Disease relevance of Prm2

• Defects in protamine-2 have been identified in sperm of infertile men, suggesting that our results may have clinical implications for the understanding of human male infertility [1].
• Protamine 2 deficiency leads to sperm DNA damage and embryo death in mice [2].
• To avoid these problems, we have produced transgenic mice carrying fusion genes in which sequences 5' to the mouse protamine-2 gene have been linked to exons 2 and 3 of the mouse c-myc gene and, separately, to the simian virus 40 (SV40) early region [3].
• Changes in the expression of P1 and P2 protamines have been found to be associated with infertility in man [4].
• Concerted changes in the YB2/RYB-a protein and protamine 2 messenger RNA in the mouse testis under heat stress [5].

High impact information on Prm2

• We disrupted the coding sequence of one allele of either Prm1 or Prm2 in embryonic stem (ES) cells derived from 129-strain mice, and injected them into blastocysts from C57BL/6-strain mice [6].
• Male chimeras produced 129-genotype sperm with disrupted Prm1 or Prm2 alleles, but failed to sire offspring carrying the 129 genome [6].
• The sequential deposition of sperm basic nuclear proteins on chromatin is disrupted, with a specific loss of protamine-2 and prolonged retention of transition protein-2 (Tnp2) in step-15 spermatids [1].
• Protamine-2 is phosphorylated by Camk4 in vitro, implicating a connection between Camk4 signalling and the exchange of basic nuclear proteins in mammalian male germ cells [1].
• Using immunohistological analysis, we determined that the endogenous Prm2 mRNA and a reporter mRNA carrying protamine 1 translational-control elements were translated in a mosaic pattern [7].

Biological context of Prm2

• Premature translation of Prm1 mRNA caused precocious condensation of spermatid nuclear DNA, abnormal head morphogenesis, and incomplete processing of Prm2 protein [8].
• Transcript analysis demonstrated that the expression of the endogenous mouse protamine Prm1 and Prm2 genes as well as the mouse transition protein Tnp2 gene were expressed along with their human transgene counterparts [9].
• ICSI with PRM2-deficient sperm resulted in activation of most metaphase II-arrested mouse eggs, but few were able to develop to the blastocyst stage [2].
• Thus lack of FSHR signaling impairs expression of TP1/2 and PRM-2 at an early stage of post-natal development causing delayed spermatogenesis [10].
• The present work shows that in transient transfection assays in GC-1 and JEG-3 cells, co-transfection of a GCNF-VP16 expression plasmid with reporter plasmids containing either the wild type Prm 1 or Prm 2 promoter established that GCNF-VP16 is able to regulate transcription from both promoters in a DR0-dependent manner [11].

Anatomical context of Prm2

• In this manuscript, we have used an RNA band shift assay to identify an activity, present in cytoplasmic fractions of meiotic spermatocytes and postmeiotic round spermatids, that binds the 3'UTRs of both Prm-1 and Prm-2 mRNA [12].
• Northern blots of hamster and rat total testis RNA probed with mP2 cDNA confirm that the protamine 2 gene in these species is transcribed into two size classes of mRNA of approximately 830 and 700 nucleotides [13].
• Most of the precursor was processed to mature P2, but high levels of incompletely processed forms remained in epididymal spermatozoa [14].

Associations of Prm2 with chemical compounds

• Processing of the precursor of protamine P2 in mouse. Identification of intermediates by their insolubility in the presence of sodium dodecyl sulfate [15].
• All six were also soluble at the same trichloroacetic acid concentration as protamine P2 and were present in chromatin of elongating spermatids [15].
• The kinetics of sperm nuclear decondensation induced by the action of physiological concentrations of heparin and glutathione was studied by comparing two rodents: the rat, with very stable protamine P1 containing chromatin (class I nuclei), and the mouse, with protamine P1 and protamine P2 (class II nuclei) [16].
• The mouse Prm-2 gene is maximally transcribed at a MgCl2 concentration of 3-5 mM and over a KCl concentration range of 40-100 mM [17].

Physical interactions of Prm2

• Our results further indicate that the Xenopus Y box-binding proteins bind to an element 5' to the mouse protamine 2 gene [18].

Other interactions of Prm2

• The expressions of transition proteins 1/2 (TP1/2) and protamine-2 (PRM-2) were greatly diminished at 21 days, but returned to normal at 35 days and 3 months after birth [10].
• Wild type GCNF, in contrast, acts as a repressor of basal transcription on both the Prm 1 and Prm 2 promoters in a DR0-dependent manner [11].
• To understand the role of chromatin structure in the expression of the mouse protamine 1, protamine 2, and transition protein 2 genes during spermatogenesis, we have examined the genomic organization of this cluster of "haploid-specific" genes [19].
• We have established a refined map of this region which places the scid gene between Prm-2 and Igl-1 [20].
• Expression of a Y-box protein, YB2/RYB-a, precedes protamine 2 expression during spermatogenesis in rodents [21].

Analytical, diagnostic and therapeutic context of Prm2

• Comet assay demonstrated a direct correlation between the fraction of sperm with haploinsufficiency of PRM2 and the frequency of sperm with damaged DNA [2].
• Processing of the precursor of protamine P2 in mouse. Peptide mapping and N-terminal sequence analysis of intermediates [22].
• The PIXE measurements reveal that the zinc content of the sperm nucleus varies proportionately with the protamine 2 content of sperm chromatin [23].
• Immunoblot analysis following acid-urea electrophoretic separation of rat sperm nuclear proteins, and of the HPLC fractions, also detected putative protamine 2 precursor proteins [24].
• Likewise, the immunoblotting experiments demonstrated that the anti-protamine 2 antibody recognized proteins with slower electrophoretic mobilities than would be expected for a mature protamine 2 [24].

References