lack of ciliary motility and asymmetric centriole appendages in this context. Here, we find that a complex consisting of CCDC61, KIAA1328 (K1328), and centlein (CNTLN) contributes to the establishment of centriole rotational asymmetry. In cells with a primary cilium, this complex is required for assembling a linker that repositions the daughter centriole close to and orthogonal to the proximal end of the mother centriole/basal body. The CCDC61/K1328/CNTLN complex also triggers the asymmetric recruitment of pericentriolar matrix components around newly assembled centrioles, which likely facilitates the later attachment of the basal body-daughter centriole linker. Overall, our results establish that rotational asymmetry relies on the coordinated recruitment of asymmetric landmarks along centrioles and is necessary for positioning the centrioles in a configuration that is widely conserved in ciliated cells.

cell biology↗

bioRxiv2021

SFI1 and centrin form a distal end complex critical for proper centriole architecture and ciliogenesis

Over the course of evolution, the function of the centrosome has been conserved in most eukaryotes, but its core architecture has evolved differently in some clades, as illustrated by the presence of centrioles in humans and a spindle pole body in yeast (SPB). Consistently, the composition of these two core elements has diverged greatly, with the exception of centrin, a protein known to form a complex with Sfi1 in yeast to structurally initiate SPB duplication. Even though SFI1 has been localized to human centrosomes, whether this complex exists at centrioles and whether its function has been conserved is still unclear. Here, using conventional fluorescence and super-resolution microscopies, we demonstrate that human SFI1 is a bona fide centriolar protein localizing to the very distal end of the centriole, where it associates with a pool of distal centrin. We also found that both proteins are recruited early during procentriole assembly and that depletion of SFI1 results in the specific loss of the distal pool of centrin, without altering centriole duplication in human cells, in contrast to its function for SPB. Instead, we found that SFI1/centrin complexes are essential for correct centriolar architecture as well as for ciliogenesis. We propose that SFI1/centrin complexes may guide centriole growth to ensure centriole integrity and function as a basal body.

cell biology↗

bioRxiv2018

Multi-scale coordination of planar cell polarity in planarians

Polarity is a universal design principle of biological systems that manifests at all organizational scales. Although well understood at the cellular level, the mechanisms that coordinate polarity at the tissue or organismal scale remain poorly understood. Here, we make use of the extreme body plan plasticity of planarian flatworms to probe the multi-scale coordination of polarity. Quantitative analysis of ciliary rootlet orientation in the epidermis reveals a global polarization field with head and tail as independent mediators of anteroposterior (A/P) polarization and the body margin influencing mediolateral (M/L) polarization. Mathematical modeling demonstrates that superposition of separate A/P- and M/L-fields can explain the global polarity field and we identify the core planar cell polarity (PCP) and Ft/Ds pathways as their specific mediators. Overall, our study establishes a mechanistic framework for the multi-scale coordination of planar polarity in planarians and establishes the core PCP and Ft/Ds pathways as evolutionarily conserved 2D-polarization module.

cell biology↗