Expression Patterns of ABLIM1 and ATF4 During Skeletal Muscle Development of Yorkshire-Landrace Crossbred Pigs

Abstract Text:

Fetal myogenesis and postnatal skeletal muscle hypertrophy in growing pigs are critical yet poorly understood processes.  Global gene expression analyses can help to identify key genes and pathways controlling skeletal muscle development.  The objective of this study was to determine patterns of gene expression in skeletal muscle of pigs at different developmental stages. A transcriptional profiling study was previously performed using the 70-mer Pigoligoarray microarray to identify genes differentially expressed during fetal and postnatal development of longissimus dorsi (LD) muscle in Yorkshire-Landrace (YL) crossbred pigs.  Pathway analyses revealed one of the top functional pathways to be Cellular Function and Maintenance.  Specifically, two differentially expressed genes in this pathway were actin binding LIM protein 1 (ABLIM1) and activating transcription factor 4 (ATF4), which function in cytoskeleton organization and gene transcription, respectively.  Results from the microarray indicated that transcript abundance of ABLIM1 was lower in postnatal LD samples (FDR < 0.01) as compared to fetal samples, whereas transcript abundance of ATF4 was higher in postnatal than in fetal LD samples (FDR < 0.01).  The specific aim of this study was to confirm the expression patterns for ABLIM1 and ATF4 in LD muscle of YL pigs at 57, 70, 90 and 105 d of gestation, and at birth, 7 and 35 d postnatal.  Total LD RNA isolated from fetuses or piglets of gilts at each developmental stage (n = 5-6 per stage) was used in qPCR assays with TaqMan chemistry to evaluate expression patterns for ABLIM1 and ATF4.  The gene peptidylprolyl isomerase A (PPIA) was used as the control for normalization.  Results of qPCR analyses confirmed the expression patterns for both ABLIM1 and ATF4.  Abundance of ABLIM1 mRNA was lower in postnatal LD muscle versus fetal (P < 0.01), whereas ATF4 mRNA abundance was higher postnatally (P < 0.001).  While little is known about the role of ABLIM1 in skeletal muscle, the ATF4 protein has been shown to be involved in transcription of amino acid transporters and to play a role in protein synthesis. Thus, increased expression of ATF4 in postnatal LD muscle may support a role for this gene in muscle hypertrophy.  This study provides new information regarding ABLIM1 and ATF4 expression during pig skeletal muscle development.

Keywords:

myogenesis, pig, qPCR