Biology subjects

Roy, A.

Publications and source records attributed to Roy, A..

At least 127 records · Page 7Linked to original sources

bioRxiv2022

Acute sleep deprivation induces synaptic remodeling at the soleus muscle neuromuscular junction in rats

Sleep is important for cognitive and physical performance. Sleep deprivation not only affects neural functions but also results in muscular fatigue. A good nights sleep reverses these functional derangements caused by sleep deprivation. The role of sleep in brain function has been extensively studied. However, its role in neuromuscular junction or skeletal muscle morphology is sparsely addressed although skeletal muscle atonia and suspended thermoregulation during rapid eye movement sleep possibly provides a conducive environment for the muscle to rest and repair; somewhat similar to slow-wave sleep for synaptic downscaling. In the present study, we have investigated the effect of 24 h sleep deprivation on the neuromuscular junction morphology and neurochemistry using electron microscopy and immunohistochemistry in the rat soleus muscle. Acute sleep deprivation altered synaptic ultra-structure viz. mitochondria, synaptic vesicle, synaptic proteins, basal lamina, and junctional folds needed for neuromuscular transmission. Further acute sleep deprivation showed the depletion of the neurotransmitter acetylcholine and the overactivity of its degrading enzyme acetylcholine esterase at the neuromuscular junction. The impact of sleep deprivation on synaptic homeostasis in the brain has been extensively reported recently. The present evidence from our studies shows new information on the role of sleep on neuromuscular junction homeostasis and its functioning. Statement of significanceSleep causes synaptic downscaling in the brain, and allows the brain to carry out various housekeeping functions. Here we have reported that the function of the sleep-wake cycle on the synaptic homeostasis extends beyond the brain. Acute sleep deprivation caused significant alteration at ultra and macrostructure of antigravity muscle and the neuromuscular junction along with adaptation to new fiber type in rats. These morpho-functional changes were well correlated with the biochemical assessment of the acetylcholine at the neuromuscular junction. These changes were partially recovered when the rats were allowed to recover from sleep deprivation. The findings suggest a new avenue for a sleep study; employing the neuromuscular junction for exploring the effect of sleep at energy and synaptic homeostasis levels.

neuroscience↗

bioRxiv2022

The extracellular RNA pool within Zea mays apoplast: composition and differential expression during Ustilago maydis infection

The existence of an extracellular pool of RNA (exRNA) has been documented in both animal and plant cells in a number of instances. These exRNA species play important role in host response against different environmental stimuli. The mechanism of their function however remains largely unknown. In this study we report the composition of the exRNA pool within the leaf apoplast of Z. mays under normal growth condition. We could detect RNA transcripts originating from both the genic as well as the intergenic regions of the nuclear, mitochondrial and chloroplast genomes of maize in our exRNA sequencing data. Our data showed increased abundance of about 75% of the exRNA transcripts during infection with a basidiomycete smut fungi, Ustilago maydis. Functional classification of the differentially abundant exRNA transcripts within U. maydis SG200 WT infected maize apoplast with respect to uninfected apoplast revealed significant enrichment of the exRNA transcripts corresponding to the ribosome biogenesis pathway. Data related to the effect of two extracellular T2 type ribonucleases, Nuc1 and Nuc2 from U. maydis on the composition of exRNA pool of maize is also presented.

plant biology↗

bioRxiv2022

PAF1 and FACT cooperate with MLL-AF4 to drive enhancer activity in leukemia

Aberrant enhancer activation has been identified as a key mechanism driving oncogene expression in many cancers. Here we use TOPmentation (Transcription factor-OPtimized ChIPmentation) to probe enhancer usage in primary MLL-rearranged acute lymphoblastic leukemia. We find that MLL-AF4, commonly held to promote transcription by binding to gene promoters, is also present at many active enhancers, where it assembles a complex of transcriptional co-activators normally found in the gene body. This includes DOT1L, ENL, PAF1, and a newly identified interaction with the histone chaperone FACT. By chemical degradation, we demonstrate that PAF1 and FACT are required for enhancer activity, including maintaining histone H3K27 acetylation, enhancer RNA transcription and enhancer-promoter interactions. This work identifies novel roles for PAF1 and FACT in enhancer function, and reveals an enhancer-targeting mechanism by which MLL-AF4 upregulates transcription, recruiting transcription machinery through a network of multivalent interactions to control enhancer activity and gene expression in acute leukemias.

molecular biology↗

bioRxiv2022

Protein kinase D promotes prostate cancer cell bone metastasis by positively regulating Runx2 in a MEK/ERK1/2-dependent manner

Most cancer patients die because of tumor metastasis not due to tumors at the primary site. Prostate tumors in advance stages frequently metastasize to the bone, which is the main cause of death for the disease. The family of protein kinase D (PKD) has been implicated in prostate cancer development, however, its role in prostate cancer metastasis has not been investigated. In this study, we examined the contribution of PKD to the metastatic potential of prostate cancer cells and the impact of PKD inhibition on prostate cancer bone metastasis in vivo. Our data showed that depletion of PKDs by siRNA or inhibition of PKD by an inhibitor CRT0066101 in a highly invasive prostate cancer PC3-ML cells potently inhibited colony formation and cell migration. Furthermore, depletion or inhibition of PKD significantly blocked invasion of PC3-ML cells and suppressed expression of genes related to bone metastasis. The reduced invasive activity resulted from PKD depletion was in part mediated through the transcription factor Runx2 as its silencing decreased PKD-mediated metastatic gene expression. Mechanistically, our data indicate that PKD modulated Runx2 target gene expression through the MEK/ERK1/2 signaling axis. Additionally, we examined whether PKD inhibitor CRT0066101 could prevent prostate cancer bone metastasis in a mouse model of metastasis, where intracardiac injection of PC3-ML cells led to metastasis of cells to the bone. We found that CRT0066101 potently decreased the frequency of micrometastases in mouse bone. These results indicate that PKDs play an important role in bone metastasis of prostate cancer cells and its inhibition may be beneficial for treatment of advanced stages of cancer.

cancer biology↗

bioRxiv2022

Subtractive proteomics analysis to uncover the potent drug targets for distinctive drug design of Candida auris

Candida auris is a serious health concern of current world that possess serious global health threat and is emerging at a high rate. Available antifungal drugs are failing to combat this pathogen as they are growing resistance toward those drugs and some strains have already showed resistant to all three available antifungal drugs in the market. Finding alternative treatments is a must, therefore, to save lives from this foe. To make the way easier for developing new treatments, we have made some insilico analysis of this pathogen to identify suitable targets for designing drugs and also suggested some potential metabolites to test in vivo condition after some computational analysis. After the subtraction of duplicate, non-essential, human homologs, non-metabolic, human microbiome similar and druggable proteins we ended up with three proteins (XP_028890156.1, XP_028891672.1 and XP_028891858.1) from a total of 5441 C. auris proteins. Blocking those proteins will result in the destruction of the pathogen while the host will remain safe from unintentional blocking. Their subcellular locations and interaction with high number of proteins also indicate their suitability as drug target candidates. After analyzing in silico docking of 29 potential antifungal from plant origin with those three proteins we selected Caledonixanthone E, Viniferin, Glaucine, Jatrorrhizine as the most potent weapon to block those proteins as they showed higher binding affinity. Furthermore, they were predicted to be safe and also showed proper ADME properties (Figure 1). O_FIG O_LINKSMALLFIG WIDTH=179 HEIGHT=200 SRC="FIGDIR/small/487516v1_fig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@5ac4bcorg.highwire.dtl.DTLVardef@12a4b3eorg.highwire.dtl.DTLVardef@1b1d825org.highwire.dtl.DTLVardef@e581b3_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1:C_FLOATNO Schematic pipeline of the process C_FIG

bioinformatics↗

bioRxiv2022

Cognitive dysfunction and anxiety resulted from synaptic downscaling, hippocampal atrophy and ventricular enlargement in i.c.v. streptozotocin injected male Wistar rats

Insulin-resistant brain state is proposed to be the early sign of Alzheimers disease(AD), which can be studied in intracerebroventricular streptozotocin (ICV-STZ) rodent model. ICV-STZ is reported to induce sporadic AD with the majority of the disease hallmarks as phenotype. On the other hand, Available experimental evidence has used varying doses of STZ (<1 to 3mg/kg) and studied its effect for different study durations, ranging from 14-270 days. Though these studies suggest 3mg/kg of ICV-STZ to be the optimum dose for progressive pathogenesis, the reason for such is elusive. Here we sought to investigate the mechanism of action of 3mg/kg ICV-STZ on cognitive and non-cognitive aspects at a follow-up interval of two weeks for two months. On 60th day, we examined layer thickness, cell density, ventricular volume, spine density, protein expression related to brain metabolism and mitochondrial function by histological examination. Findings suggest progressive loss of spatial, episodic, avoidance memory with increase in anxiety in a span of two month. Furthermore, hippocampal neurodegeneration, ventricular enlargement, diffused amyloid plaque deposition, loss of spine in dentate gyrus and imbalance in energy homeostasis was found on 60th day post injection. Interestingly, AD rats showed a uniform fraction of time spent in four quadrants of water maze with change in strategy when they were exposed to height. Our findings reveal that ICV-STZ injection at a dose of 3mg/kg can cause cognitive and neuropsychiatric abnormalities due to structural loss both at neuronal as well as synaptic level, which is tightly associated with change in neuronal metabolism.

neuroscience↗

bioRxiv2022

Human bone marrow organoids for disease modelling, discovery and validation of therapeutic targets in hematological malignancies

A lack of models that recapitulate the complexity of human bone marrow has hampered mechanistic studies of normal and malignant hematopoiesis and the validation of novel therapies. Here, we describe a step-wise, directed-differentiation protocol in which organoids are generated from iPSCs committed to mesenchymal, endothelial and hematopoietic lineages. These 3-dimensional structures capture key features of human bone marrow - stroma, lumen-forming sinusoidal vessels and myeloid cells including pro-platelet forming megakaryocytes. The organoids supported the engraftment and survival of cells from patients with blood malignancies, including cancer types notoriously difficult to maintain ex vivo. Fibrosis of the organoid occurred following TGF{beta} stimulation and engraftment with myelofibrosis but not healthy donor-derived cells, validating this platform as a powerful tool for studies of malignant cells and their interactions within a human bone marrow-like milieu. This enabling technology is likely to accelerate discovery and prioritization of novel targets for bone marrow disorders and blood cancers. Significance StatementWe present a 3D, vascularised human bone marrow organoid that supports growth of primary cells from patients with myeloid and lymphoid blood cancers. This model allows for mechanistic studies of blood cancers in the context of their microenvironment, and provides a much-needed, ex vivo tool for prioritization of new therapeutics.

cancer biology↗

bioRxiv2022

Targeting an evolutionarily conserved "E-L-L" motif in the spike protein to develop a small molecule fusion inhibitor against SARS-CoV-2

As newer variants of SARS-CoV-2 continue to pose major threats to global human health and economy, identifying novel druggable antiviral targets is the key towards sustenance. Here, we identify an evolutionary conserved "E-L-L" motif present within the HR2 domain of all human and non-human coronavirus spike (S) proteins that play a crucial role in stabilizing the post-fusion six-helix bundle (6-HB) structure and thus, fusion-mediated viral entry. Mutations within this motif reduce the fusogenicity of the S protein without affecting its stability or membrane localization. We found that posaconazole, an FDA-approved drug, binds to this "E-L-L" motif resulting in effective inhibition of SARS-CoV-2 infection in cells. While posaconazole exhibits high efficacy towards blocking S protein-mediated viral entry, mutations within the "E-L-L" motif rendered the protein completely resistant to the drug, establishing its specificity towards this motif. Our data demonstrate that posaconazole restricts early stages of infection through specific inhibition of membrane fusion and viral genome release into the host cell and is equally effective towards all major variants of concerns of SARS-CoV-2 including beta, kappa, delta, and omicron. Together, we show that this conserved essential "E-L-L" motif is an ideal target for the development of prophylactic and therapeutic interventions against SARS-CoV-2.

biochemistry↗

bioRxiv2022

Uneven terrain treadmill walking in younger and older adults

We developed a method for altering terrain unevenness on a treadmill to study gait kinematics. Terrain consisted of rigid polyurethane disks (12.7 cm diameter, 1.3-3.8 cm tall) which attached to the treadmill belt using hook-and-loop fasteners. Here, we tested four terrain unevenness conditions: Flat, Low, Medium, and High. The main objective was to test the hypothesis that increasing the unevenness of the terrain would result in greater gait kinematic variability. Seventeen younger adults (age 20-40 years), 25 higher-functioning older adults (age 65+ years), and 29 lower-functioning older adults (age 65+ years, Short Physical Performance Battery score < 10) participated. We customized the treadmill speed to each participants walking ability, keeping the speed constant across all four terrain conditions. Participants completed two 3-minute walking trials per condition. Using an inertial measurement unit placed over the sacrum and pressure sensors in the shoes, we calculated the stride-to-stride variability in step duration and sacral excursion (coefficient of variation; standard deviation expressed as percentage of the mean). Participants also self-reported their perceived stability for each condition. Terrain was a significant predictor of step duration variability, which roughly doubled from Flat to High terrain for all participant groups: younger adults (Flat 4.0%, High 8.2%), higher-functioning older adults (Flat 5.0%, High 8.9%), lower-functioning older adults (Flat 7.0%, High 14.1%). Similarly, all groups exhibited significant increases in sacral excursion variability for all three uneven terrain conditions compared to Flat. Participants were also significantly more likely to report feeling less stable walking over all three uneven terrain conditions compared to Flat. These findings support the hypothesis that altering terrain unevenness on a treadmill will increase gait kinematic variability and reduce perceived stability in younger and older adults.

bioengineering↗

bioRxiv2022

Discovery of small molecule inhibitors of Plasmodium falciparum apicoplast DNA polymerase

Malaria is caused by infection with protozoan parasites of the Plasmodium genus, which is part of the phylum Apicomplexa. Most organisms in this phylum contain a relic plastid called the apicoplast. The apicoplast genome is replicated by a single DNA polymerase (apPOL), which is an attractive target for anti-malarial drugs. We screened small-molecule libraries (206,504 compounds) using a fluorescence-based high-throughput DNA polymerase assay. Dose/response analysis and counter-screening identified 186 specific apPOL inhibitors. Toxicity screening against human HepaRG human cells removed 84 compounds and the remaining were subjected to parasite killing assays using chloroquine resistant P. falciparum parasites. Nine compounds were potent inhibitors of parasite growth and may serve as lead compounds in efforts to discover novel malaria drugs.

biochemistry↗

bioRxiv2022

Discovery of compounds that inhibit SARS-CoV-2 Mac1-ADP-ribose binding by high-throughput screening

The emergence of several zoonotic viruses in the last twenty years, especially the pandemic outbreak of SARS-CoV-2, has exposed a dearth of antiviral drug therapies for viruses with pandemic potential. Developing a diverse drug portfolio will be critical for our ability to rapidly respond to novel coronaviruses (CoVs) and other viruses with pandemic potential. Here we focus on the SARS-CoV-2 conserved macrodomain (Mac1), a small domain of non-structural protein 3 (nsp3). Mac1 is an ADP-ribosylhydrolase that cleaves mono-ADP-ribose (MAR) from target proteins, protects the virus from the anti-viral effects of host ADP-ribosyltransferases, and is critical for the replication and pathogenesis of CoVs. In this study, a luminescent-based high-throughput assay was used to screen [~]38,000 small molecules for those that could inhibit Mac1-ADP-ribose binding. We identified 5 compounds amongst 3 chemotypes that inhibit SARS-CoV-2 Mac1-ADP-ribose binding in multiple assays with IC50 values less than 100{micro}M, inhibit ADP-ribosylhydrolase activity, and have evidence of direct Mac1 binding. These chemotypes are strong candidates for further derivatization into highly effective Mac1 inhibitors.

biochemistry↗

bioRxiv2022

Design, Synthesis and Evaluation of Inhibitors of the SARS-CoV-2 nsp3 Macrodomain

A series of amino acid based 7H-pyrrolo[2,3-d]pyrimidines were designed and synthesized to discern the structure activity relationships against the SARS-CoV-2 nsp3 macrodomain (Mac1), an ADP-ribosylhydrolase that is critical for coronavirus replication and pathogenesis. Structure activity studies identified compound 15c as a low-micromolar inhibitor of Mac1 in two ADP-ribose binding assays. This compound also demonstrated inhibition in an enzymatic assay of Mac1 and displayed a thermal shift comparable to ADPr in the melting temperature of Mac1 supporting binding to the target protein. A structural model reproducibly predicted a binding mode where the pyrrolo pyrimidine forms a hydrogen bonding network with Asp22 and the amide backbone NH of Ile23 in the adenosine binding pocket and the carboxylate forms hydrogen bonds to the amide backbone of Phe157 and Asp156, part of the oxyanion subsite of Mac1. Compound 15c also demonstrated notable selectivity for coronavirus macrodomains when tested against a panel of ADP-ribose binding proteins. Together, this study identified several low MW, low M Mac1 inhibitors to use as small molecule chemical probes for this potential anti-viral target and offers starting points for further optimization. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=83 SRC="FIGDIR/small/482176v1_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@167aceorg.highwire.dtl.DTLVardef@1d88c47org.highwire.dtl.DTLVardef@1e1b34borg.highwire.dtl.DTLVardef@c2321a_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2022

Molecular insights into the recognition of acetylated histone modifications by the BRPF2 bromodomain

HBO1 (HAT bound to ORC), a member of the MYST family of histone acetyltransferases (HATs), was initially identified as a binding partner of the origin recognition complex (ORC) that acetylates free histone H3, H4, and nucleosomal H3. It functions as a quaternary complex with the BRPF (BRPF1/2/3) scaffolding protein and two accessory proteins, ING4/5 and Eaf6. BRPF2 interaction with HBO1 has been shown to be important for regulating H3K14 acetylation during embryonic development. However, how the BRPF2 directs the HBO1 HAT complex to chromatin to regulate its HAT activity towards nucleosomal substrates remains unclear. Our findings reveal novel interacting partners of the BRPF2 bromodomain that recognizes different acetyllysine residues on the N-terminus of histone H4, H3, and H2A and preferentially binds to H4K5ac, H4K8ac, and H4K5acK12ac modifications. Further, mutational analysis of BRPF2 bromodomain coupled with ITC binding and pull-down assays on the histone substrates identified critical residues responsible for acetyllysine binding. Moreover, the BRPF2 bromodomain could enrich H4K5ac mark-bearing mononucleosomes compared to other acetylated H4 marks. Consistent with this, ChIP-seq analysis revealed that BRPF2 strongly co-localizes with HBO1 at histone H4K5ac and H4K8ac marks near the TSS in the genome. Together, our study provides novel insights into how the histone binding function of the BRPF2 bromodomain directs the recruitment of the HBO1 HAT complex to chromatin to regulate gene expression.

biochemistry↗

bioRxiv2022

Postnatal developmental trajectory of sex-biased gene expression in the mouse pituitary gland

The pituitary gland regulates essential physiological processes such as growth, pubertal onset, stress response, metabolism, reproduction, and lactation. While sex biases in these functions and hormone production have been described, the underlying identity, temporal deployment, and cell-type specificity of sex-biased pituitary gene regulatory networks are not fully understood. To capture sex differences in pituitary gene regulation dynamics during postnatal development, we performed 3 untranslated region sequencing and small RNA sequencing to ascertain gene and microRNA expression respectively across five postnatal ages (postnatal days 12, 22, 27, 32, 37) that span the pubertal transition in female and male C57BL/6J mouse pituitaries (n=5-6 biological replicates for each sex at each age). We observed over 900 instances of sex-biased gene expression and 17 sex-biased microRNAs, with the majority of sex differences occurring with puberty. Using miRNA-gene target interaction databases, we identified 18 sex-biased genes that were putative targets of 5 sex-biased microRNAs. In addition, by combining our bulk RNA-seq with publicly available male and female mouse pituitary single-nuclei RNA-seq data, we obtained evidence that cell-type proportion sex differences exist prior to puberty and persist post-puberty for three major hormone-producing cell types: somatotropes, lactotropes, and gonadotropes. Finally, we predicted sex-biased genes in these three pituitary cell types after accounting for cell-type proportion differences between sexes. Our study reveals the identity and postnatal developmental trajectory of sex-biased gene expression in the mouse pituitary. This work also highlights the importance of considering sex biases in cell-type composition when understanding sex differences in the processes regulated by the pituitary gland. HighlightsO_LIMale and female mouse pituitary gland gene and miRNA expression was profiled across five postnatal ages spanning pubertal development C_LIO_LIAbundant sex differences in pituitary gene expression exist prior to puberty and become more prominent upon puberty C_LIO_LICombining expression data from genes and miRNAs revealed 18 putative sex-biased gene targets of 5 sex-biased miRNAs C_LIO_LISex differences in the proportions of somatotropes, lactotropes, and gonadotropes are predicted to occur prior to puberty C_LI

genomics↗

bioRxiv2021

A somatosensory computation that unifies bodies and tools

It is often claimed that tools are embodied by the user, but whether the brain actually repurposes its body-based computations to perform similar tasks with tools is not known. A fundamental computation for localizing touch on the body is trilateration. Here, the location of touch on a limb is computed by integrating estimates of the distance between sensory input and its boundaries (e.g., elbow and wrist of the forearm). As evidence of this computational mechanism, tactile localization on a limb is most precise near its boundaries and lowest in the middle. We show that the brain repurposes trilateration to localize touch on a tool. In a large sample of participants, we found that localizing touch on a tool produced the signature of trilateration, with highest precision close to the base and tip of the tool. A computational model of trilateration provided a good fit to the observed localization behavior. To further demonstrate the computational plausibility of repurposing trilateration, we implemented it in a three-layer neural network that was based on principles of probabilistic population coding. This network determined hit location in tool-centered coordinates by using a tools unique pattern of vibrations when contacting an object. Simulations demonstrated the expected signature of trilateration, in line with the behavioral patterns. Our results have important implications for how trilateration may be implemented by somatosensory neural populations. We conclude that trilateration is a fundamental spatial computation that unifies limbs and tools.

neuroscience↗

bioRxiv2021

An evolutionary divergent thermodynamic brake in ZAP-70 finetunes the kinetic proofreading in T cell

T cell signaling starts with assembling several tyrosine kinases and adaptor proteins to the T cell receptor (TCR), following the antigen binding. The lifetime of the TCR: antigen complex and the time delay between the recruitment and activation of each kinase determines the T cell response. The mechanism by which the time delays are implemented in TCR signaling is not fully understood. Combining experiments and kinetic modeling, we here report a thermodynamic-brake in the regulatory module of ZAP-70, which determines the ligand selectivity, and may delay the ZAP-70 activation in TCR. Phylogenetic analysis revealed that the evolution of the thermodynamic-brake coincides with the divergence of the adaptive immune system to the cell-mediated and humoral responses. Paralogous kinase Syk expressed in B cells, does not possess such a functional thermodynamic brake, which may explain higher basal activation and lack of ligand selectivity by Syk.

biochemistry↗

bioRxiv2021

Inhibition of SARS-CoV-2 spike protein palmitoylation reduces virus infectivity

Spike glycoproteins of almost all enveloped viruses are known to undergo post-translational attachment of palmitic acid moieties. The precise role of such palmitoylation of the spike protein in membrane fusion and infection is not completely understood. Here, we report that palmitoylation of the first five cysteine residues of the c-terminal cysteine-rich domain of the SARS-CoV-2 spike are indispensable for infection and palmitoylation deficient spike mutants are defective in trimerization and subsequent membrane fusion. The DHHC9 palmitoyltransferase interacts with and palmitoylates the spike protein in the ER and Golgi, and knockdown of DHHC9 results in reduced fusion and infection of SARS-CoV-2. Two bis-piperazine backbone-based DHHC9 inhibitors inhibit SARS-CoV-2 spike protein palmitoylation and the resulting progeny virion particles released are defective in fusion and infection. This establishes these palmitoyltransferase inhibitors as potential new intervention strategies against SARS-CoV-2.

molecular biology↗

bioRxiv2021

A mitochondrial electron transport chain with atypical subunit composition confers oxygen sensitivity to a mammalian chemoreceptor

The carotid body (CB) is the major chemoreceptor for blood oxygen in the control of ventilation in mammals, contributing to physiological adaptation to high altitude, pregnancy, and exercise, and its hyperactivity is linked to chronic conditions such as sleep-disorder breathing, hypertension, chronic heart failure, airway constriction, and metabolic syndrome (1-3). Upon acute hypoxia (PO2=100 mmHg to <80 mmHg), K+ channels on CB glomus cells are inhibited, causing membrane depolarization to trigger Ca+2 influx and neurotransmitter release that stimulates afferent nerves (1-3). A longstanding model proposes that the CB senses hypoxia through atypical mitochondrial electron transport chain (ETC) metabolism that is more sensitive to decreases in oxygen than other tissues. This model is supported by observations that ETC inhibition by pharmacology and gene knockout activates CB sensory activity and that smaller decreases in oxygen concentration inhibit ETC activity in CB cells compared to other cells (1-5). Determining the composition of atypical ETC subunits in the CB and their specific activities is essential to delineate molecular mechanisms underlying the mitochondrial hypothesis of oxygen sensing. Here, we identify HIGD1C, a novel hypoxia inducible gene domain factor isoform, as an ETC Complex IV (CIV) protein highly and selectively expressed in glomus cells that mediates acute oxygen sensing by the CB. We demonstrate that HIGD1C negatively regulates oxygen consumption by CIV and acts with the hypoxia-induced CIV subunit COX4I2 to enhance the sensitivity of CIV to hypoxia, constituting an important component of mitochondrial oxygen sensing in the CB. Determining how HIGD1C and other atypical CIV proteins expressed in the CB work together to confer exquisite oxygen sensing to the ETC will help us better understand how tissue- and condition-specific CIV subunits contribute to physiological function and disease (6) and allow us to potentially target these proteins to treat chronic diseases characterized by CB dysfunction (7).

physiology↗