Somatic piRNAs and Transposons are Differentially Expressed Coincident with Skeletal Muscle Atrophy and Programmed...

Area of Science:

• * Molecular Biology
• * Genetics
• * Developmental Biology

Background:

• * PIWI-interacting RNAs (piRNAs) are small RNAs crucial for transposon silencing in the germline.
• * Their presence and function in somatic cells remain largely uncharacterized and debated.
• * Transposon activity is a threat to genome integrity, necessitating robust silencing mechanisms.

Purpose of the Study:

• * To investigate the expression and function of piRNAs in somatic tissues.
• * To determine if piRNAs are present and active in the intersegmental muscles (ISMs) of *Manduca sexta*.
• * To explore the role of piRNAs in the developmental regulation of ISMs, including atrophy and programmed cell death.

Main Methods:

• * RNA sequencing (RNA-seq) to identify and quantify piRNAs and piRNA pathway gene expression in ISMs.
• * Analysis of piRNA characteristics (size, origin, amplification pathway).
• * Correlation analysis between piRNA levels, transposon activity, and hormonal regulation during muscle development and death.

Main Results:

• * piRNAs are abundantly expressed in *Manduca sexta* ISMs, derived from both genic and transposon sequences.
• * These piRNAs exhibit canonical features, including a specific size, antisense mapping to transposons, and amplification via the ping-pong pathway.
• * piRNA abundance is stable during muscle atrophy but decreases during programmed cell death, correlating with changes in transposon expression.
• * Expression of piRNA pathway genes is developmentally regulated and influenced by 20-hydroxyecdysone.

Conclusions:

• * piRNAs are demonstrably present and functional in somatic tissues, specifically insect ISMs.
• * piRNA expression is dynamically regulated during development and programmed cell death.
• * piRNAs may play a significant role in regulating transposon activity and developmental processes in somatic cells.