Page 38 - Q. Neuroscience

[Q. Neuroscience-22]

MicroRNA-24-3p regulates neuronal differentiation by

modulating hippocalcin expression

Min-Jeong Kang¹˙², Shin-Young Park¹˙²˙*, Joong-Soo Han¹˙²˙*

¹Biomedical Research Institute, Hanyang University, Seoul 04763, Republic of Korea, ²Department of Biochemistry

& Molecular Biology, College of Medicine, Hanyang University, Seoul 04763, Republic of Korea

Hippocalcin (HPCA) is a calcium-binding protein predominantly expressed in the nervous system. Here we report
that HPCA regulates neuronal differentiation. Depletion of HPCA inhibited both neurite outgrowth and

synaptophysin expression. shRNA-mediated knockdown of HPCA in the hippocampal dentate gyrus exhibited manic-

like behavior, including hyperactivity, decreased anxiety-like behavior, reduced depressive-related behavior, and
impaired learning and memory. Furthermore, HPCA depletion reduced the levels of synaptic plasticity-related
proteins. Thus, HPCA regulates neuronal differentiation both in vitro and in vivo. Interestingly, we also found that

the expression of HPCA was modulated by miR-24-3p. We showed that co-transfection of a plasmid containing the
miR-24-3p binding site from the 3'UTR of the HPCA gene and an miR-24-3p mimic effectively reduced luminescence

activity. miR-24-3p expression was decreased during neuronal differentiation, suggesting that the decreased
expression level of miR-24-3p might have upregulated mRNA expression of HPCA. In line with this, upregulation of

miR-24-3p led to a decrease in HPCA expression. Taken together, these results suggest that miR-24-3p is an
important miRNA that regulates neuronal differentiation by controlling HPCA expression.