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Introduction
Please visit www.peixotolab.org
Our laboratory employs patch clamping, live fluorescence microscopy, and biochemical approaches to study how mitochondria communicate with other cellular compartments in normal and stressed conditions. We are currently investigating the involvement of pre-synaptic mitochondria in muscle denervation during ALS.
Current institution
Additional affiliations
August 2013 - present
October 2011 - August 2013
July 2009 - October 2011
Education
September 2002 - September 2006
June 2000 - April 2002
January 1996 - March 2000
Publications
Publications (67)
Since our initial characterization of the iMACs, different di-bromocarbazole derivatives with anti-apoptotic function have been developed and tested in several mouse models of brain injury and neurodegeneration [13-21]. Owing to the increased therapeutic potential of anti-apoptotic di-bromocarbazole derivatives, we sought to expand our knowledge of...
The TIM23 complex is a hub for translocation of preproteins into or across the mitochondrial inner membrane. This dual sorting mechanism is currently being investigated, and in yeast appears to be regulated by a recently discovered subunit, the Mgr2 protein. Deletion of Mgr2p has been found to delay protein translocation into the matrix and accumul...
The mitochondrial permeability transition pore (MPTP) has resisted molecular identification. The original model of the MPTP that proposed the adenine nucleotide translocator (ANT) as the inner membrane pore-forming component was challenged when mitochondria from Ant1/2 double null mouse liver still had MPTP activity. Because mice express three Ant...
The elevated emission of reactive oxygen species (ROS) from presynaptic mitochondria is well-documented in several inflammatory and neurodegenerative diseases. However, the potential role of mitochondrial ROS in presynaptic function and plasticity remains largely understudied beyond the context of disease. Here, we investigated this potential ROS r...
Citation: Couto-Lima, C.A.; Machado, M.C.R.; Anhezini, L.; Oliveira, M.T.; Molina, R.A.d.S.; da Silva, R.R.; Lopes, G.S.; Trinca, V.; Colón, D.F.; Peixoto, P.M.; et al. EMC1 Is Required for the Sarcoplasmic Reticulum and Mitochondrial Functions in the Drosophila Muscle. Biomolecules 2024, Abstract: EMC1 is part of the endoplasmic reticulum (ER) mem...
The mitochondrial permeability transition pore (mPTP) is a channel in the inner mitochondrial membrane whose sustained opening in response to elevated mitochondrial matrix Ca ²⁺ concentrations triggers necrotic cell death. The molecular identity of mPTP is unknown. One proposed candidate is the mitochondrial ATP synthase, whose canonical function i...
The vast majority of proteins that reside within mitochondria are encoded in nuclear DNA, synthesized on cytosolic ribosomes, and imported into the organelle. Within the mitochondrion reside several types of complex machineries that mediate the sorting, translocation and integration of incoming polypeptides based on their targeting information. Amo...
The mitochondrial permeability transition pore (MPTP) has resisted molecular identification for decades. The original model of the MPTP had the adenine nucleotide translocator (ANT) as the inner membrane pore-forming component. Indeed, reconstitution experiments showed that recombinant or purified ANT generates MPTP-like pores in lipid bilayers. Th...
Mounting evidence suggests that mitochondrial dysfunction plays a causal role in the etiology and progression of Alzheimer's disease (AD). We recently showed that the carbonic anhydrase inhibitor (CAI) methazolamide (MTZ) prevents amyloid β (Aβ)‐mediated onset of apoptosis in the mouse brain. In this study, we used MTZ and, for the first time, the...
Mitochondrial biogenesis and function, since the eukaryotic merger millions of years ago to now, relies on protein import channels across its membranes. This chapter reviews the current literature on the import pathways, how they are regulated, and how they are involved in emerging mitochondrial functions, from biogenesis to transcriptional regulat...
Background
Mitochondrial dysfunction has been linked to the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Functional studies of mitochondrial bioenergetics have focused mostly on superoxide dismutase 1 (SOD1) mutants, and showed that mutant human SOD1 impairs mitochondrial oxidative phosphorylatio...
Mitochondrial Apoptotic Channel inhibitors or iMACs are di-bromocarbazole derivatives with anti-apoptotic function which have been tested and validated in several mouse models of brain injury and neurodegeneration. Owing to the increased therapeutic potential of these compounds, we sought to expand our knowledge of their mechanism of action. We inv...
The discovery of very large channels in the two membranes of mitochondria represented an astonishing finding and a turning point in the awareness of these conspicuous energy-generating organelles. Sizable channels are at the crossroads of important cellular pathways and mitochondrial functions like biogenesis, signaling, secretion, compartmentaliza...
Despite containing their own genome, mitochondria are not autonomous organelles. Over 1,146 of the known mitochondrial proteins are encoded in nuclear DNA and therefore must be imported from the cytosol. The process has been extensively studied and is known to involve several protein complexes spanning the outer and the inner mitochondrial membrane...
This chapter enables the reader to become acquainted with the currently known mitochondrial channels, some of which have unknown functions and whose study in neurons may inspire potential approaches to treatment of neurodegenerative diseases. Although fine regulation of the channels might vary from organ to organ, it is likely that general properti...
Cancer transformation involves reprograming of mitochondrial function to avert cell death mechanisms, monopolize energy metabolism, accelerate mitotic proliferation, and promote metastasis. Mitochondrial ion channels have emerged as promising therapeutic targets because of their connection to metabolic and apoptotic functions. This mini review disc...
MAC is distinct from typical ion channels in its huge pore diameter of 4–6 nm and poor ion selectivity. Although it has been identified during intracellular recordings, MAC is typically studied by patch-clamping mitochondria isolated from apoptotic cells. This mega-channel assembles in the outer membrane of mitochondria containing the pro-apoptotic...
Obstructive sleep apnea, a condition associated with chronic intermittent hypoxia (CIH), carries an increased risk of stroke. However, CIH has been reported to either increase or decrease brain injury in models of focal cerebral ischemia. The factors determining the differential effects of CIH on ischemic injury and their mechanisms remain unclear....
Objectives: We previously screened synthetic organogold compounds for anti-tumor activity in oral carcinoma cells. Here we aimed to study these compounds’ mechanism of action. Based on our previous results, we hypothesized that the organogold compounds acted on mitochondria and induced opening of the mitochondrial apoptosis-induced channel (MAC) or...
Previous studies proposed that myosin-Va regulates apoptosis by sequestering pro-apoptotic Bmf to the actin cytoskeleton through dynein light chain-2 (DLC2). Adhesion loss or other cytoskeletal perturbations would unleash Bmf, allowing it to bind and inhibit pro-survival Bcl2 proteins. Here, we demonstrated that overexpression of a myosin-Va medial...
Cell Death and Disease 4, e547 (2013). doi:10.1038/cddis.2013.45
Introduction: Multi-cellular organisms eliminate damaged cells as part of the normal cell life cycle by a regulated process of programmed cell death known as apoptosis. In mammals, apoptosis is regulated by the Bcl-2 gene family, which controls loss of outer mitochondrial membrane (OMM) permeability. Two pro-apoptotic Bcl-2 members, Bax and Bak, ol...
Honey bees have brain structures with specialized and developed systems of communication that account for memory, learning capacity and behavioral organization with a set of genes homologous to vertebrate genes. Many microtubule- and actin-based molecular motors are involved in axonal/dendritic transport. Myosin-Va is present in the honey bee Apis...
Most chemotherapeutic agents kill cancer cells by apoptosis, or programmed cell death. Many of these agents, like cisplatin, rely upon platinum for their reactivity, but recent reports show cancer cells developed resistance to platinum-based compounds. Objectives: In the present study, we compared the apoptotic effects of Cisplatin with newly synth...
Mitochondria communicate with the rest of the cell through channels located in their inner and outer membranes. Most of the time, the message is encoded by the flow of anions and cations e.g., through VDAC and PTP, respectively. However, proteins are also both imported and exported across the mitochondrial membranes e.g., through TOM and MAC, respe...
Collateral spread of apoptosis to nearby cells is referred to as the bystander effect, a process that is integral to tissue homeostasis and a challenge to anticancer therapies. In many systems, apoptosis relies on permeabilization of the mitochondrial outer membrane to factors such as cytochrome c and Smac/DIABLO. This permeabilization occurs via f...
Apoptosis is an elemental form of programmed cell death; it is fundamental to higher eukaryotes and essential to mechanisms controlling tissue homeostasis. Apoptosis is also involved in many pathologies including cancer, neurodegenerative diseases, aging, and infarcts. This cell death program is tightly regulated by Bcl-2 family proteins by control...
The presence of myosin and dynein in the ovaries of both Apis mellifera and Scaptotrigona postica was investigated in extracts and in histological sections. In the ovary extracts, motor proteins, myosins V, VI and dynein were detected by Western blot. In histological sections, they were detected by immunocytochemistry, using a mouse monoclonal anti...
Permeabilization of the mitochondrial membranes is a crucial step in apoptosis and necrosis. This phenomenon allows the release of mitochondrial death factors, which trigger or facilitate different signaling cascades ultimately causing the execution of the cell. The mitochondrial permeability transition pore (mPTP) has long been known as one of the...
Ion channels located in the outer and inner mitochondrial membranes are key regulators of cellular signaling for life and death. Permeabilization of mitochondrial membranes is one of the most critical steps in the progression of several cell death pathways. The mitochondrial apoptosis-induced channel (MAC) and the mitochondrial permeability transit...
Most chemotherapeutic agents kill cancer cells by apoptosis, or programmed cell death. Many of these agents like cisplatin rely upon platinum for their reactivity. Recently, organogold(III) compounds have been explored for use in those cases where resistance has developed against platinum-based drugs. Objectives: The cytotoxicity of four novel orga...
Background: MAC, or mitochondrial apoptosis-induced channel, forms in the outer membrane of mitochondria from proapoptotic Bcl-2 family proteins in the presence of apoptotic stimuli. During apoptosis, BAX undergoes a conformational change and translocates from the cytosol to the outer membrane of mitochondria where it oligomerizes to form the pore...
The study of mitochondrial ion channels changed our perception of these double-wrapped organelles from being just the power house of a cell to the guardian of a cell's fate. Mitochondria communicate with the cell through these special channels. Most of the time, the message is encoded by ion flow across the mitochondrial outer and inner membranes....
Accumulating literature associate mitochondrial dynamics with apoptosis, since regulation of either process has reciprocal effects. These processes seem to converge in formation of the mitochondrial apoptosis induced channel, MAC, which releases cytochrome c and triggers the degradation phase of apoptosis. While Bax and Bak, core components of MAC,...
Several groups have tried to determine the structure of the channel (MAC) formed in mitochondrial outer membranes (OM) of apoptotic cells or in synthetic membranes by Bax and related proteins/peptides, using electron microscopy (EM), atomic force microscopy and x-ray diffraction. Here, pore-like structures ∼3-10 nm were handpicked from transmission...
Coordination of Ca(2+) signaling among cells contributes to synchronization of salivary gland cell function. However, mechanisms that underlie this signaling remain elusive. Here, intercellular Ca(2+) waves (ICW) in submandibular gland cells were investigated using Fura-2 fluorescence imaging. Mechanical stimulation of single cells induced ICW prop...
MAC (mitochondrial apoptosis-induced channel) forms in the mitochondrial outer membrane and unleashes cytochrome c to orchestrate the execution of the cell. MAC opening is the commitment step of intrinsic apoptosis. Hence closure of MAC may prevent apoptosis. Compounds that blocked the release of fluorescein from liposomes by recombinant Bax were t...
The death of one cell can precipitate the death of nearby cells in a process referred to as the bystander effect. We investigated whether mitochondrial apoptosis generated a bystander effect and, if so, by which pathway. Microinjection with cytochrome c mimicked function of the mitochondrial apoptosis-induced channel MAC and caused apoptosis of bot...
Aqueous channels are at the core of the translocase of the outer membrane (TOM) and the translocase of the inner membrane for the transport of preproteins (TIM23), the translocases mediating the transport of proteins across the outer and inner mitochondrial membranes. Yet, the existence of a channel associated to the translocase of the inner membra...
Translocation of the presequence is an early event in import of preproteins across the mitochondrial inner membrane by the TIM23 complex. Import of signal peptides, whose sequences mimic mitochondrial import presequences, was measured using a novel, qualitative, fluorescence assay in about 1h. This peptide assay was used in conjunction with classic...
In a previous work, we demonstrated that the induction of arginase I favored the replication of Leishmania inside macrophages. Now we have analyzed the differential expression of this enzyme in the mouse model of L. major infection. Ours results show that arginase I is induced in both susceptible and resistant mice during the development of
the dis...
The ongoing efforts to sequence the honey bee genome require additional initiatives to define its transcriptome. Towards this end, we employed the Open Reading frame ESTs (ORESTES) strategy to generate profiles for the life cycle of Apis mellifera workers.
Of the 5,021 ORESTES, 35.2% matched with previously deposited Apis ESTs. The analysis of the...
The application of electrophysiological techni-ques, in particular patch-clamping, to mitochondrial membranes represented a turning point on the biophysics of mitochondria. The electrophysiological approaches used in these studies as well as the information they provide are outlined. The advantages and drawbacks of each one of these techniques are...
Questions
Questions (3)
I am following a protocol from Ana G Barata's (who is no longer in research and has no contact info):
Basically, the goal is to measure ratiometric changes in roGFP2 fluorescence (405/488 nm excitation).
Because 405 excitation gives noisy images they recommend thresholding aside from routine background removal.
My specific issue is that thresholding creates binary images (without brightness gradients), so the ratios (using the image calculator as in Barata’s and Morgan’s papers) are also binary.
I'd appreciate any specific advice or if someone has a protocol to share.
THANK YOU!
Is anyone using roGFP2-orp1 in drosophila? I am struggling to calibrate mito-roGFP2-orp1 in motor neurons (d42 driver) larval abdominal muscle preparations. Tried 1uM-2mM diamide and later H202 directly (in Hl3.1 buffer) and all I see is a drop in both 405 and 488 fluorescence, rather than a ratiometric increase. I'd appreciate any advice or the opportunity to collaborate on this.
Thank you!
P.
I would appreciate feedback (and protocols) on whether or not it is feasible to establish functional synapses between motor neuron and skeletal muscle cell lines.
Thank you!
P.
