Talib, S. Z. A. | Search bioRxiv

bioRxiv2026

SAS-1 and SSNA-1 form dynamic centriolar satellites in C. elegans

Centriolar satellites are dynamic pericentrosomal assemblies that regulate centrosomal protein homeostasis and ciliogenesis. While extensively characterized in vertebrates, their existence and assembly principles in other systems are less well understood. Here, we identify SAS-1 and its interaction partner SSNA-1 as core components of centriolar satellite-like structures in C. elegans. We show that SAS-1 satellites occupy a previously unrecognized centrosomal layer positioned between the pericentriolar material and a specialized endoplasmic reticulum. SAS-1 satellites exhibit many features of biomolecular condensates, such as dose-dependent formation, rapid dynamics, and sensitivity to disruption of weak hydrophobic interactions, while their organization depends on the microtubule cytoskeleton. Mechanistically we identify the unstructured and so far, uncharacterized N-terminal region of SAS-1 being functionally important for embryonic viability, satellite formation and binding to microtubules. Our findings demonstrate that C. elegans possesses bona fide centriolar satellites that share many features with vertebrate satellites, highlighting their evolutionary conservation and importance across species. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=156 SRC="FIGDIR/small/708307v2_ufig1.gif" ALT="Figure 1"> View larger version (64K): org.highwire.dtl.DTLVardef@4ca11org.highwire.dtl.DTLVardef@6e4a1borg.highwire.dtl.DTLVardef@c34132org.highwire.dtl.DTLVardef@ed4029_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

Differential splice isoforms of mouse CDK2 play functionally redundant roles during mitotic and meiotic division

In most mammals, the cell cycle kinase; cyclin-dependent kinase 2 (CDK2) is expressed as two major isoforms due to the inclusion or exclusion of an alternatively spliced exon. The shorter CDK2 isoform: CDK2S, is expressed constitutively during the cell cycle and can be detected in many different tissue types. In contrast, the longer isoform: CDK2L, shows preferential expression in meiotically dividing cells of the germ cells and upon S-phase entry during mitotic cell division. Both CDK2L and CDK2S form heteromeric complexes with cyclins A2 and E1 in vitro. However, complexes comprised of each isoform differ considerably in their kinase activity towards known CDK substrates. It is currently unknown whether the long and short isoforms of CDK2 play functionally different roles in vivo during either mitotic and meiotic divisions as conventional knockout methodology leads to the loss of both isoforms. In this study, we find that both CDK2L and CDK2S are sufficient to support both mitotic and meiotic division when expressed in the absence of the other. This data contributes to the explanation of the apparent tolerance of the evolutionary loss of CDK2L expression in humans.

cell biology↗