Regulation of gastric acid secretion in situ by an endogenous activator protein: Studies with activator-specific antibody

Monospecific polyclonal antibody was raised against a homogenous preparation of endogenous activator protein (HAF) for the gastric H+,K+-ATPase system. Antibody was used to assess the regulatory role of the HAF in gastric acid secretion by isolated rabbit glands in situ. Immunohistochemical studies revealed aredistribution of theHAFtowards discrete intracellular zones following stimulation of the glands with histamine. The antibody, when inserted into the stimulated gastric glands by digitonin permeabilization, could effectively block the acid forming ability of the cells. The data offers, for the first time, some concrete in situ evidence for the role of the HAF as an intracellular regulator of gastric H+ transport .The manuscript was written (in the early 1990) soon after the data were collected, but never submitted to a journal with the hope of getting better gel picture and fluorescent micrograph which did not materialize due to unavoidable circumstances

Myofibril-Inducing RNA (MIR) is essential for tropomyosin expression and myofibrillogenesis in axolotl hearts

The Mexican axolotl, Ambystoma mexicanum, carries the naturally-occurring recessive mutant gene 'c' that results in a failure of homozygous (c/c) embryos to form hearts that beat because of an absence of organized myofibrils. Our previous studies have shown that a noncoding RNA, Myofibril-Inducing RNA (MIR), is capable of promoting myofibrillogenesis and heart beating in the mutant (c/c) axolotls. The present study demonstrates that the MIR gene is essential for tropomyosin (TM) expression in axolotl hearts during development. Gene expression studies show that mRNA expression of various tropomyosin isoforms in untreated mutant hearts and in normal hearts knocked down with double-stranded MIR (dsMIR) are similar to untreated normal. However, at the protein level, selected tropomyosin isoforms are significantly reduced in mutant and dsMIR treated normal hearts. These results suggest that MIR is involved in controlling the translation or post-translation of various TM isoforms and subsequently of regulating cardiac contractility

Micro Rna-499C Induces the Differentiation of Mouse Embryonic Stem Cells (mESCs) into Cardiomyocytes

Background: A microRNA, miR499c, has been discovered in human fetal heart which rescues mutant hearts in cardiac nonfunction mutant axolotl (salamander) embryos and also induces the differentiation of mouse embryonic stem cells (mESCs) to form into definitive cardiomyocytes. Results: Eight days after transfection with MiR499c, approximately 75-80% of the stem cells develop typical cardiomyocyte morphologies and express the cardiac specific marker, Troponin T, as well as the muscle proteins, tropomyosin and α-actinin, as shown by immunohistochemical staining. qRT-PCR confirms that transfection with MiR499c increases expression of troponin T and tropomyosin and further shows an increased expression of myosin as well as Wnt11 and Sox17. Untreated controls do not show significant expression of these proteins. Conclusion: It is evident that the miR499c induces the development of contractile myofibrils characteristic of striated cardiac muscle indicating that the miR499c microRNA plays an important role in the differentiation of cardiomyocytes