single-channel-electrophysiology-using-miniaturized-montalmueller

Single-Channel Electrophysiology Using a Miniaturized Montal&#8211;Mueller Planar Lipid Bilayer System for Recording a Synthetic K<sub>2P</sub> Channel

The functional reconstitution of ion channels into planar lipid bilayers provides a strategy to investigate channel activity at the single-molecule level. ...

University of Pavia

The second messenger cyclic AMP regulates many nuclear processes including transcription, pre-mRNA splicing and mitosis. While most functions are attributed to protein kinase A, accumulating evidence suggests that not all nuclear cyclic AMP-dependent effects are mediated by this kinase, implying that other effectors may be involved. Here we explore the nuclear roles of Exchange Protein Activated by cyclic AMP 1. We find that it enters the nucleus where forms reversible biomolecular condensates in response to cyclic AMP. This phenomenon depends on intrinsically disordered regions present at its amino-terminus and is independent of protein kinase A. Finally, we demonstrate that nuclear Exchange Protein Activated by cyclic AMP 1 condensates assemble at genomic loci on chromosome 6 in the proximity of Histone Locus Bodies and promote the transcription of a histone gene cluster. Collectively, our data reveal an unexpected mechanism through which cyclic AMP contributes to nuclear spatial compartmentalization and promotes the transcription of specific genes.

Cyclic AMP induces reversible EPAC1 condensates that regulate histone transcription.

The voltage-dependent anion-selective channel (VDAC) plays a crucial role in mitochondrial function, and VDAC paralogs are considered to ensure the differential integration of mitochondrial functions with cellular activities. Heterologous expression of VDAC paralogs in the yeast Δ mutant cells is often employed in studies of functional differentiation of human VDAC paralogs (hVDAC1-hVDAC3) regardless of the presence of the yeast second VDAC paralog (yVDAC2) encoded by the  gene. Here, we applied ΔΔ double mutants and relevant Δ and Δ single mutants, derived from two  strains (M3 and BY4741) differing distinctly in auxotrophic markers but commonly used for heterologous expression of hVDAC paralogs, to study the effect of the presence of yVDAC2 and cell genotypes including , the latter resulting in a low level of hydrogen sulfide (HS), on the complementation potential of heterologous expression of hVDAC paralogs. The results indicated that yVDAC2 might contribute to the complementation potential. Moreover, the possibility to reverse the growth phenotype through heterologous expression of hVDAC paralogs in the presence of the applied yeast cell genotype backgrounds was particularly diverse for hVDAC3 and depended on the presence of the protein cysteine residues and expression of . Thus, the difference in the set of auxotrophic markers in yeast cells, including  contributing to the HS level, may create a different background for the modification of cysteine residues in hVDAC3 and thus explain the different effects of the presence and deletion of cysteine residues in hVDAC3 in M3-ΔΔ and BY4741-ΔΔ cells. The different phenotypes displayed by BY4741-ΔΔ and M3-ΔΔ cells following heterologous expression of a particular hVDAC paralog make them valuable models for the study of human VDAC proteins, especially hVDAC3, as a representative of VDAC protein sensitive to the reduction-oxidation state.

Article	Year
Cyclic AMP induces reversible EPAC1 condensates that regulate histone transcription. Nature communications\| PubMed ID: 37684224	2023
Developing a Novel and Optimized Yeast Model for Human VDAC Research. International journal of molecular sciences\| PubMed ID: 39684721	2024

Deborah Musso

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