A novel p38 MAPK target dyxin is rapidly induced by mechanical load in the heart

Abstract

Dyxin is a novel LIM domain protein acting as a transcriptional cofactor with GATA transcription factors. Here, we characterized dyxin as a p38 mitogen-activated protein kinase (MAPK) regulated gene, since combined upstream MAPK kinase 3b and wild-type p38 alpha MAPK gene transfer increased left ventricular dyxin mRNA and protein levels in vivo. We also studied cardiac dyxin expression in experimental models of pressure overload and myocardial infarction (MI) in vivo. Angiotensin II infusion increased left ventricular dyxin mRNA levels (9.4-fold, p<0.001) rapidly at 6 h followed by induction of protein levels. Furthermore, simultaneous administration of p38 MAPK inhibitor SB203580 abolished angiotensin II-induced activation of dyxin gene expression. During the post-infarction remodeling process, increased dyxin mRNA levels (7.7-fold, p<0.01) were noted at day 1 followed by the increase in proteins levels at 2 weeks after MI (1.5-fold, p<0.05). Moreover, direct wall stretch by using isolated rat heart preparation as well as direct mechanical stretch of cardiomyocytes in vitro activated dyxin gene expression within 1 h. Our results indicate that dyxin expression is rapidly upregulated in response to mechanical load, this increase being at least partly mediated by p38 MAPK. These results suggest that dyxin may play an important role in regulating hypertrophic process.

Characterization of the Regulatory Mechanisms of Activating Transcription Factor 3 by Hypertrophic Stimuli in Rat Cardiomyocytes

“…The MKK3b, MKK6b and WT p38β adenoviruses have been described previously [20]. The ATF3–overexpressing adenovirus (serotype 5) was generated as previously described [21]. Briefly, a full-length coding region of ATF3 cDNA was subcloned into the SalI and HindIII sites of the pShuttle-CMV vector (Qbiogene Inc, Montreal, Canada).…”

“…Total RNA from left ventricular tissue was isolated by the guanidine thiocyanate-CsCl method and from cultured cardiomyocytes with TRIzol Reagent according to the manufacturer's protocol (Invitrogen) by using Phase Lock Gel system (Eppendorf AG, Hamburg, Germany) [21]. Rat ATF3, BNP, ANP, IL-6, PAI-1, osteopontin (OSP), bone morphogenetic protein-2 (BMP-2) and ribosomal 18S mRNA levels were measured by real-time RT-qPCR as previously described [12].…”

Calcineurin signaling in the heart: The importance of time and place

“…LMCD1 levels increase in pressure overload, following MI and in response to AngII infusion [241, 242]. Transgenic over-expression of LMCD1 increases calcineurin activation in response to pressure overload and accentuates pathological remodeling in vivo , whereas depletion of LMCD1 blunts NFAT activation in vitro [242].…”

The interactome of LIM domain proteins: The contributions of LIM domain proteins to heart failure and heart development

“…Although many of these transcription factors are associated with development, interestingly, many are reactivated during pathological cardiac remodelling and hypertrophy 76, 77. Dyxin mRNA and protein levels exhibit a rapid biphasic (4 and 48 h) increase in the LV in response to pressure overload/biomechanical stress 78. This indicates that it is not only involved in the initial response to stress but also in the later hypertrophic remodelling stages.…”