A Diacylglycerol-Gated Cation Channel in Vomeronasal Neuron Dendrites Is Impaired in TRPC2 Mutant Mice

Lucas, Philippe; Ukhanov, Kirill; Leinders‐Zufall, Trese; Zufall, Frank

doi:10.1016/s0896-6273(03)00675-5

Cited by 290 publications

(268 citation statements)

References 66 publications

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“…This raises the possibility that espins located on the outside of a stereociliary or microvillar PAB could function in part as linkers that help connect the PAB to the plasma membrane. In addition, PIP2 is a substrate for phospholipase C, which cleaves PIP2 into diacylglycerol and inositol 1,4,5-trisphosphate and is believed to play a prominent role in sensory transduction in cells that contain espins [42,67,68]. Thus, it is possible that espins regulate the availability of PIP2 in an isoform-specific way.…”

Section: Binding Pip2 and Ligands For Proline-rich Peptidesmentioning

confidence: 99%

Espins and the actin cytoskeleton of hair cell stereocilia and sensory cell microvilli

Sekerková

Zheng

Loomis

et al. 2006

Cell. Mol. Life Sci.

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The espins are novel actin-bundling proteins that are produced in multiple isoforms from a single gene. They are present at high concentration in the parallel actin bundle of hair cell stereocilia and are the target of deafness mutations in mice and humans. Espins are also enriched in the microvilli of taste receptor cells, solitary chemoreceptor cells, vomeronasal sensory neurons and Merkel cells, suggesting that espins play important roles in the microvillar projections of vertebrate sensory cells. Espins are potent actin-bundling proteins that are not inhibited by Ca 2+ . In cells, they efficiently elongate parallel actin bundles and, thereby, help determine the steady-state length of microvilli and stereocilia. Espins bind actin monomer via their WH2 domain and can assemble actin bundles in cells. Certain espin isoforms can also bind phosphatidylinositol 4,5-bisphosphate, profilins or SH3 proteins. These biological activities distinguish espins from other actin-bundling proteins and may make them well-suited to sensory cells. KeywordsEspin; actin; hair cell; stereocilia; microvilli; sensory; deafness; taste The stereocilia and microvilli of vertebrate sensory cells and their actinbundling proteinsMany classes of vertebrate sensory cells detect chemical or mechanical stimuli through microvilli or their derivatives, such as stereocilia. These relatively long-lived, fingerlike specializations of the plasma membrane are built around a common cytoskeletal element -the parallel actin bundle (PAB) [1]. PABs consist of tightly packed collections of actin filaments cross-linked by actin-bundling proteins. The filaments are aligned along their longitudinal axis and display a uniform polarity with respect to their preferred ends for actin monomer addition, which in microvilli and stereocilia is positioned at the distal tip. The PAB displays hallmarks of a supramolecular scaffold that determines the placement, dimensions, flexibility and signaling properties of microvilli and stereocilia. Although filopodia also contain a PAB at their core and are believed to sense the local environment, they are considerably more dynamic and differ significantly from microvilli and stereocilia in their molecular composition and biogenesis [2].

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Section: Binding Pip2 and Ligands For Proline-rich Peptidesmentioning

confidence: 99%

Espins and the actin cytoskeleton of hair cell stereocilia and sensory cell microvilli

Sekerková

Zheng

Loomis

et al. 2006

Cell. Mol. Life Sci.

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“…One functional characteristic distinguishing these two subgroups is the ability of diacylglycerol (DAG) to activate TRPC3/6/7 channels but not TRPC1/4/5 channels (2, 6 -11). DAG also activates TRPC2 channels; however, this channel is not expressed in higher mammals and is restricted mostly to the vomeronasal organ (12). As a product of receptor-induced PLC activation, DAG is an obvious mediator of TRPC channel activation.…”

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confidence: 99%

Role of Endogenous TRPC6 Channels in Ca2+ Signal Generation in A7r5 Smooth Muscle Cells

Soboloff¹,

Spassova²,

Xu³

et al. 2005

Journal of Biological Chemistry

151

123

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The ubiquitously expressed canonical transient receptor potential (TRPC) ion channels are considered important in Ca 2؉ signal generation, but their mechanisms of activation and roles remain elusive. Whereas most studies have examined overexpressed TRPC channels, we used molecular, biochemical, and electrophysiological approaches to assess the expression and function of endogenous TRPC channels in A7r5 smooth muscle cells. Real time PCR and Western analyses reveal TRPC6 as the only member of the diacylglycerol-responsive TRPC3/6/7 subfamily of channels expressed at significant levels in A7r5 cells. TRPC1, TRPC4, and TRPC5 were also abundant. An outwardly rectifying, nonselective cation current was activated by phospholipase C-coupled vasopressin receptor activation or by the diacylglycerol analogue, oleoyl-2-acetyl-snglycerol (OAG). Introduction of TRPC6 small interfering RNA sequences into A7r5 cells by electroporation led to 90% reduction of TRPC6 transcript and 80% reduction of TRPC6 protein without any detectable compensatory changes in the expression of other TRPC channels. The OAG-activated nonselective cation current was similarly reduced by TRPC6 RNA interference. Intracellular Ca 2؉ measurements using fura-2 revealed that thapsigargin-induced store-operated Ca 2؉ entry was unaffected by TRPC6 knockdown, whereas vasopressin-induced Ca 2؉ entry was suppressed by more than 50%. In contrast, OAG-induced Ca 2؉ transients were unaffected by TRPC6 knockdown. Nevertheless, OAG-induced Ca through plasma membrane channels (1-3). Although identification of the latter has proven elusive, members of the canonical transient receptor potential (TRPC) 3 channel family have been leading contenders (2-5). The TRPC channels all appear to be activated in response to phospholipase C (PLC)-coupled receptors (2-8). Within the TRPC family, there are two structurally divided subgroups: TRPC3, TRPC6, and TRPC7 channels (TRPC3/6/7) and TRPC1, TRPC4, and TRPC5 (TRPC1/4/5). One functional characteristic distinguishing these two subgroups is the ability of diacylglycerol (DAG) to activate TRPC3/6/7 channels but not TRPC1/4/5 channels (2, 6 -11). DAG also activates TRPC2 channels; however, this channel is not expressed in higher mammals and is restricted mostly to the vomeronasal organ (12). As a product of receptor-induced PLC activation, DAG is an obvious mediator of TRPC channel activation. However, its role in the activation of endogenously expressed TRPC3/6/7 channels is uncertain (7,8,(13)(14)(15). The majority of studies revealing the action of DAG on TRPC channels have been undertaken using overexpression systems (2,7,8,14,15). Such expression may differ from endogenous TRPC expression. For example, considering that TRPC channels probably function as tetramers (4, 5), overexpression may result in a predominance of homotetrameric structures, whereas endogenous expression may reflect heteromers between TRPC channel subtypes, resulting in quite different properties (2, 4, 5). In addition, since TRPC channels may function within ...

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“…DAG, the substrate of the DGK reaction, is a key intracellular signaling factor that activates PKCs, Ras guanyl nucleotidereleasing proteins, and some transient receptor potential channels (3,4). DAG also recruits a number of proteins to membrane compartments, including the chimaerins, PKD, and the Munc13 proteins (3).…”

mentioning

confidence: 99%

Diacylglycerol kinase δ regulates protein kinase C and epidermal growth factor receptor signaling

Crotty

Cai

Sakane

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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Diacylglycerol kinases (DGKs) phosphorylate diacylglycerol (DAG) to terminate its signaling. To study DGK␦, we disrupted its gene in mice and found that DGK␦ deficiency reduced EGF receptor (EGFR) protein expression and activity. Similar to EGFR knockout mice, DGK␦-deficient pups were born with open eyelids and died shortly after birth. PKCs are activated by DAG and phosphorylate EGFR to reduce its expression and activity. We found DAG accumulation, increased threonine phosphorylation of EGFR, enhanced phosphorylation of other PKC substrates, and increased PKC autophosphorylation in DGK␦ knockout cells, indicating that DGK␦ regulates EGFR by modulating PKC signaling. D iacylglycerol kinases (DGKs) catalyze the phosphorylation of diacylglycerol (DAG) to produce phosphatidic acid (1, 2). DAG, the substrate of the DGK reaction, is a key intracellular signaling factor that activates PKCs, Ras guanyl nucleotidereleasing proteins, and some transient receptor potential channels (3, 4). DAG also recruits a number of proteins to membrane compartments, including the chimaerins, PKD, and the Munc13 proteins (3). Its effects on numerous and diverse targets underscores the importance of DAG signaling and indicates that DAG affects a broad array of signaling events. Because the consumption of DAG by DGKs is thought to attenuate these actions, the DGK reaction is biologically important and likely regulates numerous DAG signaling pathways.Mammalian DGKs differ in their structures, patterns of tissue expression, and catalytic properties. Ten of them have been identified and are classified into five subtypes based on their structural motifs (1, 2, 5, 6). Their structural diversity and distinct expression patterns indicate that each isoform may perform a different biological function. Supporting functional diversity, the DGK knockout mice that have been studied to date have distinct phenotypes, including resistance to seizures in DGK knockout mice (7), attenuated Ras signaling in DGK knockouts (8), and hyperactive T cell signaling in DGK -deficient mice (9).As a type II DGK, DGK␦ has a characteristic pleckstrin homology domain and a sterile ␣-motif domain (Fig. 1A). To determine its biological function, we generated mice with a targeted mutation of the DGK␦ gene. Our data indicate an important role for DGK␦ in modulating PKC and EGF receptor (EGFR) signaling. Results and DiscussionWe used mice to make a targeted deletion of the N-terminal portion of the DGK␦ catalytic domain (see Fig. 7, which is published as supporting information on the PNAS web site). Southern blot analysis of tail DNA confirmed proper insertion of the targeting vector (data not shown), and RT-PCR demonstrated absence of DGK␦ mRNA in homozygous mutant cells (Fig. 7C). Also confirming DGK␦ gene inactivation, DGK␦ protein was absent in knockout keratinocyte and dermal fibroblast cell lysates (Fig. 7D). Deleting DGK␦ did not significantly affect mRNA expression of other DGKs in brain tissue (Fig. 7E). Finally, to establish the expression pattern of DGK␦ in WT mice...

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A Diacylglycerol-Gated Cation Channel in Vomeronasal Neuron Dendrites Is Impaired in TRPC2 Mutant Mice

Cited by 290 publications

References 66 publications

Espins and the actin cytoskeleton of hair cell stereocilia and sensory cell microvilli

Espins and the actin cytoskeleton of hair cell stereocilia and sensory cell microvilli

Role of Endogenous TRPC6 Channels in Ca2+ Signal Generation in A7r5 Smooth Muscle Cells

Diacylglycerol kinase δ regulates protein kinase C and epidermal growth factor receptor signaling

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