Overexpression of Long Non-coding RNA 4933425B07Rik Causes Urinary Malformations in Mice

Area of Science:

• Developmental Biology
• Genetics
• Molecular Biology

Background:

• Congenital anomalies of the kidney and urinary tract (CAKUT) are common birth defects and a leading cause of pediatric end-stage renal disease.
• The precise etiological mechanisms of CAKUT, beyond genetics and environment, remain incompletely understood.
• Long non-coding RNAs (lncRNAs) are implicated in various developmental processes, but their role in kidney and urinary tract development is largely unexplored.

Purpose of the Study:

• To investigate the role of lncRNA 4933425B07Rik (Rik) in the development of CAKUT.
• To elucidate the molecular mechanisms by which Rik influences kidney and urinary tract development.

Main Methods:

• Utilized piggyBac (PB) transposon-based mutagenesis to generate a mouse model with Rik PB insertion (RikPB/PB).
• Analyzed urinary system development, specifically renal hypo/dysplasia, in RikPB/PB mice.
• Performed embryonic kidney culture to assess ureteric bud (UB) branching.
• Employed RNA-sequencing (RNA-seq), quantitative real-time polymerase chain reaction (RT-PCR), and immunofluorescence assays to evaluate gene and protein expression levels.

Main Results:

• PB insertion led to Rik overexpression and significant urinary system developmental abnormalities, primarily renal hypo/dysplasia, in RikPB/PB mice.
• RikPB/PB embryonic kidneys exhibited significantly reduced ureteric bud branching.
• Bone morphogenetic protein 4 (Bmp4), a key regulator of UB branching, was significantly downregulated in RikPB/PB embryonic kidneys.
• Downregulation of pSmad1/5/8, a downstream signaling molecule of BMP4, was observed via immunofluorescence.

Conclusions:

• Abnormal expression of lncRNA Rik is implicated in the pathogenesis of CAKUT.
• Rik may induce CAKUT by downregulating Bmp4 expression, subsequently impairing ureteric bud branching and leading to renal developmental defects.