Biology subjects

Presman, D. M.

Publications and source records attributed to Presman, D. M..

7 recordsLinked to original sources

bioRxiv2026

Pair correlation function analysis revealed different nuclear translocation mechanisms for glucocorticoid receptor's monomeric and dimeric forms

Glucocorticoids are among the most widely prescribed drugs globally due to their potent anti-inflammatory and immunosuppressive actions. These effects are primarily mediated by the glucocorticoid receptor (GR), a ligand-activated transcription factor that translocates from the cytoplasm to the nucleus to regulate hundreds of genes. Although nuclear entry is a prerequisite for its genomic response, the mechanisms governing this process remain unresolved; specifically, whether the receptor translocates as a monomer or a dimer remains a subject of significant controversy. Here, we employed the pair correlation function (pCF) approach to quantify the nuclear translocation of single fluorescent GR molecules in live cells. This minimally invasive method identifies correlations between intensity fluctuations generated by molecules moving from the cytoplasm into the nucleus. Our results demonstrate that GRs quaternary structure and conformation modulate GR transport. While GR monomers rely exclusively on passive diffusion, GR dimers also utilize the microtubule-dynein machinery for active transport, proving that dimerization can precede nuclear import. Furthermore, the perinuclear vimentin network facilitates faster translocation by constraining actively transported dimers near nuclear pores. Collectively, our work reconciles contradicting reports regarding GR stoichiometry during import by demonstrating that both monomers and dimers translocate, albeit through distinct mechanisms. Importantly, these results reopen the door for a microtubule-dependent, heterocomplex-independent model of GR translocation, suggesting that the cytoskeleton is an integral, yet overlooked, component of the GR signaling pathway.

biophysics↗

bioRxiv2025

Bile acids target an exposed cavity in the glucocorticoid receptor modulating receptor self-assembly, chromatin binding and transcriptional activity

The glucocorticoid receptor (GR) is an essential transcription factor that controls metabolism and homeostasis. Glucocorticoids (GCs) activate the GR upon occupying the internal ligand-binding pocket (LBP) of its ligand-binding domain (GR-LBD), which has been the focus of most previous structure-function studies. Synthetic GCs such as dexamethasone are widely used to treat inflammatory diseases, but their chronic use results in major side effects, whose molecular underpinnings remain unresolved. Here we present a thorough analysis of the topography of GR-LBD and its ability to bind small-molecule compounds, especially cholesterol derivatives. We show that one important class of steroids, bile acids, bind to previously unidentified and highly conserved, surface-exposed cavities on GR-LBD. We show that bile acids affect GR turnover and self-assembly in living cells, modulating receptor transcriptional activity. These findings reveal a previously unrecognized mechanism of GR regulation, with implications for the design of GCs with novel mechanisms of action. TeaserBile acids modulate the activity of the glucocorticoid receptor upon binding to an exposed allosteric pocket thereby influencing transcriptional regulation and receptor self-assembly in living cells.

molecular biology↗

bioRxiv2024

The multimerization pathway of the glucocorticoid receptor

The glucocorticoid receptor (GR) is a leading drug target due to its anti-inflammatory and immunosuppressive roles. The functional oligomeric conformation of full-length GR (FL-GR), which is key for its biological activity, remains disputed. Here we present a new crystal structure of agonist-bound GR ligand-binding domain (GR-LBD) comprising eight copies of a non-canonical dimer. The biological relevance of this dimer for receptor multimerization in living cells has been verified by studying single-and double-point mutants of FL-GR in fluorescence microscopy (Number & Brightness) and transcriptomic analysis. Self-association of this GR-LBD basic dimer in two mutually exclusive assemblies reveals clues for FL-GR multimerization and activity in cells. We propose a model for the structure of multidomain GR based on our new data and suggest a detailed oligomerization pathway. This model reconciles all currently available structural and functional information and provides a more comprehensive understanding of the rare glucocorticoid resistance disorder (Chrousos syndrome).

biochemistry↗

bioRxiv2024

Hallmarks of glucocorticoid receptor condensates involvement in transcription regulation

Several proteins necessary for mRNA production concentrate in intranuclear condensates, which are proposed to affect transcriptional output. The glucocorticoid receptor (GR) is a ligand-activated transcription factor that regulates the expression of hundreds of genes relevant to many physiological and pathological processes. As with all members of the steroid receptor family, GR forms condensates of unknown function. Here, we examine whether GR condensates are involved in transcription regulation using Airyscan super-resolution microscopy and nano-antibodies targeting initiation and elongating states of RNA polymerase II (Pol2). We observed subpopulations of GR condensates colocalizing with initiating and, surprisingly, elongating Pol2 foci. The analysis of GR mutants with different transcriptional outputs suggests a correlation between condensate formation capability and transcription initiation. Moreover, the number of GR molecules within initiation and elongation condensates appears to be linked to transcriptional activity. Taken together, our data suggests an involvement of GR condensates in transcription initiation and elongation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/623561v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@969a77org.highwire.dtl.DTLVardef@176fcfborg.highwire.dtl.DTLVardef@dae13dorg.highwire.dtl.DTLVardef@1f96c3b_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2023

The mineralocorticoid receptor forms higher order oligomers upon DNA binding

The prevailing model of steroid hormone nuclear receptor function assumes ligand-induced homodimer formation followed by binding to DNA hormone response elements (HREs). This model has been challenged by evidence showing that the glucocorticoid receptor (GR) forms tetramers upon ligand and DNA binding, which then drive receptor-mediated gene transactivation and transrepression. GR and the closely-related mineralocorticoid receptors (MR) interact to transduce corticosteroid hormone signaling, but whether they share the same quaternary arrangement is unknown. Here, we used a fluorescence imaging technique, Number & Brightness, to study oligomerization in a cell system allowing real-time analysis of receptor-DNA interactions. Agonist-bound MR forms tetramers in the nucleoplasm and higher order oligomers upon binding to HREs. Antagonists form intermediate quaternary arrangements, suggesting that large oligomers are essential for function. Divergence between MR and GR quaternary structure is driven by different functionality of known and new multimerization interfaces, which does not preclude formation of heteromers. Thus, influencing oligomerization may be important to selectively modulate corticosteroid signaling.

biophysics↗

bioRxiv2022

Single-molecule tracking reveals two low-mobility states for chromatin and transcriptional regulators within the nucleus

How transcription factors (TFs) navigate the complex nuclear environment to assemble the transcriptional machinery at specific genomic loci remains elusive. Using single-molecule tracking, coupled with machine learning, we examined the mobility of multiple transcriptional regulators. We show that H2B and ten different transcriptional regulators display two distinct low-mobility states. Our results indicate that both states represent dynamic interactions with chromatin. Ligand activation results in a dramatic increase in the proportion of steroid receptors in the lowest mobility state. Mutational analysis revealed that only chromatin interactions in the lowest mobility state require an intact DNA-binding domain as well as oligomerization domains. Importantly, these states are not spatially separated as previously believed but in fact, individual H2B and TF molecules can dynamically switch between them. Together, our results identify two unique and distinct low-mobility states of transcriptional regulators that appear to represent common pathways for transcription activation in mammalian cells.

biophysics↗

bioRxiv2019

A New Model for Single-Molecule Tracking Analysis of Transcription Factor Dynamics

Single-molecule tracking (SMT) allows the study of transcription factor (TF) dynamics in the nucleus, giving important information regarding the search and binding behaviour of these proteins in the nuclear environment. Dwell time distributions for most TFs have been described by SMT to follow bi-exponential behaviour. This is consistent with the existence of two discrete populations bound to chromatin in vivo, one non-specifically bound to chromatin (i.e. searching mode) and another specifically bound to target sites, as originally defined by decades of biochemical studies. However, alternative models have started to emerge, from multiple exponential components to power-law distributions. Here, we present an analytical pipeline with an unbiased model selection approach based on different statistical metrics to determine the model that best explains SMT data. We found that a broad spectrum of TFs (including glucocorticoid receptor, oestrogen receptor, FOXA1, CTCF) follow a power-law distribution, blurring the temporal line between non-specific and specific binding, and suggesting that productive binding may involve longer binding events than previously thought. We propose a continuum of affinities model to explain the experimental data, consistent with the movement of TFs through complex interactions with multiple nuclear domains as well as binding and searching on the chromatin template.

biophysics↗