%0 Journal Article
%T Expression of TPM1, a Novel Sarcomeric Isoform of the TPM1 Gene, in Mouse Heart and Skeletal Muscle
%A Syamalima Dube
%A Lauren Panebianco
%A Amr A. Matoq
%A Henry N. Chionuma
%A Christopher R. Denz
%A Bernard J. Poiesz
%A Dipak K. Dube
%J Molecular Biology International
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/896068
%X We have investigated the expression of TPM1汐 and TPM1百 in mouse striated muscles. TPM1汐 and TMP1百 were amplified from the cDNA of mouse heart by using conventional RT-PCR. We have cloned the PCR amplified DNA and determined the nucleotide sequences. Deduced amino acid sequences show that there are three amino acid changes in mouse exon 2a when compared with the human TPM1百. However, the deduced amino acid sequences of human TPM1汐 and mouse TPM1汐 are identical. Conventional RT-PCR data as well as qRT-PCR data, calculating both absolute copy number and relative expression, revealed that the expression of TPM1百 is significantly lower compared to TPM1汐 in both mouse heart and skeletal muscle. It was also found that the expression level of TPM1百 transcripts in mouse heart is higher than it is in skeletal muscle. To the best of our knowledge, this is the first report of the expression of TPM1百 in mammalian skeletal muscle. 1. Introduction Tropomyosins (TMs) are a family of highly conserved actin binding proteins which are expressed in all eukaryotes from yeast to humans. TMs play a critical role in the control of Ca+2-regulated thin filament function in striated muscle contraction. Except for zebrafish, in vertebrates, there are four known tropomyosin (TPM) genes (designated as TPM1, TPM2, TPM3, and TPM4) [1每6]. In zebrafish, six tropomyosin genes have been reported [7]. Each of the TPM genes generates a multitude of tissue and developmental specific isoforms via alternate splicing. TPM1 is known to produce at least ten alternatively spliced transcript variants [8]. In mammals, the predominant striated muscle isoform is TPM1汐 containing exons 1a, 2b, 3, 4, 5, 6b, 7, 8, and 9a/b, which encode 284 amino acid residues. Our laboratory first reported another striated muscle isoform known as TPM1百 in axolotl heart [9] that contains exons 1a, 2a (instead of exon 2b), 3, 4, 5, 6b, 7, 8, and 9a/b. We also reported the expression of TPM1百 in axolotl skeletal muscle [8], human heart [10], and embryonic chicken heart [11]. In humans, TPM1百 is expressed in both fetal and adult hearts, whereas in chicken both TPM1汐 and TPM1百 are expressed only in embryonic heart [11]. Interestingly, transgenic mice that overexpressed human TPM1百, in a cardiac-specific manner, were found to develop a dilated cardiomyopathy-like syndrome [12]. However, it was not clear whether TPM1百 is expressed in normal mouse hearts. Two possible reasons for observing some abnormalities in TG mouse hearts ectopically overexpressing human TPM1百 were that too much TPM1百 is toxic to the mouse cardiomyocyte or
%U http://www.hindawi.com/journals/mbi/2014/896068/