Mitochondrial VDAC Can Be Phosphorylated by Cyclic AMP-Dependent Protein Kinase

Bera, Amal Kanti; Ghosh, Subhendu; Das, Sudipto

doi:10.1006/bbrc.1995.1491

Cited by 76 publications

(64 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A factor that may contribute to the modulation of the VDAC's oligomeric state is its phosphorylation state. VDAC1 possesses a number of potential phosphorylatable residues, several of which have been shown to undergo phosphorylation (11,13). Thus, it is possible that protein kinases control VDAC oligomerization by phosphorylating the VDAC itself or its binding partners.…”

Section: Discussionmentioning

confidence: 99%

Oligomerization of the Mitochondrial Protein Voltage-Dependent Anion Channel Is Coupled to the Induction of Apoptosis

Keinan

Tyomkin

Shoshan‐Barmatz

2010

Molecular and Cellular Biology

210

246

View full text Add to dashboard Cite

Accumulating evidence implicates that the voltage-dependent anion channel (VDAC) functions in mitochondrion-mediated apoptosis and as a critical player in the release of apoptogenic proteins, such as cytochrome c, triggering caspase activation and apoptosis. The mechanisms regulating cytochrome c release and the molecular architecture of the cytochrome c-conducting channel remain unknown. Here the relationship between VDAC oligomerization and the induction of apoptosis was examined. We demonstrated that apoptosis induction by various stimuli was accompanied by highly increased VDAC oligomerization, as revealed by cross-linking and directly monitored in living cells using bioluminescence resonance energy transfer technology. VDAC oligomerization was induced in all cell types and with all apoptosis inducers used, including staurosporine, curcumin, As 2 O 3 , etoposide, cisplatin, selenite, tumor necrosis factor alpha (TNF-␣), H 2 O 2 , and UV irradiation, all acting through different mechanisms yet all involving mitochondria. Moreover, correlation between the levels of VDAC oligomerization and apoptosis was observed. Furthermore, the apoptosis inhibitor 4,4-diisothiocyanostilbene-2,2-disulfonic acid (DIDS) inhibited VDAC oligomerization. Finally, a caspase inhibitor had no effect on VDAC oligomerization and cytochrome c release. We propose that VDAC oligomerization is involved in mitochondrion-mediated apoptosis and may represent a general mechanism common to numerous apoptogens acting via different initiating cascades. Thus, targeting the oligomeric status of VDAC, and hence apoptosis, offers a therapeutic strategy for combating cancers and neurodegenerative diseases.It is well accepted that mitochondria serve as integrators and amplifiers of programmed cell death through the regulation of apoptosis, mediating the release of proapoptotic proteins and/or disrupting cellular energy metabolism (25). During the transduction of an apoptotic signal into the cell, an alteration in mitochondrial membrane permeability occurs, facilitating the release of apoptogenic proteins, such as cytochrome c (Cyto c), apoptosis-inducing factor (AIF), and Smac/DIABLO, from the intermembrane space into the cytosol (45). These proteins participate in complex processes resulting in the activation of proteases and nucleases, leading to protein and DNA degradation and, ultimately, cell death (25). However, it remains unclear how these apoptotic initiators cross the outer mitochondrial membrane (OMM) and are released into the cytosol. While some models predict that such release is facilitated by swelling of the mitochondrial matrix and subsequent rupture of the OMM, other models predict the formation of protein-conducting channels that are large enough to allow the passage of Cyto c and other proteins into the cytosol without compromising OMM integrity (15,44,47). The voltage-dependent anion channel (VDAC) offers such a route (45).Located in the OMM, the VDAC forms the main interface between the mitochondrial and cellular metabolisms by medi...

show abstract

Section: Discussionmentioning

confidence: 99%

Oligomerization of the Mitochondrial Protein Voltage-Dependent Anion Channel Is Coupled to the Induction of Apoptosis

Keinan

Tyomkin

Shoshan‐Barmatz

2010

Molecular and Cellular Biology

210

246

View full text Add to dashboard Cite

show abstract

“…Moreover, phosphorylation of both inner and outer mitochondrial membrane proteins has been documented, specifically phosphorylation of complex V by CaMKII (38). Voltagedependent anion channels are also phosphorylated by PKA (5,34), which can increase the delivery rate of ATP from the mitochondria to the cytosol. Therefore, it is plausible to conclude that an increase in Ca 2ϩ -cAMP/PKA and CaMKII signaling to the mitochondria is a mechanism to increase the ATP production rate required to support the enhanced ATP production to meet the increased ATP demand imposed by an increased spontaneous AP firing rate.…”

Section: Discussionmentioning

confidence: 99%

Mechanisms that match ATP supply to demand in cardiac pacemaker cells during high ATP demand

Yaniv

Spurgeon

Ziman

et al. 2013

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

EG. Mechanisms that match ATP supply to demand in cardiac pacemaker cells during high ATP demand. Am J Physiol Heart Circ Physiol 304: H1428 -H1438, 2013. First published April 19, 2013 doi:10.1152/ajpheart.00969.2012.-The spontaneous action potential (AP) firing rate of sinoatrial node cells (SANCs) involves high-throughput signaling via Ca 2ϩ -calmodulin activated adenylyl cyclases (AC), cAMP-mediated protein kinase A (PKA), and Ca 2ϩ / calmodulin-dependent protein kinase II (CaMKII)-dependent phosphorylation of SR Ca 2ϩ cycling and surface membrane ion channel proteins. When the throughput of this signaling increases, e.g., in response to ␤-adrenergic receptor activation, the resultant increase in spontaneous AP firing rate increases the demand for ATP. We hypothesized that an increase of ATP production to match the increased ATP demand is achieved via a direct effect of increased mitochondrial Ca 2ϩ (Ca 2ϩ m) and an indirect effect via enhanced Ca 2ϩ -cAMP/PKA-CaMKII signaling to mitochondria. To increase ATP demand, single isolated rabbit SANCs were superfused by physiological saline at 35 Ϯ 0.5°C with isoproterenol, or by phosphodiesterase or protein phosphatase inhibition. We measured cytosolic and mitochondrial Ca 2ϩ and flavoprotein fluorescence in single SANC, and we measured cAMP, ATP, and O2 consumption in SANC suspensions. Although the increase in spontaneous AP firing rate was accompanied by an increase in O2 consumption, the ATP level and flavoprotein fluorescence remained constant, indicating that ATP production had increased. Both Ca 2ϩ m and cAMP increased concurrently with the increase in AP firing rate. When Ca 2ϩ m was reduced by Ru360, the increase in spontaneous AP firing rate in response to isoproterenol was reduced by 25%. Thus, both an increase in Ca 2ϩ m and an increase in Ca 2ϩ activated cAMP-PKA-CaMKII signaling regulate the increase in ATP supply to meet ATP demand above the basal level.calcium-activated adenylyl cyclase; bioenergetics; pacemaker automaticity REGULATION OF SINOATRIAL NODE cells (SANCs) pacemaker function involves a coupled-clock system (Fig. 1) (2,19). This high-throughput Ca 2ϩ -calmodulin-activated AC/PKA-CaMKII-Ca 2ϩ release signaling cascade in pacemaker cells is regulated in a feed-forward manner (27, 43) and requires physiological "brakes" to maintain the basal spontaneous action potential (AP) firing rate well below its maximum (Fig. 1). This regulation is accomplished by basal phosphodiesterase (PDE) (15, 27, 37) and protein phosphatase activity (1, 44) (Fig. 1). ATP is required to activate AC to produce cAMP, and a significant part of ATP is consumed to pump Ca 2ϩ into the SR, to maintain Na ϩ /K ϩ pump function and to maintain cell ionic homeostasis. Our prior studies indicate that the ATP supply required to support the basal SANC firing rate is also controlled by the Ca 2ϩ -AC/PKA-CaMKII cascade (39, 41) (Fig. 1). When the AP firing rate increases, e.g., in response to ␤-adrenergic receptor (␤-AR) stimulation (see Fig. 1), ATP production must increase to...

show abstract

“…Conversely, inhibitors of GSK3␤ decrease ⌬⌿ m , and VDAC2 phosphorylation by GSK3␤ seems to promote channel opening. PKA and GSK3␤ are serine/threonine kinases shown to phosphorylate the VDAC in vitro (Bera et al, 1995;Pastorino et al, 2002;Das et al, 2008). Phosphorylation also increases the sensitivity of VDACs reconstituted into planar lipid bilayers to inhibition by tubulin.…”

Section: Mitochondrial Metabolism In Cancer Cellsmentioning

confidence: 99%

Warburg Revisited: Regulation of Mitochondrial Metabolism by Voltage-Dependent Anion Channels in Cancer Cells

Maldonado

Lemasters

2012

J Pharmacol Exp Ther

View full text Add to dashboard Cite

The bioenergetics of cancer cells is characterized by a high rate of aerobic glycolysis and suppression of mitochondrial metabolism (Warburg phenomenon). Mitochondrial metabolism requires inward and outward flux of hydrophilic metabolites, including ATP, ADP and respiratory substrates, through voltage-dependent anion channels (VDACs) in the mitochondrial outer membrane. Although VDACs were once considered to be constitutively open, closure of the VDAC is emerging as an adjustable limiter (governator) of mitochondrial metabolism. Studies of VDACs reconstituted into planar lipid bilayers show that tubulin at nanomolar concentrations decreases VDAC conductance. In tumor cell lines, microtubule-destabilizing agents increase cytoplasmic free tubulin and decrease mitochondrial membrane potential (⌬⌿ m ), whereas microtubule stabilization increases ⌬⌿ m . Tubulin-dependent suppression of ⌬⌿ m is further potentiated by protein kinase A activation and glycogen synthase kinase-3␤ inhibition. Knockdown of different VDAC isoforms, especially of the least abundant isoform, VDAC3, also decreases ⌬⌿ m , cellular ATP, and NADH/NAD ϩ , suggesting that VDAC1 and VDAC2 are most inhibited by free tubulin. The brake on mitochondrial metabolism imposed by the VDAC governator probably is released when spindles form and free tubulin decreases as cells enter mitosis, which better provides for the high ATP demands of chromosome separation and cytokinesis. In conclusion, tubulin-dependent closure of VDACs represents a new mechanism contributing to the suppression of mitochondrial metabolism in the Warburg phenomenon.

show abstract

Mitochondrial VDAC Can Be Phosphorylated by Cyclic AMP-Dependent Protein Kinase

Cited by 76 publications

References 0 publications

Oligomerization of the Mitochondrial Protein Voltage-Dependent Anion Channel Is Coupled to the Induction of Apoptosis

Oligomerization of the Mitochondrial Protein Voltage-Dependent Anion Channel Is Coupled to the Induction of Apoptosis

Mechanisms that match ATP supply to demand in cardiac pacemaker cells during high ATP demand

Warburg Revisited: Regulation of Mitochondrial Metabolism by Voltage-Dependent Anion Channels in Cancer Cells

Contact Info

Product

Resources

About