scholarly journals Sphingosine kinases and their metabolites modulate endolysosomal trafficking in photoreceptors

2011 ◽  
Vol 192 (4) ◽  
pp. 557-567 ◽  
Author(s):  
Ikuko Yonamine ◽  
Takeshi Bamba ◽  
Niraj K. Nirala ◽  
Nahid Jesmin ◽  
Teresa Kosakowska-Cholody ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Endosomal Trafficking ◽  
Loss Of Function ◽  
Late Endosomes ◽  
Sphingosine 1 Phosphate ◽  
Sphingosine Kinases ◽  
Transient Receptor ◽  
G Protein Coupled

Internalized membrane proteins are either transported to late endosomes and lysosomes for degradation or recycled to the plasma membrane. Although proteins involved in trafficking and sorting have been well studied, far less is known about the lipid molecules that regulate the intracellular trafficking of membrane proteins. We studied the function of sphingosine kinases and their metabolites in endosomal trafficking using Drosophila melanogaster photoreceptors as a model system. Gain- and loss-of-function analyses show that sphingosine kinases affect trafficking of the G protein–coupled receptor Rhodopsin and the light-sensitive transient receptor potential (TRP) channel by modulating the levels of dihydrosphingosine 1 phosphate (DHS1P) and sphingosine 1 phosphate (S1P). An increase in DHS1P levels relative to S1P leads to the enhanced lysosomal degradation of Rhodopsin and TRP and retinal degeneration in wild-type photoreceptors. Our results suggest that sphingosine kinases and their metabolites modulate photoreceptor homeostasis by influencing endolysosomal trafficking of Rhodopsin and TRP.

What Evolutionary Evidence Implies About the Identity of the Mechanoelectrical Couplers in Vascular Smooth Muscle Cells

Physiology ◽  
2021 ◽  
Vol 36 (5) ◽  
pp. 292-306
Author(s):  
Heather A. Drummond
Keyword(s):  
Transient Receptor Potential ◽  
Molecular Model ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Potential Channels ◽  
Transient Receptor ◽  
Paradigm Shifting ◽  
G Protein Coupled ◽  
Evolutionary Role

Loss of pressure-induced vasoconstriction increases susceptibility to renal and cerebral vascular injury. Favored paradigms underlying initiation of the response include transient receptor potential channels coupled to G protein-coupled receptors or integrins as transducers. Degenerin channels may also mediate the response. This review addresses the 1) evolutionary role of these molecules in mechanosensing, 2) limitations to identifying mechanosensitive molecules, and 3) paradigm shifting molecular model for a VSMC mechanosensor.

scholarly journals Dissecting independent channel and scaffolding roles of the Drosophila transient receptor potential channel

2005 ◽  
Vol 171 (4) ◽  
pp. 685-694 ◽  
Author(s):  
Tao Wang ◽  
Yuchen Jiao ◽  
Craig Montell
Keyword(s):  
Cell Death ◽  
Retinal Degeneration ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Loss Of Function ◽  
Visual Transduction ◽  
Channel Function ◽  
Transient Receptor ◽  
The Impact

Drosophila transient receptor potential (TRP) serves dual roles as a cation channel and as a molecular anchor for the PDZ protein, INAD (inactivation no afterpotential D). Null mutations in trp cause impairment of visual transduction, mislocalization of INAD, and retinal degeneration. However, the impact of specifically altering TRP channel function is not known because existing loss-of-function alleles greatly reduce protein expression. In the current study we describe the isolation of a set of new trp alleles, including trp14 with an amino acid substitution juxtaposed to the TRP domain. The trp14 flies stably express TRP and display normal molecular anchoring, but defective channel function. Elimination of the anchoring function alone in trpΔ1272, had minor effects on retinal morphology whereas disruption of channel function caused profound light-induced cell death. This retinal degeneration was greatly suppressed by elimination of the Na+/Ca2+ exchanger, CalX, indicating that the cell death was due primarily to deficient Ca2+ entry rather than disruption of the TRP-anchoring function.

scholarly journals Lysophospholipid (LPA) receptors (version 2020.5) in the IUPHAR/BPS Guide to Pharmacology Database

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
Victoria Blaho ◽  
Jerold Chun ◽  
Danielle Jones ◽  
Deepa Jonnalagadda ◽  
Yasuyuki Kihara ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Ventricular Zone ◽  
Receptor Potential ◽  
Binding Pocket ◽  
Binding Affinities ◽  
Lpa Receptor ◽  
Lpa Receptors ◽  
Sphingosine 1 Phosphate ◽  
Bona Fide ◽  
Transient Receptor

Lysophosphatidic acid (LPA) receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Lysophospholipid Receptors [54, 18, 80, 125]) are activated by the endogenous phospholipid LPA. The first receptor, LPA1, was identified as ventricular zone gene-1 (vzg-1) [39], leading to deorphanisation of members of the endothelial differentiation gene (edg) family as other LPA receptors along with sphingosine 1-phosphate (S1P) receptors. Additional LPA receptor GPCRs were later identified. Gene names have been codified as LPAR1, etc. to reflect the receptor function of proteins. The crystal structure of LPA1 was solved and demonstrates extracellular LPA access to the binding pocket, consistent with proposed delivery via autotaxin [12]. These studies have also implicated cross-talk with endocannabinoids via phosphorylated intermediates that can also activate these receptors. The identified receptors can account for most, although not all, LPA-induced phenomena in the literature, indicating that a majority of LPA-dependent phenomena are receptor-mediated. Binding affinities of unlabeled, natural LPA and AEAp to LPA1 were measured using backscattering interferometry (pKd = 9) [81, 102]. Binding affinities were 77-fold lower than than values obtained using radioactivity [124]. Targeted deletion of LPA receptors has clarified signalling pathways and identified physiological and pathophysiological roles. Independent validation by multiple groups has been reported in the peer-reviewed literature for all six LPA receptors described in the tables, including further validation using a distinct read-out via a novel TGFα "shedding" assay [47]. LPA LPA has been proposed to be a ligand for GPCR35 [92], supported by a recent study revealing that LPA modulates macrophage function through GPR35 [53]. However CXCL17 is reported to be a ligand for GPR35/CXCR8 [74]. Moreover, LPA has also been described as an agonist for the transient receptor potential (Trp) ion channel TRPV1 [85] and TRPA1 [57]. All of these proposed non-GPCR receptor identities require confirmation and are not currently recognized as bona fide LPA receptors.

scholarly journals Lipid–Protein Interactions in Niemann–Pick Type C Disease: Insights from Molecular Modeling

2019 ◽  
Vol 20 (3) ◽  
pp. 717 ◽  
Author(s):  
Simon Wheeler ◽  
Ralf Schmid ◽  
Dan J Sillence
Keyword(s):  
Protein Interactions ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Late Endosomes ◽  
Type C ◽  
Transient Receptor ◽  
Niemann Pick ◽  
Lipid Protein Interactions ◽  
Protein Attachment ◽  
Accumulation Of Lipids

The accumulation of lipids in the late endosomes and lysosomes of Niemann–Pick type C disease (NPCD) cells is a consequence of the dysfunction of one protein (usually NPC1) but induces dysfunction in many proteins. We used molecular docking to propose (a) that NPC1 exports not just cholesterol, but also sphingosine, (b) that the cholesterol sensitivity of big potassium channel (BK) can be traced to a previously unappreciated site on the channel’s voltage sensor, (c) that transient receptor potential mucolipin 1 (TRPML1) inhibition by sphingomyelin is likely an indirect effect, and (d) that phosphoinositides are responsible for both the mislocalization of annexin A2 (AnxA2) and a soluble NSF (N-ethylmaleimide Sensitive Fusion) protein attachment receptor (SNARE) recycling defect. These results are set in the context of existing knowledge of NPCD to sketch an account of the endolysosomal pathology key to this disease.

scholarly journals Understanding diverse TRPV1 signaling – an update

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1978
Author(s):  
Michael Andresen
Keyword(s):  
Sensory Neurons ◽  
Synaptic Vesicles ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
G Protein Coupled Receptors ◽  
Transient Receptor Potential Vanilloid ◽  
Discrete Population ◽  
Transient Receptor ◽  
G Protein Coupled ◽  
Central Terminal

The transient receptor potential vanilloid 1 (TRPV1) is densely expressed in spinal sensory neurons as well as in cranial sensory neurons, including their central terminal endings. Recent work in the less familiar cranial sensory neurons, despite their many similarities with spinal sensory neurons, suggest that TRPV1 acts as a calcium channel to release a discrete population of synaptic vesicles. The modular and independent regulation of release offers new questions about nanodomain organization of release and selective actions of G protein–coupled receptors.

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