IndraLab

Statements

PEX5L increases the amount of HCN1. 21 / 21
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"In contrast, TRIP8b (1a-4) enhances surface expression of HCN1."
21555075
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"As mentioned above, these isoforms exert distinct effects on HCN1 trafficking : TRIP8b (1a-4) strongly increases HCN1 surface expression; TRIP8b (1a) produces a ~ 10 fold decrease of HCN1 surface expression in Xenopus oocytes but enhances HCN1 expression in a mammalian cell line; and TRIP8b (1b-2) essentially abolishes surface expression in both oocytes and mammalian cells (> 50-fold decrease) by promoting channel endocytosis."
21411649
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"In a viral rescue experiment in Hcn1 -/- animals, overexpression of TRIP8b (1a-4) along with HCN1 led to expression of HCN1 in the axons of CA1 pyramidal neurons [47]."
32189562
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"Coexpression of Nedd4-2 and HCN1 drastically reduced the HCN1 mediated h-current amplitude (85-92%) in Xenopus laevis oocytes and reduced surface expression (34%) of HCN1 channels in HEK293 cells, thereby opposing effects of tetratricopeptide repeat containing Rab8b interacting protein (TRIP8b)-(1a-4), an auxiliary subunit that promotes HCN1 surface expression."
24451387
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"The opposing effects of different TRIP8b isoforms to upregulate or down-regulate levels of HCN1 expression provide an attractive molecular mechanism to mediate the reported up- and downregulation of I h and HCN1 levels as a function of neural activity."
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"Co-transfection of GFP-TRIP8b (1a-4) with HCN1 WT increased the surface expression of HCN1 WT by fivefold."
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"To explore whether lysosomal degradation contributes to reduced HCN1 protein levels in cells lacking TRIP8b, we transfected HEK293T cells with HCN1 and an isoform of TRIP8b known to enhance HCN1 surface expression, TRIP8b (1a-4), or with a TRIP8b construct that binds TRIP8b but lacks the alternatively spliced N-terminus that controls surface expression (TRIP8bDeltaN)."
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"Indeed, whereas TRIP8b (1a-4) strongly increases HCN1 surface expression, this isoform decreases the surface expression of HCN2."
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"TRIP8b (1a-4) and TRIP8b (1a-2-4) (the naming convention lists the alternatively spliced exons) cause a 4-6 fold increase in surface expression of HCN1 channels when co-expressed in Xenopus oocytes."
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"Unlike TRIP8b (1b-2), TRIP8b (1bs-2) increases surface expression of HCN1 in HEK293 cells and indicates that the presence of the 25 amino acid segment of 1b in combination with exon 2 leads to the internalization of HCN1 channels [28]."
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"In contrast, deletion of the TPR domain fully blocks the ability of TRIP8b (1a-4) to upregulate HCN1 surface expression (TRIP8b DeltaTPR, XREF_FIG)."
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"The ability of TRIP8b (1a-4) to upregulate surface membrane expression of HCN1 DeltaSNL raises the question as to why this interaction failed to localize properly the mutant channel to the CA1 distal dendrites."
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"To test the hypothesis that TRIP8b (1a-4) enhances HCN1 surface expression and targets the channel to its proper dendritic locale whereas TRIP8b (1a) prevents axonal expression of the channel, we examined the effects of viral overexpression of these two TRIP8b isoforms, both fused to an HA tag to allow us to distinguish exogenous from endogenous protein."
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"Of the two remaining hippocampal TRIP8b isoforms, TRIP8b (1a-4) promoted HCN1 surface expression in dendrites whereas TRIP8b (1a) suppressed HCN1 misexpression in axons."
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"In contrast, TRIP8b (1a-4) increases the level of GFP-HCN1 associated with the dendritic plasma membrane when over-expressed in neurons in vivo (see below, Figure 7)."
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"XREF_BIBR previously reported that the reduction of all TRIP8b isoforms with siRNA suppresses HCN1 membrane expression and Ih in hippocampal neurons in dissociated cell culture."
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"Indeed, the effects of the internal deletion resembled the effects of the HCN1 SNL truncation and TRIP8b N to K mutations described above, with a significant loss of the ability of TRIP8b (1a) and TRIP8b (1b-2) to downregulate HCN1 surface expression."
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"This suggests that the lack of effect of wild-type TRIP8b (1a-2) on I h levels may result from opposing influences of distinct sequences to enhance HCN1 expression and promote channel internalization."
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"Downregulation of HCN1 surface expression by TRIP8b (1a) in Xenopus oocytes is dependent on the presence of a dileucine adaptor protein trafficking motif in the N-terminal domain of the TRIP8b protein."
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"As a positive control, HCN1 WT was co-expressed with GFP tagged TRIP8b (1a-4), because this specific splice isoform of TRIP8b is known to increase surface expression of HCN1 [XREF_BIBR, XREF_BIBR, XREF_BIBR]."
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"The most abundant isoform in hippocampus, TRIP8b (1a-4), dramatically enhances surface expression of HCN1 channels, whereas other isoforms (such as the low abundant 1b-2 isoform) may have opposite effects and abolish HCN1 membrane trafficking XREF_BIBR, XREF_BIBR."
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