Ciliary GPCR-based transcriptome as a key regulator of cilia length control

Area of Science:

• Cell Biology
• Molecular Biology
• Neuroscience

Background:

• Primary cilia are sensory organelles crucial for cellular signaling, with their length influencing function.
• Melanin-concentrating hormone (MCH) receptor 1 (MCHR1) is enriched in cilia and implicated in feeding and mood regulation.
• MCH is known to shorten cilia length, but the underlying molecular mechanisms via ciliary MCHR1 are not fully understood.

Purpose of the Study:

• To identify molecular targets involved in MCHR1-mediated cilia length regulation by analyzing transcriptome changes.
• To elucidate the signaling pathway by which MCH binding to MCHR1 leads to cilia shortening.

Main Methods:

• RNA sequencing was performed on MCHR1-expressing hTERT-RPE1 cells treated with MCH.
• Quantitative real-time PCR, gene knockdown, and CRISPR/Cas9 knockout were used for validation.
• Downstream signaling pathways and protein interactions were investigated.

Main Results:

• MCH treatment significantly altered gene expression, upregulating 424 genes and downregulating 112 genes.
• PDZ and LIM domain-containing protein 5 (PDLIM5) was identified as a key mediator of MCHR1-induced cilia shortening.
• Alpha-actinin 1/4 was identified as a downstream target of PDLIM5, crucial for MCH-induced cilia shortening.

Conclusions:

• This study uncovers a novel regulatory pathway involving PDLIM5 and alpha-actinin 1/4 in MCHR1-mediated cilia length control.
• The findings provide new insights into the molecular mechanisms underlying cilia length regulation.
• These results may contribute to understanding the pathophysiology of obesity and mood disorders.