Proteins encoded by human Down syndrome critical region gene 1-like 2 (DSCR1L2) mRNA and by a novel DSCR1L2 mRNA isoform interact with cardiac troponin I (TNNI3).
Down syndrome critical region gene 1-like 2 (DSCR1L2) belongs to the human DSCR1-like gene family, which also includes DSCR1 and DSCR1L1. Both DSCR1 and DSCR1L1 proteins interact with calcineurin, a calcium/calmodulin-dependent phosphatase. To date, no interactor has been described for DSCR1L2. The aim of this work was to perform a first functional study of DSCR1L2 using yeast two-hybrid analysis conducted on a human heart cDNA library. Here, we report the interaction between DSCR1L2 and the human cardiac troponin I (TNNI3), the heart-specific inhibitory subunit of the troponin complex, a central component of the contractile apparatus. This interaction was confirmed by both yeast cotransformation and GST (glutathione-sepharose transferase) fusion protein assay. Moreover, a new DSCR1L2 mRNA isoform, generated by alternative splicing, was identified and cloned in different tissues: it lacks two central exons, encoding the most conserved domains among the DSCR1-like protein family. A quantitative relative reverse transcription-polymerase chain reaction (RT-PCR) assay showed that in heart tissue the normalized expression level ratio for DSCR1L2 and DSCR1L2-E2E5 mRNA isoforms is 3.5:1, respectively. The yeast cotransformation and GST fusion protein assay demonstrated the interaction between this new DSCR1L2 variant and the human cardiac troponin I and the prominent role of DSCR1L2 exon 2 in determining binding between both DSCR1L2 isoforms and TNNI3. These data indicate an entirely new role for a DSCR1-like family gene, suggesting a possible involvement of DSCR1L2 in cardiac contraction.
Canaider
Silvia
S
Department of Histology, Embryology and Applied Biology, University of Bologna, Via Belmeloro 8, 40126 Bologna, Italy.
Facchin
Federica
F
Griffoni
Cristiana
C
Casadei
Raffaella
R
Vitale
Lorenza
L
Lenzi
Luca
L
Frabetti
Flavia
F
D'Addabbo
Pietro
P
Carinci
Paolo
P
Zannotti
Maria
M
Strippoli
Pierluigi
P
D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D019210:Troponin I / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D015003:Yeasts / Q000166:cytology
D048868:Adaptor Proteins, Signal Transducing; D018076:DNA, Complementary; D020033:Protein Isoforms; D011506:Proteins; C408372:RCAN3 protein, human; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D019210:Troponin I; D005978:Glutathione