Altered expression of CYP17A1 and CYP19A1 in undescended testes of dogs with unilateral cryptorchidism

A massive alteration of gene expression in undescended testicles of dogs and the association of KAT6A variants with cryptorchidism

Cryptorchidism is the most common form of disorder of sex development in male dogs, but its hereditary predisposition is poorly elucidated. The gonadal transcriptome of nine unilaterally cryptorchid dogs and seven control dogs was analyzed using RNA-seq. Comparison between the scrotal and inguinal gonads of unilateral cryptorchid dogs revealed 8,028 differentially expressed genes (DEGs) (3,377 up-regulated and 4,651 down-regulated). A similar number of DEGs (7,619) was found by comparing the undescended testicles with the descended testicles of the control dogs. The methylation status of the selected DEGs was also analyzed, with three out of nine studied DEGs showing altered patterns. Bioinformatic analysis of the cDNA sequences revealed 20,366 SNP variants, six of which showed significant differences in allelic counts between cryptorchid and control dogs. Validation studies in larger cohorts of cryptorchid (n = 122) and control (n = 173) dogs showed that the TT genotype (rs850666472, p.Ala1230Val) and the AA genotype in 3'UTR (16:23716202G>A) in KATA6, responsible for acetylation of lysine 9 in histone H3, are associated with cryptorchidism (P = 0.0383). Both the transcript level of KAT6A and H3K9 acetylation were lower in undescended testes, and additionally, the acetylation depended on the genotypes in exon 17 and the 3'UTR. Our study showed that the massive alteration of the transcriptome in undescended testicles is not caused by germinal DNA variants in DEG regulatory sequences but is partly associated with an aberrant DNA methylation and H3K9 acetylation patterns. Moreover, variants of KAT6A can be considered markers associated with the risk of this disorder.

Reproductive Management in Catteries: Optimising health and wellbeing through veterinarian-breeder collaboration

PRACTICAL RELEVANCE

Many veterinarians - even those engaged in small animal reproduction - are uncomfortable with taking care of cat breeders or being in charge of catteries. Likely reasons for this are that feline reproduction is largely under-represented in undergraduate and graduate reproduction teaching, as well as in postgraduate education and science, whereas cat breeders themselves are often well informed and actively share knowledge with other cat breeders via the internet and social media.

CLINICAL CHALLENGES

A variety of problems can exist within a cattery, and collaboration between veterinarian and breeder to solve these is ultimately beneficial for the breeder, for the veterinarian, and for the health and wellbeing of the individual cats and of the cattery as a whole.

AIM

This review presents a comprehensive overview of aspects of cattery management that might negatively impact reproduction, including sanitation, hygiene and infectious disease control. It also discusses monitoring of reproductive performance, breeding recommendations, and the diagnostic and therapeutic approach to some common and specific problems.

EQUIPMENT AND TECHNICAL SKILLS

Reproductive management in the cattery requires no specialised equipment, as such. What it does need is an open mind, in terms of seeing how things are done, an open ear, for listening to the breeder, and the veterinarian's clinical skills in palpation, auscultation and, where required, further examination of the animals. Keeping abreast of the latest information on infectious diseases, disinfection and genetics ensures proper advice is provided.

EVIDENCE BASE

Current knowledge of reproductive management in catteries is summarised in order to apply an evidence-based approach, whenever possible. Notwithstanding, much of the information remains empirical.

Transcriptomic Analysis of Testicular Gene Expression in a Dog Model of Experimentally Induced Cryptorchidism

Cryptorchidism, a condition in which testes fail to descend from the abdomen into the scrotum, is a risk factor for infertility and germ cell cancer. Normally, tight junctions between adjacent Sertoli cells in the testes form a blood–testes barrier that regulates spermatogenesis; however, the effect of cryptorchidism on tight junctions is not well-understood. We established a model of heat-induced testicular damage in dogs using surgical cryptorchidism. We sequenced RNA to investigate whether certain transcripts are expressed at higher rates in heat-damaged versus normally descended testes. Claudins, cell adhesion molecules, were relatively highly expressed in cryptorchid testes: claudins 2, 3, 5, 11, and 18 were significantly increased in cryptorchid testes and reduced by orchiopexy. SOX9-positive Sertoli cells were present in the seminiferous tubules in both cryptorchid and control testes. Using real-time PCR and Western blot analysis to compare Sertoli cells cultured at 34 °C and 37 °C, we found that Sertoli cell claudins 2, 3, 5, 11, and 18 were significantly increased at 37 °C; however, accumulation was higher in the G0/G1 phase in Sertoli cells cultured at 34 °C. These results indicate that testicular hyperthermia caused by cryptorchidism affects claudin expression, regulated germ cell death, and the proliferation of Sertoli cells.

Analysis of transcript and methylation levels of INSL3 and RXFP2 in undescended and descended dog testes suggested promising biomarkers associated with cryptorchidism

Cryptorchidism is the most common disorder of sex development (DSD) in dogs. This malformation is associated with reduced fertility and with a higher risk of gonadal cancer. Testicular descent is a complex process, and the functions of many environmental and genetic factors are crucial for the proper migration of fetal gonads into the scrotum. Among these, the hormone INSL3 (insulin-like peptide 3) and its receptor RXFP2 (relaxin family peptide receptor 2) play crucial roles in the transabdominal migration of the testes. The genetic background of canine cryptorchidism is poorly elucidated. The aim of this study was to compare the transcript and methylation levels of INSL3 and RXFP2 genes in undescended and descended testes of isolated unilateral cryptorchids, and in gonads of control male dogs with scrotal testes. Next, we searched for polymorphic variants in the 5'-regulatory regions of both genes associated with predispositions to cryptorchidism. The INSL3 transcript level was significantly higher in the undescended testes than in the descended testes of both the affected and control dogs. On the other hand, the mRNA level of RXFP2 was significantly lower in the retained gonads of cryptorchids than in the scrotal testes. The methylation level of a single CpG site located 15 bp upstream of the translation start codon in INSL3 was significantly higher in the testes of the control dogs than in both gonads of cryptorchids. The methylation level of 14 CpG sites in the coding region of INSL3 was significantly higher in undescended testes than in the scrotal testes, which may be associated with the higher mRNA levels of INSL3 observed in these samples. The methylation pattern of two CpG sites in the 5'-flanking region of RXFP2 was similar in both descended and undescended testes. We detected three and seven single nucleotide polymorphisms (SNPs) in the 5'-regulatory regions of INSL3 and RXFP2, respectively. Among these, the frequency of A > C substitution (ss7093349755) located 495 bp upstream of the transcription start site of RXFP2 differed significantly between cryptorchids and control dogs. Our study showed two possible genetic biomarkers associated with canine cryptorchidism: a hypomethylation of a single CpG site in the 5'-flanking region of INSL3, and the ss7093349755 SNP in the 5'-flanking region of RXFP2.