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Biology subjects

Williams, G. L.

Publications and source records attributed to Williams, G. L..

3 recordsLinked to original sources

The novel curcumin analogue AKT-100 targets mutant p53 in gynecologic cancer cells

Loss of normal p53 tumor-suppressive activity is common in advanced cancers, where TP53 mutations produce either p53-null states or highly expressed missense proteins with gain of oncogenic function. Mutant p53 proteins not only lose wild type p53 pro-apoptotic and DNA repair functions but also acquire new activities, including constitutive STAT3 activation. We hypothesize that directly targeting missense mutant p53 instead of downstream pathways is advantageous. Curcumin analogues have been reported to bind mutant p53, motivating the development of AKT-100, a novel analogue designed to restore wild type p53 functionality. AKT-100 binds mutant p53 and STAT3, as shown by fluorescence quenching, and inhibits STAT3 Tyr705 phosphorylation in KLE and COV362 cells. This agent exhibits potent cytotoxicity in gynecological cancer cells with IC50 values ranging from 4 nm to 2.51 {micro}M, and demonstrates synergy with the PARP inhibitor olaparib and with chemotherapy by suppressing alternative DNA repair mechanisms associated with therapeutic resistance. RNA sequencing and immunoblotting confirms AKT-100 reactivates wild type p53 transcriptional profiles regulating cell cycle arrest (CDKN1A/p21, GADD45A), apoptosis (PMAIP1/Noxa, DR5), and inhibits DNA replication and repair. These findings support AKT-100 as a promising therapeutic agent with the dual capabilities of directly targeting oncogenic mutant p53 and constitutively active STAT3. HighlightsO_LIAKT-100 is a novel curcumin analogue that functions as a WT p53 reactivator. C_LIO_LIAKT-100 inhibits STAT3 phosphorylation at Tyrosine 705 in endometrial and ovarian cancer cells. C_LIO_LICell proliferation is inhibited in multiple ovarian and serous endometrial cancer cell lines with AKT-100 as a single agent. C_LIO_LIAKT-100 is synergistic with PARP inhibitor olaparib and chemotherapy drugs carboplatin and paclitaxel. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/680794v3_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@1fdb8a8org.highwire.dtl.DTLVardef@6648acorg.highwire.dtl.DTLVardef@12d301aorg.highwire.dtl.DTLVardef@1b1370f_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

TBK1 is ubiquitinated by TRIM5alpha to assemble mitophagy machinery

Ubiquitination of mitochondrial proteins provides a basis for the downstream recruitment of mitophagy machinery, yet whether ubiquitination of the machinery itself contributes to mitophagy is unknown. Here, we show that K63-linked polyubiquitination of the key mitophagy regulator TBK1 is essential for its mitophagy functions. This modification is catalyzed by the ubiquitin ligase TRIM5. Mitochondrial damage triggers TRIM5s auto-ubiquitination and its interaction with ubiquitin-binding autophagy adaptors including NDP52, optineurin, and NBR1. Autophagy adaptors, along with TRIM27, enable TRIM5 to engage with TBK1. TRIM5 with intact ubiquitination function is required for the proper accumulation of active TBK1 on damaged mitochondria in Parkin-dependent and Parkin-independent mitophagy pathways. Additionally, we show that TRIM5 can directly recruit autophagy initiation machinery to damaged mitochondria. Our data support a model in which TRIM5 provides a self-amplifying, mitochondria-localized, ubiquitin-based, assembly platform for TBK1 and mitophagy adaptors that is ultimately required to recruit the core autophagy machinery.

cell biology↗

Interactomic analysis reveals a new homeostatic role for the HIV restriction factor TRIM5α in mitophagy

The protein TRIM5 has multiple roles in anti-retroviral defense, but the mechanisms underlying TRIM5 action are unclear. Here, we used an APEX2-based proteomics approach to identify TRIM5-interacting proteins. Analysis of the TRIM5 interactome found proteins participating in a wide variety of cellular functions including regulating antiviral signaling pathways. We used this data set to uncover a novel role for TRIM5 in mitophagy, an autophagy-based mode of mitochondrial quality control that is compromised in multiple human diseases. Mitochondrial damage triggered the relocalization of TRIM5 to ER-mitochondria contact sites where TRIM5 colocalized with markers of autophagy initiation and autophagosome biogenesis. Furthermore, we found that TRIM5 knockout attenuated both Parkin-dependent and Parkin-independent mitophagy by preventing the recruitment of autophagy regulators FIP200 and ATG13 to unhealthy mitochondria. Finally, TRIM5 knockout cells showed reduced mitochondrial function under basal conditions and were more susceptible to uncontrolled immune activation and cell death in response to mitochondrial damage than were wild type cells. Taken together, our studies have identified a homeostatic role for a protein previously recognized exclusively for its antiviral actions.

cell biology↗