PRKRA Localizes to Nuage Structures and the Ectoplasmic Specialization and Tubulobulbar Complexes in Rat and Mouse Testis

Junya Suzuki,Sadaki Yokota

doi:10.1155/2014/634290

Abstract

The cytoplasmic RNA-induced silencing complex (RISC) contains dsRNA binding proteins, including PRKRA, TRBP, and Dicer. RISC localizes to P-bodies. The nuage of the spermatogenic cells has function similar to the P-bodies. We study whether PRKRA localizes to nuage of spermatogenic cells of rat and mouse. PRKRA localized to four types of nuage structures, including aggregates of 60–90 nm particles, irregularly-shaped perinuclear granules, and intermitochondrial cement of pachytene spermatocytes, and chromatoid bodies of round spermatids. In addition, PRKRA is associated with dense material surrounding tubulobulbar complexes and with the ectoplasmic specialization. The results suggest that PRKRA functions in the nuage as an element of RNA silencing system and plays unknown role in the ectoplasmic specialization and at the tubulobulbar complexes of Sertoli cells attaching the head of late spermatids.

Highlights

PRKRA, a protein kinase, interferon-inducible double stranded RNA dependent activator protein kinase, known as PACT, a protein activator of the interferon-induced protein kinase, is a product of PRKRA gene [1, 2] and is a member of the double-stranded RNAs (dsRNAs) binding protein family [3]
The 36 kDa protein appeared in all cell fractions, whereas the 30 kDa protein was detected in mitochondria and microsomal fractions but not in cytosolic fraction
The 36 kDa and 30 kDa proteins were approximately consistent with the molecular masses of PRKRA isoform 1 and isoform 3 reported in Swiss-Prot, respectively

Summary

Introduction

PRKRA, a protein kinase, interferon-inducible double stranded RNA dependent activator protein kinase, known as PACT, a protein activator of the interferon-induced protein kinase, is a product of PRKRA gene [1, 2] and is a member of the dsRNA binding protein family [3]. PRKRA is contained in the cytoplasmic RNA-induced silencing complex (RISC) together with transactivation response RNA binding protein (TRBP) and Dicer [4,5,6]. These proteins process premicroRNAs into mature microRNAs (miRNAs) that target specific mRNA species for regulation. RISC assembles into processing bodies (P-bodies) which are specific cytoplasmic foci in somatic eukaryotic cells [7,8,9]. There are specific cytoplasmic foci similar to the P-bodies in spermatogenic cells, which are called nuage [15,16,17,18]

Methods

Results

Conclusion