Allyn C Howlett

Allyn C Howlett
Wake Forest School of Medicine · Department of Physiology and Pharmacology

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216
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Publications

Publications (216)
Article
Cannabinoid Receptor Interacting Protein isoform 1b (CRIP1b) is known to interact with the CB1 receptor. Alternative splicing of the CNRIP1 gene produces CRIP1a and CRIP1b with a difference in the third exon only. Exons 1 and 2 encode for a functional domain in both proteins. CRIP1a is involved in regulating CB1 receptor internalization, but the fu...
Chapter
Full-text available
G protein-coupled receptors (GPCRs) are important regulators of cellular signaling functions and therefore are a major target for drug discovery. The CB1 cannabinoid receptor is among the most highly expressed GPCRs in neurons, where it regulates many differentiated neuronal functions. One model system for studying the biochemistry of neuronal resp...
Chapter
The CB1 and CB2 cannabinoid receptors (CB1R, CB2R) are members of the G protein-coupled receptor (GPCR) family that were identified over 20 years ago. CB1Rs and CB2Rs mediate the effects of Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the principal psychoactive constituent of marijuana, and subsequently identified endogenous cannabinoids (endocannabinoids) an...
Article
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Recent studies have used conditional knockout mice to selectively delete the D2 autoreceptor; however, these approaches result in global deletion of D2 autoreceptors early in development. The present study takes a different approach using RNA interference (RNAi) to knockdown the expression of the D2 receptors (D2R) in the substantia nigra (SN), inc...
Article
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Cannabinoid Receptor Interacting Protein1a (CRIP1a) is a CB1 receptor (CB1R) distal C-terminus-associated protein that alters CB1R interactions with G-proteins (Blume et al.,2015; Smith et al.,2015). We tested the hypothesis that CRIP1a is capable of also altering CB1R interactions with β-arrestin proteins that interact with the CB1R at the C-termi...
Article
Dysregulated expression and function of dopamine D2 receptors (D2Rs) are implicated in drug addiction, Parkinson's disease and schizophrenia. In the current study, we examined whether D2Rs are modulated by regulator of G protein signaling 2 (RGS2), a member of the RGS family that regulates G protein signaling via acceleration of GTPase activity. Us...
Article
Cannabinoid Receptor Interacting Protein1a (CRIP1a) is a CB1 receptor (CB1R) distal C-terminus-associated protein that modulates CB1R signaling via G proteins, and CB1R down-regulation but not desensitization (Blume et al.,2015; Smith et al.,2015). In the present study, we determined the involvement of CRIP1a in CB1R plasma membrane trafficking. To...
Article
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CB1 cannabinoid receptors are expressed on vagal afferent fibers and neurons within the solitary tract nucleus (NTS), providing anatomical evidence for their role in arterial baroreflex modulation. To better understand the relationship between the brain renin-angiotensin system (RAS) and endocannabinoid expression within the NTS, we measured dorsal...
Conference Paper
CB1 cannabinoid receptors (CB1R) are found in abundance in the neurons where they can affect neuronal plasticity by modulating intracellular signal transduction mechanisms including cAMP (1) and Ca2+ (2,3) dynamics. The presence of the G-protein coupled calcium-sensing receptor (CaS) has been previously demonstrated in N18TG2 neuroblastoma cells (4...
Article
To improve overall healthcare and to reduce health disparities, efforts must focus on increasing the diversity of personnel trained in the biomedical sciences. Here, we describe the development, implementation, and relative outcomes of three pipeline training programs in biomedical sciences research designed to increase workforce diversity institut...
Article
Background: CB1 cannabinoid receptors (CB1Rs) stimulate Gi/o-dependent signaling pathways. CB1R-mediated cAMP increases were proposed to result from Gs activation, but CB1R-stimulated GTPγS binding to Gs has not heretofore been investigated. Methods: Three models of CB1R-stimulated cAMP production were tested: pertussis toxin disruption of Gi/o...
Article
Hypertension resulting from elevated brain angiotensin (Ang) II is associated with impaired functioning of neural reflexes regulating sympathetic and parasympathetic outflow. Restoration of normal baroreflex sensitivity (BRS) for control of heart rate (HR) is achieved in a rat model of Ang II - dependent hypertension [(mRen2)27 transgenic rats] by...
Article
Low-frequency ultrasound (LFU) in the frequency range 30-40 kHz administered using different delivery methods (waterbath and noncontact spray) has shown positive effects on chronic wound healing rates in humans, but the underlying mechanisms are only beginning to be explored. To examine the effects of LFU delivered at 35 kHz on the morphology and m...
Article
The GABAB receptor is a therapeutic target for CNS and neuropathic disorders; however, few preclinical studies have explored effects of chronic stimulation. This study evaluated acute and chronic baclofen treatments on GABAB-activated G-proteins and signaling protein phosphorylation as indicators of GABAB signaling capacity. Brain sections from rat...
Article
Full-text available
Cannabinoid CB1 receptors (CB1R) mediate the presynaptic effects of endocannabinoids in the central nervous system (CNS) and most behavioral effects of exogenous cannabinoids. Cannabinoid Receptor-Interacting Protein 1a (CRIP1a) binds to the CB1R C-terminus and can attenuate constitutive CB1R-mediated inhibition of Ca(2+) channel activity. We now d...
Article
Full-text available
As they age, Sprague-Dawley (SD) rats develop elevated systolic blood pressure associated with impaired baroreflex sensitivity (BRS) for control of heart rate. We previously demonstrated in young hypertensive (mRen2)27 rats that impaired BRS is restored by CB1 cannabinoid receptor blockade in the solitary tract nucleus (NTS), consistent with elevat...
Article
CB1 cannabinoid receptors (CB1R) are one of the most abundantly expressed G protein coupled receptors (GPCR) in the CNS and regulate diverse neuronal functions. The identification of GPCR interacting proteins has provided additional insight into the fine-tuning and regulation of numerous GPCRs. The cannabinoid receptor interacting protein 1a (CRIP1...
Conference Paper
Objectives To investigate the role of COX-derived prostanoids and the endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide (AEA) on uterine vascular control during early pregnancy in a rodent model of preeclampsia. Methods The transgenic female rat containing the human angiotensinogen (hAGN) gene mated with the male transgenic containing h...
Article
Full-text available
Isolation and structure elucidation of most of the major cannabinoid constituents - including Δ(9)-tetrahydrocannabinol (Δ(9)-THC), which is the principal psychoactive molecule in Cannabis sativa - was achieved in the 1960s and 1970s. It was followed by the identification of two cannabinoid receptors in the 1980s and the early 1990s and by the iden...
Article
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We investigated acute and chronic effects of CB1 cannabinoid receptor blockade in renin-angiotensin system-dependent hypertension using rimonabant (SR141716A), an orally active antagonist with central and peripheral actions. In transgenic (mRen2)27 rats, a model of angiotensin II-dependent hypertension with increased body mass and insulin resistanc...
Chapter
The progression from Raphael Mechoulam's identification of Δ9-tetrahydrocannabinol as the primary psychoactive component of cannabis, through the design of cannabinoid analogues by academic and pharmaceutical chemists, to the discovery of CB1 and CB2 cannabinoid receptors, brings us to modern pharmacological investigation. The CB1 receptor interact...
Article
Full-text available
Increased vascular sensitivity to angiotensin II (Ang II) is a marker of a hypertensive human pregnancy. Recent evidence of interactions between the renin-angiotensin system and the endocannabinoid system suggests that anandamide and 2-arachidonoylglycerol may modulate Ang II contraction. We hypothesized that these interactions may contribute to th...
Article
Skin fibroblasts comprise the first barrier of defense against wounds, and tobacco products directly contact the oral cavity. Cultured human dermal fibroblasts were exposed to smokeless tobacco extract (STE), total particulate matter (TPM) from tobacco smoke, or nicotine at concentrations comparable to those found in these extracts for 1 h or 5 h....
Article
The contribution of individual CB receptors (CB1 R and CB2 R) to normal micturition has not been clearly defined. Our goal was to study if differences in urodynamic parameters or in vitro bladder contractility can be demonstrated between CB2 R knockout (CB2 RKO) and C57BL/6J control (wild type, WT) mice. Female WT and CB2 RKO mice underwent bladder...
Article
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Dopamine D2 autoreceptors located on the midbrain dopaminergic neurons modulate dopamine (DA) neuron firing, DA release, and DA synthesis through a negative feedback mechanism. Dysfunctional D2 autoreceptors following repeated drug exposure could lead to aberrant DA activity in the ventral tegmental area (VTA) and projection areas such as nucleus a...
Article
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The serine hydrolase α/β hydrolase domain 6 (ABHD6) has recently been implicated as a key lipase for the endocannabinoid 2-arachidonylglycerol (2-AG) in the brain. However, the biochemical and physiological function for ABHD6 outside of the central nervous system has not been established. To address this, we utilized targeted antisense oligonucleot...
Article
The effect of the endocannabinoid system (ECS) on weight and energy metabolism is well accepted, but long term contributions of the ECS to cardiovascular regulation are not established. Evidence for receptor and signaling interactions between the ECS and the renin-angiotensin system (RAS) in brain and vasculature is emerging. In transgenic (mRen2)2...
Article
Full-text available
Complete artificial saliva (CAS) is a saliva substitute often used as a vehicle for test articles, including smokeless tobacco products. In the course of a study employing normal adult human dermal fibroblasts (HDFa) as a model in vitro, we discovered that CAS as a vehicle introduced a significant change in the expression of proinflammatory cytokin...
Article
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Tyrosine phosphorylation (Tyr-P) of focal adhesion kinase (FAK) regulates FAK activation. Phosphorylated FAK Tyr 397 binds Src family kinases (Src), which in turn directly phosphorylate FAK Tyr 576/577 to produce maximal FAK enzymatic activity. CB1 cannabinoid receptors (CB1) are abundantly expressed in the nervous system and influence FAK activati...
Article
Normal aging may limit the signaling efficacy of certain GPCRs by disturbing the function of specific Gα-subunits and leading to deficient modulation of intracellular functions that subserve synaptic plasticity, learning and memory. Evidence suggests that Gα(q/11) is more sensitive to the effects of aging relative to other Gα-subunits, including Gα...
Article
Although biochemical and physiological evidence suggests a strong interaction between striatal CB(1) cannabinoid (CB(1) R) and D(2) dopamine (D(2) R) receptors, the mechanisms are poorly understood. We targeted medium spiny neurons (MSNs) of the indirect pathway using shRNA to knockdown either CB(1) R or D(2) R. Chronic reduction in either receptor...
Article
Full-text available
Lower extremity amputations and foot ulcers are complications associated with diabetes, and have been shown to affect diabetic African Americans (AA) three times as often as diabetic non-Hispanic Whites (NHW). Possible causes for the increased risk include ethnic differences in structure and function within the dermis of the lower extremity. Testin...
Article
BACKGROUND AND PURPOSESignalling networks that regulate the progression of cannabinoid CB1 receptor‐mediated extracellular signal‐regulated kinase (ERK) activation in neurons are poorly understood. We investigated the cellular mechanisms involved in CB1 receptor‐stimulated ERK phosphorylation in a neuronal cell model. EXPERIMENTAL APPROACHMurine N1...
Article
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The CB(1) cannabinoid receptor is regulated by its association with membrane microdomains such as lipid rafts. Here, we investigated the role of palmitoylation of the CB(1) receptor by analysing the functional consequences of site-specific mutation of Cys(415) , the likely site of palmitoylation at the end of helix 8, in terms of membrane associati...
Article
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Background and purpose: Signalling networks that regulate the progression of cannabinoid CB(1) receptor-mediated extracellular signal-regulated kinase (ERK) activation in neurons are poorly understood. We investigated the cellular mechanisms involved in CB(1) receptor-stimulated ERK phosphorylation in a neuronal cell model. Experimental approach:...
Article
This review evaluates the cellular mechanisms of constitutive activity of the cannabinoid (CB) receptors, its reversal by inverse agonists, and discusses the pitfalls and problems in the interpretation of the research data. The notion is presented that endogenously produced anandamide (AEA) and 2-arachidonoylglycerol (2-AG) serve as autocrine or pa...
Article
Full-text available
There are at least two types of cannabinoid receptors (CB(1) and CB(2)). Ligands activating these G protein-coupled receptors (GPCRs) include the phytocannabinoid Δ(9)-tetrahydrocannabinol, numerous synthetic compounds, and endogenous compounds known as endocannabinoids. Cannabinoid receptor antagonists have also been developed. Some of these ligan...
Article
Previous research has demonstrated that concurrent systemic administration of CB(1) cannabinoid and mu-opioid receptor agonists increases feeding in rats. However, the possible neural loci of this cooperative effect have yet to be identified. These studies tested whether the nucleus accumbens shell may be one site of the interactive effects of opio...
Article
Full-text available
CB1 receptors are G-protein coupled receptors (GPCRs) abundant in neurons, in which they modulate neurotransmission. The CB(1) receptor influence on memory and learning is well recognized, and disease states associated with CB(1) receptors are observed in addiction disorders, motor dysfunction, schizophrenia, and in bipolar, depression, and anxiety...
Article
Full-text available
The endocannabinoids anandamide and 2-arachidonoylglycerol are lipid mediators that signal via CB(1) and CB(2) cannabinoid receptors and Gi/o-proteins to inhibit adenylyl cyclase and stimulate mitogen-activated protein kinase. In the brain, CB(1) receptors interact with opioid receptors in close proximity, and these receptors may share G-proteins a...
Article
Full-text available
The proximal portion of the C-terminus of the CB 1 cannabinoid receptor is a primary determinant for G-protein activation. A 17 residue proximal C-terminal peptide (rodent CB1 401–417), the intracellular loop 4 (IL4) peptide, mimicked the receptor's G-protein activation domain. Because of the importance of the cationic amino acids to G-protein acti...
Article
Full-text available
In our previous studies, CB1 cannabinoid receptor agonists stimulated production of cyclic GMP and translocation of nitric oxide (NO)-sensitive guanylyl cyclase in neuronal cells (Jones et al., Neuropharmacology 54:23–30, 2008). The purpose of these studies was to elucidate the signal transduction of cannabinoid-mediated neuronal nitric oxide synth...
Chapter
CB1 and CB2 cannabinoid receptors are associated with Gi/o proteins to activate signal transduction pathways that include inhibition of adenylyl cyclase, activation of mitogen activated protein kinase (MAPK), and regulation of ion channels (CB1 only). Agonists for these receptors include structurally diverse cannabinoid, aminoalkylindole, and eicos...
Chapter
The CB1 cannabinoid receptor is a G-protein-coupled receptor (GPCR) that can be stimulated by cannabinoid and nonclassical cannabinoids, aminoalkylindoles, and endocannabinoids. Constitutive activity of CB1 receptors allows inverse agonists such as arylpyrazoles to modulate activity in the absence of an agonist, and can allow sequestration of Gi/o...
Article
Full-text available
Endocannabinoid, opioid, and dopamine systems interact to exhibit cannabinoid receptor neuromodulation of opioid peptides and D(4) dopamine receptor gene expression in CB(1)-cannabinoid-deficient mouse striatum. Using CB(1)-transgenic mice, we examine primary age-sex influences and interactions on opioid and dopamine system members' gene expression...
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Compound 6 poses within the CB1 receptor having optimal Affinity lowest energy values.
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Compound 1 poses within the CB1 receptor having optimal Affinity lowest energy values.
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Compound 2 poses within the CB1 receptor having optimal Affinity lowest energy values.
Article
Full-text available
CB1 cannabinoid receptors are G-protein coupled receptors for endocannabinoids including anandamide and 2-arachidonoylglycerol. Because these arachidonic acid metabolites possess a 20-carbon polyene chain as the alkyl terminal moiety, they are highly flexible with the potential to adopt multiple biologically relevant conformations, particularly tho...
Article
Cannabinoid agonists regulate NO and cyclic AMP production in N18TG2 neuroblastoma cells, leading to the hypothesis that neuronal cyclic GMP production could be regulated by CB(1) cannabinoid receptors. NO (nitric oxide)-sensitive guanylyl cyclase (GC) is a heterodimeric cytosolic protein that mediates the down-stream effects of NO. Genes of protei...
Article
Full-text available
The CB1 cannabinoid receptor is a G-protein coupled receptor that has important physiological roles in synaptic plasticity, analgesia, appetite, and neuroprotection. We report the discovery of two structurally related CB1 cannabinoid receptor interacting proteins (CRIP1a and CRIP1b) that bind to the distal C-terminal tail of CB1. CRIP1a and CRIP1b...
Article
Full-text available
The proximal portion of the C-terminus of the CB(1) cannabinoid receptor is a primary determinant for G-protein activation. A 17 residue proximal C-terminal peptide (rodent CB1 401-417), the intracellular loop 4 (IL4) peptide, mimicked the receptor's G-protein activation domain. Because of the importance of the cationic amino acids to G-protein act...
Article
Full-text available
The intracellular C-terminal helix 8 (H8) of the CB1 cannabinoid receptor deviates from the highly conserved NPXXY(X)5,6F G-protein-coupled receptor motif, possessing a Leu instead of a Phe. We compared the signal transduction capabilities of CB1 with those of an L7.60F mutation and an L7.60I mutation that mimics the CB2 sequence. The two mutant re...
Article
Full-text available
(1) This study investigated the functional genomics of glucocorticoid and opioid receptor stimulation in cellular adaptations using a cultured neuronal cell model. (2) Human SH-SY5Y neuroblastoma cells grown in hormone-depleted serum were treated for 2-days with the glucocorticoid receptor-II agonist dexamethasone (30 nM); the mu-opioid receptor ag...
Article
We have previously shown that the endocannabinoid anandamide and its metabolically stable analog (R)-methanandamide produce vasorelaxation in rabbit aortic ring preparations in an endothelium-dependent manner that could not be mimicked by other CB(1) cannabinoid receptor agonists (Am J Physiol 282: H2046-H2054, 2002). Here, we show that (R)-methana...
Article
The rat dorsal root ganglion (DRG) Ca(2+)-sensing receptor (CaR) was stably expressed in-frame as an enhanced green fluorescent protein (EGFP) fusion protein in human embryonic kidney (HEK)293 cells, and is functionally linked to changes in intracellular Ca(2+) concentration ([Ca(2+)](i)). RT-PCR analysis indicated the presence of the message for t...
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Scene 2 of TUNNELS. A woman is suffering from withdrawal in her heroin dependence.
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Scene 3 of TUNNELS. A drug dealer describes the marketing and sale of crack cocaine.