miR-1, miR-29, miR-30, miR-133, and miR-150 have often been found to be downregulated, miR-21, miR-23a, miR-125, miR-195, miR-199, and miR-214 are upregulated with cardiac hypertrophy. MicroRNAs act as negative regulators of gene expression by inhibiting the translation or promoting the degradation of target mRNAs. On being loaded into the RNA-induced silencing complex, the mature miRNA associates with target mRNAs and acts as a negative regulator of gene expression by promoting mRNA degradation or inhibiting translation.Translational inhibition seems to be the predominant mechanism in mammals; however, target genes that are strongly downregulated on the protein level often show a reduced mRNA level,suggesting that mRNA destabilization is a major contributor to gene silencing.

The representative genes in cardiac diseases which are possible targets of miRNA mediated silencing include Cx40, CX43, GATA4, ERK, MAPK, AKT etc.

For further reading I am sharing a combined pdf file with relevant literature.

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Not only increased, few miRNA will be decreased. Binding of miRNA to mRNA targets reduces the expression level of protein.

Pls read it from wiki r pubmed

http://en.wikipedia.org/wiki/MicroRNA

miR-1, miR-29, miR-30, miR-133, and miR-150 have often been found to be downregulated, miR-21, miR-23a, miR-125, miR-195, miR-199, and miR-214 are upregulated with cardiac hypertrophy. MicroRNAs act as negative regulators of gene expression by inhibiting the translation or promoting the degradation of target mRNAs. On being loaded into the RNA-induced silencing complex, the mature miRNA associates with target mRNAs and acts as a negative regulator of gene expression by promoting mRNA degradation or inhibiting translation.Translational inhibition seems to be the predominant mechanism in mammals; however, target genes that are strongly downregulated on the protein level often show a reduced mRNA level,suggesting that mRNA destabilization is a major contributor to gene silencing.

The representative genes in cardiac diseases which are possible targets of miRNA mediated silencing include Cx40, CX43, GATA4, ERK, MAPK, AKT etc.

For further reading I am sharing a combined pdf file with relevant literature.

Best-

Depend on the diseases and also origin of samples you can find different mi-RNA patter. For instance, in the same disease mi-RNA expression pattern can be different between plasma and tissues.