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Table 1 A comparison of piRNA biogenesis among C. elegans, Drosophila, mice and humans

From: An old weapon with a new function: PIWI-interacting RNAs in neurodegenerative diseases

 

C. elegans

Drosophila

Mouse

Human

Reference

Size

21 nt

23-29 nt

24-30 nt

26-32 nt

[23,24,25,26]

Structure

5′ Uridine

3′ 2′-O-methylation

5′ Uridine

3′ 2′-O-methylation

5′ Uridine

3′ 2′-O-methylation

5′ Uridine

[4, 25,26,27]

PIWI proteins

PRG-1

Piwi

Aub

Ago3

MIWI (PIWIL1)

MILI (PIWIL2)

MIWI2 (PIWIL4)

HIWI (PIWIL1)

HILI (PIWIL2)

HIWI3 (PIWIL3)

HIWI2 (PIWIL4)

[19,20,21,22, 28]

Transcription loci

Type I loci,

Type II loci,

mainly from chromosome IV

flamenco loci, 42AB loci, distributed across all chromosomes

Distinct intergenic loci, distributed across all chromosomes

Distributed across 22 autosomal chromosomes and X chromosome

[24, 26, 29,30,31,32]

Amplification

RdRp

Ping-pong cycle

Ping-pong cycle

Ping-pong cycle

[33,34,35,36]

Biogenesis factor

FKH transcription factors,

TOFU genes, PRG-1,

EGO-1

RDC complex,

MitoPLD/Zuc,

TDRD proteins,

PIWI proteins

A-MYB transcription factor,

MitoPLD/Zuc,

TDRD proteins,

PIWI proteins

PIWI proteins

[23, 33, 37]

Downstream effects

RNA degradation,

histone modification,

22G-RNA biogenesis

RNA degradation,

histone modification

RNA degradation,

histone modification,

DNA methylation

RNA degradation,

histone modification,

DNA methylation

[23, 33, 37]

  1. Abbreviations: RdRp RNA-dependent RNA polymerases, RDC complex Rhino-Deadlock-Cutoff complex, FKH Fork head