Biology subjects

Stemm-Wolf, A. J.

Publications and source records attributed to Stemm-Wolf, A. J..

4 recordsLinked to original sources

bioRxiv2026

Tet Trim-Away: A conditional rapid protein degradation system for Tetrahymena thermophila

Tetrahymena thermophila is a ciliated protist that has played pivotal roles in biological discovery. Functional studies of Tetrahymena proteins have largely relied on gene knockouts. Because protein depletion upon knockout typically spans multiple cell cycles, compensatory mechanisms can confound phenotypic interpretation. To instead enable rapid and acute protein depletion, we modified and adapted the Trim-Away system for use in Tetrahymena (Tet Trim-Away). Trim-Away is based on the E3 ubiquitin ligase, TRIM21, that binds to antibody-bound proteins and targets them for proteasome mediated degradation. Here, Trim-Away was modified with a fusion of the N-terminal RBCC (RING, B-box, coiled-coil) domains of TRIM21 with an -mCherry (mCh) nanobody sequence that recognizes endogenously tagged mCh proteins of interest (NbmCh). Expression of the RBCC:NbmCh degron, which is controlled by an inducible promotor, promotes rapid target protein depletion within 30 minutes and can be sustained for weeks. Tet Trim-Away is reversible, functions against targets in multiple cellular compartments, and produces loss-of-function phenotypes in Tetrahymena cells.

cell biology↗

bioRxiv2024

The Unkempt RNA binding protein reveals a local translation program in centriole overduplication

Excess centrosomes cause defects in mitosis, cell-signaling, and cell migration, and therefore their assembly is tightly regulated. Plk4 controls centriole duplication at the heart of centrosome assembly, and elevation of Plk4 promotes centrosome amplification (CA), a founding event of tumorigenesis. Here, we investigate the transcriptional consequences of elevated Plk4 and find Unkempt, a gene encoding an RNA binding protein with roles in translational regulation, to be one of only two upregulated mRNAs. Unk protein localizes to centrosomes and Cep131-positive centriolar satellites and is required for Plk4-induced centriole overduplication in an RNA-binding dependent manner. Translation is enriched at centrosomes and centriolar satellites with Unk and Cep131 promoting this localized translation. A transient centrosomal downregulation of translation occurs early in Plk4-induced CA. CNOT9, an Unk interactor and component of the translational inhibitory CCR4-NOT complex, localizes to centrosomes at this time. In summary, centriolar satellites and Unk promote local translation as part of a translational program that ensures centriole duplication.

cell biology↗

bioRxiv2021

The SON RNA splicing factor is required for intracellular trafficking that promotes centriole assembly

Control of centrosome assembly is critical for cell division, intracellular trafficking and cilia. Regulation of centrosome number occurs through the precise duplication of centrioles that reside in centrosomes. Here we explored transcriptional control of centriole assembly and find that the RNA splicing factor SON is specifically required for completing procentriole assembly. Whole genome mRNA sequencing identified genes whose splicing and expression are affected by the reduction of SON, with an enrichment in genes involved in the microtubule cytoskeleton, centrosome and centriolar satellites. SON is required for the proper splicing and expression of CEP131 which encodes a major centriolar satellite protein and is required to organize the trafficking and microtubule network around the centrosomes. This study highlights the importance of the distinct microtubule trafficking network that is intimately associated with nascent centrioles and is responsible for procentriole development.

cell biology↗

bioRxiv2019

Tetrahymena Poc5 is a transient basal body component that is important for basal body maturation

Basal bodies (BBs) are microtubule-based organelles that template and stabilize cilia at the cell surface. Centrins ubiquitously associate with BBs and function in BB assembly, maturation, and stability. Human POC5 (hPOC5) is a highly conserved centrin-binding protein that binds centrins through Sfi1p-like repeats and is required for building full-length, mature centrioles. Here, we use the BB-rich cytoskeleton of Tetrahymena thermophila to characterize Poc5 BB functions. Tetrahymena Poc5 (TtPoc5) uniquely incorporates into assembling BBs and is then removed from mature BBs prior to ciliogenesis. Complete genomic knockout of TtPOC5 leads to a significantly increased production of BBs yet a markedly reduced ciliary density, both of which are rescued by reintroduction of TtPoc5. A second Tetrahymena POC5-like gene, SFR1, is similarly implicated in modulating BB production. When TtPOC5 and SFR1 are co-deleted, cell viability is compromised, and levels of BB overproduction are exacerbated. Overproduced BBs display defective transition zone formation and a diminished capacity for ciliogenesis. This study uncovers a requirement for Poc5 in building mature BBs, providing a possible functional link between hPOC5 mutations and impaired cilia.\n\nSUMMARY STATEMENTLoss of Tetrahymena thermophila Poc5 reveals an important role for this centrin-binding protein in basal body maturation, which also impacts basal body production and ciliogenesis.

cell biology↗