Localizing acethyl-serotonin transferase by electron microscopy

Kerenyi, N; Sótonyi, Péter; Somogyi, E

doi:10.1007/bf02463562

Cited by 17 publications

(9 citation statements)

References 11 publications

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“…In contrast, Yang et al observed that the SNAT was present in the mitochondrial intermembrane space close to the outer membrane (42). This seems to support the observations of Kerenyi et al (43,44) that SNAT product was observed in the mitochondrial intermembrane space of pinealocytes. Based on the current data, it is difficult to localize melatonin synthesis exclusively in the matrix or in the intermembrane space of mitochondria.…”

Section: Fig 2 Localization Of Snat In Rat Choroid Plexus Endothelimentioning

confidence: 62%

Mitochondria: the birth place, battle ground and the site of melatonin metabolism in cells

2019

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It was a surprising discovery when mitochondria, as the power houses of cells, were also found to synthesize the potent mitochondrial targeted antioxidant, melatonin. The melatonin synthetic enzyme serotonin N-acetyltransferase (SNAT) was found in matrix and also in the intermembrane space of mitochondria. We hypothesize that the melatonin synthesis occurs in the matrix due to substrate (N-acetyl co-enzyme A) availability while the intermembrane space may serve as the recycling pool of SNAT to regulate the melatonin circadian rhythm. Another surprise was that the melatonin membrane receptors, including MT1 and MT2, were also present in mitochondria. The protective effects of melatonin against neuronal injury induced by brain ischemia/reperfusion were proven to be mainly mediated by mitochondrial melatonin receptors rather than the cell surface membrane receptors which is contrary to the classical principle. In addition, melatonin metabolic enzyme has also been identified in the mitochondria. This enzyme can convert melatonin to N-acetylserotonin to strengthen the antitumor effects of melatonin. Thus, mitochondria are the generator, battle ground and metabolic sites of melatonin. The biological significance of the strong association between mitochondria and melatonin should be intensively investigated.

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Section: Fig 2 Localization Of Snat In Rat Choroid Plexus Endothelimentioning

confidence: 62%

Mitochondria: the birth place, battle ground and the site of melatonin metabolism in cells

2019

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“…Chloroplasts are the major site of melatonin production and mitochondria were also reported to produce melatonin only in animals . There are no reports to show whether plant mitochondria synthesize melatonin.…”

Section: Discussionmentioning

confidence: 99%

Plant mitochondria synthesize melatonin and enhance the tolerance of plants to drought stress

Wang

Chao

Zheng

et al. 2017

Journal of Pineal Research

228

158

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Synthesis of melatonin in mitochondria was reported in animals. However, there is no report on whether plant mitochondria also produce melatonin. Herein, we show that plant mitochondria are a major site for melatonin synthesis. In an in vitro study, isolated apple mitochondria had the capacity to generate melatonin. Subcellular localization analysis documented that an apple SNAT isoform, MzSNAT5, was localized in the mitochondria of both Arabidopsis protoplasts and apple callus cells. The kinetic analysis revealed that the recombinant MzSNAT5 protein exhibited high enzymatic activity to catalyze serotonin to N-acetylserotonin with the K and V of 55 μmol/L and 0.909 pmol/min/mg protein at 35°C, respectively; this pathway functioned over a wide range of temperatures from 5 to 75°C. In an in vivo study, MzSNAT5 was drought inducible. The transgenic Arabidopsis ectopically expressing MzSNAT5 elevated the melatonin level and, hence, enhanced drought tolerance. The mechanistic study indicated that the ectopically expressing MzSNAT5 allows plant mitochondria to increase melatonin synthesis. As a potent free radical scavenger, melatonin reduces the oxidative stress caused by the elevated reactive oxygen species which are generated under drought stress in plants. Our findings provide evidence that engineered melatonin-enriched plants exhibit enhanced oxidative tolerance.

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“…These changes suggest that an additional function of mitochondria, besides ATP production, may be associated with melatonin synthesis. Interestingly, Kerenyi et al observed that the reaction product of AANAT was exclusively localized in the mitochondria of mouse pinealocytes [96,97]. These authors failed to explain the potential significance of their observations; therefore, their reports did not draw the attention of pineal scientists.…”

Section: Mitochondria: the Major Sites For Melatonin Synthesis Andmentioning

confidence: 99%

Melatonin: A Mitochondrial Targeting Molecule Involving Mitochondrial Protection and Dynamics

Tan

Manchester

Qin

et al. 2016

IJMS

322

256

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Melatonin has been speculated to be mainly synthesized by mitochondria. This speculation is supported by the recent discovery that aralkylamine N-acetyltransferase/serotonin N-acetyltransferase (AANAT/SNAT) is localized in mitochondria of oocytes and the isolated mitochondria generate melatonin. We have also speculated that melatonin is a mitochondria-targeted antioxidant. It accumulates in mitochondria with high concentration against a concentration gradient. This is probably achieved by an active transportation via mitochondrial melatonin transporter(s). Melatonin protects mitochondria by scavenging reactive oxygen species (ROS), inhibiting the mitochondrial permeability transition pore (MPTP), and activating uncoupling proteins (UCPs). Thus, melatonin maintains the optimal mitochondrial membrane potential and preserves mitochondrial functions. In addition, mitochondrial biogenesis and dynamics is also regulated by melatonin. In most cases, melatonin reduces mitochondrial fission and elevates their fusion. Mitochondrial dynamics exhibit an oscillatory pattern which matches the melatonin circadian secretory rhythm in pinealeocytes and probably in other cells. Recently, melatonin has been found to promote mitophagy and improve homeostasis of mitochondria.

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Localizing acethyl-serotonin transferase by electron microscopy

Cited by 17 publications

References 11 publications

Mitochondria: the birth place, battle ground and the site of melatonin metabolism in cells

Mitochondria: the birth place, battle ground and the site of melatonin metabolism in cells

Plant mitochondria synthesize melatonin and enhance the tolerance of plants to drought stress

Melatonin: A Mitochondrial Targeting Molecule Involving Mitochondrial Protection and Dynamics

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