Page 33 - Biennial Report 2018-20 Jun 2021

HYPERCHOLESTEROLEMIA AND THE ROLE OF miRNA miR-128

In the laboratory led by Neeru Saini, a mouse model of high-fat diet induced
hypercholesterolemia is being used to study the role of miRNA-128 in liver physiology. The
impact of modulation of miRNA-128 on the liver is being studied using RNA-seq. The project aims
to functionally evaluate the significance of altered genes or pathways using in vitro systems and
construct regulatory networks. 6-week-old mice were fed either normal (chow diet) or a high-
fat (60% energy derived from fats) diet for 12 weeks to induce hypercholesterolemia. C57BL6
mice treated with a high-fat diet showed a significant increase in body weight (35-50 gram). After
the development of hypercholesterolaemia in mice, the dose of anti-miR-128 as well as its
negative control was standardized. Serum and hepatic lipid profiles improved significantly in
hypercholesterolemic mice following anti-miR-128 treatment.

Serum total cholesterol and
low-density lipoprotein-
cholesterol (LDL-C) were
significantly decreased
whereas high-density
lipoprotein-cholesterol
(HDL-C) and bile acids (BAs)
level were increased
following anti-miR128
treatment. Genes of the
cholesterol and BAs
metabolism were studied by
transcriptome microarray.
Further selected genes of
cholesterol and BAs
metabolism were quantified
by qRT-PCR. The active levels
of selected enzymes in the
cholesterol and BAs
metabolism were quantified
by western blotting. The 3-
hydroxy 3- methyl glutaryl
co-A reductase (HMGCR)
was downregulated and low-
density lipoprotein receptors (LDLR) was upregulated along with cholesterol 7a-hydroxylase
(CYP7A1), after anti-miR-128 treatment in hypercholesterolemic mice. LDLR, the central
receptor involved in serum LDL-C clearance, is actively targeted by miR-128. An increased NF- B
(Nuclear Factor Kappa B Subunit 1) mediated inflammatory response was invoked by an up-
regulation of RIG-I (retinoic acid inducible gene-I) receptors and interferon gamma both,
following anti-miR-128 treatment. This study elucidates the central role of miR-128 in regulating
cholesterol metabolism.

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