Measurement of matrix enzyme activity in isolated mitochondria made permeable with toluene.

Mitochondria isolated from rat liver and heart were made permeable to normally nonpentrating substrates and cofactors by treatment with toluene. The optimal conditions for preparing stable, permeable mitochondria were 2% toluene for 2 min at 4 °C in a buffered, isotonic medium containing 8.5% polyethylene glycol (Mr 6000–7500). Without polyethylene glycol, the toluene-treated mitochondria were unstable and released their matrix enzymes. The treated mitochondria were particularly unstable in dilute suspension under normal assay conditions of their enzyme activities. The levels of matrix enzyme activities unmasked by toluene treatment of mitochondria were very close to those of sonicated mitochondria under identical assay conditions. Mitochondria made permeable with toluene lost only small amounts of their protein and retained a major fraction of the nucleotides and coenzymes. Electron microscopic examination of toluenetreated mitochondria indicated that they were relatively intact with swollen and vesiculated cristae membranes. Such preparations will allow the study of mitochondrial enzymes at approximate in vivo concentrations.     

The Carboxy-Terminal Modulator Protein (CTMP) Regulates Mitochondrial Dynamics

Background

Mitochondria are central to the metabolism of cells and participate in many regulatory and signaling events. They are looked upon as dynamic tubular networks. We showed recently that the Carboxy-Terminal Modulator Protein (CTMP) is a mitochondrial protein that may be released into the cytosol under apoptotic conditions.

Methodology/Principal Findings

Here we report an unexpected function of CTMP in mitochondrial homeostasis. In this study, both full length CTMP, and a CTMP mutant refractory to N-terminal cleavage and leading to an immature protein promote clustering of spherical mitochondria, suggesting a role for CTMP in the fission process. Indeed, cellular depletion of CTMP led to accumulation of swollen and interconnected mitochondria, without affecting the mitochondrial fusion process. Importantly, in vivo results support the relevance of these findings, as mitochondria from livers of adult CTMP knockout mice had a similar phenotype to cells depleted of CTMP.

Conclusions/Significance

Together, these results lead us to propose that CTMP has a major function in mitochondrial dynamics and could be involved in the regulation of mitochondrial functions.     

Corn Mitochondrial Swelling and Contraction-an Alternate Interpretation

Mitochondria isolated from 3-day-old etiolated corn shoots (Zea mays L.) can be categorized into three separate groups, each group characteristic of the cell type from which the mitochondria were isolated. Phloem sieve tubes and some adjacent parenchyma cells contain mitochondria that have few cristae and little amorphous matrix. Mitochondria from meristematic and undifferentiated cells have more cristae and matrix. Vaculate and differentiated cells have mitochondria with well-developed cristae and abundant matrix. Each mitochondrial type exhibits typical in vitro spontaneous swelling and substrate-induced contraction responses. characterized by change or lack of change in cristae size and in density of amorphous material. For the second and third types of mitochondria, swelling and contraction are characterized by a change in degree of cristae size and in matrix density. The first type undergoes few changes upon swelling or contraction. Radical changes of the inner membrane, withdrawal and infolding, are associated with cell differentiation and not with swelling and contraction of isolated corn shoot mitochondria.     

The morphological site of synthesis of cytochrome c in mammalian cells (Krebs cells)

In Krebs ascites-tumour cells, cytochrome c is segregated in the mitochondria and the level in microsomes could not be measured. At 22° in glucose–buffer Krebs cells synthesized a spectrum of proteins including cytochrome c. Mild osmotic shock in the presence of ribonuclease had little effect on incorporation of [¹⁴C]-leucine or [¹⁴C]valine into mixed mitochondrial protein but strongly inhibited synthesis of non-mitochondrial cytoplasmic proteins. Under these conditions, labelling of cytochrome c was also strongly inhibited. After pulse labelling of Krebs cells at 22° for 10min. the cytcchrome radioactivity found in mitochondria was higher than in microsomes. After addition of unlabelled amino acid as `chase' there was 137% increase in radioactivity of cytochrome c but only a 3% increase in radioactivity of whole-cell protein. It is concluded that the peptide chain of cytochome c is synthesized on cytoplasmic ribosomes. Mitochondria therefore do not have the character of self-replicating entities, but are formed by the cooperative function of messenger RNA of cytoplasmic ribosomes and, possibly, of intramitochondrial messenger derived from the mitochondrial DNA.     

Ultrastructural Changes during Swelling and Contraction of Mitochondria from Cold-hardened and Non-hardened Winter Wheat

Mitochondria isolated from both 2 and 24 C grown winter wheat (Triticum aestivum L.) undergo spontaneous swelling in isomolar KCI solutions, but only 24 C mitochondria exhibit a substrate-induced contraction response. Electron microscopic examination revealed that 24 C mitochondria have more clearly defined cristae, less matrix material, and are generally more electron-dense than 2 C mitochondria. During swelling, the matrix material of both 2 and 24 C mitochondria expands and the mitochondria become less electron-dense. After partial swelling, 24 C mitochondria contract upon addition of succinate, and regain structural characteristics similar to those of untreated mitochondria. In contrast, mitochondria from 2 C seedlings continue to swell after addition of substrate, and many of the mitochondria become irregular in shape and lose much of their matrix material. A comparison of results obtained from absorbancy measurements, electron microscopy, and a Coulter Counter indicate that swelling and contraction involve changes both in over-all volume, and internal structural characteristics of mitochondria from 2 and 24 C grown seedlings. Electron microscopic examination of shoot cells showed that mitochondria in 24 C grown seedlings possessed more recognizable cristae and greater internal organization than mitochondria in 2 C seedlings.     

Spatial and Temporal Influences on the Cell-Specific Distribution of Glycine Decarboxylase in Leaves of Wheat (Triticum aestivum L.) and Pea (Pisum sativum L.)

The distribution of glycine decarboxylase (GDC) in leaves of pea (Pisum sativum L.) and wheat (Triticum aestivum L.) has been investigated using immunogold labeling of the P-protein subunit of the GDC complex. Mitochondria in photosynthetic mesophyll cells were densely labeled, whereas those in nonphotosynthetic vascular parenchyma and epidermal cells were only weakly labeled. In pea leaves the density of immunogold labeling on mitochondria in the chloroplast-containing bundle sheath and stomatal guard cells was intermediate between that in mesophyll and epidermal cells. In both species the density of labeling on mitochondria in a cell appeared to reflect the photosynthetic capacity of the cell. This relationship was further examined in wheat where a natural developmental gradient exists along the lamina such that cell maturity increases with distance from the basal meristem. In this case the density of labeling on mesophyll cell mitochondria increased with photosynthetic development and with increasing maturity of the cell. Vascular cell mitochondria, however, became less densely labeled as the cells matured. The results indicate a close, positive correlation between the concentration of GDC in the mitochondria and the photosynthetic status of the host cell. This relationship is maintained effectively under the influence of both spatial (i.e. cellular differentiation across the lamina) and temporal (i.e. cellular development along the lamina) constraints.     

Nicotinamide Nucleotide Transhydrogenase (Nnt) Links the Substrate Requirement in Brain Mitochondria for Hydrogen Peroxide Removal to the Thioredoxin/Peroxiredoxin (Trx/Prx) System

Mitochondrial reactive oxygen species are implicated in the etiology of multiple neurodegenerative diseases, including Parkinson disease. Mitochondria are known to be net producers of ROS, but recently we have shown that brain mitochondria can consume mitochondrial hydrogen peroxide (H₂O₂) in a respiration-dependent manner predominantly by the thioredoxin/peroxiredoxin system. Here, we sought to determine the mechanism linking mitochondrial respiration with H₂O₂ catabolism in brain mitochondria and dopaminergic cells. We hypothesized that nicotinamide nucleotide transhydrogenase (Nnt), which utilizes the proton gradient to generate NADPH from NADH and NADP⁺, provides the link between mitochondrial respiration and H₂O₂ detoxification through the thioredoxin/peroxiredoxin system. Pharmacological inhibition of Nnt in isolated brain mitochondria significantly decreased their ability to consume H₂O₂ in the presence, but not absence, of respiration substrates. Nnt inhibition in liver mitochondria, which do not require substrates to detoxify H₂O₂, had no effect. Pharmacological inhibition or lentiviral knockdown of Nnt in N27 dopaminergic cells (a) decreased H₂O₂ catabolism, (b) decreased NADPH and increased NADP⁺ levels, and (c) decreased basal, spare, and maximal mitochondrial oxygen consumption rates. Nnt-deficient cells possessed higher levels of oxidized mitochondrial Prx, which rendered them more susceptible to steady-state increases in H₂O₂ and cell death following exposure to subtoxic levels of paraquat. These data implicate Nnt as the critical link between the metabolic and H₂O₂ antioxidant function in brain mitochondria and suggests Nnt as a potential therapeutic target to improve the redox balance in conditions of oxidative stress associated with neurodegenerative diseases.     

Mitochondrial-driven sustained active water vapour absorption (WVA) in the firebrat, Thermobia domestica (Packard), during development and the moulting cycle

Rapid pre-functional mitochondrial biogenesis in the short-lived first-instar nymph occurs in the cells of the developing posterior rectal sacs which when mature are the organs believed to be responsible for sustained active water vapour absorption (WVA) in the firebrat Thermobia domestica (Packard). During the second instar, the mitochondria migrate apically and begin to associate with deep portasome-studded infolds of the apical plasma membrane (apm), just as WVA starts sporadically. By mid to late in the third instar the mature mitochondria-apm apical complex is fully developed, with elongated tubular mitochondria vertically packed hexagonally in transverse section and adpressed to the deeply pleated infolds of the apm, giving the greatest known concentration of mitochondria. This coincides with peak mass-specific WVA. During moults, WVA temporarily ceases as the sac cells secrete a new cuticle overlying the sac epithelium. Their apical complex fully regresses. Mitochondria migrate perinuclearly. The apm is pinched-off into numerous small portasome-studded pouches which remain sequestered within the cytoplasm. Towards the end of the moult the apm pouches reassemble into deeply pleated infolds into which the mitochondria migrate and elongate, rapidly re-establishing the hexagonal array of the apical complex. This coincides with the recommencement of WVA.     

Spermatogenesis and sperm structure of Acerella muscorum, (Ionescu, 1930) (Hexapoda, Protura)

The general organization of the male genital system, the spermatogenesis and the sperm structure of the proturan Acerella muscorum have been described. At the apex of testis apical huge cells are present; their cytoplasm contains a conventional centriole, a large amount of dense material and several less electron-dense masses surrounded by mitochondria. Spermatocytes have normal centrioles and are interconnected by cytoplasmic bridges. Such bridges seem to be absent between spermatid cells and justify the lack of synchronization of cell maturation. Spermatids are almost globular cells with a spheroidal nucleus and a large mass of dense material corresponding to the centriole adjunct. Within this mass a centriole is preserved. Mitochondria of normal structure are located between the nucleus and the plasma membrane. The spermatids are surrounded by a thick membrane. No flagellar structure is formed. Sperm have a compact spheroidal nucleus, a large cap of centriole adjunct material within which a centriole is still visible. A layer of mitochondria is located over the nucleus. The cytoplasm is reduced in comparison to spermatids; many dense bodies are interspersed with sperm in the testicular lumen. The sperm are small, immotile cells of about 2.5-3 μm in diameter.     

Spermatogenesis and sperm structure in Carpoglyphus lactis (L.) (Acari: Astigmata)

Testes, spermatogenesis and spermatozoa are described in the mite Carpoglyphus lactis (L.), the first representative of the Hemisarcoptoidea superfamily studied ultrastructurally. Paired testes are located posteriorly in the idiosoma, with germaria situated dorsolaterally. The germarium consists of a compact group of spermatogonia; no testicular central cell was found. The remainder of the gonad is occupied by germ cells in different stages of spermatogenesis, distributed separately rather than in cysts, and embedded in a few large somatic cells filling the remaining space. Spermatocytes are covered by a spongy layer, a product of the Golgi apparatus. Spermatids are anucleate. Their chromatin condenses into granular and then tubular threads. As spermiogenesis progresses, the spongy layer assembles at a single site and forms a structure termed the spongy body; mitochondria become electron dense, elongate and gather forming a bundle; a narrow ER cistern, promptly transforming into a dense lamella, appears between the mitochondria and chromatin. Mature spermatozoa are small, highly electron-dense cells interdigitating with others via superficial protrusions. They possess chromatin threads, electron-dense lamella and mitochondria, but do not have an acrosome.Our results support the monophyly of Astigmata, but do not explain the phylogenetic affinities of Hemisarcoptoidea to other superfamilies of astigmatic mites.     

Mitochondrial involvement in cell death of non-mammalian eukaryotes

Although mitochondria are essential organelles for long-term survival of eukaryotic cells, recent discoveries in biochemistry and genetics have advanced our understanding of the requirements for mitochondria in cell death. Much of what we understand about cell death is based on the identification of conserved cell death genes in Drosophila melanogaster and Caenorhabditis elegans. However, the role of mitochondria in cell death in these models has been much less clear. Considering the active role that mitochondria play in apoptosis in mammalian cells, the mitochondrial contribution to cell death in non-mammalian systems has been an area of active investigation. In this article, we review the current research on this topic in three non-mammalian models, C. elegans, Drosophila, and Saccharomyces cerevisiae. In addition, we discuss how non-mammalian models have provided important insight into the mechanisms of human disease as they relate to the mitochondrial pathway of cell death. The unique perspective derived from each of these model systems provides a more complete understanding of mitochondria in programmed cell death. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.     

THE FINE STRUCTURE OF PUROMYCIN-INDUCED CHANGES IN MOUSE ENTORHINAL CORTEX

Bitemporal intracerebral injections of puromycin in mice suppress indefinitely expression of memory of avoidance-discrimination learning. Ultrastructural studies of the entorhinal cortex of puromycin-treated mice revealed the following: (a) Abnormalities were not observed in presynaptic terminals and synaptic clefts; many postsynaptic dendrites or somas contained swollen mitochondria. (b) Dispersion of polyribosomes into single units or condensation of ribosomes into irregular aggregates with loss of "distinctiveness" was noted in a few neurons 7–27 hr after puromycin treatment. (c) Cytoplasmic aggregates of granular or amorphous material were frequently noted within otherwise normal neuronal perikarya. (d) Mitochondria in many neuronal perikarya and dendrites were swollen. Mitochondria in axons, presynaptic terminals, and glial cells were unaltered. The relationships between these lesions and the effect of puromycin on protein synthesis and memory are examined. It is suggested that the disaggregation of polysomes is too limited to explain the effect of puromycin on memory. Special emphasis is given to the swelling of mitochondria. The possible mechanisms and the significance of this lesion are discussed.     

Biogenesis of mitochondria. The effects of catabolite repression on the in vitro phospholipid synthetic capacities of subcellular fractions of respiratory-competent and respiratory-deficient strains of Saccharomyces cerevisiae.

A respiratory-competent wild-type strain and a nuclear isogenic, mitochondrial DNA-less, petite mutant strain of Saccharomyces cerevisiae were grown under conditions of catabolite repression in batch cultures and under conditions of catabolite derepression in chemostat cultures. Subcellular fractions were isolated and the capacity of these fractions to incorporate sn-[2-³H]glycerol 3-phosphate into phospholipids was studied. Neither catabolite repression nor loss of mitochondrial DNA appreciably altered the total in vitro lipid synthesized by mitochondrial fractions during the incubation. Mitochondria isolated from catabolite-derepressed wild-type and petite cells had approximately the same specific activity in vitro for the synthesis of phosphatidylinositol. phosphatidic acid, phosphatidylethanolamine, phosphatidylserine, and neutral lipids. Mitochondria isolated from the petite cells retained the capacity to synthesize phosphatidylglycerol and diphosphatidylglycerol, although the synthesis of these phospholipids was far less extensive than that by the mitochondria isolated from the wild-type cells. In both cases, mitochondria prepared from catabolite-repressed cells synthesized a greater proportion of phosphatidylserine than did mitochondria from catabolite-derepressed cells. The proportions of phospholipid species synthesized in vitro by the microsomal fractions studied were not grossly affected by catabolite repression or loss of mitochondrial DNA.     

Targeting Mitochondria by Zn(II)N-Alkylpyridylporphyrins: The Impact of Compound Sub-Mitochondrial Partition on Cell Respiration and Overall Photodynamic Efficacy

Mitochondria play a key role in aerobic ATP production and redox control. They harness crucial metabolic pathways and control cell death mechanisms, properties that make these organelles essential for survival of most eukaryotic cells. Cancer cells have altered cell death pathways and typically show a shift towards anaerobic glycolysis for energy production, factors which point to mitochondria as potential culprits in cancer development. Targeting mitochondria is an attractive approach to tumor control, but design of pharmaceutical agents based on rational approaches is still not well established. The aim of this study was to investigate which structural features of specially designed Zn(II)N-alkylpyridylporphyrins would direct them to mitochondria and to particular mitochondrial targets. Since Zn(II)N-alkylpyridylporphyrins can act as highly efficient photosensitizers, their localization can be confirmed by photodamage to particular mitochondrial components. Using cultured LS174T adenocarcinoma cells, we found that subcellular distribution of Zn-porphyrins is directed by the nature of the substituents attached to the meso pyridyl nitrogens at the porphyrin ring. Increasing the length of the aliphatic chain from one carbon (methyl) to six carbons (hexyl) increased mitochondrial uptake of the compounds. Such modifications also affected sub-mitochondrial distribution of the Zn-porphyrins. The amphiphilic hexyl derivative (ZnTnHex-2-PyP) localized in the vicinity of cytochrome c oxidase complex, causing its inactivation during illumination. Photoinactivation of critical cellular targets explains the superior efficiency of the hexyl derivative in causing mitochondrial photodamage, and suppressing cellular respiration and survival. Design of potent photosensitizers and redox-active scavengers of free radicals should take into consideration not only selective organelle uptake and localization, but also selective targeting of critical macromolecular structures.     

Spermitin: A Novel Mitochondrial Protein in Drosophila Spermatids

Mitochondria, important energy centers in the cell, also control sperm cell morphogenesis. Drosophila spermatids have a remarkably large mitochondrial formation called the nebenkern. Immediately following meiosis during sperm development, the mitochondria in the spermatid fuse together into two large aggregates which then wrap around one another to produce the spherical nebenkern: a giant mitochondrion about 6 micrometers in diameter. The fused mitochondria play an important role in sperm tail elongation by providing a structural platform to support the elongation of sperm cells. We have identified a novel testis-specific protein, Spermitin (Sprn), a protein with a Pleckstrin homology-like (PH) domain related to Ran-binding protein 1 at its C-terminus. Fluorescence microscopy showed that Sprn localizes at mitochondria in transfected Kc167 cells, and in the nebenkern throughout spermatid morphogenesis. The role of Sprn is unclear, as sprn mutant males are fertile, and have sperm tail length comparable to the wild-type.     

Activities of isolated mitochondria and mitochondrial enzymes from aerobically and anaerobically germinated barnyard grass (echinochloa) seedlings

Activity of mitochondria isolated from whole seedlings of Echinochloa crus-galli (L.) Beauv. var oryzicola germinated under aerobic and anaerobic conditions for 5 to 7 days was investigated. Mitochondria from both treatments exhibited good respiratory control and ADP/O ratios. Although O₂ uptake was low in anaerobic mitochondria, activity rapidly increased when the seedlings were transferred to air. Mitochondria from both aerobically and anaerobically grown seedlings of E. crus-galli var oryzicola maintained up to 66% of their initial respiration rate in the presence of both cyanide and salicylhydroxamic acid, and the inhibitory effects of cyanide and azide were additive. In addition, antimycin A was not an effective inhibitor of respiration. Reduced-minus-oxidized absorption spectra revealed that cytochromes a, a₃, and b were reduced to a greater extent and cytochrome c was reduced to a lesser extent in anaerobically germinated seedlings relative to that in aerobically germinated seedlings. An absorption maximum in the cytochrome d region of the spectrum was reduced to the same extent under both germination conditions and an absorption maximum at 577 nm was present only in anaerobically germinated seedlings. Anaerobically germinated seedlings contained 70% of the cytochrome c oxidase activity found in air grown seedlings. Upon exposure to air, the developmental pattern of this enzyme in anaerobically germinated seedlings was similar to air controls. Succinate dehydrogenase activity in anaerobic seedlings was only 45% of the activity found in aerobically germinated seeds, but within 1 hour of exposure to air, the activity had increased to control levels. The results suggest that mitochondria isolated from E. crus-galli var oryzicola differ from other plants studied and that the potential for mitochondrial function during anaerobiosis exists.     

Histological studies on the marsupium of two terrestrial isopods (Crustacea,Isopoda, Oniscidea)

The marsupium, a brood pouch in peracarid crustaceans (Crustacea, Malacostraca) has evolved in terrestrial environment for providing nutrition and optimal conditions for embryogenesis. In the present study we give details on the histology and ultrastructure of its constituting elements such as oostegites and cotyledons. Marsupia of two different eco-morphological types of woodlice, namely the non-conglobating species Trachelipus rathkii Brandt, 1833 and the conglobating species Cylisticus convexus De Geer, 1778 were investigated. Light microscopic (LM) studies showed some differences in the main structure of the two species’ brood pouch: in Trachelipus rathkii, a ‘clinger’ type woodlice, the oostegites bend outwards during brood incubation as growing offspring require more space, while in Cylisticus convexus, a ‘roller’ type isopod, the sternites arch into the body cavity to ensure space for developing offspring and still allowing conglobation of the gravid females. The quantitative analysis of the oostegites’ cuticle proved that the outer part is about 2.5 - 3 times thicker compared to the inner part in both species. Electron microscopic (TEM) examinations show only small histological differences in the oostegites and cotyledon structure of the two species. Cellular elements and moderately electron dense fleecy precipitate are found in the hemolymph space between the two cuticles of oostegites. The cells contain PAS positive polysaccharide areas. TEM studies revealed some differences in the cotyledon ultrastructure of the two species. Cotyledons of Trachelipus rathkii consist of cells with cristate mitochondria and granular endoplasmic reticulum with cisterns. Cotyledons of Cylisticus convexus consist of cells with densely cristate mitochondria and ribosomes attached to vesicular membrane structures. In both species cells with electron dense bodies were observed. We conclude that - besides the differences in marsupial shapes - the fine structure of the oostegites and cotyledons is hardly affected by the eco-morphological type, specifically the conglobating or non-conglobating character of the studied species.     

Functional and Numerical Responses of Three Species of Predatory Phytoseiid Mites (Acari: Phytoseiidae) to Thrips flavidulus (Thysanoptera: Thripidae)

Phytoseiid mites are considered the most effective natural enemies of pest mites. They also have been shown to attack pest thrips. It is unknown, however, whether phytoseiid mites can reduce high densities of Thrips flavidulus (Bagnall). We addressed this question by the study of functional and numerical responses. The aim of this research was to evaluate the potential predation success of the adults of three predatory mites, Neoseiulus cucumeris (Oudemans), Neoseiulus barkeri (Hughes), and Euseius nicholsi (Ehara & Lee), against the first-instar of T. flavidulus in a climatic chamber at five different temperatures. The results showed that the functional responses of those predators reflected the Holling type II functional response and were density dependent and positively related to temperature. For the three predatory mites, predation and successful attack rates increased with increasing temperature up to 26°C, reducing afterward. Handling time had the opposite trend. Reproductive ability also increased with an increase in temperature and prey consumption.     

Manganese (III) meso-tetrakis N-ethylpyridinium-2-yl porphyrin acts as a pro-oxidant to inhibit electron transport chain proteins,modulate bioenergetics,and enhance the response to chemotherapy in lymphoma cells

The manganese porphyrin, manganese (III) meso-tetrakis N-ethylpyridinium-2-yl porphyrin (MnTE-2-PyP⁵⁺), acts as a pro-oxidant in the presence of intracellular H₂O₂. Mitochondria are the most prominent source of intracellular ROS and important regulators of the intrinsic apoptotic pathway. Due to the increased oxidants near and within the mitochondria, we hypothesized that the mitochondria are a target of the pro-oxidative activity of MnTE-2-PyP⁵⁺ and that we could exploit this effect to enhance the chemotherapeutic response in lymphoma. In this study, we demonstrate that MnTE-2-PyP⁵⁺ modulates the mitochondrial redox environment and sensitizes lymphoma cells to antilymphoma chemotherapeutics. MnTE-2-PyP⁵⁺ increased dexamethasone-induced mitochondrial ROS and oxidation of the mitochondrial glutathione pool in lymphoma cells. The combination treatment induced glutathionylation of Complexes I, III, and IV in the electron transport chain, and decreased the activity of Complexes I and III, but not the activity of Complex IV. Treatment with the porphyrin and dexamethasone also decreased cellular ATP levels. Rho(0) malignant T-cells with impaired mitochondrial electron transport chain function were less sensitive to the combination treatment than wild-type cells. These findings suggest that mitochondria are important for the porphyrin’s ability to enhance cell death. MnTE-2-PyP⁵⁺ also augmented the effects of 2-deoxy-D-glucose (2DG), an antiglycolytic agent. In combination with 2DG, MnTE-2-PyP⁵⁺ increased protein glutathionylation, decreased ATP levels more than 2DG treatment alone, and enhanced 2DG-induced cell death in primary B-ALL cells. MnTE-2-PyP⁵⁺ did not enhance dexamethasone- or 2DG-induced cell death in normal cells. Our findings suggest that MnTE-2-PyP⁵⁺ has potential as an adjuvant for the treatment of hematologic malignancies.