Extra sensory perception: the role of Gpr receptors in the kidney

Clostridium butyricum Prevents Dysbiosis and the Rise in Blood Pressure in Spontaneously Hypertensive Rats

Hypertension is accompanied by dysbiosis and a decrease in the relative abundance of short-chain fatty acid (SCFA)-producing bacteria. However, there is no report to examine the role of C. butyricum in blood pressure regulation. We hypothesized that a decrease in the relative abundance of SCFA-producing bacteria in the gut was the cause of spontaneously hypertensive rats (SHR)-induced hypertension. C. butyricum and captopril were used to treat adult SHR for six weeks. C. butyricum modulated SHR-induced dysbiosis and significantly reduced systolic blood pressure (SBP) in SHR (p < 0.01). A 16S rRNA analysis determined changes in the relative abundance of the mainly SCFA-producing bacteria Akkermansia muciniphila, Lactobacillus amylovorus, and Agthobacter rectalis, which increased significantly. Total SCFAs, and particularly butyrate concentrations, in the SHR cecum and plasma were reduced (p < 0.05), while C. butyricum prevented this effect. Likewise, we supplemented SHR with butyrate for six weeks. We analyzed the flora composition, cecum SCFA concentration, and inflammatory response. The results showed that butyrate prevented SHR-induced hypertension and inflammation, and the decline of cecum SCFA concentrations (p < 0.05). This research revealed that increasing cecum butyrate concentrations by probiotics, or direct butyrate supplementation, prevented the adverse effects of SHR on intestinal flora, vascular, and blood pressure.

The gut microbiome and obstructive sleep apnea syndrome in children

Obstructive sleep apnea syndrome (OSAS) in children has become a major public health problem that affects the physical and mental growth of children. OSAS can result in adverse outcomes during growth and development, inhibiting the normal development of the metabolic, cardiovascular, and immune systems. OSAS is characterized by partial or complete obstruction of the upper airway, and prolonged obstruction that causes intermittent hypoxia and sleep fragmentation in children. The human microbiota is a complex community that is in dynamic equilibrium in the human body. Intermittent hypoxia and sleep fragmentation induced by childhood OSAS alter the composition of the gut microbiome. At the same time, changes in the gut microbiome affect sleep patterns in children through immunomodulatory and metabolic mechanisms, and induce further comorbidities, such as obesity, hypertension, and cardiovascular disease. This article discusses recent progress in research into the mechanisms of OSAS-induced changes in the gut microbiota and its pathophysiology in children.

Prebiotics, Probiotics, and Acetate Supplementation Prevent Hypertension in a Model of Obstructive Sleep Apnea

Disruption of the gut microbiota, termed gut dysbiosis, has been described in animal models of hypertension and hypertensive patients. We have shown that gut dysbiosis plays a causal role in the development of hypertension in a rat model of obstructive sleep apnea (OSA). Functional analysis of the dysbiotic microbiota in OSA demonstrates a loss of short chain fatty acid-producing bacteria. However, measurements of short chain fatty acid concentrations and testing of their role in blood pressure regulation are lacking. We hypothesized that reduced short chain fatty acids in the gut are responsible for OSA-induced hypertension. OSA significantly increased systolic blood pressure at 7 and 14 days ( P<0.05), an effect that was abolished by the probiotic Clostridium butyricum or the prebiotic Hylon VII. The 16S rRNA analysis identified several short chain fatty acid-producing bacteria that were significantly increased by Cbutyricum and Hylon treatment. Acetate concentration in the cecum was decreased by 48% after OSA ( P<0.05), an effect that was prevented by Cbutyricum and Hylon. Cbutyricum and Hylon reduced OSA-induced dysbiosis, epithelial goblet cell loss, mucus barrier thinning, and activation of brain microglia ( P<0.05 for each). To examine the role of acetate in OSA-induced hypertension, we chronically infused acetate into the cecum during 2 weeks of sham or OSA. Restoring cecal acetate concentration prevented OSA-induced gut inflammation and hypertension ( P<0.05). These studies identify acetate as a key player in OSA-induced hypertension. We demonstrate that various methods to increase cecal acetate concentrations are protective from the adverse effects of OSA on the microbiota, gut, brain, and blood pressure.

Putative chemosensory receptors are differentially expressed in the sensory organs of male and female crown-of-thorns starfish, Acanthaster planci

BACKGROUND

Chemosensation is a critical signalling process for all organisms and is achieved through the interaction between chemosensory receptors and their ligands. The Crown-of-thorns starfish, Acanthaster planci species complex (COTS), is a predator of coral polyps and Acanthaster cf. solaris is currently considered to be one of the main drivers of coral loss on the Great Barrier Reef in Queensland, Australia.

RESULTS

This study reveals the presence of putative variant Ionotropic Receptors (IRs) which are differentially expressed in the olfactory organs of COTS. Several other types of G protein-coupled receptors such as adrenergic, metabotropic glutamate, cholecystokinin, trace-amine associated, GRL101 and GPCR52 receptors have also been identified. Several receptors display male-biased expression within the sensory tentacles, indicating possible reproductive significance.

CONCLUSIONS

Many of the receptors identified in this study may have a role in reproduction and are therefore key targets for further investigation. Based on their differential expression within the olfactory organs and presence in multiple tissues, it is possible that several of these receptor types have expanded within the Echinoderm lineage. Many are likely to be species-specific with novel ligand-binding affinity and a diverse range of functions. This study is the first to describe the presence of variant Ionotropic Glutamate Receptors in any Echinoderm, and is only the second study to investigate chemosensory receptors in any starfish or marine pest. These results represent a significant step forward in understanding the chemosensory abilities of COTS.

Attenuation of Microbiotal Dysbiosis and Hypertension in a CRISPR/Cas9 Gene Ablation Rat Model of GPER1

G-protein-coupled estrogen receptor, Gper1, has been implicated in cardiovascular disease, but its mechanistic role in blood pressure control is poorly understood. Here, we demonstrate that genetically salt-sensitive hypertensive rats with complete genomic excision of Gper1 by a multiplexed guide RNA CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9 (CRISPR associated proteins) approach present with lower blood pressure, which was accompanied by altered microbiota, different levels of circulating short chain fatty acids, and improved vascular relaxation. Microbiotal transplantation from hypertensive Gper1+/+ rats reversed the cardiovascular protective effect exerted by the genomic deletion of Gper1. Thus, this study reveals a role for Gper1 in promoting microbiotal alterations that contribute to cardiovascular pathology. However, the exact mechanism by which Gper1 regulates blood pressure is still unknown. Our results indicate that the function of Gper1 is contextually dependent on the microbiome, whereby, contemplation of using Gper1 as a target for therapy of cardiovascular disease requires caution.

Expression of the candidate fat taste receptors in human fungiform papillae and the association with fat taste function

Significant experimental evidence supports fat as a taste modality; however, the associated peripheral mechanisms are not well established. Several candidate taste receptors have been identified, but their expression pattern and potential functions in human fungiform papillae remain unknown. The aim of this study is to identify the fat taste candidate receptors and ion channels that were expressed in human fungiform taste buds and their association with oral sensory of fatty acids. For the expression analysis, quantitative RT-PCR (qRT-PCR) from RNA extracted from human fungiform papillae samples was used to determine the expression of candidate fatty acid receptors and ion channels. Western blotting analysis was used to confirm the presence of the proteins in fungiform papillae. Immunohistochemistry analysis was used to localise the expressed receptors or ion channels in the taste buds of fungiform papillae. The correlation study was analysed between the expression level of the expressed fat taste receptors or ion channels indicated by qRT-PCR and fat taste threshold, liking of fatty food and fat intake. As a result, qRT-PCR and western blotting indicated that mRNA and protein of CD36, FFAR4, FFAR2, GPR84 and delayed rectifying K+ channels are expressed in human fungiform taste buds. The expression level of CD36 was associated with the liking difference score (R −0·567, β=−0·04, P=0·04) between high-fat and low-fat food and FFAR2 was associated with total fat intake (ρ=−0·535, β=−0·01, P=0·003) and saturated fat intake (ρ=−0·641, β=−0·02, P=0·008).

Olfactory Receptors in Non-Chemosensory Organs: The Nervous System in Health and Disease

Olfactory receptors (ORs) and down-stream functional signaling molecules adenylyl cyclase 3 (AC3), olfactory G protein α subunit (Gαolf), OR transporters receptor transporter proteins 1 and 2 (RTP1 and RTP2), receptor expression enhancing protein 1 (REEP1), and UDP-glucuronosyltransferases (UGTs) are expressed in neurons of the human and murine central nervous system (CNS). In vitro studies have shown that these receptors react to external stimuli and therefore are equipped to be functional. However, ORs are not directly related to the detection of odors. Several molecules delivered from the blood, cerebrospinal fluid, neighboring local neurons and glial cells, distant cells through the extracellular space, and the cells’ own self-regulating internal homeostasis can be postulated as possible ligands. Moreover, a single neuron outside the olfactory epithelium expresses more than one receptor, and the mechanism of transcriptional regulation may be different in olfactory epithelia and brain neurons. OR gene expression is altered in several neurodegenerative diseases including Parkinson’s disease (PD), Alzheimer’s disease (AD), progressive supranuclear palsy (PSP) and sporadic Creutzfeldt-Jakob disease (sCJD) subtypes MM1 and VV2 with disease-, region- and subtype-specific patterns. Altered gene expression is also observed in the prefrontal cortex in schizophrenia with a major but not total influence of chlorpromazine treatment. Preliminary parallel observations have also shown the presence of taste receptors (TASRs), mainly of the bitter taste family, in the mammalian brain, whose function is not related to taste. TASRs in brain are also abnormally regulated in neurodegenerative diseases. These seminal observations point to the need for further studies on ORs and TASRs chemoreceptors in the mammalian brain.

Quantitative deep mapping of the cultured podocyte proteome uncovers shifts in proteostatic mechanisms during differentiation

The renal filtration barrier is maintained by the renal podocyte, an epithelial postmitotic cell. Immortalized mouse podocyte cell lines-both in the differentiated and undifferentiated state-are widely utilized tools to estimate podocyte injury and cytoskeletal rearrangement processes in vitro. Here, we mapped the cultured podocyte proteome at a depth of more than 8,800 proteins and quantified 7,240 proteins. Copy numbers of proteins mutated in forms of hereditary nephrotic syndrome or focal segmental glomerulosclerosis (FSGS) were assessed. We found that cultured podocytes express abundant copy numbers of endogenous receptors, such as tyrosine kinase membrane receptors, the G protein-coupled receptor (GPCR), NPR3 (ANP receptor), and several poorly characterized GPCRs. The data set was correlated with deep mapping mRNA sequencing ("mRNAseq") data from the native mouse podocyte, the native mouse podocyte proteome and staining intensities from the human protein atlas. The generated data set was similar to these previously published resources, but several native and high-abundant podocyte-specific proteins were not identified in the data set. Notably, this data set detected general perturbations in proteostatic mechanisms as a dominant alteration during podocyte differentiation, with high proteasome activity in the undifferentiated state and markedly increased expression of lysosomal proteins in the differentiated state. Phosphoproteomics analysis of mouse podocytes at a resolution of more than 3,000 sites suggested a preference of phosphorylation of actin filament-associated proteins in the differentiated state. The data set obtained here provides a resource and provides the means for deep mapping of the native podocyte proteome and phosphoproteome in a similar manner.

Identification and characterization of novel renal sensory receptors

Recent studies have highlighted the important roles that “sensory” receptors (olfactory receptors, taste receptors, and orphan “GPR” receptors) play in a variety of tissues, including the kidney. Although several studies have identified important roles that individual sensory receptors play in the kidney, there has not been a systematic analysis of the renal repertoire of sensory receptors. In this study, we identify novel renal sensory receptors belonging to the GPR (n = 76), olfactory receptor (n = 6), and taste receptor (n = 11) gene families. A variety of reverse transcriptase (RT)- PCR screening strategies were used to identify novel renal sensory receptors, which were subsequently confirmed using gene-specific primers. The tissue-specific distribution of these receptors was determined, and the novel renal ORs were cloned from whole mouse kidney. Renal ORs that trafficked properly in vitro were screened for potential ligands using a dual-luciferase ligand screen, and novel ligands were identified for Olfr691. These studies demonstrate that multiple sensory receptors are expressed in the kidney beyond those previously identified. These results greatly expand the known repertoire of renal sensory receptors. Importantly, the mRNA of many of the receptors identified in this study are expressed highly in the kidney (comparable to well-known and extensively studied renal GPCRs), and in future studies it will be important to elucidate the roles that these novel renal receptors play in renal physiology.