Upregulation of the activating transcription
factor (ATF)6 pathway of the UPR in transgenic mice with cardiac-restricted expression of a
tamoxifen-activated form of ATF6 results in increased expression of ER-resident
chaperones (GRP78 and −98), better functional recovery, and reduced necrotic and apoptotic
cell death in hearts after I/R . However, pharmacologic inhibition of
ATF6 during I/R exacerbates contractile dysfunction and increased mortality rate following
myocardial infarction (Toko et al., 2010). ATF6 activation induces the expression of
numerous gene products, including mesencephalic astrocyte-derived neurotrophic factor
(MANF), as well as the ER stress response Derlin-3 gene and may do so by modifying miRNA levels . Addition of recombinant MANF protected cultured cardiomyocytes from simulated I/R injury, while
miRNA knockdown of MANF increased cell death under these conditions
recombinant MANF protected cultured cardiomyocytes from simulated I/R injury, while
miRNA knockdown of MANF increased cell death under these conditions