Human RPF1 and ESF1 in Pre-rRNA Processing and the Assembly of Pre-Ribosomal Particles: A Functional Study

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• Ribosome biogenesis is vital for cell function and tightly regulated in eukaryotes.
• Ribosome biogenesis factors include proteins with enzymatic and structural roles, some with yeast homologs.
• The functions of human RPF1 and ESF1 in early ribosome biogenesis remain largely unknown.

Purpose of the Study:

• To investigate the roles of human RPF1 and ESF1 in ribosome biogenesis.
• To determine the impact of RPF1 and ESF1 downregulation on pre-ribosome processing.

Main Methods:

• Utilized a loss-of-function shRNA/siRNA approach in HEK293 cells.
• Analyzed changes in RNA products derived from 47S pre-rRNA after RPF1 and ESF1 downregulation.

Main Results:

• Downregulation of RPF1 and ESF1 significantly altered 47S pre-rRNA processing patterns.
• RPF1 and ESF1 were found to associate with distinct pre-ribosomal particles: pre-60S and pre-40S, respectively.
• Evidence suggests RPF1 and ESF1 are not directly involved in pre-rRNA cleavage but facilitate optimal substrate conformation.

Conclusions:

• RPF1 and ESF1 play distinct roles in early ribosome biogenesis, associating with pre-60S and pre-40S particles, respectively.
• These factors likely facilitate pre-rRNA processing by influencing RNA conformation rather than direct cleavage.
• The findings shed light on the less-studied early stages of ribosome biogenesis in higher eukaryotes.