Identification of PKCα-dependent phosphoproteins in mouse retina

Wakeham, Colin M.; Wilmarth, Phillip A.; Cunliffe, Jennifer M.; Klimek, John; Ren, Guosheng; David, Larry L.; Morgans, Catherine W.

doi:10.1016/j.jprot.2019.103423

Cited by 17 publications

(20 citation statements)

References 73 publications

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“…Furthermore, the Th gene for tyrosine hydroxylase was expressed by ACs in cluster 25, suggesting that 5T4 + ACs are also catecholaminergic (CAII or CA2; Figure 2B). These results strongly suggested that 5T4 is expressed not only by excitatory RBCs but also by inhibitory ACs (Figure 2C; Imamura et al, 2006;Wakeham et al, 2019). However, the relative amount of TPBG (the 5T4 homolog) mRNA seems to be low in macaque (Peng et al, 2019) or human (Yan et al, 2020b) retina.…”

Section: Expression Of 5t4 In Rod Bipolar Cells and A Subtype Of Amacmentioning

confidence: 84%

“…5T4 is a type I transmembrane glycoprotein with an N-terminal extracellular domain comprising seven LRRs (24 amino acids each), flanked by characteristic LRR-N and LRR-C regions, and interspersed by seven N-linked glycosylation sites ( Figure 1C; King et al, 1999;Imamura et al, 2006;Zhao et al, 2014). The intracellular domain of 5T4 is capped by a class 1 PDZ-interacting motif ( Figure 1C; Imamura et al, 2006;Zhao et al, 2014) and contains two serine residues, which are likely phosphorylated by protein kinase Cα (PKCα; Wakeham et al, 2019Wakeham et al, , 2020.…”

Section: Lrr-containing Oncofetal Trophoblast Glycoprotein 5t4mentioning

confidence: 99%

“…In the rod pathways of the retina, rod BCs (RBCs) are the first excitatory interneurons in the rod circuit to receive lightdependent synaptic input from rod photoreceptors in the outer plexiform layer (OPL), and give rise to retinal output via AII ACs in the IPL (Figure 2A). Although RBCs are primarily responsible for dark-adapted low-light vision, they contribute to retinal output under a diverse range of lighting conditions (Euler et al, 2014); however, the molecular mechanisms involved in RBC adaptation to changing luminance conditions remain unknown (Rampino and Nawy, 2011;Wakeham et al, 2019). Imamura et al (2006) identified 5T4-positive interneurons in the adult mouse retina.…”

Section: Expression Of 5t4 In Rod Bipolar Cells and A Subtype Of Amacmentioning

confidence: 99%

“…5T4 is expressed mainly by RBCs whose processes are dispersed in the lower half of the IPL near the ganglion cell layer, as well as by a subpopulation of ACs whose dendrites branch at a single sublamina between ON and OFF sublayers in the IPL (Figures 2A,C). Recently, Wakeham et al (2019) performed mass spectroscopy with multiplexed tandem mass tags to reveal that 5T4 acts as a PKCαdependent phosphoprotein in RBCs. These authors then showed that 5T4 protein localizes to the somas, dendrites, and axon terminals of RBCs, as well as the somas and dendrites of an uncharacterized group of ACs (Figures 2B,C; Wakeham et al, 2020).…”

Section: Expression Of 5t4 In Rod Bipolar Cells and A Subtype Of Amacmentioning

confidence: 99%

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LRR-Containing Oncofetal Trophoblast Glycoprotein 5T4 Shapes Neural Circuits in Olfactory and Visual Systems

Tsuboi

2020

Front. Mol. Neurosci.

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In mammals, the sensory experience can regulate the development of various brain structures, including the cortex, hippocampus, retina, and olfactory bulb (OB). Odor experience-evoked neural activity drives the development of dendrites on excitatory projection neurons in the OB, such as mitral and tufted cells, as well as inhibitory interneurons. OB interneurons are generated continuously in the subventricular zone and differentiate into granule cells (GCs) and periglomerular cells (PGCs). However, it remains unknown what role each type of OB interneuron plays in controlling olfactory behaviors. Recent studies showed that among the various types of OB interneurons, a subtype of GCs expressing oncofetal trophoblast glycoprotein 5T4 is required for simple odor detection and discrimination behaviors. Mouse 5T4 (also known as Tpbg) is a type I membrane glycoprotein whose extracellular domain contains seven leucine-rich repeats (LRRs) sandwiched between characteristic LRR-N and LRR-C regions. Recently, it was found that the developmental expression of 5T4 increases dramatically in the retina just before eye-opening. Single-cell transcriptomics further suggests that 5T4 is involved in the development and maintenance of functional synapses in a subset of retinal interneurons, including rod bipolar cells (RBCs) and amacrine cells (ACs). Collectively, 5T4, expressed in interneurons of the OB and retina, plays a key role in sensory processing in the olfactory and visual systems.

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Section: Expression Of 5t4 In Rod Bipolar Cells and A Subtype Of Amacmentioning

confidence: 84%

Section: Lrr-containing Oncofetal Trophoblast Glycoprotein 5t4mentioning

confidence: 99%

Section: Expression Of 5t4 In Rod Bipolar Cells and A Subtype Of Amacmentioning

confidence: 99%

Section: Expression Of 5t4 In Rod Bipolar Cells and A Subtype Of Amacmentioning

confidence: 99%

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LRR-Containing Oncofetal Trophoblast Glycoprotein 5T4 Shapes Neural Circuits in Olfactory and Visual Systems

Tsuboi

2020

Front. Mol. Neurosci.

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“…The enriched phosphopeptides were purified by solid phase extraction using UltraMicroSpin columns (The Nest Group, Inc.) and dried down in preparation for TMT labeling. The enriched phosphopeptides from the SR and KR cells were then labeled with TMT reagents as recommended by the manufacturer (Thermo Scientific), mixed, and analyzed by two-dimensional liquid chromatography/mass spectrometry using an Orbitrap Fusion Tribrid mass spectrometer (Thermo Scientific) as previously described [61]. The full proteomic dataset can be found in the PRIDE database with the following accession number (provided upon publication).…”

Section: Methodsmentioning

confidence: 99%

The serine-threonine kinase TAO3 promotes cancer invasion and tumor growth by facilitating trafficking of endosomes containing the invadopodia scaffold TKS5α

Iizuka

Quintavalle

Navarro

et al. 2020

Preprint

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1Invadopodia are actin-based proteolytic membrane protrusions required for invasive behavior and 2 tumor growth. We used our high-content screening assay to identify kinases impacting 3 invadopodia formation. Among the top hits we selected TAO3, a STE20-like kinase of the GCK 4 subfamily, for further analysis. TAO3 was over-expressed in many human cancers, and regulated 5 invadopodia formation in melanoma, breast and bladder cancers. Furthermore, TAO3 catalytic 6 activity facilitated melanoma growth in 3-dimensional matrices and in vivo. We developed potent 7 catalytic inhibitors of TAO3 that inhibited invadopodia formation and function, and tumor cell 8 extravasation and growth. Using these inhibitors, we determined that TAO3 activity was required 9 for endosomal trafficking of TKS5α, an obligate invadopodia scaffold protein. A 10 phosphoproteomics screen for TAO3 substrates revealed the dynein subunit protein LIC2 as a 11 relevant substrate. Knockdown of LIC2 or expression of a phosphomimetic form promoted 12 invadopodia formation. Thus, TAO3 is a new therapeutic target with a distinct mechanism of 13 action. 14 15 SIGNIFICANCE 16Targeting tumor invasive behavior represents an understudied opportunity. We used an unbiased 17 screening approach to identify kinases required for invadopodia formation and function. We 18 validated TAO3, both genetically and with a novel inhibitor, and determined TAO3 function. Our

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Expression and distribution of trophoblast glycoprotein in the mouse retina

Wakeham

Ren

Morgans

2020

J of Comparative Neurology

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We recently identified the leucine-rich repeat adhesion protein, trophoblast glycoprotein (TPBG), as a novel PKCa-dependent phosphoprotein in retinal rod bipolar cells (RBCs). Since TPBG has not been thoroughly examined in the retina, this study characterizes the localization and expression patterns of TPBG in the developing and adult mouse retina using two antibodies, one against the N-terminal, leucine-rich domain and the other against the C-terminal PDZinteracting motif. Both antibodies labeled dendrites and synaptic terminals of RBCs, as well as the cell bodies and dendrites of an uncharacterized class of amacrine cell. In transfected HEK293 cells, TPBG was localized to the plasma membrane and intracellular membranes and was associated with the tips of thin filopodia-like membrane projections. TPBG immunofluorescence in RBCs detected with the C-terminal antibody was strongly dependent on the activity state of the adult retina, with less labeling in dark-adapted compared to light-adapted retina, and less labeling in light-adapted PKCa knockout and TRPM1 knockout retinas compared to wild type, despite no change in total TPBG detected by immunoblotting. These results suggest that the C-terminal epitope is blocked in the dark-adapted and knockout retinas compared to light-adapted wild type retinas, possibly through interaction with a PDZ domain protein. During development, TPBG expression increases dramatically just prior to eye opening with a time course closely correlated with that of TRPM1 expression. In the retina, leucine-rich repeat proteins like TPBG have been implicated in the development and maintenance of functional bipolar cell synapses, and TPBG may play a similar role in RBCs.

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Identification of PKCα-dependent phosphoproteins in mouse retina

Cited by 17 publications

References 73 publications

LRR-Containing Oncofetal Trophoblast Glycoprotein 5T4 Shapes Neural Circuits in Olfactory and Visual Systems

LRR-Containing Oncofetal Trophoblast Glycoprotein 5T4 Shapes Neural Circuits in Olfactory and Visual Systems

The serine-threonine kinase TAO3 promotes cancer invasion and tumor growth by facilitating trafficking of endosomes containing the invadopodia scaffold TKS5α

Expression and distribution of trophoblast glycoprotein in the mouse retina

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