Phospholipase C beta 1 in the dentate gyrus gates fear memory formation through regulation of neuronal excitability.

Memory processes rely on a molecular signaling system that balances the interplay between positive and negative modulators. Recent research has focused on identifying memory-regulating genes and their mechanisms. Phospholipase C beta 1 (PLCß1), highly expressed in the hippocampus, reportedly serves as a convergence point for signal transduction through G protein-coupled receptors. However, the detailed role of PLCß1 in memory function has not been elucidated. Here, we demonstrate that PLCß1 in the dentate gyrus functions as a memory suppressor. We reveal that mice lacking PLCß1 in the dentate gyrus exhibit a heightened fear response and impaired memory extinction, and this excessive fear response is repressed by upregulation of PLCß1 through its overexpression or activation using a newly developed optogenetic system. Last, our results demonstrate that PLCß1 overexpression partially inhibits exaggerated fear response caused by traumatic experience. Together, PLCß1 is crucial in regulating contextual fear memory formation and potentially enhancing the resilience to trauma-related conditions.

A new light on PLCß!

In this issue of Cell Chemical Biology, Kim et al.1 present a novel optogenetic tool, opto-PLCß, to control PLCß signaling optically. In addition to eliciting PIP2 hydrolysis and downstream signaling in cells, opto-PLCß also enabled probing the impact of PLCß signaling on amygdala synaptic plasticity and fear learning in mice.

Ileal Crohn's Disease Exhibits Reduced Activity of Phospholipase C-ß3-Dependent Wnt/ß-Catenin Signaling Pathway.

Crohn's disease is a chronic, debilitating, inflammatory bowel disease. Here, we report a critical role of phospholipase C-ß3 (PLC-ß3) in intestinal homeostasis. In PLC-ß3-deficient mice, exposure to oral dextran sodium sulfate induced lethality and severe inflammation in the small intestine. The lethality was due to PLC-ß3 deficiency in multiple non-hematopoietic cell types. PLC-ß3 deficiency resulted in reduced Wnt/ß-catenin signaling, which is essential for homeostasis and the regeneration of the intestinal epithelium. PLC-ß3 regulated the Wnt/ß-catenin pathway in small intestinal epithelial cells (IECs) at transcriptional, epigenetic, and, potentially, protein-protein interaction levels. PLC-ß3-deficient IECs were unable to respond to stimulation by R-spondin 1, an enhancer of Wnt/ß-catenin signaling. Reduced expression of PLC-ß3 and its signature genes was found in biopsies of patients with ileal Crohn's disease. PLC-ß regulation of Wnt signaling was evolutionally conserved in Drosophila. Our data indicate that a reduction in PLC-ß3-mediated Wnt/ß-catenin signaling contributes to the pathogenesis of ileal Crohn's disease.

Elucidating the Role of circTIAM1 in Guangling Large-Tailed Sheep Adipocyte Proliferation and Differentiation via the miR-485-3p/PLCB1 Pathway.

Fat tissue-a vital energy storage organ-is intricately regulated by various factors, including circular RNA, which plays a significant role in modulating fat development and lipid metabolism. Therefore, this study aims to clarify the regulatory mechanism of sheep adipocyte proliferation and differentiation by investigating the involvement of circTIAM1, miR-485-3p, and its target gene PLCB1. Through previous sequencing data, circTIAM1 was identified in sheep adipocytes, with its circularization mechanism elucidated, confirming its cytoplasmic localization. Experimental evidence from RNase R treatment and transcription inhibitors highlighted that circTIAM1 is more stable than linear RNA. Additionally, circTIAM1 promoted sheep adipocyte proliferation and differentiation. Furthermore, bioinformatic analysis demonstrated a robust interaction between miR-485-3p and circTIAM1. Further experiments revealed that miR-485-3p inhibits fat cell proliferation and differentiation by inhibiting PLCB1, with circTIAM1 alleviating the inhibitory effect via competitive binding. In summary, our findings elucidate the mechanism through which circTIAM1 regulates Guangling Large-Tailed sheep adipocyte proliferation and differentiation via the miR-485-3p-PLCB1 pathway, offering a novel perspective for further exploring fat metabolism regulation.

Biasing Gßγ Downstream Signaling with Gallein Inhibits Development of Morphine Tolerance and Potentiates Morphine-Induced Nociception in a Tolerant State.

Opioid analgesics are widely used as a treatment option for pain management and relief. However, the misuse of opioid analgesics has contributed to the current opioid epidemic in the United States. Prescribed opioids such as morphine, codeine, oxycodone, and fentanyl are mu-opioid receptor (MOR) agonists primarily used in the clinic to treat pain or during medical procedures, but development of tolerance limits their utility for treatment of chronic pain. Here we explored the effects of biasing Gßγ signaling on tolerance development after chronic morphine treatment in vivo. We hypothesized that biasing Gßγ signaling with gallein could prevent activation of regulatory signaling pathways that result in tolerance to antinociceptive effects of MOR agonists. Gallein has been shown to bind to Gßγ and inhibit interactions of Gßγ with phospholipase-Cß3 (PLCß3) or G-protein-coupled receptor kinase 2 (GRK2) but not G-protein inwardly rectifying potassium (GIRK) channels. In mice, morphine-induced antinociception was evaluated in the 55°C warm water tail withdrawal assay. We used two paradigms for gallein treatment: administration during and after three times-daily morphine administration. Our results show that gallein cotreatment during repeated administration of morphine decreased opioid tolerance development and that gallein treatment in an opioid-tolerant state enhanced the potency of morphine. Mechanistically, our data suggest that PLCß3 is necessary for potentiating effects of gallein in an opioid-tolerant state but not in preventing the development of tolerance. These studies demonstrate that small molecules that target Gßγ signaling could reduce the need for large doses of opioid analgesics to treat pain by producing an opioid-sparing effect. SIGNIFICANCE STATEMENT: Biasing Gßγ signaling prevents tolerance to repeated morphine administration in vivo and potentiates the antinociceptive effects of morphine in an opioid-tolerant state. Mechanistically, phospholipase-Cß is necessary for potentiating effects of gallein in an opioid-tolerant state but not in preventing the development of tolerance. This study identifies a novel treatment strategy to decrease the development of tolerance to the analgesic effects of mu-opioid receptor agonists, which are necessary to improve pain treatment and decrease the incidence of opioid use disorder.

PLCß4 driven by cadmium-exposure during gestation and lactation contributes to cognitive deficits by suppressing PIP2/PLCγ1/CREB/BDNF signaling pathway in male offspring.

The fetus and infants are particularly vulnerable to Cadmium (Cd) due to the immaturity of the blood-brain barrier. In utero and early life exposure to Cd is associated with cognitive deficits. Although such exposure has attracted widespread attention, its gender-specificity remains controversial, and there are no reports disclosing the underlying mechanism of gender­specific neurotoxicity. We extensively evaluated the learning and cognitive functions and synaptic plasticity of male and female rats exposed to maternal Cd. Maternal Cd exposure induced learning and memory deficits in male offspring rats, but not in female offspring rats. PLCß4 was identified as a critical protein, which might be related to the gender­specific cognitive deficits in male rats. The up-regulated PLCß4 competed with PLCγ1 to bind to PIP2, which counteracted the hydrolysis of PIP2 by PLCγ1. The decreased activation of PLCγ1 inhibited the phosphorylation of CREB to reduce BDNF transcription, which consequently resulted in the damage of hippocampal neurons and cognitive deficiency. Moreover, the low level of BDNF promoted AEP activation to induce Aß deposition in the hippocampus. These findings highlight that PLCß4 might be a potential target for the therapy of learning and cognitive deficits caused by Cd exposure in early life.

LncRNA AC100826.1 regulated PLCB1 to promote progression in non-small cell lung cancer.

BACKGROUND: Lung cancer is the most common malignant tumor. In the present study, we identified a long non-coding RNA (lncRNA) AC100826.1 (simplify to Lnc1), which was highly expressed in non-small cell lung cancer (NSCLC) tissues compared with the paracancerous tissues. We also observed the critical role of Lnc1 in regulating the metastasis ability of NSCLC cells. METHODS: RNA sequencing was performed to detect differential expression levels of lncRNAs in NSCLC tissues and its paracancerous tissues. Effects of Lnc1 on cell proliferation, invasion, and migration were determined by CCK-8, transwell and scratch assays. The xenograft experiment confirmed the effect of Lnc1 on NSCLC cells proliferation and migration abilities in vivo. RT-qPCR and western blots were performed to determine the expression levels of mRNAs and proteins. RESULTS: The expression level of Lnc1 was related to multiple pathological results, knockdown of Lnc1 can inhibit the proliferation and metastasis abilities of NSCLC cells. silencing phospholipase C, ß1(PLCB1) can reverse the promoting effects of overexpression Lnc1 on NSCLC cells proliferation and migration abilities. In addition, the Rap1 signaling pathway was implicated in the regulation of Lnc1 in NSCLC metastasis. CONCLUSION: Our results suggest that Lnc1 regulated the metastatic ability of NSCLC cells through targeting the PLCB1/Rap1 signal pathway.

OSBPL2 compound heterozygous variants cause dyschromatosis, ichthyosis, deafness and atopic disease syndrome.

PURPOSE: In this study, we identified and diagnosed a novel inherited condition called Dyschromatosis, Ichthyosis, Deafness, and Atopic Disease (DIDA) syndrome. We present a series of studies to clarify the pathogenic variants and specific mechanism. METHODS: Exome sequencing and Sanger sequencing was conducted in affected and unaffected family members. A variety of human and cell studies were performed to explore the pathogenic process of keratosis. RESULTS: Our finding indicated that DIDA syndrome was caused by compound heterozygous variants in the oxysterol-binding protein-related protein 2 (OSBPL2) gene. Furthermore, our findings revealed a direct interaction between OSBPL2 and Phosphoinositide phospholipase C-beta-3 (PLCB3), a key player in hyperkeratosis. OSBPL2 effectively inhibits the ubiquitylation of PLCB3, thereby stabilizing PLCB3. Conversely, OSBPL2 variants lead to enhanced ubiquitination and subsequent degradation of PLCB3, leading to epidermal hyperkeratosis, characterized by aberrant proliferation and delayed terminal differentiation of keratinocytes. CONCLUSIONS: Our study not only unveiled the association between OSBPL2 variants and the newly identified DIDA syndrome but also shed light on the underlying mechanism.

A light-controlled phospholipase C for imaging of lipid dynamics and controlling neural plasticity.

Phospholipase C (PLC) is a key enzyme that regulates physiological processes via lipid and calcium signaling. Despite advances in protein engineering, no tools are available for direct PLC control. Here, we developed a novel optogenetic tool, light-controlled PLCß (opto-PLCß). Opto-PLCß uses a light-induced dimer module, which directs an engineered PLC to the plasma membrane in a light-dependent manner. Our design includes an autoinhibitory capacity, ensuring stringent control over PLC activity. Opto-PLCß triggers reversible calcium responses and lipid dynamics in a restricted region, allowing precise spatiotemporal control of PLC signaling. Using our system, we discovered that phospholipase D-mediated phosphatidic acid contributes to diacylglycerol clearance on the plasma membrane. Moreover, we extended its applicability in vivo, demonstrating that opto-PLCß can enhance amygdala synaptic plasticity and associative fear learning in mice. Thus, opto-PLCß offers precise spatiotemporal control, enabling comprehensive investigation of PLC-mediated signaling pathways, lipid dynamics, and their physiological consequences in vivo.

Auriculocondylar syndrome 2 caused by a novel PLCB4 variant in a male Chinese neonate: A case report and review of the literature.

BACKGROUND: Auriculocondylar syndrome (ARCND) is a rare congenital craniofacial developmental malformation syndrome of the first and second pharyngeal arches with external ear malformation at the junction between the lobe and helix, micromaxillary malformation, and mandibular condylar hypoplasia. Four subtypes of ARCND have been described so far, that is, ARCND1 (OMIM # 602483), ARCND2 (ARCND2A, OMIM # 614669; ARCND2B, OMIM # 620458), ARCND3 (OMIM # 615706), and ARCND4 (OMIM # 620457). METHODS: This study reports a case of ARCND2 resulting from a novel pathogenic variant in the PLCB4 gene, and summarizes PLCB4 gene mutation sites and phenotypes of ARCND2. RESULTS: The proband, a 5-day-old male neonate, was referred to our hospital for respiratory distress. Micrognathia, microstomia, distinctive question mark ears, as well as mandibular condyle hypoplasia were identified. Trio-based whole-exome sequencing identified a novel missense variant of NM_001377142.1:c.1928C>T (NP_001364071.1:p.Ser643Phe) in the PLCB4 gene, which was predicted to impair the local structural stability with a result that the protein function might be affected. From a review of the literature, only 36 patients with PLCB4 gene mutations were retrieved. CONCLUSION: As with other studies examining familial cases of ARCND2, incomplete penetrance and variable expressivity were observed within different families' heterozygous mutations in PLCB4 gene. Although, motor and intellectual development are in the normal range in the vast majority of patients with ARCND2, long-term follow-up and assessment are still required.

Histological evaluation of the alpaca (Vicugna pacos) vomeronasal organ.

Little is known about the neuronal structure of the vomeronasal organ (VNO), a receptor organ responsible for pheromone perception, in the alpaca (Vicugna pacos). This study was performed to determine the localization of neuronal elements, including protein gene product 9.5 (PGP 9.5), a pan-neuronal marker, olfactory marker protein (OMP), a marker of mature olfactory receptor cells, and phospholipase C beta 2 (PLC-ß2), a marker of solitary chemoreceptor cells (SCCs), in the VNO. OMP was identified in receptor cells of the vomeronasal sensory epithelium (VSE), while PGP 9.5 and PLC-ß2 were localized in both the VSE and vomeronasal non-sensory epithelium. Collectively, these results suggested that the alpaca VNO possesses SCCs and olfactory receptor cells, which recognize both harmful substances and pheromones.

Unraveling Hidden Cell Signaling Pathways Using Biophysical Methods: Application to the Gαq/Phospholipase Cß Signaling System.

The success of pharmaceutical therapies relies on how well cells respond to a particular drug, but accurately predicting responses can be difficult due to the complex and numerous potential molecular interactions that are possible in cells, and the responses of individuals can be variable due to cryptic and unexpected interactions. With the advancement of proteomics and fluorescence imaging methods, it is now possible to elucidate novel secondary signaling pathways and predict unexpected responses that might otherwise be missed, allowing for the development of better therapeutics. The Gαq/PLCß signaling pathway is activated by agents that mediate allergic responses, neurotransmission, and heart rate, as well as other functions that are critical for survival. This Review describes the factors that must be considered in delineating signaling pathways and describes the novel translational role that we have uncovered for this signaling pathway.

Lnc-PLCB1 is stabilized by METTL14 induced m6A modification and inhibits Helicobacter pylori mediated gastric cancer by destabilizing DDX21.

Helicobacter pylori (H. pylori) infection is considered to be an important factor in gastric cancer (GC). Long noncoding RNA (lncRNA) and m6A modification are involved in the occurrence and development of GC, but the role of lncRNA m6A modification in the development of GC mediated by H. pylori is still unclear. Here, we found that H. pylori infection downregulated the expression of lnc-PLCB1 through METTL14-mediated m6A modification and IRF2-mediated transcriptional regulation. Overexpression of lnc-PLCB1 inhibited the proliferation and migration of GC cells, while downregulation of lnc-PLCB1 promoted the proliferation and migration ability of GC cells. In addition, clinical analysis showed that lnc-PLCB1 is lower in GC tissues than in normal tissues. Further study found that lnc-PLCB1 reduced the protein stability of its binding protein DEAD-box helicase 21 (DDX21) and then downregulated the expression of CCND1 and Slug, thereby playing tumour suppressing role in the occurrence and development of GC. In conclusion, the METTL14/lnc-PLCB1/DDX21 axis plays an important role in H. pylori-mediated GC, and lnc-PLCB1 can be used as a new target for GC treatment.

TRPM4 and PLCß3 contribute to normal behavioral responses to an array of sweeteners and carbohydrates but PLCß3 is not needed for taste-driven licking for glucose.

The peripheral taste system is more complex than previously thought. The novel taste-signaling proteins TRPM4 and PLCß3 appear to function in normal taste responding as part of Type II taste cell signaling or as part of a broadly responsive (BR) taste cell that can respond to some or all classes of tastants. This work begins to disentangle the roles of intracellular components found in Type II taste cells (TRPM5, TRPM4, and IP3R3) or the BR taste cells (PLCß3 and TRPM4) in driving behavioral responses to various saccharides and other sweeteners in brief-access taste tests. We found that TRPM4, TRPM5, TRPM4/5, and IP3R3 knockout (KO) mice show blunted or abolished responding to all stimuli compared with wild-type. IP3R3 KO mice did, however, lick more for glucose than fructose following extensive experience with the 2 sugars. PLCß3 KO mice were largely unresponsive to all stimuli except they showed normal concentration-dependent responding to glucose. The results show that key intracellular signaling proteins associated with Type II and BR taste cells are mutually required for taste-driven responses to a wide range of sweet and carbohydrate stimuli, except glucose. This confirms and extends a previous finding demonstrating that Type II and BR cells are both necessary for taste-driven licking to sucrose. Glucose appears to engage unique intracellular taste-signaling mechanisms, which remain to be fully elucidated.

A polypeptide derived from pilose antler ameliorates CUMS-induced depression-like behavior by SENP2-PLCß4 signaling axis.

Neurogenesis is known to be closely associated with depression. We aimed to investigate whether a polypeptide monomer derived from pilose antler (polypeptide sequence LSALEGVFYP, PAP) exerts an antidepressant effect by influencing neurogenesis, and to elucidate the mechanism of its antidepressant action. Behavioral tests were performed to observe the antidepressant effect of PAP. Neurogenesis in the dentate gyrus (DG) region of hippocampus was observed by immunofluorescence. The expression of key proteins of Sentrin/SUMO-specific proteases 2 (SENP2)- Phosphoinositide-specific phospholipase C beta 4 (PLCß4) pathway was accessed by co-immunoprecipitation (Co-IP), and the calcium homeostasis associated proteins were observed via Western blot (WB). Subsequently, temozolomide (TMZ) pharmacologically blocked neurogenesis to verify the antidepressant effect of PAP on neurogenesis. The mechanism of PAP antidepressant effect was verified by constructing a sh-SENP2 virus vector to silence SENP2 protein. Finally, corticosterone (CORT)-induced PC12 cell model was used to verify whether PAP was involved in the process of deconjugated PLCß4 SUMOylated. The results showed that PAP improved depression-like behavior and neurogenesis induced by chronic unpredictable mild stimulation (CUMS). In addition, PAP acted on SENP2-PLCß4 pathway to deconjugate the SUMOylation of PLCß4 and affect calcium homeostasis. Pharmacological blockade of neurogenesis by TMZ treatment impaired the antidepressant efficacy of PAP. Knockout of SENP2 in the CUMS model attenuated the antidepressant response of PAP, and the impaired neurogenesis was not ameliorated by PAP treatment. In summary, PAP acted on the SENP2-PLCß4 signaling pathway to inhibit the SUMOylation of PLCß4 and maintain calcium homeostasis, thereby protecting neurogenesis and playing an antidepressant role.

Spatiotemporal Optical Control of Gαq-PLCß Interactions.

Cells experience time-varying and spatially heterogeneous chemokine signals in vivo, activating cell surface proteins including G protein-coupled receptors (GPCRs). The Gαq pathway activation by GPCRs is a major signaling axis with broad physiological and pathological significance. Compared with other Gα members, GαqGTP activates many crucial effectors, including PLCß (Phospholipase Cß) and Rho GEFs (Rho guanine nucleotide exchange factors). PLCß regulates many key processes, such as hematopoiesis, synaptogenesis, and cell cycle, and is therefore implicated in terminal-debilitating diseases, including cancer, epilepsy, Huntington's Disease, and Alzheimer's Disease. However, due to a lack of genetic and pharmacological tools, examining how the dynamic regulation of PLCß signaling controls cellular physiology has been difficult. Since activated PLCß induces several abrupt cellular changes, including cell morphology, examining how the other pathways downstream of Gq-GPCRs contribute to the overall signaling has also been difficult. Here we show the engineering, validation, and application of a highly selective and efficient optogenetic inhibitor (Opto-dHTH) to completely disrupt GαqGTP-PLCß interactions reversibly in user-defined cellular-subcellular regions on optical command. Using this newly gained PLCß signaling control, our data indicate that the molecular competition between RhoGEFs and PLCß for GαqGTP determines the potency of Gq-GPCR-governed directional cell migration.

Genetic mutation of Tas2r104/Tas2r105/Tas2r114 cluster leads to a loss of taste perception to denatonium benzoate and cucurbitacin B.

BACKGROUND: Bitter taste receptors (Tas2rs) are generally considered to sense various bitter compounds to escape the intake of toxic substances. Bitter taste receptors have been found to widely express in extraoral tissues and have important physiological functions outside the gustatory system in vivo. METHODS: To investigate the physiological functions of the bitter taste receptor cluster Tas2r106/Tas2r104/Tas2r105/Tas2r114 in lingual and extraoral tissues, multiple Tas2rs mutant mice and Gnat3 were produced using CRISPR/Cas9 gene-editing technique. A mixture containing Cas9 and sgRNA mRNAs for Tas2rs and Gnat3 gene was microinjected into the cytoplasm of the zygotes. Then, T7EN1 assays and sequencing were used to screen genetic mutation at the target sites in founder mice. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunostaining were used to study the expression level of taste signaling cascade and bitter taste receptor in taste buds. Perception to taste substance was also studied using two-bottle preference tests. RESULTS: We successfully produced several Tas2rs and Gnat3 mutant mice using the CRISPR/Cas9 technique. Immunostaining results showed that the expression of GNAT3 and PLCB2 was not altered in Tas2rs mutant mice. But qRT-PCR results revealed the changed expression profile of mTas2rs gene in taste buds of these mutant mice. With two-bottle preference tests, these mutant mice eliminate responses to cycloheximide due to genetic mutation of Tas2r105. In addition, these mutant mice showed a loss of taste perception to quinine dihydrochloride, denatonium benzoate, and cucurbitacin B (CuB). Gnat3-mediated taste receptor and its signal pathway contribute to CuB perception. CONCLUSIONS: These findings implied that these mutant mice would be a valuable means to understand the biological functions of TAS2Rs in extraoral tissues and investigate bitter compound-induced responses mediated by these TAS2Rs in many extraoral tissues.

The mechanism of Gαq regulation of PLCß3-catalyzed PIP2 hydrolysis.

PLCß (Phospholipase Cß) enzymes cleave phosphatidylinositol 4,5-bisphosphate (PIP2) producing IP3 and DAG (diacylglycerol). PIP2 modulates the function of many ion channels, while IP3 and DAG regulate intracellular Ca2+ levels and protein phosphorylation by protein kinase C, respectively. PLCß enzymes are under the control of G protein coupled receptor signaling through direct interactions with G proteins Gßγ and Gαq and have been shown to be coincidence detectors for dual stimulation of Gαq and Gαi-coupled receptors. PLCßs are aqueous-soluble cytoplasmic enzymes but partition onto the membrane surface to access their lipid substrate, complicating their functional and structural characterization. Using newly developed methods, we recently showed that Gßγ activates PLCß3 by recruiting it to the membrane. Using these same methods, here we show that Gαq increases the catalytic rate constant, kcat, of PLCß3. Since stimulation of PLCß3 by Gαq depends on an autoinhibitory element (the X-Y linker), we propose that Gαq produces partial relief of the X-Y linker autoinhibition through an allosteric mechanism. We also determined membrane-bound structures of the PLCß3·Gαq and PLCß3·Gßγ(2)·Gαq complexes, which show that these G proteins can bind simultaneously and independently of each other to regulate PLCß3 activity. The structures rationalize a finding in the enzyme assay, that costimulation by both G proteins follows a product rule of each independent stimulus. We conclude that baseline activity of PLCß3 is strongly suppressed, but the effect of G proteins, especially acting together, provides a robust stimulus upon G protein stimulation.

Expression of taste sentinels, T1R, T2R, and PLCß2, on the passageway for olfactory signals in zebrafish.

The senses of taste and smell detect overlapping sets of chemical compounds in fish, e.g. amino acids are detected by both senses. However, so far taste and smell organs appeared morphologically to be very distinct, with a specialized olfactory epithelium for detection of odors and taste buds located in the oral cavity and lip for detection of tastants. Here, we report dense clusters of cells expressing T1R and T2R receptors as well as their signal transduction molecule PLCß2 in nostrils of zebrafish, i.e. on the entrance funnel through which odor molecules must pass to be detected by olfactory sensory neurons. Quantitative evaluation shows the density of these chemosensory cells in the nostrils to be as high or higher than that in the established taste organs oral cavity and lower lip. Hydrodynamic flow is maximal at the nostril rim enabling high throughput chemosensation in this organ. Taken together, our results suggest a sentinel function for these chemosensory cells in the nostril.

Cadmium facilitates the formation of large lipid droplets via PLCß2-DAG-DGKε-PA signal pathway in Leydig cells.

Cadmium (Cd) exposure damages the reproductive system. Lipid droplets (LDs) play an important role in steroid-producing cells to provide raw material for steroid hormone. We have found that the LDs of Leydig cells exposed to Cd are bigger than those of normal cells, but the effects on steroidogenesis and its underlying mechanism remains unclear. Using Isobaric tag for relative and absolute quantitation (iTARQ) proteomics, phosphodiesterase beta-2 (PLCß2) was identified as the most significantly up-regulated protein in immature Leydig cells (ILCs) and adult Leydig cells (ALCs) derived from male rats exposed to maternal Cd. Consistent with high expression of PLCß2, the size of LDs was increased in Leydig cells exposed to Cd, accompanied by reduction in cholesterol and progesterone (P4) levels. However, the high PLCß2 did not result in high diacylglycerol (DAG) level, because Cd exposure up-regulated diacylglycerol kinases ε (DGKε) to promote the conversion from DAG to phosphatidic acid (PA). Exogenous PA, which was consistent with the intracellular PA concentration induced by Cd, facilitated the formation of large LDs in R2C cells, followed by reduced P4 level in the culture medium. When PLCß2 expression was knocked down, the increased DGKε caused by Cd was reversed, and then the PA level was decreased to normal. As results, large LDs returned to normal size, and the level of total cholesterol was improved to restore steroidogenesis. The accumulation of PA regulated by PLCß2-DAG-DGKε signal pathway is responsible for the formation of large LDs and insufficient steroid hormone synthesis in Leydig cells exposed to Cd. These data highlight that LD is an important target organelle for Cd-induced steroid hormone deficiency in males.