Modulation of the subcellular distribution of calmodulin by melatonin in MDCK cells

Abstract

In this paper we describe the interaction of melatonin with calmodulin in MDCK cells. The double staining immunofluorescent method showed that calmodulin in control MDCK cells appeared as fluorescent spots at the cell periphery. In contrast, MDCK cells cultured with 10(-9) M melatonin for 6, 12, 24 hr or for 4 days showed that calmodulin fluorescent spots were distributed throughout the cytoplasm as well as in the nucleus. These calmodulin rearrangements were reversed 6 hr after melatonin withdrawal. Moreover, calmodulin radioimmunoassay showed that in 10(-9) M melatonin-treated cells, membrane-bound calmodulin content was increased by 78% whereas cytosolic calmodulin decreased by 60%. Simultaneous labeling of MDCK cells with specific antibodies against calmodulin and melatonin showed that not only does the indole enter the cell, but that it has the same subcellular distribution as calmodulin. Besides the early responses induced by the melatonin antagonism to calmodulin, the results suggest that the indole may also induce long-term cellular responses by changing calmodulin concentrations in specific cellular compartments.

Melatonin as a cytoskeletal modulator: implications for cell physiology and disease

“…Similar effects are obtained with the CaM antagonists trifluoperazine (10 μ M) and compound 48/80 (30 μ g/mL) [32]. The CaM antagonism by melatonin is supported by the fact that the indole binds with high affinity (180 pM) to purified liposome‐incorporated CaM [34] as well as to membrane‐bound [35] and cytoplasmic CaM [36], and because in vitro this indole inhibits the activity of CaM‐dependent enzymes such as cAMP phosphodiesterase [37], nitric oxide synthase [38] and CaM‐kinase II [39]. Direct interaction of melatonin with intact calcium‐saturated CaM has also been recently studied by fluorescence and nuclear magnetic resonance spectroscopies [40].…”

A Combination of Melatonin and Alpha Lipoic Acid has Greater Cardioprotective Effect than Either of them Singly Against Cadmium-Induced Oxidative Damage

“…Further, melatonin has been shown to reduce oxidative stress-induced post-ischemic myocardial recovery, protect against ischemia reperfusion injury, reduce cardiac arrhythmia, and protect against various other forms of cardiovascular abnormalities [12][13][14][15][16]. In addition to being an effective free radical scavenger, melatonin also enhances the activity of the membrane calcium pump [17] that regulates calmodulin [18] and decreases the intracellular calcium concentration [19]. Moreover, melatonin has been reported in several dietary plants and as a phytochemical in olive oil and, recently, it has been suggested that melatonin present in edible plants may improve human health by virtue of its biological activities and good bioavailability [20].…”

Melatonin: a well‐documented antioxidant with conditional pro‐oxidant actions

“…Interestingly, an earlier study reported that melatonin at a physiological concentration (1 n m ) modulated the subcellular localization of calmodulin in MDCK cells . Whether pharmacological levels of melatonin affect the intracellular position of calmodulin remains to be determined.…”