1,721,004 research outputs found
cAMP-dependent protein kinase regulates the mitochondrial import of the nuclear encoded NDUFS4 subunit of complex I
No full textThe subunits of complex I encoded by the mammalian nuclear genes NDUFS4 (AQDQ protein) and NDUFB11 (ESSS protein) contain serine/ threonine consensus phosphorylation sequences (CPS) in their presequence, the first also in the C-terminus. We have studied the impact of PKA mediated phosphorylation on the mitochondrial import of in vitro and in vivo synthesized NDUFS4 protein. The intramitochondrial accumulation of the mature form of in vitro synthesized NDUFS4 protein, but not that of ESSS protein, was promoted by PKA and depressed by alkaline phosphatase (AP). In HeLa cells, control or transfected with the NDUFS4 cDNA construct, the mitochondrial level of mature NDUFS4 protein was promoted by 8-Br-cAMP and depressed by H89. Ser173Ala mutagenesis in the C-terminus CPS abolished the appearance in mitochondria of the mature form of NDUFS4 protein. The promoting effect of PKA on the mitochondrial accumulation of mature NDUFS4 protein appears to be due to inhibition of its retrograde diffusion into the cytosol. (C) 2008 Elsevier Inc. All rights reserved
CAMP RESPONSE ELEMENT-BINDING PROTEIN (CREB) IS IMPORTED INTO MITOCHONDRIA AND PROMOTES PROTEIN SYNTHESIS
No full textThe cAMP response element-binding protein (CREB) is a ubiquitous transcription factor in the higher eukaryotes that, once phosphorylated, promotes transcription of cAMP response element-regulated genes. We have studied the mitochondrial import of CREB and its effect on the expression of mtDNA-encoded proteins. [(35)S]Methionine-labelled CREB, synthesized in vitro in the Rabbit Reticulocyte Lysate system using a construct of the human cDNA, was imported into the matrix of isolated rat liver mitochondria by a membrane potential and TOM complex-dependent process. The imported CREB caused cAMP-dependent promotion of the synthesis of mitochondrially encoded subunits of oxidative phosphorylation enzyme complexes. Thus, CREB moves from the cytosol to mitochondria, in addition to the nucleus, and, when phosphorylated by cAMP-dependent protein kinase, promotes the expression of mitochondrial genes
cAMP –dependent protein kinase promotes the mitochondrial import of the nuclear encoded NDUFS4 subunit of complex I. The role of heat shock proteins
No full textcAMP/Ca2+ response-element binding protein CREB plays a central role in the biogenesis of respiratory chain proteins in mammalian cells
No full textIn mammalian cells, promotion of mitochondrial biogenesis
by various agents involves cAMP and Ca21-mediated signal
transduction pathways. Recruitment of these pathways results
in phosphorylation by cAMP and Ca21-dependent protein kinases
of cAMP/Ca21 response element-binding protein (CREB).
Phosphorylation of CREB, bound to transcriptional complexes
of target genes, activates a down-stream cascade of transcriptional
complexes, which involve in sequence, the nuclear factors
TORCs, PGC-1, NRF1 and NRF2, and the mitochondrial factor
mitochondrial transcriptional factor A. CREB also binds
directly to the D-loop of mitochondrial DNA and activates its
expression. Activation of this network of transcriptional complexes
results in concerted promotion of the expression of nuclear
and mitochondrial genes encoding subunits of oxidative
phosphorylation complexes
beta-agonist isoproterenol rescues the activity of complex I, damaged by oxidative stress insult, promoting the mitochondrial import and dynamic assembly of the NDUFS4 subunit
No full textInhibition of Drp1-mediated mitochondrial fission improves mitochondrial dynamics and bioenergetics stimulating neurogenesis in hippocampal progenitor cells from a Down syndrome mouse model.
Full text linkFunctional and structural damages to mitochondria have been critically associated with the pathogenesis of Down syndrome (DS), a human multifactorial disease caused by trisomy of chromosome 21 and associated with neurodevelopmental delay, intellectual disability and early neurodegeneration. Recently, we demonstrated in neural progenitor cells (NPCs) isolated from the hippocampus of Ts65Dn mice -a widely used model of DS - a severe impairment of mitochondrial bioenergetics and biogenesis and reduced NPC proliferation. Here we further investigated the origin of mitochondrial dysfunction in DS and explored a possible mechanistic link among alteration of mitochondrial dynamics, mitochondrial dysfunctions and defective neurogenesis in DS. We first analyzed mitochondrial network and structure by both confocal and transmission electron microscopy as well as by evaluating the levels of key proteins involved in the fission and fusion machinery. We found a fragmentation of mitochondria due to an increase in mitochondrial fission associated with an up-regulation of dynamin-related protein 1 (Drp1), and a decrease in mitochondrial fusion associated with a down-regulation of mitofusin 2 (Mnf2) and increased proteolysis of optic atrophy 1 (Opa1). Next, using the well-known neuroprotective agent mitochondrial division inhibitor 1 (Mdivi-1), we assessed whether the inhibition of mitochondrial fission might reverse alteration of mitochondrial dynamics and mitochondrial dysfunctions in DS neural progenitors cells. We demonstrate here for the first time, that Mdivi-1 restores mitochondrial network organization, mitochondrial energy production and ultimately improves proliferation and neuronal differentiation of NPCs. This research paves the way for the discovery of new therapeutic tools in managing some DS-associated clinical manifestations
cAMP/PKA Signaling Modulates Mitochondrial Supercomplex Organization
Full text linkThe oxidative phosphorylation (OXPHOS) system couples the transfer of electrons to oxygen with pumping of protons across the inner mitochondrial membrane, ensuring the ATP production. Evidence suggests that respiratory chain complexes may also assemble into supramolecular structures, called supercomplexes (SCs). The SCs appear to increase the efficiency/capacity of OXPHOS and reduce the reactive oxygen species (ROS) production, especially that which is produced by complex I. Studies suggest a mutual regulation between complex I and SCs, while SCs organization is important for complex I assembly/stability, complex I is involved in the supercomplex formation. Complex I is a pacemaker of the OXPHOS system, and it has been shown that the PKA-dependent phosphorylation of some of its subunits increases the activity of the complex, reducing the ROS production. In this work, using in ex vivo and in vitro models, we show that the activation of cAMP/PKA cascade resulted in an increase in SCs formation associated with an enhanced capacity of electron flux and ATP production rate. This is also associated with the phosphorylation of the NDUFS4 subunit of complex I. This aspect highlights the key role of complex I in cellular energy production
The regulation of PTC containing transcripts of the human NDUFS4 gene of complex I of respiratory chain and the impact of pathological mutations
No full textThe regulation of alternative transcripts of the NDUFS4 gene of complex I of the respiratory chain has been Studied in human cell lines. One of the alternative transcripts (SV1) is subjected to the NMD degradation pathway which involves the hUPF1 and hUPF2 factors. Another transcript (SV3) appears to be controlled in the nuclear fraction and to be enhanced when hUPF1 is depleted, but unaffected by translation inhibitors or when hUPF2 expression is down-regulated. A pathological homozygous nonsense mutation in exon 1, found in a patient affected by mitochondrial disorder, inactivated in the patient's fibroblasts NMD degradation of SV1 and enhanced the nuclear production of SV3. In another patient with a homozygous splice acceptor site mutation in intron 1, SV3, which was the only transcript of NDUFS4 gene to be produced, accumulated in fibroblasts. (C) 2008 Elsevier Masson SAS. All rights reserved
cAMP regulates the functional activity, coupling efficiency and structural organization of mammalian FOF1 ATP synthase.
Full text linkThe present study shows that in isolated mitochondria and myoblast cultures depletion of cAMP, induced by sAC inhibition, depresses both ATP synthesis and hydrolysis by the FOF1 ATP synthase (complex V) of the oxidative phosphorylation system (OXPHOS). These effects are accompanied by the decrease of the respiratory membrane potential, decreased level of FOF1 connecting subunits and depressed oligomerization of the complex. All these effects of sAC inhibition are prevented by the addition of the membrane-permeant 8-Br-cAMP. These results show, for the first time, that cAMP promotes ATP production by complex V and prevents, at the same time, its detour to a mitochondrial membrane leak conductance, which is involved in cell death
A larger spectrum of intragenic STRs improves linkage analysis and localization of intragenic recombination detection in the dystrophin gene: an analysis of 93 families from Southern Italy. J. Mol. Diagn.
No full textDuchenne/Becker muscular dystrophies (D/BMD) are
X-linked recessive disorders resulting from dystrophin
gene mutations. Intragenic recombination in the dystrophin
gene occurs with a high frequency. Therefore,
determination of the location and frequency of recombination
improves D/BMD carrier detection and prenatal
diagnosis in families in which the disease-causing
mutation cannot be detected by most conventional
methods. We describe herein a linkage analysis performed
using a fast method based on capillary gel electrophoresis
of fluorescent-labeled amplified alleles of
15 intragenic short tandem repeats spanning the entire
dystrophin gene. On characterization of recombination
events in 93 unrelated D/BMD families from southern
Italy, we mapped 25 intragenic recombinations out of
273 informative meioses analyzed. The terminal regions
of a gene are notoriously challenging for linkage analysis
because some recombination events could be
missed in case of lack of informativeness of the outermost
markers. Many recombination events (10/25)
identified in this study were located at the terminal
regions of the dystrophin gene, and some were found
by typing of several informative short tandem repeats
located in these regions. Moreover, about 24% of the
recombination events found in this study mapped to
the 3 region of the gene, in contrast with the low
frequency (4 to 15%) reported by others
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