Bidirectional regulation of fragile X mental retardation protein phosphorylation controls rhodopsin homoeostasis

• 来源期刊: 分子细胞生物学报（英文版）
• 年，卷（期）: 2017,（2）
• 页码范围: 104-116
• 页数: 13页
• 语种: 英文
• DOI: 10.1093/jmcb/mjw041

摘要

Homoeostatic regulation of the light sensor,rhodopsin,is critical for the maintenance of light sensitivity and survival of photoreceptors.The major fly rhodopsin,Rh1,undergoes light-induced endocytosis and degradation,but its protein and mRNA levels remain constant during light/dark cycles.It is not clear how translation of Rh1 is regulated.Here,we show that adult photoreceptors maintain a constant,abundant quantity of ninoE mRNA,which encodes Rh1.We demonstrate that the Fmr1 protein associates with ninoE mRNA and represses its translation.Further,light exposure triggers a calcium-dependent dephosphorylation of Fmr1,which relieves suppression of Rh1 translation.We demonstrate that Mts,the catalytic subunit of protein phosphatase 2A (PP2A),mediates light-induced Fmr1 dephosphorylation in a regulatory B subunit of PP2A (CKa)-dependent manner.Finally,we show that blocking light-induced Rh1 translation results in reduced light sensitivity.Our results reveal the molecular mechanism of Rh1 homoeostasis and physiological consequence of Rh1 dysregulation.