Alkbh1 and Tzfp repress a non-repeat piRNA cluster in pachytene spermatocytes |
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| Authors: | Line M. Nordstrand Kari Furu Jonas Paulsen Torbj?rn Rognes Arne Klungland |
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| Affiliation: | 1Department of Microbiology, Centre for Molecular Biology and Neuroscience, Oslo University Hospital, Rikshospitalet, PO Box 4950, 2Institute for Medical Informatics, Oslo University Hospital, The Norwegian Radium Hospital, PO Box 4953, Nydalen, NO-0424 Oslo, 3Department of Informatics, University of Oslo, PO Box 1080, Blindern, NO-0316 Oslo and 4Institute of Basic Medical Sciences, University of Oslo, PO Box 1018, Blindern, NO-0315 Oslo, Norway |
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| Abstract: | Piwi proteins and Piwi-interacting small RNAs (piRNAs) have known functions in transposon silencing in the male germline of fetal and newborn mice. Both are also present in adult testes; however, their function here remains a mystery. Here, we confirm that most piRNAs in meiotic spermatocytes originate from clusters in non-repeat intergenic regions of DNA. The regulation of these piRNA clusters, including the processing of the precursor transcripts into individual piRNAs, is accomplished through mostly unknown processes. We present a possible regulatory mechanism for one such cluster, named cluster 1082B, located on chromosome 7 in the mouse genome. The 1082B precursor transcript and its 788 unique piRNAs are repressed by the Alkbh1 dioxygenase and the testis-specific transcription repressor Tzfp. We observe a remarkable >1000-fold upregulation of individual piRNAs in pachytene spermatocytes isolated from Alkbh1- and Tzfp-deficient murine testes. Repression of cluster 1082B is further supported by the identification of a 10-bp Tzfp recognition sequence contained within the precursor transcript. Downregulation of LINE1 and IAP transcripts in the Alkbh1- and Tzfp-deficient mice leads us to propose a potential role for the 1082B-encoded piRNAs in transposon control. |
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