A specific role for PRND in goat foetal Leydig cells is suggested by prion family gene expression during gonad development in goats and mice

Phthalate plasticizer decreases the prion-like protein doppel essential for structural integrity and function of spermatozoa

Di-n-butyl phthalate (DBP), a well-known endocrine disruptor, causes male reproductive dysfunction. To understand the underlying mechanisms, we performed histological, endocrinological, and biochemical analyses and assessed the expression of genes involved in spermatogenesis and sperm function according to OECD test guideline 407. Following 28 days of administration of the lowest observed adverse effect level dose of DBP to mice, no significant changes in body weight, testis and epididymis weights and histology, serum testosterone level, or testicular daily sperm production were found. Nonetheless, the motility of the epididymal sperm of the DBP group was significantly decreased together with an increase in the incidence of bent tails and abnormal heads. In the testes of the DBP group, lipid peroxidation (LPO) level was significantly increased and testicular Bcl-2 mRNA level was significantly decreased together with an increase in the Bax/Bcl-2 mRNA ratio. In the testes of the DBP group, levels of Prnd mRNA and protein and Pou4f1 mRNA, an activator of the Prnd promotor, were significantly decreased. Of note, prion-like protein doppel (PRND) was significantly decreased together with decreased PRND immunoreactivity in the head, midpiece, and tail of sperm. In the testes of the DBP group, levels of Sox9, Sgp1, and Sgp2 mRNA, which are functional Sertoli cell markers, were significantly decreased. Level of Amh mRNA, a Sertoli cell immaturity marker, was significantly increased together with that of Inha mRNA, suggesting deregulation of the brain-gonadal axis. Together, our findings suggest that DBP at present dosage may potentiate LPO generation and Sertoli cell immaturity via downregulation of Sox9 and disruption of the Pou4f1-Prnd gene network in post-meiotic germ cells without visible changes in spermatogenesis or testosterone level. This may result in structural and functional abnormalities in spermatozoa. Additionally, our findings suggest that assessment of the male reproductive toxicity of phthalate ester plasticizers based on conventional OECD test guidelines should be reconsidered.

Stress Resilience of Spermatozoa and Blood Mononuclear Cells without Prion Protein

The cellular prion protein PrP^C is highly expressed in neurons, but also present in non-neuronal tissues, including the testicles and spermatozoa. Most immune cells and their bone marrow precursors also express PrP^C. Clearly, this protein operates in highly diverse cellular contexts. Investigations into putative stress-protective roles for PrP^C have resulted in an array of functions, such as inhibition of apoptosis, stimulation of anti-oxidant enzymes, scavenging roles, and a role in nuclear DNA repair. We have studied stress resilience of spermatozoa and peripheral blood mononuclear cells (PBMCs) derived from non-transgenic goats that lack PrP^C (PRNP^Ter/Ter) compared with cells from normal (PRNP^+/+) goats. Spermatozoa were analyzed for freeze tolerance, DNA integrity, viability, motility, ATP levels, and acrosome intactness at rest and after acute stress, induced by Cu²⁺ ions, as well as levels of reactive oxygen species (ROS) after exposure to FeSO₄ and H₂O₂. Surprisingly, PrP^C-negative spermatozoa reacted similarly to normal spermatozoa in all read-outs. Moreover, in vitro exposure of PBMCs to Doxorubicin, H₂O₂ and methyl methanesulfonate (MMS), revealed no effect of PrP^C on cellular survival or global accumulation of DNA damage. Similar results were obtained with human neuroblastoma (SH-SY5Y) cell lines stably expressing varying levels of PrP^C. RNA sequencing of PBMCs (n = 8 of PRNP^+/+ and PRNP^Ter/Ter) showed that basal level expression of genes encoding DNA repair enzymes, ROS scavenging, and antioxidant enzymes were unaffected by the absence of PrP^C. Data presented here questions the in vitro cytoprotective roles previously attributed to PrP^C, although not excluding such functions in other cell types or tissues during inflammatory stress.

Detection of a new 20-bp insertion/deletion (indel) within sheep PRND gene using mathematical expectation (ME) method

Prion-related protein doppel gene (PRND), as an essential member of the mammalian prion gene family, is associated with the scrapie susceptibility as well as phenotype traits, so the genetic variation of the PRND has been highly concerned recently, including the single nucleiotide polymorphism (SNP) and insertion/deletion (indel). Therefore, the objective of present study was to examine the possible indel variants by mathematical expectation (ME) detection method as well as explore its associations with phenotype traits. A novel 20-bp indel was verified in 623 tested individuals representing 4 diversity sheep breeds. The results showed that 3 genotypes were detected and the minor allelic frequency were 0.008 (Lanzhou Fat-Tail sheep, LFTS), 0.084 (Small Tail Han sheep, STHS), 0.021(Tong sheep, TS) and 0.083 (Hu sheep, HS), respectively. Comparing with the traditional method of detecting samples one by one, the reaction times with ME method was decreased by 36.22% (STHS), 37.00% (HS), 68.67% (TS) and 83.33% (LFTS), respectively. Besides, this locus was significantly associated to cannon circumference index (P = 0.012) and trunk index (P = 0.037) in the Hu sheep breed. Notably, it was not concordance with the present result of DNA sequencing (GCTGTCCCTGCAGGGCTTCT) and dbSNPase of NCBI (NC_443194: g.46184887- 46184906delCTGCTGTCCCTGCAGGGCTT). Consequently, it was the first time to detect the new 20-bp indel of sheep PRND gene by ME strategy, which might provide a valuable theoretical basis for marker-assisted selection in sheep genetics and breeding.