title: Molecular cloning, characterisation and expression analysis of melanoma differentiation associated gene 5 (MDA5) of green chromide, Etroplus suratensis.
abstract: Innate immune system recognises pathogen-associated molecular patterns (PAMPs) by limited number of germline encoded and non-clonally developed pathogen recognition receptors (PRRs). Retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) are important cytosolic PRRs for sensing viral RNAs. The receptor encoded by melanoma differentiation associated gene 5 (MDA5), an RLR, recognises viral RNA and enhances antiviral response in host cells. The full-length MDA5 cDNA in Etroplus suratensis was cloned and found to have 3673 nucleotides encoding a polypeptide of 978 amino acids. The deduced amino acid sequence contains four main structural domains: two CARD domains in the N-terminal region, a DExDc (DEAH/DEAD box helicase domain), HELICc (C-terminal helicase) domain and a C-terminal regulatory domain (RD). Phylogenetic analysis revealed a close relationship of E. suratensis MDA5 (EsMDA5) with MDA5 of Neolamprologus brichardi and Oreochromis niloticus, both belonging to Cichlidae family. EsMDA5 transcripts were ubiquitously expressed in all the 12 tissues tested in healthy fish. Although, transcript level was found to be the highest in muscle, high expression was also detected in the spleen, head kidney and hindgut. In poly I:C-injected fish, EsMDA5 transcripts showed peak expression in the spleen, intestine and heart at 12h post-injection (hpi). However, in gill and kidney tissues, maximum up-regulation of EsMDA5 was observed at 6 and 48 hpi, respectively. Further, liver tissue showed an increasing trend in expression profile from 6 to 48 hpi. Interferon promoter stimulator-1 (IPS-1) gene, an adaptor triggering RIG-I- and MDA5-mediated type I interferon induction, also showed up-regulated expression at initial time-points in poly I:C-injected E. suratensis. The constitutive expression and up-regulation of EsMDA5 and the IPS-1 genes in different tissues indicate that EsMDA5 may play an important role in sensing viral PAMPs in conjunction with IPS-1.
authors.affiliation: Central Institute of Fisheries Education, Off-Yari Road, Versova, Andheri (W), Mumbai 400061, India.
authors.forename: Aadil
authors.initials: A
authors.lastname: Bhat
authors.affiliation: Central Institute of Fisheries Education, Off-Yari Road, Versova, Andheri (W), Mumbai 400061, India.
authors.forename: Anutosh
authors.initials: A
authors.lastname: Paria
authors.affiliation: Central Institute of Fisheries Education, Off-Yari Road, Versova, Andheri (W), Mumbai 400061, India.
authors.forename: A
authors.initials: A
authors.lastname: Deepika
authors.affiliation: Central Institute of Fisheries Education, Off-Yari Road, Versova, Andheri (W), Mumbai 400061, India.
authors.forename: K
authors.initials: K
authors.lastname: Sreedharan
authors.affiliation: Central Institute of Fisheries Education, Off-Yari Road, Versova, Andheri (W), Mumbai 400061, India.
authors.forename: M
authors.initials: M
authors.lastname: Makesh
authors.affiliation: Central Institute of Fisheries Education, Off-Yari Road, Versova, Andheri (W), Mumbai 400061, India.
authors.forename: Megha K
authors.initials: MK
authors.lastname: Bedekar
authors.affiliation: Central Institute of Fisheries Education, Off-Yari Road, Versova, Andheri (W), Mumbai 400061, India.
authors.forename: C S
authors.initials: CS
authors.lastname: Purushothaman
authors.affiliation: Central Institute of Fisheries Education, Off-Yari Road, Versova, Andheri (W), Mumbai 400061, India. Electronic address: rajendrankv@hotmail.com.
authors.forename: K V
authors.initials: KV
authors.lastname: Rajendran
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D023681:Cichlids / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D029941:Fish Proteins; D053487:DEAD-box RNA Helicases
keywords: Etroplus suratensis; Gene expression; IPS-1; MDA5; Poly I:C; RLR