Biology subjects

Van Sciver, R. E.

Publications and source records attributed to Van Sciver, R. E..

4 recordsLinked to original sources

bioRxiv2025

Ciliary ARLs drive renal cystogenesis

BackgroundPolycystic kidney disease (PKD) is the leading genetic cause of renal failure, resulting in the accumulation of fluid filled cysts and gross enlargement of the kidney. Mutations in PKD1 or PKD2, which encode ciliary polycystin proteins, are the most common cause of PKD. These proteins function in a cilia-dependent cyst activation (CDCA) pathway-one that requires cilia for its pro-cystic function-yet the molecular driver(s) of this pathway are unknown. ARL13B is a regulatory GTPase enriched in cilia and links to renal cystogenesis. ARL13B possesses guanine nucleotide exchange factor (GEF) activity for ARL3, another ARL with links to cilia. MethodsWe used two distinct Arl13b mouse alleles to investigate whether ARL13B is a component of the CDCA pathway: Arl13bV358A encodes for enzymatically normal ARL13B that is undetectable in cilia, and Arl13bR79Q encodes for cilia-localized ARL13B lacking a residue critical for its ARL3 GEF activity. We used these alleles in a Pkd1-deficient adult mouse model and investigated renal morphology (H&E and cystic index analysis), physiology (blood urea nitrogen measurements), renal fibrosis (picrosirius staining and -smooth muscle actin levels), renal injury (SOX9 immunofluorescent staining and quantification), and Wnt signaling ({beta}-catenin and cyclin D1 protein levels). ResultsWe found that loss of ciliary ARL13B or mutation of a single residue critical for its ARL3 GEF activity suppressed Pkd1-dependent cysts. We observed reductions in kidney size, cystic index, and blood urea nitrogen. We also observed suppression of renal fibrosis, renal injury, and {beta}-catenin and cyclin D1 protein levels. ConclusionsOur results identified a subcellular location and mechanism driving Pkd1-dependent renal cystogenesis. We demonstrated that expression of a critical residue for ARL13Bs GEF activity specifically in cilia is a key mechanism of the CDCA pathway driving renal cystogenesis. Key PointsO_LILoss of ciliary ARL13B suppressed renal cystogenesis in an adult mouse model of polycystic kidney disease (PKD) without ablating cilia C_LIO_LILoss of ciliary ARL13B or mutation of the residue critical for its GEF activity did not affect renal morphology or physiology in an adult induced mouse model C_LIO_LIMutation of a residue critical for ARL13B activation of ARL3 suppressed cystic phenotypes in Pkd1-dependent cysts C_LI

genetics↗

bioRxiv2025

ARL13B-Cerulean rescues Arl13b-null mouse from embryonic lethality and reveals a role for ARL13B in spermatogenesis

ARL13B is a regulatory GTPase enriched in cilia, making it a popular marker for this organelle. Arl13bhnn/hnn mice lack ARL13B expression, die during midgestation, and exhibit defects in ciliogenesis. The R26Arl13b-Fucci2aR biosensor mouse line directs the expression of fluorescently tagged full-length Arl13b cDNA upon Cre recombination. To determine whether constitutive, ubiquitous expression of ARL13B-Cerulean can replace endogenous gene expression, we generated Arl13bhnn/hnn animals expressing ARL13B-Cerulean. We show that Arl13bhnn/hnn;Arl13b-Cerulean mice survive to adulthood with no obvious physical or behavioral defects, indicating that the fluorescently tagged protein can functionally replace the endogenous protein during development. However, we observed that rescued males failed to sire offspring, revealing a role for ARL13B in spermatogenesis. This work shows that the R26Arl13b-Fucci2aR mouse contains an inducible allele of Arl13b capable of functioning in most tissues and biological processes.

genetics↗

bioRxiv2023

Ciliary ARL13B inhibits developmental kidney cystogenesis in mouse

ARL13B is a small GTPase enriched in cilia. Deletion of Arl13b in mouse kidney results in renal cysts and an associated absence of primary cilia. Similarly, ablation of cilia leads to kidney cysts. To investigate whether ARL13B functions from within cilia to direct kidney development, we examined kidneys of mice expressing an engineered cilia-excluded ARL13B variant, ARL13BV358A. These mice retained renal cilia and developed cystic kidneys. Because ARL13B functions as a guanine nucleotide exchange factor (GEF) for ARL3, we examined kidneys of mice expressing an ARL13B variant that lacks ARL3 GEF activity, ARL13BR79Q. We found normal kidney development with no evidence of cysts in these mice. Taken together, our results show that ARL13B functions within cilia to inhibit renal cystogenesis during mouse development, and that this function does not depend on its role as a GEF for ARL3.

developmental biology↗

bioRxiv2020

The phylogenetic functional conservation of Drosophila Seven-In-Absentia (SINA) E3 ligase and its two human paralogs, SIAH1 and SIAH2, in Drosophila eye development

Seven-IN-Absentia (SINA) is the most downstream signaling gatekeeper identified thus far in the RAS/EGFR pathway that controls photoreceptor cell fate determination in Drosophila. Underscoring the central importance of SINA is its phylogenetic conservation in metazoans, with over 83% amino acid identities shared between Drosophila SINA and human SINA homologs (SIAHs). SIAH is a major tumor vulnerability in multidrug-resistant and incurable cancer. SIAH inhibition is an effective strategy to shut down the tumor-driving K-RAS/EGFR/HER2 pathway activation that promotes malignant tumor growth and metastatic dissemination. To further delineate the SINA function in the RAS/EGFR pathway, a genetic modifier screen was conducted, and 28 new sina mutant alleles were isolated via ethyl methanesulfonate (EMS) and X-ray mutagenesis. Among them, 26 of the new sina mutants are embryonic, larval, or pupal lethal, and stronger than the five published sina mutants (sina1, sina2, sina3, sina4, and sina5) which are early adult lethal. By sequencing the SINA-coding region of sinaES10, sinaES26, sinaES79, and sinaES473 homozygous mutant animals, we identified three invariable amino acid residues in SINAs RING-domain whose single point mutation ablates SINA function. To demonstrate the functional conservation of this medically important family of RING domain E3 ligases in Drosophila, we established a collection of transgenic lines, expressing either wild type (WT) or proteolysis-deficient (PD) SINA/SIAH inhibitors of Drosophila SINAWT/PD and human SIAH1WT/PD/2WT/PD under tissue-specific GAL4-drivers in Drosophila eye, wing, and salary gland. Our results showed that Drosophila SINA and human SIAH1/2 are functionally conserved. Our bioengineered SINAPD/SIAHPD inhibitors are effective in blocking the RAS-dependent neuronal cell fate determination in Drosophila.

developmental biology↗