Biology subjects

Moresco, J. J.

Publications and source records attributed to Moresco, J. J..

3 recordsLinked to original sources

bioRxiv2018

The Heterotaxy Gene, CCDC11, is Essential for Cytokinesis and Cell-Cell Adhesion Via RhoA Regulation

Mutations in CCDC11 have been identified in multiple patients with heterotaxy (Htx), a disorder of left-right (LR) patterning of the internal organs. In Xenopus, depletion of Ccdc11 causes defects in LR patterning, recapitulating the patient phenotype. Upon Ccdc11 depletion, normally monociliated cells of the Left-Right Organizer (LRO) exhibit multiple cilia per cell. Unexpectedly, we found that Ccdc11 is necessary for successful cytokinesis, and the multiciliation observed in Ccdc11-depleted cells was due to failed cytokinesis. Furthermore, CCDC11 depletion alters cell-cell adhesion with reduction in junctional localization of adhesion molecules. The small GTPase RhoA is critical for cytokinesis and cell-cell adhesion. Because the CCDC11 depletion phenotypes are reminiscent of RhoA loss of function, we investigated a possible connection to regulation of RhoA signaling. We demonstrate that CCDC11 is localized to the cytokinetic contractile ring overlapping with RhoA during cytokinesis and regulates total RhoA protein levels. Our results suggest that CCDC11 connects cytokinesis and LR patterning via RhoA regulation, providing a potential mechanism for heterotaxy disease pathogenesis.

cell biology↗

bioRxiv2018

CBD-1 scaffolds two independent complexes required for eggshell vitelline layer formation and egg activation in C. elegans

Metazoan eggs have a specialized coat of extracellular matrix that aids in sperm-egg recognition. The coat is rapidly remodeled after fertilization to prevent polyspermy and establish a more permanent barrier to protect the developing embryo. In nematodes, this coat is called the vitelline layer, which is remodeled into the outermost layer of a rigid and impermeable eggshell. We have identified three key components of the vitelline layer structural scaffold - PERM-2, PERM-4 and CBD-1, the first such proteins to be described in the nematode C. elegans. CBD-1 recruited PERM-2 and PERM-4 to the nascent vitelline layer via two N-terminal chitin-binding domains. After fertilization, all three proteins redistributed from the zygote surface to the outer eggshell. Depletion of PERM-2 and PERM-4 from the scaffold led to a porous vitelline layer that permitted soluble factors to leak through the eggshell and resulted in embryonic death. In addition to its role in vitelline layer assembly, CBD-1 is also known to scaffold a protein complex required for fertilization and egg activation (EGG-1-5/CHS-1/MBK-2). We found the PERM complex and EGG complex to be structurally and functionally independent, and regulated through distinct domains of CBD-1. CBD-1 is thus a multifaceted regulator that promotes distinct aspects of vitelline layer assembly and egg activation. In sum, our findings identify the first vitelline layer components in nematodes, and provide a foundation through which to explore both conserved and species-specific strategies used by animals to build protective barriers following fertilization.

developmental biology↗

bioRxiv2018

Regulated nuclear accumulation of a histone methyltransferase times the onset of heterochromatin formation in C. elegans embryos

Heterochromatin formation during early embryogenesis is timed precisely, but it has been elusive how this process is regulated. Here we report the discovery of a histone methyltransferase complex whose nuclear accumulation and activation establishes the onset of heterochromatin formation in C. elegans embryos. We find that the inception of heterochromatin generation coincides with the accumulation of the Histone H3 Lysine 9 (H3K9) methyltransferase MET-2 (SETDB) into nuclear hubs. The absence of MET-2 results in delayed and disturbed heterochromatin formation, whereas accelerated nuclear localization of the methyltransferase leads to precocious H3K9 methylation. We identify two factors that bind to and function with MET-2: LIN-65, which resembles ATF7IP, localizes MET-2 into nuclear hubs, and ARLE-14, orthologous to ARL14EP, promotes stable association of MET-2 with chromatin. These data reveal that nuclear accumulation of MET-2 in conjunction with LIN-65 and ARLE-14 regulates timing of heterochromatin domains during embryogenesis.\n\nONE SENTENCE SUMMARYMET-2/SETDB1 and interactors LIN-65/ATF7IP and ARLE-14/ARL14EP initiate heterochromatin formation during embryogenesis.

developmental biology↗