Biology subjects

Yun, P.

Publications and source records attributed to Yun, P..

5 recordsLinked to original sources

bioRxiv2025

Delineating plant responses to the 3',5'- and 2',3'-cAMP isomers

Similar to animals, both the 3,5- and the 2,3-cAMP isomers are present in plants. The former is the enzymatic product of adenylate cyclases (ACs), the latter is an RNA degradation product. While there is increasing evidence that both isomers can elicit or modulate a broad range of physiological responses, the question of isomer specificity of responses has remained largely unresolved. To delineate isomer-specific responses in Arabidopsis thaliana at the systems level, we have combined a comparative proteomics and electrophysiological approaches. Both isomers cause distinct systemic effects on the proteome, with the 2,3 isomer notably affecting systems-level functions like transcriptional regulation. None of the isomers affects net ion fluxes in the root under control conditions, but both were able to attenuate the magnitude of oxidative stress-induced K+ net loss and Ca2+ uptake by 2-fold. Isomer-specific responses of single molecular targets were assessed in the cyclic nucleotide-gated channels 2 and 18 (CNGC2 and CNGC18). Both channels are gated by the 3,5-cAMP isomer only, suggesting that the gating is isomer-specific and this implies that gating in vivo depends on catalytically active ACs. HighlightsDistinct Arabidopsis responses to 3,5- and 2,3-cAMP uncover isomer-specific molecular targets and physiological effects in cyclic nucleotide signaling.

plant biology↗

bioRxiv2023

Guanylate cyclase activity of TIR1/AFB auxin receptorsin rapid auxin responses

The plant hormone auxin is perceived by TIR1/AFB receptors, which mediate transcriptional reprogramming via a ubiquitination- and cAMP-dependent mechanism. Same receptors mediate also rapid, non-transcriptional growth responses that are mechanistically less well understood. Here, we demonstrate that TIR1/AFB receptors possess not only adenylate cyclase but also guanylate cyclase activity. Auxin perception independently activates cAMP and cGMP production by TIR1/AFBs in vitro and elevates both cAMP and cGMP levels in planta. Genetic and synthetic biology approaches revealed that AFB1 guanylate cyclase activity is required for the rapid cytosolic Ca2+ transients and root growth inhibition. This unprecedented combination of adenylate and guanylate cyclase activities within a single hormone receptor establishes a new paradigm for how one perception mechanism can mediate distinct downstream responses. One-Sentence SummaryTIR1/AFB auxin receptors possess both, adenylate and guanylate cyclase activities, mediating transcriptional reprogramming and rapid Ca2+-dependent growth responses, respectively.

plant biology↗

bioRxiv2023

Collagen type VI regulates TGFβ bioavailability in skeletal muscle

Collagen VI-related disorders (COL6-RDs) are a group of rare muscular dystrophies caused by pathogenic variants in collagen VI genes (COL6A1, COL6A2, and COL6A3). Collagen type VI is a heterotrimeric, microfibrillar component of the muscle extracellular matrix (ECM), predominantly secreted by resident fibroadipogenic precursor cells in skeletal muscle. The absence or mislocalizatoion of collagen VI in the ECM underlies the non-cell autonomous dysfunction and dystrophic changes in skeletal muscle with an as of yet elusive direct mechanistic link between the ECM and myofiber dysfunction. Here, we conduct a comprehensive natural history and outcome study in a novel mouse model of COL6-RDs (Col6a2-/-mice) using standardized (Treat-NMD) functional, histological, and physiologic parameter. Notably, we identify a conspicuous dysregulation of the TGF{beta} pathway early in the disease process and propose that the collagen VI deficient matrix is not capable of regulating the dynamic TGF{beta} bioavailability at baseline and also in response to muscle injury. Thus, we propose a new mechanism for pathogenesis of the disease that links the ECM regulation of TGF{beta} with downstream skeletal muscle abnormalities, paving the way for developing and validating therapeutics that target this pathway.

neuroscience↗

bioRxiv2021

The AFB1 auxin receptor controls rapid auxin signaling and root growth through membrane depolarization in Arabidopsis thaliana

The existence of an electric gradient across membranes is essential for a cell operation. In plants, application of the growth regulator auxin (IAA) causes almost instantaneous membrane depolarization in various cell types, making membrane depolarization a hallmark of the rapid non-transcriptional responses to IAA. Auxin triggers rapid root growth inhibition; a process that underlies gravitropic bending. The growth and depolarization responses to auxin show remarkable similarities in dynamics, requirement of auxin influx and the involvement of the TIR1/AFB auxin coreceptors, but whether auxin-induced depolarization participates in root growth inhibition remains unanswered. Here, we established a toolbox to dynamically visualize membrane potential in vivo in Arabidopsis thaliana roots by combining the DISBAC2(3) fluorescent probe with microfluidics and vertical stage microscopy. This way we show that auxin-induced membrane depolarization tightly correlates with rapid root growth inhibition and that the cells of the transition zone/early elongation zone are the most responsive to auxin. Further, we demonstrate that auxin cycling in and out of the cells through AUX1 influx and PIN2 efflux is not essential for membrane depolarization and rapid root growth inhibition but acts as a facilitator of these responses. The rapid membrane depolarization by auxin instead strictly depends on the AFB1 auxin receptor, while the other TIR1/AFB paralogues contribute to this response. The lack of membrane depolarization in the afb1 mutant explains the lack of the immediate root growth inhibition. Finally, we show that AFB1 is required for the rapid depolarization and rapid growth inhibition of cells at the lower side of the gravistimulated root. These results are instrumental in understanding the physiological significance of membrane depolarization for the gravitropic response of the root and clarify the role of AFB1 as the receptor central for rapid auxin responses, adding another piece to the puzzle in understanding the biology of the phytohormone auxin.

plant biology↗

bioRxiv2020

A new method for distinguishing human and mouse cells in situ

The mouse xenograft model is one of the most widely used animal model for biomedicine research. It is vital to distinguish the cells from different species, especially for the spatial distribution information. However, the available strategies of species-specific detection are either inapplicable in situ or of low specificity. Here, we reported a method based on DAPI staining, which offers an effective, convenient way that accurately identifies human and mouse nuclei at single-cell level in situ. This method was proven to be effective in cell co-culture and tumor xenograft tissue section. Microscopic imaging results shows obvious DAPI plaques-like structures in mouse nuclei, but absent in human nuclei. Moreover, we found these structures are co-localized with mouse major satellite DNA, which is located pericentromere in mouse, but absent in human. Our study provides a high-performance method that can be widely used for distinguish human and mouse cell in situ.

cell biology↗