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In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.

Melatonin modulates a wide array of physiological events with pleiotropic effects on the immune system. While the relevance of specific melatonin membrane receptors has been well established for several biological functions, retinoic acid-related orphan receptor alpha (ROR) has been suggested as a mediator of nuclear melatonin signalling by results obtained from pharmacological approaches. However, a melatonin-mediated downstream effect cannot be ruled out, and further evidence is needed to support a direct interaction between melatonin and ROR. Here, we show that ROR is mainly located in human Jurkat T-cell nucleus, and it is co-immunoprecipitated with melatonin. Moreover, immunocytochemistry studies confirmed the co-localization of melatonin and ROR. Melatonin promoted a time-dependent decrease in nuclear ROR levels, suggesting a role in the ROR transcriptional activity. Interestingly, ROR acts as a molecular switch implicated in the mutually exclusive generation of Th17 and Treg cells, both involved in the harm/protection balance of immune conditions such as autoimmunity or acute transplant rejection. Therefore, the identification of melatonin as a natural modulator of ROR gives it a tremendous therapeutic potential for a variety of clinical disorders.
Output:
Melatonin synthesized by T lymphocytes as a ligand of the retinoic acid-related orphan receptor.