Background: The Nanos gene is a key translational regulator of specific mRNAs involved in Drosophila germ cell development. Disruption of mammalian homologues, Nanos2 or Nanos3, causes male infertility in mice. In humans, however, no evidence of NANOS2 or NANOS3 mutations causing male infertility has been reported. Although Nanos1 seems dispensable for mouse reproduction, we sought to analyse for the first time its homologue in infertile men. Methods: A group of 195 patients manifesting non-obstructive azoospermia or oligozoospermia were tested for mutations of the NANOS1 gene, using single-strand conformation polymorphism and DNA sequencing. Results: Three types of NANOS1 gene mutations were identified in five patients and were absent in 800 chromosomes of fertile men. Pedigree analysis indicated a dominant inheritance pattern with penetration limited to males. Two mutations caused deletions of single amino acids, p.Pro77_Ser78delinsPro and p.Ala173del, each of them identified in two unrelated patients. Both types of deletions were located in the NANOS1 N-terminus (responsible for protein interactions) and were associated with a lack of germ cells in testes. Interestingly, the Pro77_Ser78delinsPro mutation altered interaction of NANOS1 with a microRNA biogenesis factor, GEMIN3. The third identified mutation, p.[(Arg246His; Arg276Tyr)], found in the C-terminal RNA-binding domain, was present in a single oligo-astheno-teratozoospermic man. We bioinformatically demonstrated that the p.Arg246His substitution causes a decrease in the positive charge of this domain, potentially altering RNA-binding. Conclusions: This is the first report describing the association of NANOS1 gene mutations with human infertility. Two different infertility phenotypes may reflect distinct functions of N-terminal versus C-terminal regions of NANOS1.

The highly conserved Nanos gene was found to encode a translational repressor necessary for germ-cell development in lower organisms. The mammalian homologue, Nanos2, was recently found to be expressed in the mouse germ cells. Since its disruption caused infertility exclusively in males, we sought to study the significance of this gene in human male reproduction. Here, we describe for the first time the expression pattern of the NANOS2 gene in human tissues and show that it is testis specific. We found that NANOS2 protein is present in prenatal germ cells and at later stages in spermatogenesis. To elucidate the role of NANOS2 in human germ-line development, we screened this gene for mutations in 214 males with isolated sterility and spermatogenic abnormalities. We identified two heterozygous variants, each in a different oligospermic patient, the second allele being the wild-type. The influence of the first variant, a missense mutation H68Q on the sterility phenotype, was not obvious since it was accompanied by a microdeletion within the AZF region of the Y chromosome. The second variant contained a silent mutation, H109H. Although both mutations were situated within the most conserved RNA-binding domain and were absent in 400 fertile males, it is not obvious that they cause male infertility.

Until recently, post-transcriptional gene regulation (PTGR), in contrast to transcriptional regulation, was not extensively explored in cancer, even though it seems to be highly important. PUM proteins are well described in the PTGR of several organisms and contain the PUF RNA-binding domain that recognizes the UGUANAUA motif, located mostly in the 3′ untranslated region (3′UTR) of target mRNAs. Depending on the protein cofactors recruited by PUM proteins, target mRNAs are directed towards translation, repression, activation, degradation, or specific localization. Abnormal profiles of PUM expression have been shown in several types of cancer, in some of them being different for PUM1 and PUM2. This review summarizes the dysregulation of PUM1 and PUM2 expression in several cancer tissues. It also describes the regulatory mechanisms behind the activity of PUMs, including cooperation with microRNA and non-coding RNA machineries, as well as the alternative polyadenylation pathway. It also emphasizes the importance of future studies to gain a more complete picture of the role of PUM proteins in different types of cancer. Such studies may result in identification of novel targets for future cancer therapies.

SPIN1 is a proto-oncogene and SPIN3 is a tumor suppressor in human seminoma SPIN1 is a proto-oncogene and SPIN3 is a tumor suppressor in human seminoma

The intricate landscape of tRNA modification presents persistent analytical challenges, which have impeded efforts to simultaneously resolve sequence, modification, and aminoacylation state at the level of individual tRNAs. To address these challenges, we introduce “aa-tRNA-seq”, an integrated method that uses chemical ligation to sandwich the amino acid of a charged tRNA in between the body of the tRNA and an adaptor oligonucleotide, followed by high throughput nanopore sequencing. Our approach reveals the identity of the amino acids attached to all tRNAs in a cellular sample, at the single molecule level. We describe machine learning models that enable the accurate identification of amino acid identities based on the unique signal distortions generated by the interactions between the amino acid in the RNA backbone and the nanopore motor protein and reader head. We apply aa-tRNA-seq to characterize the impact of the loss of specific tRNA modification enzymes, confirming the hypomodification-associated instability of specific tRNAs, and identifying additional candidate targets of modification. Our studies lay the groundwork for understanding the efficiency and fidelity of tRNA aminoacylation as a function of tRNA sequence, modification, and environmental conditions.