Calcimycin mediates mycobacterial killing by inducing intracellular calcium-regulated autophagy in a P2RX7 dependent manner

• Published in: Biochimica et biophysica acta. General subjects Vol. 1861; no. 12; pp. 3190 - 3200
• Main Authors: Mawatwal, Shradha, Behura, Assirbad, Ghosh, Abhirupa, Kidwai, Saqib, Mishra, Abtar, Deep, Amar, Agarwal, Sakshi, Saha, Sudipto, Singh, Ramandeep, Dhiman, Rohan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2017
• Subjects: adenosine triphosphate; Adenosine Triphosphate - physiology; Anti-Bacterial Agents - pharmacology; antibacterial properties; autocrine signaling; Autophagy; Autophagy - drug effects; Calcimycin; Calcimycin - pharmacology; calcium; Calcium - metabolism; Cells, Cultured; gene expression regulation; genes; Human; Humans; macrophages; Mycobacterium bovis - drug effects; Mycobacterium bovis - metabolism; Mycobacterium bovis BCG; P2RX7; phenotype; purinergic receptors; Receptors, Purinergic P2X7 - physiology; screening; Tuberculosis; Human; P2RX7; Tuberculosis; Calcimycin; Autophagy
• ISSN: 0304-4165; 1872-8006
• DOI: 10.1016/j.bbagen.2017.09.010

Phenotypic screening led to the identification of calcimycin as a potent inhibitor of Mycobacterium bovis BCG (M. bovis BCG) growth in vitro and in THP-1 cells. In the present study, we aim to decipher the mechanism of antimycobacterial activity of calcimycin. We noticed that treatment with calcimycin led to up-regulation of different autophagy markers like Beclin-1, autophagy-related gene (Atg) 7, Atg 3 and enhanced microtubule-associated protein 1A/1B-light chain 3-I (LC3-I) to LC3-II conversion in macrophages. This calcimycin-mediated killing of intracellular M. smegmatis and M. bovis BCG was abrogated in the presence of 3-methyladenine (3-MA). We also demonstrate that calcimycin binding with purinergic receptor P2X7 (P2RX7) led to increase in intracellular calcium level that regulates the extracellular release of ATP. ATP was able to regulate calcimycin-induced autophagy through P2RX7 in an autocrine fashion. Blocking of either P2RX7 expression by 1-[N,O-bis(5-Isoquinolinesulfonyl)-N-methyl-l-tyrosyl]-4-phenylpiperazine (KN-62) or reducing intracellular calcium levels by 1,2-Bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetra (acetoxy-methyl) ester (BAPTA-AM) abrogated the antimycobacterial activity of calcimycin. Taken together, these results showed that calcimycin exerts its antimycobacterial effect by regulating intracellular calcium-dependent ATP release that induces autophagy in a P2RX7 dependent manner. •Calcimycin treatment induced autophagy in PMA differentiated THP-1 cells.•Calcimycin inhibited intracellular mycobacterial growth through autophagy.•Intracellular calcium level regulated ATP release in calcimycin treated cells.•ATP through P2RX7 receptor controlled autophagy upon calcimycin treatment.•P2RX7 inhibition abrogated antimycobacterial effect of calcimycin.