Biology subjects

Boone, D.

Publications and source records attributed to Boone, D..

5 recordsLinked to original sources

bioRxiv2026

Double-bond geometry determines fatty acid metabolic fate and ferroptosis sensitivity

Ferroptosis is driven by the accumulation of oxidatively damaged membrane phospholipids, making membrane lipid composition a central determinant of cell death sensitivity. While fatty acid chain length and degree of unsaturation are well-established regulators of ferroptosis, whether fatty acid stereochemistry contributes to ferroptosis susceptibility is mostly unexplored. Here, we systematically screened structurally diverse fatty acids for their ability to modulate ferroptosis and unexpectedly identified trans-unsaturated fatty acids as potent sensitizers. Compared with its cis counterpart linoleic acid, the trans polyunsaturated fatty acid (PUFA) linoelaidic acid more strongly enhanced lipid peroxidation and promoted the accumulation of ferroptosis-susceptible phospholipid species. Unexpectedly, the trans monounsaturated fatty acid petroselaidic acid also sensitized cells to ferroptosis, whereas its cis stereoisomer petroselinic acid suppressed ferroptosis. Mechanistically, petroselaidic acid required stearoyl-CoA desaturase-dependent conversion to a PUFA, directly demonstrating that double-bond geometry can redirect fatty acid metabolic fate through altered recognition by lipid metabolic enzymes. Although linoelaidic acid and petroselaidic acid followed distinct metabolic pathways, both converged on phospholipid remodeling that expanded pools of ferroptosis-susceptible membrane lipids. Together, our findings demonstrate that fatty acid double-bond geometry determines their metabolic fate and the membrane phospholipid composition, establishing lipid stereochemistry as a previously unrecognized structural determinant of ferroptosis sensitivity.

cell biology↗

bioRxiv2024

FAF2 is a bifunctional regulator of peroxisomal homeostasis and saturated lipid responses

Exposure to saturated fatty acids (SFAs), such as palmitic acid, can lead to cellular metabolic dysfunction known as lipotoxicity. Although canonical adaptive metabolic processes like lipid storage or desaturation are known cellular responses to saturated fat exposure, the link between SFA metabolism and organellar biology remains an area of active inquiry. We performed a genome-wide CRISPR knockout screen in human epithelial cells to identify modulators of SFA toxicity. The screen revealed peroxisomal proteins, especially those that impact ether lipid synthesis, as important regulators of lipotoxicity. We identified Fas-associated factor family member 2 (FAF2) as a critical bifunctional co-regulator of peroxisomal and fatty acid biology. We further uncovered a new biological function for the ubiquitin-regulatory X (UBX) and UAS thioredoxin-like domains of FAF2, demonstrating their requirement for peroxisomal protein abundance and SFA-induced cellular stress. Our work highlights the role of FAF2 in regulating peroxisomal abundance and function, and the peroxisome as a key organelle in the cellular response to SFAs.

cell biology↗

bioRxiv2023

MRTF promotes breast cancer cell motility through SRF-dependent upregulation of DIAPH3 expression

Dysregulated actin cytoskeleton gives rise to aberrant cell motility and metastatic spread of tumor cells. This study evaluates the effect of overexpression of wild-type vs functional mutants of MRTF-A on migration and invasion of breast cancer (BC) cells. Our studies indicate that SRFs interaction is critical for MRTF-A-induced promotion of both 2D and 3D cell migration, while the SAP-domain function is important selectively for 3D cell migration. Increased MRTF-A activity is associated with more effective membrane protrusion, a phenotype that is attributed predominantly to SRFs interaction of MRTF. We demonstrate formin-family protein mDia2 as an important mediator of MRTF-stimulated actin polymerization at the leading edge and cell migration. Multiplexed quantitative immunohistochemistry and transcriptome analyses of clinical BC specimens further demonstrate a positive correlation between nuclear localization of MRTF with malignant traits of cancer cells and enrichment of MRTF-SRF gene signature in pair-matched distant metastases vs primary tumors. In conclusion, this study establishes a novel mechanism of MRTF-dependent regulation of cell migration and provides evidence for the association between MRTF activity and increased malignancy in human breast cancer, justifying future development of a specific small molecule inhibitor of the MRTF-SRF transcriptional complex as a potential therapeutic agent in breast cancer. SIGNIFICANCEO_LIActin cytoskeletal dysregulation gives rise to metastatic dissemination of cancer cells. This study mechanistically investigates the impact of specific functional disruption of MRTF (a transcriptional co-factor of SRF) on breast cancer cell migration. C_LIO_LIThis study establishes a novel mechanism linking mDia2 to MRTF-dependent regulation of cell migration and provides clinical evidence for the association between MRTF activity and increased malignancy in human breast cancer. C_LIO_LIFindings from these studies justify future exploration of specific small molecule inhibitor of the MRTF-SRF transcriptional complex as a potential therapeutic agent in breast cancer. C_LI

cell biology↗

bioRxiv2023

MRTF activity in breast cancer cells promotes osteoclastogenesis through a paracrine action of CTGF

Bone is a frequent site for breast cancer metastasis. The vast majority of breast cancer-associated metastasis is osteolytic in nature, and RANKL (receptor activator for nuclear factor {kappa}B)-induced differentiation of bone marrow-derived macrophages (BMDMs) to osteoclasts (OCLs) is a key requirement for osteolytic metastatic growth of cancer cells. In this study, we demonstrate that Myocardin-related transcription factor (MRTF) in breast cancer cells plays an important role in paracrine modulation of RANKL-induced osteoclast differentiation. This is partly attributed to MRTFs critical role in maintaining the basal cellular expression of connective tissue growth factor (CTGF), findings that align with a strong positive correlation between CTGF expression and MRTF-A gene signature in the human disease context. Luminex analyses reveal that MRTF depletion in breast cancer cells has a broad impact on OCL-regulatory cell-secreted factors that extend beyond CTGF. Experimental metastasis studies demonstrate that MRTF depletion diminishes OCL abundance and bone colonization breast cancer cells in vivo, suggesting that MRTF inhibition could be an effective strategy to diminish OCL formation and skeletal involvement in breast cancer. In summary, this study highlights a novel tumor-extrinsic function of MRTF relevant to breast cancer metastasis. SIGNIFICANCE STATEMENTO_LIMRTF, a transcriptional coactivator of SRF, is known to promote breast cancer progression through its tumor-cell-intrinsic function. Whether and how MRTF activity in tumor cells modulates other types of cells in the tumor microenvironment are not clearly understood. C_LIO_LIThis study uncovers a novel tumor-cell-extrinsic function of MRTF in breast cancer cells in promoting osteoclast differentiation partly through CTGF regulation, and further demonstrates MRTFs requirement for bone colonization of breast cancer cells in vivo. C_LIO_LIOur studies suggest that MRTF inhibition could be an effective strategy to diminish osteoclast formation and skeletal involvement in metastatic breast cancer. C_LI

cancer biology↗

bioRxiv2023

RETINOID ORPHAN RECEPTOR GAMMA T (RORgT) PROMOTES INFLAMMATORY EOSINOPHILIA BUT IS DISPENSABLE FOR INNATE IMMUNE-MEDIATED COLITIS

Inflammatory bowel diseases (IBD) result from uncontrolled inflammation in the intestinal mucosa leading to damage and loss of function. Both innate and adaptive immunity contribute to the inflammation of IBD and innate and adaptive immune cells reciprocally activate each other in a forward feedback loop. In order to better understand innate immune contributions to IBD, we developed a model of spontaneous 100% penetrant, early onset colitis that occurs in the absence of adaptive immunity by crossing villin-TNFAIP3 mice to RAG1-/- mice (TRAG mice). This model is driven by microbes and features increased levels of innate lymphoid cells in the intestinal mucosa. To investigate the role of type 3 innate lymphoid cells (ILC3) in the innate colitis of TRAG mice, we crossed them to retinoid orphan receptor gamma t deficient (Ror{gamma}t-/-) mice. Ror{gamma}t-/- x TRAG mice exhibited markedly reduced eosinophilia in the colonic mucosa, but colitis persisted in these mice. Colitis in Ror{gamma}t-/- x TRAG mice was characterized by increased infiltration of the intestinal mucosa by neutrophils, inflammatory monocytes, macrophages and other innate cells. RNA and cellular profiles of Ror{gamma}t-/- x TRAG mice were consistent with a lack of ILC3 and ILC3 derived cytokines, reduced antimicrobial factors, increased activation oof epithelial repair processes and reduced activation of epithelial cell STAT3. The colitis in Ror{gamma}t-/- x TRAG mice was ameliorated by antibiotic treatment indicating that microbes contribute to the ILC3-independent colitis of these mice. Thus, Ror{gamma}t promotes eosinophilia but Ror{gamma}t and Ror{gamma}t-dependent ILC3 are dispensable for the innate colitis in TRAG mice.

immunology↗