The secreted micropeptide C4orf48 enhances renal fibrosis via an RNA-binding mechanism

Area of Science:

• Nephrology
• Molecular Biology
• Biochemistry

Background:

• Renal interstitial fibrosis is a key driver of chronic kidney disease (CKD) progression.
• Current treatments lack specificity to halt or reverse renal fibrosis.
• The role of specific micropeptides in fibrosis is not well understood.

Purpose of the Study:

• To investigate the role of the secreted micropeptide C4orf48 (Cf48) in renal interstitial fibrosis.
• To determine if Cf48 acts as a mediator or enhancer of kidney fibrosis.
• To explore Cf48 as a potential therapeutic target for CKD.

Main Methods:

• Utilized ribosome profiling to identify upregulated micropeptides in a mouse model of diabetic nephropathy.
• Quantified Cf48 RNA, protein, and serum levels in human and experimental CKD.
• Employed gene deletion, antisense oligonucleotide knockdown, and in vitro cell culture models.
• Investigated Cf48's mechanism of action using recombinant Cf48 (rCf48), transferrin receptor assays, and RNA immunoprecipitation-sequencing (RIP-seq).

Main Results:

• C4orf48 (Cf48) was upregulated in tubular epithelial cells and serum in human and experimental CKD, correlating with disease severity.
• Cf48 overexpression accelerated renal fibrosis in mice, while Cf48 deletion/knockdown significantly reduced fibrosis.
• In vitro, rCf48 enhanced TGF-β1-induced fibrotic responses in renal cells via the transferrin receptor.
• Cf48 was identified as an RNA-binding peptide that binds to the 3'UTR of fibrotic genes (e.g., Serpine1), increasing their mRNA half-life.

Conclusions:

• The secreted micropeptide C4orf48 (Cf48) is a novel enhancer of renal interstitial fibrosis.
• Cf48 promotes extracellular matrix production by acting as an RNA-binding peptide.
• Cf48 represents a potential therapeutic target for mitigating fibrosis in chronic kidney disease.