Polymorphism of the GRTH/DDX25 gene in normal and infertile Japanese men: a missense mutation associated with loss of GRTH phosphorylation.
The gonadotropin-regulated testicular RNA helicase (GRTH/Ddx25) is present in Leydig and germ cells of rodents, and is essential for fertility in mice. This study evaluated the incidence of GRTH/DDX25 gene mutations in a group of infertile patients with non-obstructive azoospermia (NOA), 85% with a preponderance of Sertoli cells in the seminiferous tubule and 15% with spermatogenic arrest, and compared them to a group of fertile subjects. Exonic sequences in the GRTH gene were screened using denaturing high-performance liquid chromatography of the genomic DNA from 143 NOA and 100 fertile Japanese men. A unique heterozygous missense mutation Arg(242)His in exon 8 was identified in 5.8% of Sertoli cell-only patients and in 1% of normal subjects. Although the mutant protein was efficiently expressed in COS-1 cells, only the 56 kDa nuclear/cytoplasmic non-phosphorylated species was present, whereas the 61 kDa cytosolic phosporylated species was absent. In addition, a silent mutation was identified in exon 11 in NOA subjects. The Arg(242)His missense mutation of the GRTH/DDX25 gene associated with expression of a protein with reduced basicity, and the absence of the phospho-GRTH species, could be of relevance to some of the functional aspects of the protein that impact on germ cell development and/or function.
Tsai-Morris
Chon-Hwa
CH
Section on Molecular Endocrinology, Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institute of Health, Bethesda, MD 20892, USA.
Koh
Eitetsu
E
Sheng
Yi
Y
Maeda
Yuji
Y
Gutti
Ravi
R
Namiki
Mikio
M
Dufau
Maria L
ML
D000328:Adult; D000818:Animals; D044466:Asian People / Q000235:genetics; D015153:Blotting, Western; D019556:COS Cells; D002522:Chlorocebus aethiops; D002851:Chromatography, High Pressure Liquid; D053487:DEAD-box RNA Helicases / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007246:Infertility / Q000208:ethnology / Q000235:genetics* / Q000378:metabolism; D007564:Japan; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020125:Mutation, Missense; D010766:Phosphorylation; D011110:Polymorphism, Genetic
C510069:DDX25 protein, human; D053487:DEAD-box RNA Helicases