Differential expression and localization of Ankrd2 isoforms in human skeletal and cardiac muscles

Abstract

Four human Ankrd2 transcripts, reported in the Ensembl database, code for distinct protein isoforms (360, 333, 327 and 300 aa), and so far, their existence, specific expression and localization patterns have not been studied in detail. Ankrd2 is preferentially expressed in the slow fibers of skeletal muscle. It is found in both the nuclei and the cytoplasm of skeletal muscle cells, and its localization is prone to change during differentiation and upon stress. Ankrd2 has also been detected in the heart, in ventricular cardiomyocytes and in the intercalated disks (ICDs). The main objective of this study was to distinguish between the Ankrd2 isoforms and to determine the contribution of each one to the general profile of Ankrd2 expression in striated muscles. We demonstrated that the known expression and localization pattern of Ankrd2 in striated muscle can be attributed to the isoform of 333 aa which is dominant in both tissues, while the designated cardiac and canonical isoform of 360 aa was less expressed in both tissues. The 360 aa isoform has a distinct nuclear localization in human skeletal muscle, as well as in primary myoblasts and myotubes. In contrast to the isoform of 333 aa, it was not preferentially expressed in slow fibers and not localized to the ICDs of human cardiomyocytes. Regulation of the expression of both isoforms is achieved at the transcriptional level. Our results set the stage for investigation of the specific functions and interactions of the Ankrd2 isoforms in healthy and diseased human striated muscles.

Human skeletal muscle type 1 fibre distribution and response of stress-sensing proteins along the titin molecule after submaximal exhaustive exercise

“…This is in line with finding from animal studies that stretch increased Ankrd2 level are related to slow type muscles and/or muscle undergoing transformation towards slower fibre types (Mckoy et al 2005, Tsukamoto et al 2002. Jasnic-Savovic et al (2016) has recently reported the expression of two ANKRD2 isoforms. The function of these isoforms is unknown at the moment.…”

Epigenetic regulation of VENTXP1 suppresses tumor proliferation via miR-205-5p/ANKRD2/NF-kB signaling in head and neck squamous cell carcinoma

“…In addition, the expression levels of ANKRD2 were elevated and those of miR-125a-3p were decreased in VENTXP1-overexpressing HNSCC cell lines. Besides, several studies have verified that ANKRD2 can modulate NF-kB-mediated inflammatory responses 22 , 42 . According to the results, our study indicated that ANKRD2 could inhibit HNSCC proliferation by downregulating the NF-kB signaling pathway.…”

Emery-Dreifuss Muscular Dystrophy-Associated Mutant Forms of Lamin A Recruit the Stress Responsive Protein Ankrd2 into the Nucleus, Affecting the Cellular Response to Oxidative Stress

“…Very recently, it has been reported that, besides the S-Ankrd2 isoform studied in this paper, nuclei of primary differentiated myotubes also feature a longer Ankrd2 isoform, that is M-Ankrd2, which is identical to the S- one except for a unique region of 27 amino acids at its N-terminus [3]. As our findings suggest, the accumulation of Ankrd2 shown in affected myotubes might be due to the stronger interaction formed between S-Ankrd2 and the EDMD2-lamin A.…”

“…GFP-tagged human Ankrd2 cDNA, encoding for the S-Ankrd2 isoform of 333 aminoacids, described by Jasnic-Savovic et al [3], was cloned into the pCDNA 3.1 eukaryotic expression vector (Invitrogen). For Flag-lamin A: Flag-lamin A WT [32], Flag-lamin A WT cDNA was used as a template to generate mutants C661M, L647R, R401C, R527P and H506P by means of QuikChange strategy (Agilent Technologies, Santa Clara, USA).…”

“…Ankrd2, Ankyrin repeat protein 2, is a mechanosensing protein, belonging to the MARP (Muscle Ankyrin Repeat Protein) family and is mainly expressed in skeletal muscle [1-3]. Ankrd2 gene expression is positively modulated by MyoD, a muscle-specific transcription factor, that ensures Ankrd2 expression to be low in cycling myoblasts, however its expression increases upon muscle differentiation [4].…”