Microdomain organization and frequency‐dependence of CREB‐dependent transcriptional signaling in heart cells

Abstract

Voltage-gated Ca(v)1.2 calcium channels couple membrane depolarization to cAMP response-element-binding protein (CREB)-dependent transcriptional activation. To investigate the spatial and temporal organization of CREB-dependent transcriptional nuclear microdomains, we combined perforated patch-clamp technique and FRET microscopy for monitoring CREB and CREB-binding protein interaction in the nuclei of live cells. The experimental approach to the quantitative assessment of CREB-dependent transcriptional signaling evoked by cAMP- and Ca(v)1.2-dependent mechanisms was devised in COS1 cells expressing recombinant Ca(v)1.2 calcium channels. Using continuous 2-dimensional wavelet transform and time series analyses, we found that nuclear CREB-dependent transcriptional signaling is organized differentially in spatially and temporally separated microdomains of 4 distinct types. In rat neonatal cardiomyocytes, CREB-dependent transcription is mediated by the cAMP-initiated CaMKII-sensitive and Ca(v)1.2-initiated CaMKII-insensitive mechanisms. The latter microdomains show a tendency to exhibit periodic behavior correlated with spontaneous contraction of myocytes suggestive of frequency-dependent CREB-dependent transcriptional regulation in the heart.

Regulation of CREB signaling through L-type Ca2+channels by Nipsnap-2

“…18,19 This signaling involves phosphorylation, at Ser 133, of the transcription factor CREB 20 which drives expression of genes involved in synaptic function. 19,21,22 To investigate if increased L-type current density observed in Nipsnap2 overexpressing CAD cells can signal to CREB, we measured the activation of CREB. First, we tested the idea that Nipsnap2-mediated increase in Ca 2+ influx via L-type Ca 2+ influx increases CREB activation.…”

CACNA1C (Cav1.2) in the pathophysiology of psychiatric disease

“…One gene in which such genetic polymorphisms have been identified is CACNA1C , which codes for the pore-forming α 1C subunit of the L-type voltage-gated calcium channel (LTCC), referred to as Ca v 1.2. Ca v 1.2 couples transient activation of inward calcium current to transcriptional regulation and plays an important role in dendritic development, neuronal survival, synaptic plasticity, memory formation, learning, and behavior (Barad, 2003; Dudkin et al, 1990; Kobrinsky et al, 2011; Moosmang et al, 2005; Shibasaki et al, 2010; West et al, 2001; Wheeler et al, 2008; White et al, 2008; Yoshii and Watabe, 1994). …”

“…The investigation of CREB-dependent transcriptional regulation by the LTCC and cAMP established their role in activation of transient and stable signaling sub-microdomains of mixed and individual type (Kobrinsky et al, 2011). These discrete signaling microdomains might be differentially associated with such specialized processes as spontaneous contractions of muscle cells or the long-term changes underlying synaptic plasticity.…”

Selective fluorophore-assisted light inactivation of voltage-gated calcium channels

“…This property provides an opportunity to combine the fluorescent cell imaging of calcium channels with selective functional inactivation of their specific subsets in the live cell. 6 The whole cell calcium channel peak currents were recorded before, simultaneously with and after the termination of photobleaching of EYFP fused to the N-or C-terminus of the Ca v 1.2 α 1C subunit. Continuous illumination (13 W/cm 2 ) caused on average 75.0 ± 1.5% (1 min) and 86.5 ± 1.5% (2 min) photobleaching of EYFP (n = 10).…”