Biology subjects

Peng, Y.-J.

Publications and source records attributed to Peng, Y.-J..

8 recordsLinked to original sources

bioRxiv2026

Hierarchical Assembly of Native Cytoplasmic Lattices Revealed by Cryo-EM

Oocytes depend on maternal factors for maturation and early embryogenesis. Cytoplasmic lattices (CPLs) are distinctive fibrillar structures in mammalian oocyte cytoplasm implicated in maternal factor storage and developmental competence, yet their molecular composition and architecture remain elusive. Here, we use cryo-electron microscopy to resolve the high-resolution structure of native mouse oocyte CPLs. We identify 14 intrinsic components of multiple copies that assemble into filaments in which PADI6-mediated self-assembly and two subtypes of subcortical maternal complexes (SCMCs) form the core scaffold. Unexpectedly, we discover that /{beta}-tubulin dimers and two autoinhibited ubiquitination modules (UHRF1-UBE2D3, SKP1-FBXW18) are internal components of CPLs. We also uncover multivalent interactions that organize adjacent CPL filaments into higher-order helical bundles. By integrating CPL structure with biochemical and proteomic data, we propose a hierarchical assembly mechanism of CPLs, from subcomplexes to filaments to supramolecular lattices. Our study offers mechanistic insights into how maternal proteins are spatially organized to ensure successful early embryonic development and provides a structural foundation for understanding female infertility related to CPL-associated gene mutations.

developmental biology↗

bioRxiv2024

ADENYLATE CYCLASE 3 MEDIATES CAROTID BODY ACTIVATION AND AUTONOMIC DYSFUNCTION IN A SLEEP APNEA MODEL

Patients with obstructive sleep apnea (OSA) experience chronic intermittent hypoxia (CIH). OSA patients and CIH-treated rodents exhibit autonomic dysfunction, characterized by overactive sympathetic nervous system and hypertension, mediated through hyperactive carotid body (CB) chemoreflex. Activation of olfactory receptor 78 (Olfr78) by hydrogen sulfide (H2S) is implicated in CB activation and autonomic responses to CIH, but the downstream signaling pathways remain unknown. Given that odorant receptor signaling is coupled to adenylyl cyclase 3 (Adcy3), we hypothesized that Adcy3-dependent cAMP contributes to CB and autonomic responses to CIH. Our findings show that CIH increases cAMP levels in the CB, a response absent in Adcy3, Cth, and Olfr78 null mice. CBs from Cth and Olfr78 mutant mice lacked persulfidation response to CIH, indicating that Adcy3 activation by CIH requires Olfr78 activation by H2S. CIH also enhanced glomus cell Ca2+ influx, an effect absent in Cnga2 and Adcy3 mutants, suggesting that CIH-induced cAMP mediates enhanced Ca2+ responses through cyclic nucleotide-gated channels. Furthermore, Adcy3 null mice did not exhibit neither CB activation nor autonomic dysfunction by CIH. These results demonstrate that Adcy3-dependent cAMP is a downstream signaling pathway to H2S/Olfr78, mediating CIH-induced CB activation and autonomic dysfunction.

physiology↗

bioRxiv2024

Peripheral glia and neurons jointly regulate activity-induced synaptic remodeling at the Drosophila neuromuscular junction

In the nervous system, reliable communication depends on the ability of neurons to adaptively remodel their synaptic structure and function in response to changes in neuronal activity. While neurons are the main drivers of synaptic plasticity, glial cells are increasingly recognized for their roles as active modulators. However, the underlying molecular mechanisms remain unclear. Here, using Drosophila neuromuscular junction as a model system for a tripartite synapse, we show that peripheral glial cells collaborate with neurons at the NMJ to regulate activity-induced synaptic remodeling, in part through a protein called shriveled (Shv). Shv is an activator of integrin signaling previously shown to be released by neurons during intense stimulation at the fly NMJ to regulate activity-induced synaptic remodeling. We demonstrate that Shv is also present in peripheral glia, and glial Shv is both necessary and sufficient for synaptic remodeling. However, unlike neuronal Shv, glial Shv does not activate integrin signaling at the NMJ. Instead, it regulates synaptic plasticity in two ways: 1) maintaining the extracellular balance of neuronal Shv proteins to regulate integrin signaling, and 2) controlling ambient extracellular glutamate concentration to regulate postsynaptic glutamate receptor abundance. Loss of glial cells showed the same phenotype as loss of Shv in glia. Together, these results reveal that neurons and glial cells homeostatically regulate extracellular Shv protein levels to control activity-induced synaptic remodeling. Additionally, peripheral glia maintains postsynaptic glutamate receptor abundance and contribute to activity-induced synaptic remodeling by regulating ambient glutamate concentration at the fly NMJ.

neuroscience↗

bioRxiv2023

Nonribosomal peptide synthetases require dynamic interaction between modular domains

Nonribosomal peptide synthetases (NRPSs) are large multidomain enzymes for the synthesis of a variety of bioactive peptides in a modular and pipelined fashion. Here, we investigated how the condensation (C) domain and the adenylation (A) domain cooperate with each other for the efficient catalytic activity in microcystin NRPS modules. We solved two crystal structures of the microcystin NRPS modules, representing two newly identified conformations in the NRPS catalytic cycle. Our data reveals that the dynamic interaction between the C and the A domains in these modules are mediated by the conserved "RXGR" motif, and this interaction is important for the adenylation activity. Furthermore, the "RXGR" motif-mediated dynamic interaction and its functional regulation is prevalent in different NRPSs modules possessing both the A and the C domains. This study provides new insight into the catalytic mechanism of NRPSs and should inspire novel ideas in NRPS enzyme engineering in synthetic biology.

biochemistry↗

bioRxiv2022

Homeostatic responses to hypoxia by the carotid body and adrenal medulla are based on mutual antagonism between HIF-1α and HIF-2α

Respiration and blood pressure (BP) are regulated to maintain optimal delivery of O2 to every cell in the body. Arterial hypoxemia is sensed by the carotid body (CB), which initiates sympathetic reflex arcs to the diaphragm to increase ventilation, and to the adrenal medulla (AM) to increase catecholamine secretion and thereby increase BP. However, the underlying molecular mechanisms have not been fully delineated. Here, we report that the relative activities of hypoxia-inducible factor-1 (HIF-1) and HIF-2 determine the set point for the CB and AM, with respect to their maintenance of BP and respiration. In Hif2a+/- mice, which are heterozygous for a knockout allele at the locus encoding HIF-2, expression of HIF-1 and NADPH oxidase 2 was increased in the CB and AM, resulting in an oxidized intracellular redox state with augmented sensitivity to hypoxia, increased BP, and respiratory abnormalities, which were all normalized by treatment with a HIF-1 inhibitor or a superoxide anion scavenger. By contrast, in Hif1a+/- mice, which are heterozygous for a knockout allele at the locus encoding HIF-1, the expression of HIF-2 and superoxide dismutase 2 was increased in the CB and AM, resulting in a reduced intracellular redox state with impaired CB and ventilatory responses to chronic hypoxia, which were normalized by treatment with a HIF-2 inhibitor. None of the abnormalities that were observed in Hif1a+/- or Hif2a+/- mice were observed in Hif1a+/-; Hif2a+/- double- heterozygous mice. Our results demonstrate that redox balance in the CB and AM, which is determined by mutual antagonism between HIF- isoforms, establishes the set point for responses of the CB and AM to hypoxia, and is required for the maintenance of normal BP and respiration.

physiology↗

bioRxiv2022

GASEOUS TRANSMITTER MODULATION OF HYPOGLOSSAL MOTONEURON ACTIVITY

Obstructive sleep apnea (OSA) is characterized by sporadic collapse of the upper airway leading to periodic disruptions in breathing. Upper airway patency governed by genioglossal nerve activity originates from the hypoglossal motor nucleus. Mice with targeted deletion of the gene Hmox2, encoding the carbon monoxide (CO) producing enzyme, heme oxygenase-2 (HO-2), exhibit severe OSA, yet the contribution of central HO-2 dysregulation to the phenomenon is unknown. Using the rhythmic brainstem slice preparation, which contains the preBotzinger complex (preBotC) and the hypoglossal nucleus, we tested the hypothesis that central HO-2 dysregulation weakens hypoglossal motoneuron output. Disrupting HO-2 activity increased transmission failure as determined by the intermittent inability of the preBotC rhythm to trigger output from the hypoglossal nucleus. Failed transmission was associated with a reduced input-output relationship between the preBotC and the motor nucleus. These network phenomena were related to smaller inspiratory drive currents and reduced intrinsic excitability among hypoglossal neurons. In addition to HO-2, hypoglossal neurons also expressed the CO-regulated H2S producing enzyme cystathionine {square}-lyase (CSE). H2S abundance was higher in hypoglossal neurons of HO-2 null mice than wild-type controls. Disrupting CSE function normalized transmission in HO-2 null mice and an H2S donor mimicked the effects of HO-2 dysregulation. These findings demonstrate a hitherto uncharacterized modulation of hypoglossal activity through the interaction of HO-2 and CSE-derived H2S, and supports the perspective that centrally derived HO-2 activity plays an important role regulating upper airway control.

neuroscience↗

bioRxiv2019

Impaired carotid body hypoxic sensing in mice deficient in olfactory receptor 78

Carotid bodies are the sensory organs for detecting hypoxemia (decreased arterial blood oxygen levels) and ensuing chemo reflex is a major regulator of breathing and blood pressure. Chang et al (2015) proposed that olfactory receptor 78 (Olfr78) plays a major role in hypoxic sensing by the carotid body. However, such a possibility was questioned by a subsequent study ((Torres-Torrelo et al. 2018). The discrepancy between the two reports prompted the present study to re-examine the role of Olfr78 in hypoxic sensing by the carotid body (CB). Studies were performed on age and gender matched Olfr78 knock out mice generated on BL6 and JAX backgrounds and corresponding wild type mice. Breathing was monitored by plethysmography in un-sedated and efferent phrenic nerve activity in anesthetized mice. Carotid body sensory nerve activity was determined ex vivo and [Ca2+]i responses were monitored in isolated glomus cells, the primary O2 sensing cells of the carotid body. Olfr78 null mice on both BL6 and JAX backgrounds exhibited attenuated hypoxic ventilatory response, whereas breathing responses to CO2 were unaffected. The magnitude of hyperoxia-induced depression of breathing (Dejours test), which is an indirect measure of carotid body hypoxic sensing, was markedly reduced in Olfr78 mutant mice on both background strains. Furthermore, carotid body sensory nerve and glomus cell [Ca2+]i responses to hypoxia were attenuated in BL6 and JAX Olfr78 null mice. These results suggest that Olfr78 plays an important role in hypoxic sensing by the carotid body.

physiology↗

bioRxiv2019

High Spatial Resolution Ambient Ionization Mass Spectrometry Imaging Using Microscopy Image Fusion

Mass spectrometry imaging (MSI) using ambient ionization technique enables a direct chemical investigation of biological samples with minimal sample pretreatment. However, detailed morphological information of the sample is often lost due to its limited spatial resolution. In this study, predictive high-resolution molecular imaging was produced by the fusion of ambient ionization MSI with optical microscopy of routine hematoxylin and eosin (H&E) staining produces. Specifically, desorption electrospray ionization (DESI) and nanospray desorption electrospray ionization (nanoDESI) mass spectrometry are employed to visualize lipid and protein species on mice tissue sections. The resulting molecular distributions obtained by ambient ionization MSI-microscopy fusion are verified with matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) MSI and immunohistochemistry (IHC) staining. Label-free molecular imaging with 5-m spatial resolution can be acquired using DESI and nanoDESI, whereas the typical spatial resolution of ambient ionization MSI is ~100 m. In this regard, sharpened molecular histology of tissue sections is achieved, providing complementary references to the pathology. Such a multimodality integration enables the discovery of potential tumor biomarkers. After image fusion, more than a dozen of potential biomarkers that could be used to determine the tumor margins on a metastatic mouse lung tissue section and Luminal B breast tumor tissue section are identified.

bioinformatics↗