Biology subjects

Kao, H.-Y.

Publications and source records attributed to Kao, H.-Y..

7 recordsLinked to original sources

bioRxiv2025

PML1-Mediated Feedforward Loop Through PI3K and MAPK Axes Drives Endocrine Resistance

Treatment of estrogen receptor-positive (ER+) breast cancer is significantly hindered by endocrine resistance. We identified PML1 as a key therapeutic entity that can be targeted to overcome resistance. Endocrine-resistant breast cancer cells share three key characteristics: elevated PML1 protein levels, enhanced activity of PI3K, MAPK, or both signaling pathways, and reduced ER activity. We developed a PML1 gene signature that predicts poor prognosis and correlates strongly with PI3K, MAPK, and endocrine resistance gene signatures, as evident by cellular studies, scRNA-seq analysis, and spatial transcriptomics of endocrine therapy-treated tumors. This signature is present in endocrine-resistant breast cancer cells harboring the Y537S ER mutation. We consistently demonstrate high PML1 protein levels across cells resistant to various treatments, including 4-hydroxytamoxifen, fulvestrant, elacestrant, and CDK4/6 inhibitors. Furthermore, treatments with these therapeutic agents or knockdown of ESR1 mRNA also increase PML1 protein levels. Mechanistically, we show that ER inhibition through fulvestrant treatment activates PI3K and MAPK signaling, which enhance PML1 protein stability and synthesis. PML1 then drives a feedforward loop by stimulating the expression of cytokine and growth factor mRNAs, including CCL5 and HBEGF, further amplifying PI3K and MAPK signaling. Consequently, in endocrine-resistant cells, endocrine therapies, while inactivating ER, paradoxically reinforce this loop through increased PI3K/MAPK activation and PML1 protein accumulation, ultimately compromising therapeutic efficacy. Finally, we demonstrated that arsenic trioxide, an FDA-approved, PML-reducing drug, effectively disrupts this feedforward loop, offering a promising strategy for treating resistant metastatic breast cancer. STATEMENT OF SIGNIFICANCEEndocrine resistance remains a major obstacle in treating estrogen receptor-positive metastatic breast cancer. Our study identifies PML1 as a central mediator of this resistance, revealing how it maintains a self-reinforcing signaling network through PI3K and MAPK pathways by enhancing the production of cytokines and growth factors. The clinical significance of our findings is threefold: we establish PML1 as a biomarker for therapy resistance, demonstrate its mechanistic role in treatment failure, and show that FDA-approved arsenic trioxide can disrupt PML1-driven resistance. These insights provide a direct path to clinical translation, as combining arsenic trioxide with existing therapies could benefit patients with limited treatment options.

cancer biology↗

bioRxiv2025

Mitoxantrone inhibits and downregulates ERα through binding at the DBD-LBD interface

Targeting the estrogen receptor (ER or ER) through competitive antagonists, receptor downregulators, or estrogen synthesis inhibition remains the primary therapeutic strategy for luminal breast cancer. We have identified a novel mechanism of ER inhibition by targeting the critical interface between its DNA-binding domain (DBD) and ligand-binding domain (LBD). We demonstrate that mitoxantrone (MTO), a topoisomerase II inhibitor, binds at this previously unexplored DBD-LBD interface. Using comprehensive computational, biophysical, biochemical, and cellular analyses, we show that independent of its DNA damage response activity, MTO binding induces distinct conformational changes in ER, leading to its cytoplasmic redistribution and subsequent proteasomal degradation. Notably, MTO effectively inhibits clinically relevant ER mutations (Y537S and D538G) that confer resistance to current endocrine therapies, outperforming fulvestrant in both in vitro and in vivo assays. Our findings establish domain-domain interaction targeting as a viable therapeutic strategy for ER, with translational implications for other nuclear receptors.

cancer biology↗

bioRxiv2023

Phosphorylation modulates estrogen receptor disorder by altering long-range hydrophobic interactions

Protein intrinsic disorder is coupled to a range of biological phenomena, from gene regulation to cancer progression. Phosphorylation of the estrogen receptor (ER) at Ser118 through its disordered N-terminal domain (NTD) activates its transcriptional function, but it is challenging to rationalize how this modification regulates ER activity. Using biophysical approaches of small-angle X-ray scattering and nuclear magnetic resonance spectroscopy, we demonstrate that Ser118 phosphorylation triggers long-range conformational changes in ER-NTD, particularly between two hydrophobic clusters of residual structures. Alanine substitution of hydrophobic amino acids near Ser118 produces similar conformational alterations and rescues impaired ER activity caused by a phosphorylation-deficient mutant. These findings establish a direct link between phosphorylation-induced conformational changes and the activation function of this disordered protein as a promising avenue to block ER transcriptional activation.

biophysics↗

bioRxiv2022

Phencyclidine disrupts neural coordination and cognitive control by dysregulating translation

BackgroundPhencyclidine (PCP) causes psychosis, is abused with increasing frequency, and was extensively used in antipsychotic drug discovery. PCP discoordinates hippocampal ensemble action potential discharge and impairs cognitive control in rats, but how this uncompetitive N-methyl-D-aspartate receptor (NMDAR) antagonist impairs cognition remains unknown. MethodsThe effects of PCP were investigated i) on hippocampal CA1 ensemble action potential discharge in vivo in urethane-anesthetized rats and during awake behavior in mice; ii) on synaptic responses in ex vivo mouse hippocampus slices; iii) in mice on a hippocampus-dependent active place avoidance task that requires cognitive control; and iv) on activating the molecular machinery of translation in acute hippocampus slices. Mechanistic causality was assessed by comparing the PCP effects to the effects of inhibitors of protein synthesis, group-1-type metabotropic glutamate receptors (mGluR1/5), and subunit-selective NMDARs. ResultsConsistent with ionotropic actions, PCP discoordinated CA1 ensemble action potential discharge. PCP caused hyperactivity, and impaired active place avoidance, despite learning the task before PCP. Consistent with metabotropic actions, PCP exaggerated protein-synthesis dependent DHPG-induced mGluR1/5-stimulated long-term synaptic depression (LTD). Pretreatment with anisomycin or the mGluR1/5-antagonist MPEP, both of which repress translation, prevented the PCP-induced discoordination, and the cognitive and sensorimotor impairments. PCP as well as the NR2A-containing NMDAR-antagonist NVP-AAM077 unbalanced translation that engages the AKT, mTOR and 4EBP1 translation machinery and increased protein synthesis, whereas the NR2B-containing antagonist Ro25-6981 did not. ConclusionsPCP dysregulates translation, acting through NR2A-containing NMDAR subtypes, recruiting mGluR1/5 signaling pathways, leading to the neural discoordination that is central to the cognitive and sensorimotor impairments.

neuroscience↗

bioRxiv2020

Transcriptome analysis of hippocampal subfields identifies gene expression profiles associated with long-term active place avoidance memory

The hippocampus plays a critical role in storing and retrieving spatial information. By targeting the dorsal hippocampus and manipulating specific "candidate" molecules using pharmacological and genetic manipulations, we have previously discovered that long-term active place avoidance memory requires transient activation of particular molecules in dorsal hippocampus. These molecules include amongst others, the persistent kinases Ca-calmodulin kinase II (CaMKII) and the atypical protein kinase C isoform PKC{iota} /{lambda} for acquisition of the conditioned behavior, whereas persistent activation of the other atypical PKC, protein kinase M zeta (PKM{zeta}) is necessary for maintaining the memory for at least a month. It nonetheless remains unclear what other molecules and their interactions maintain active place avoidance long-term memory, and the candidate molecule approach is both impractical and inadequate to identify new candidates since there are so many to survey. Here we use a complementary approach to identify candidates by transcriptional profiling of hippocampus subregions after formation of the long-term active place avoidance memory. Interestingly, 24-h after conditioning and soon after expressing memory retention, immediate early genes were upregulated in the dentate gyrus but not Ammons horn of the memory expressing group. In addition to determining what genes are differentially regulated during memory maintenance, we performed an integrative, unbiased survey of the genes with expression levels that covary with behavioral measures of active place avoidance memory persistence. Gene Ontology analysis of the most differentially expressed genes shows that active place avoidance memory is associated with activation of transcription and synaptic differentiation in dentate gyrus but not CA3 or CA1, whereas hypothesis-driven candidate molecule analyses identified insignificant changes in the expression of many LTP-associated molecules in the various hippocampal subfields, nor did they covary with active place avoidance memory expression, ruling out strong transcriptional regulation but not translational regulation, which was not investigated. These findings and the data set establish an unbiased resource to screen for molecules and evaluate hypotheses for the molecular components of a hippocampus-dependent, long-term active place avoidance memory.

neuroscience↗

bioRxiv2017

Phencyclidine discoordinates hippocampal network activity but not place fields

We used the psychotomimetic phencyclidine (PCP) to investigate the relationships between cognitive behavior, coordinated neural network function and information processing within the hippocampus place cell system. We report in rats that PCP (5mg/kg i.p.) impairs a well-learned hippocampus-dependent place avoidance behavior in rats that requires cognitive control, even when PCP is injected directly into dorsal hippocampus. PCP increases 60-100 Hz medium gamma oscillations in hippocampus CA1 and these increases correlate with the cognitive impairment caused by systemic PCP administration. PCP discoordinates theta-modulated medium and slow gamma oscillations in CA1 local field potentials (LFP) such that medium gamma oscillations become more theta-organized than slow gamma oscillations. CA1 place cell firing fields are preserved under PCP but the drug discoordinates the sub-second temporal organization of discharge amongst place cells. This discoordination causes place cell ensemble representations of a familiar space to cease resembling pre-PCP representations, despite preserved place fields. These findings point to the cognitive impairments caused by PCP arising from neural discoordination. PCP disrupts the timing of discharge with respect to the sub-second timescales of theta and gamma oscillations in the LFP. Because these oscillations arise from local inhibitory synaptic activity, these findings point to excitation-inhibition discoordination as the root of PCP-induced cognitive impairment.\n\nSIGNIFICANCE STATEMENTHippocampal neural discharge is temporally coordinated on timescales of theta and gamma oscillations in the local field potential, and the discharge of a subset of pyramidal neurons called \"place cells\" is spatially organized such that discharge is restricted to locations called a cells \"place field.\" Because this temporal coordination and spatial discharge organization is thought to represent spatial knowledge, we used the psychotomimetic phencyclidine (PCP) to disrupt cognitive behavior and assess the importance of neural coordination and place fields for spatial cognition. PCP impaired the judicious use of spatial information and discoordinated hippocampal discharge, without disrupting firing fields. These findings dissociate place fields from spatial cognitive behavior and suggest that hippocampus discharge coordination is crucial to spatial cognition.

neuroscience↗

bioRxiv2017

Analysis of hippocampal transcriptomic responses to technical and biological perturbations

Cost-effective next-generation sequencing has made unbiased gene expression analysis possible. Single-neuron gene expression studies may be especially important for understanding nervous system structure and function because of the neuron-specific functionality and plasticity that defines functional neural circuits. Cellular dissociation is a prerequisite technical manipulation for single-cell and single cell-population studies, but the extent to which the cellular dissociation process cells affects neural gene expression has not been determined, nor has it been determined how gene expression is altered by the stress that accompanies many of the behavioral manipulations that are required to study learning and memory and other cognitive functions. Here, we determined to which extent cellular dissociation-induced changes in hippocampal gene expression might confound studies on the behavioral and physiological functions of the hippocampus. We processed tissue punch samples from the dentate gyrus (DG), CA3, and CA1 hippocampus subfields using either a tissue homogenization protocol or a cellular dissociation protocol in preparation for RNA sequencing analysis to evaluate the impact of the tissue preparation. Then, we evaluated the effect of stressful experience and cognitive training on hippocampus subfield specific gene expression and determined to which extent these response overlap with the cellular dissociation response. Finally, we assessed the extent to which the subfield-specific gene expression patterns are consistent with those identified in a recently published hippocampus subfield-specific gene expression database. We report substantial differences in baseline subfield-specific gene expression, that 1% of the hippocampal transcriptome is altered by the process of cellular dissociation, that an even weaker alteration is detected 24 h after stressful experience, and that while these alterations are largely distinct from the subfield specific response of the hippocampus transcriptome to cognitive training, there is nonetheless some important confounding overlap. These findings of the concordant and discordant effects of technical and behavioral manipulations should inform the design of future neural transcriptome studies and thus facilitate a more comprehensive understanding of hippocampal function.

neuroscience↗