Mol. Hum. Reprod. Advance Access originally published online on October 11, 2007
Molecular Human Reproduction 2007 13(11):815-820; doi:10.1093/molehr/gam064
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Krüppel-like factor 4 expression in normal and pathological human testes
1 Stem Cell Research Group, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany 2 Institute of Anatomy, Developmental Biology, University of Essen Medical School, Hufelandstrasse 55, 45122 Essen, Germany 3 Institute of Veterinary Anatomy, Histology and Embryology, University of Giessen, Frankfurter Strasse 98, 35392 Giessen, Germany 4 School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia 5Department of Urology and Pediatric Urology, University Hospital, Rudolf-Buchheim-Strasse 7, 35385 Giessen, Germany 6Present address: Departments of Animal Science, McGill Nutrition and Food Science Centre, McGill University, MacDonald Campus, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, QC, Canada H9X 3V9
7 Correspondence address. Tel: +49-551-3851-132; Fax: +49-551-3851-288; E-mail: rbehr{at}dpz.eu
Krüppel-like factor 4 (KLF4) is a transcription factor involved in many cellular and developmental processes such as terminal differentiation of cells and carcinogenesis. Mice lacking KLF4 die post-natally due to skin barrier deficiencies and exhibit several additional cellular defects. The adult rodent testis expresses high levels of Klf4 mRNA. Using in situ hybridization, we previously localized most of the Klf4 mRNA to round spermatids in mice. Moreover, in rodent Sertoli cells, Klf4 is strongly inducible by FSH. Here, we show by northern blot analysis that the human testis also strongly expresses KLF4. Applying immunohistochemistry, we localized KLF4 protein to the nuclei of round spermatids during normal spermatogenesis stages II–IV. Analysing round spermatid maturation arrests, strong cytoplasmic staining could be seen in two samples. We failed to detect KLF4 in human Sertoli cells. Most human Leydig cells expressed KLF4 at high levels in the nucleus. However, some individual Leydig cells lacked KLF4, suggesting different functional states of the Leydig cells. The strong expression of KLF4 in the human testis and the importance of KLF4 in several mouse tissues suggest a significant role for KLF4 in the human testis. A first hint at a role for KLF4 during spermiogenesis could be the altered subcellular localization of the protein during arrested spermiogenesis.
Key words: KLF4/Leydig cell/spermatid/spermatogenesis/testis
Submitted on July 19, 2007; resubmitted on August 23, 2007; accepted on September 4, 2007.