Biology subjects

Dean, C. A.

Publications and source records attributed to Dean, C. A..

5 recordsLinked to original sources

bioRxiv2026

Evolutionary contingency facilitates scent divergence in an emergent orchid population

Reproductive isolation can evolve rapidly even among populations with extensive genetic similarity, but the mechanisms underlying this divergence remain an open question in evolutionary biology. Here, we investigate the genetic basis of floral scent divergence, a key trait mediating differential pollinator attraction, in a group of nascent Gongora orchid lineages that occur in sympatry. We combined whole-genome resequencing and floral transcriptomics to characterize the transition from the monoterpene-emitting 'M chemotype' to the pollinator-isolated phenylpropanoid-emitting 'A chemotype' nested within it. While overall genetic differentiation was low, a few highly differentiated regions contained candidate genes in biosynthetic pathways. Of particular interest was a putative o-methyltransferase exhibiting evidence of a recent selective sweep in the A chemotype, with much higher expression in scent-emitting floral tissues of A than in M. Transcriptomic comparison with a more distantly related monoterpene-emitting lineage ('X chemotype') further revealed the coordinated and elevated expression of phenylpropanoid biosynthetic genes in M despite its absence of aromatic floral volatiles, including a putative key enzyme potentially involved in directing metabolic flux towards monolignol biosynthesis. Together, our results support a model in which pre-existing activity in a metabolic pathway may facilitate the evolution of a novel floral scent phenotype, potentially making transitions across the adaptive landscape of scent more accessible than others. We propose that such evolutionary contingency may help explain how divergent scent profiles, and consequently, reproductive isolation, can evolve rapidly via few genetic changes.

evolutionary biology↗

bioRxiv2026

Regulation of protein kinase pathways in primary neuron model of anti-NMDA receptor encephalitis.

The most common form of autoimmune encephalitis is associated with antibodies that target N-methyl-D-aspartic acid receptors (NMDARs). NMDARs play a pivotal role in neurotransmission and synaptic plasticity. Mounting evidence has shown that antibody targeting of the NMDAR GluN1 subunit, as in anti-NMDAR encephalitis, leads to NMDAR cross-linking and receptor internalization. However, the underlying signaling pathways affected by antibodies targeting NMDARs remain to be explored. We previously demonstrated that a human GluN1 monoclonal antibody 5F5 (GluN1 mAb 5F5) rapidly localizes to and regulates synaptic NMDAR function at native synapses of primary hippocampal neurons. Here, we sought to explore signaling targets of GluN1 mAb 5F5 in primary cortical neurons of either sex using subcellular fractionation, Western blotting, and label-free quantitative phosphoproteomics by mass spectrometry. We find that human GluN1 mAb 5F5 does not change NMDAR abundance or surface levels of GluN1 on primary cortical neurons at 2 hr. Despite this, we observe that GluN1 mAb 5F5 alters the phosphoproteome in synaptoneurosomes and regulates numerous synapse-related biological processes and protein kinase activities. Bioinformatic analyses suggest that these phosphoproteomic changes are positively correlated with NMDAR activation and negatively correlated with NMDAR inhibition. Together, these data suggest that GluN1 mAb 5F5 alters intracellular kinase signaling pathways in primary cortical neurons, likely by activating the NMDAR. These studies may help to identify novel therapeutic strategies for anti-NMDAR encephalitis and other antibody-mediated encephalitides targeting cell surface antigens.

neuroscience↗

bioRxiv2025

CLM296: a highly selective inhibitor targeting ALDH1A3-driven tumor growth and metastasis in breast cancer

Aldehyde dehydrogenase 1A3 (ALDH1A3) increases tumor growth, metastasis, and chemoresistance in many solid tumors, including triple-negative breast cancer (TNBC), glioblastoma, melanoma, lung, and colon cancers, yet no clinically approved inhibitors exist. Here, we present CLM296, a novel and highly selective ALDH1A3 inhibitor designed to address this unmet need. CLM296 exhibits potent inhibition of ALDH1A3 activity in TNBC cells (half-maximal inhibitory concentration = 2 nM) with no off-target effects on the highly homologous ALDH1A1 isoform. RNA sequencing confirmed its specificity, demonstrating selective suppression of ALDH1A3-regulated gene expression only, and a lack of effect in control cells that have minimal ALDH1A3 expression. Transwell assays showed that CLM296 reduced the increased invasion of cells induced by ALDH1A3. Once daily dosing of 4mg/kg CLM296 in mice specifically reduced ALDH1A3-mediated gene expression in tumors and impeded ALDH1A3-driven tumor growth and lung metastasis in TNBC xenografts. There was no observed toxicity in the mice as evidenced by stable mouse body weights and no significant changes in blood creatinine and ALT levels. Pharmacokinetic studies of CLM296 revealed broad tissue distribution, including tumor, lung, liver, and brain. With oral administration the terminal elimination half-life of CLM296 exceeded 12 hours, resulting in sustained ALDH1A3-inhibiting concentrations beyond 24 hours. Together, these findings establish CLM296 as a potential first-in-class ALDH1A3 inhibitor with high selectivity for ALDH1A3, favorable pharmacokinetics, and a positive preclinical safety profile. CLM296 represents a promising therapeutic candidate to complement standard-of-care treatments in ALDH1A3+ cancers.

cancer biology↗

bioRxiv2023

The CPSF phosphatase module links transcription termination to chromatin silencing

The interconnections between co-transcriptional regulation, chromatin environment and transcriptional output remain poorly understood. Here, we investigate the mechanism underlying RNA 3 processing-mediated Polycomb silencing of Arabidopsis FLOWERING LOCUS C (FLC). We show a requirement for APRF1, a homologue of yeast Swd2 and human WDR82, known to regulate RNA Pol II during transcription termination. APRF1 interacts with TOPP4 (yeast Glc7/human PP1) and LD, the latter showing structural features found in Ref2/PNUTS; all components of the yeast and human phosphatase module of the CPF 3end processing machinery. LD has been shown to co-associate in vivo with the histone H3 K4 demethylase FLD. We show APRF1 and LD couple CPF-mediated cleavage and polyadenylation with removal of H3K4 monomethylation in the body of FLC, and this influences subsequent transcription. This work shows how transcription termination can change the local chromatin environment to modulate transcription of Arabidopsis FLC and affect flowering time.

molecular biology↗

bioRxiv2020

Human-specific GAPDH RT-qPCR is an accurate and sensitive method of xenograft metastasis quantification

Metastasis is the primary cause of cancer-related mortality. Having experimental models that accurately reflect changes in the metastatic burden is imperative for developing improved treatments and a better understanding of the disease. The murine xenograft tumor model mimics the human scenario and provides a platform for in vivo and ex vivo metastasis quantification analyses. Histological analysis of hematoxylin and eosin (H&E) stained thin sections has been the gold standard for quantifying metastasis ex vivo but gaining favor for its ease and accuracy is reverse transcription-qualitative polymerase chain reaction (RT-qPCR). Herein we directly compare histological and RT-qPCR-based methods for quantifying lung metastasis in a murine xenograft tumor model. Furthermore, we have introduced a variation of the RT-qPCR method; human-specific glyceraldehyde 3-phosphate dehydrogenase (GAPDH) RT-qPCR, which allows quantification of metastasis in xenograft models, without the requirement of overexpression of exogenous genes. Human-specific GAPDH RT-qPCR detected increased lung metastasis resulting from aldehyde dehydrogenase 1A3 (ALDH1A3) expression in MDA-MB-231 breast cancer cells orthotopically implanted in NOD/SCID mice. Further, in the xenograft tumor model, human-specific GAPDH RT-qPCR was more sensitive and cost-effective than quantification of lung metastasis by histological analysis of H&E stained fixed thin sections. The two assays were highly correlative in terms of determining relative metastatic burden, suggesting that the human-specific GAPDH RT-qPCR method could be used as a standard method for quantification of disseminated human cells in murine xenograft models.

cancer biology↗