Anti-NPPB monoclonal antibody, clone 18H5

Background Long non-coding RNAs (lncRNAs) are a class of RNA molecules with diverse regulatory functions during embryonic development, normal life, and disease in higher organisms. However, research on the role of lncRNAs in cardiovascular diseases and in particular heart failure is still in its infancy. The exceptionally well conserved nuclear lncRNA Metastasis associated in lung adenocarcinoma transcript 1 (Malat-1) is a regulator of mRNA splicing and highly expressed in the heart. Malat-1 modulates hypoxia-induced vessel growth, activates ERK/MAPK signaling, and scavenges the anti-hypertrophic microRNA-133. We therefore hypothesized that Malat-1 may act as regulator of cardiac hypertrophy and failure during cardiac pressure overload induced by thoracic aortic constriction (TAC) in mice. Results Absence of Malat-1 did not affect cardiac hypertrophy upon pressure overload: Heart weight to tibia length ratio significantly increased in WT mice (sham: 5.78 +/- 0.55, TAC 9.79 +/- 1.82 g/mm; p<0.001) but to a similar extend also in Malat-1 knockout (KO) mice (sham: 6.21 +/- 1.12, TAC 8.91 +/- 1.74 g/mm; p<0.01) with no significant difference between genotypes. As expected, TAC significantly reduced left ventricular fractional shortening in WT (sham: 38.81 +/- 6.53%, TAC: 23.14 +/- 11.99%; p<0.01) but to a comparable degree also in KO mice (sham: 37.01 +/- 4.19%, TAC: 25.98 +/- 9.75%; p<0.05). Histological hallmarks of myocardial remodeling, such as cardiomyocyte hypertrophy, increased interstitial fibrosis, reduced capillary density, and immune cell infiltration, did not differ significantly between WT and KO mice after TAC. In line, the absence of Malat-1 did not significantly affect angiotensin II-induced cardiac hypertrophy, dysfunction, and overall remodeling. Above that, pressure overload by TAC significantly induced mRNA levels of the hypertrophy marker genes Nppa, Nppb and Acta1, to a similar extend in both genotypes. Alternative splicing of Ndrg2 after TAC was apparent in WT (isoform ratio; sham: 2.97 +/- 0.26, TAC 1.57 +/- 0.40; p<0.0001) and KO mice (sham: 3.64 +/- 0.37; TAC: 2.24 +/- 0.76; p<0.0001) and interestingly differed between genotypes both at baseline and after pressure overload (p<0.05 each). Conclusion These findings confirm a role for the lncRNA Malat-1 in mRNA splicing. However, no critical role for Malat-1 was found in pressure overload-induced heart failure in mice, despite its reported role in vascularization, ERK/MAPK signaling, and regulation of miR-133.

In eutherian mammals, fluid secretion is essential for intestinal function. This is driven by electrogenic Cl- secretion, which involves a NaK2Cl cotransporter (NKCC1) in the enterocyte basolateral membrane and the cystic fibrosis transmembrane conductance regulator ( CFTR) in the apical membrane. However, in the possum ileum, NKCC1 expression is low and secretagogues stimulate electrogenic HCO3- secretion driven by a basolateral NaHCO3 cotransporter (pNBCe1). Here we investigated whether electrogenic anion secretion occurs in possum duodenum and jejunum and determined the role of CFTR in possum intestinal anion secretion. Prostaglandin E-2 (PGE(2)) and forskolin stimulated a large increase in ileal short-circuit current (I-sc), consistent with electrogenic HCO3- secretion, but had little effect on the duodenal and jejunal I-sc. Furthermore, 5-nitro-2-(3-phenylpropylamino) benzoic acid ( NPPB) and N-(2-naphthalenyl)-[(3,5-dibromo-2,4-dihydroxyphenyl) methylene] glycine hydrazide (GlyH101) inhibited cloned possum CFTR in cultured cells and the PGE(2)-stimulated ileal I-sc, implicating CFTR in ileal HCO3 secretion. Consistent with this, CFTR is expressed in the apical membrane of ileal crypt and lower villous cells, which also express pNBCe1 in the basolateral membrane. In contrast, duodenal and jejunal CFTR expression is low relative to the ileum. Jejunal pNBCe1 expression is also low, whereas duodenal and ileal pNBCe1 expression are comparable. All regions have low NKCC1 expression. These results indicate that cAMP-dependent electrogenic Cl- secretion does not occur in the possum small intestine because of the absence of CFTR and NKCC1. Furthermore, CFTR functions as the apical anion conductance associated with HCO3- secretion and its distribution limits electrogenic HCO3- secretion to the ileum.