Proteomic analysis of testis biopsies in men treated with transient scrotal hyperthermia reveals the potential targets for contraceptive development

Abstract

Mild testicular heating safely and reversibly suppresses spermatogenesis. In this study, we attempted to clarify the underlying molecular mechanism(s) involved in heat-induced spermatogenesis suppression in human testis. We conducted global proteomic analyses of human testicular biopsies before, and at 2 and 9 wk after heat treatment. Thirty-one and Twenty-six known proteins were identified with significant differential expression at 2 and 9 wk after heat treatment, respectively. These were used to characterize the cellular and molecular events in the testes when seminiferous epithelia became damaged (2 wk) and recovered (9 wk). At 2 wk post-treatment, the changed expression of a series of proteins could promote apoptosis or suppress proliferation and cell survival. At 9 wk post-treatment, the changed expression of proteins mainly promoted cell proliferation, differentiation and survival, but resisted cell apoptosis. Among those heat-regulated proteins, HNRNPH1 was selected for the further functional study. We found that HNRNPH1 was an anti-apoptosis protein that could regulate the expression of other heat-induced proteins. In conclusion, heat-induced reversible suppression of spermatogenesis occurred by modulating the expression of proteins related to proliferation, differentiation, apoptosis and cell survival pathways. These differentially expressed proteins were found to be key molecular targets affecting spermatogenesis after heat treatment.

Transient Scrotal Hyperthermia Induces Lipid Droplet Accumulation and Reveals a Different ADFP Expression Pattern between the Testes and Liver in Mice

“…Lipid droplets contain a core of neutral lipid surrounded by a phospholipid monolayer and are coated by specific proteins [27]. In the present study, we used a mouse model for scrotal transient heat stress as previously described [16], [28], [29]. We determined that testicular lipid droplets dramatically increased following a brief period of scrotal hyperthermia, and that they gradually regressed to normal levels after a week of recovery.…”

“…In recent studies, we examined the suppressive effect of testicular heat treatment on spermatogenesis in humans [14] and mice [15]. We have also studied the molecular mechanism of the effect of heat on spermatogenesis, primarily in germ cells [15], [16].…”

Mild induced testicular and epididymal hyperthermia alters sperm chromatin integrity in men

“…This fall may result from: 1) an early germ cell release from germinal epithelium that was reflected in an increased total round cell count as early as D20 during hyperthermia and that corresponded to degeneration of germ cells (spermatocytes) resulting from either a direct effect of heat on germ cells, Sertoli-Sertoli and Sertoli-germ cell junctions, and/or on permeability of the blood-testes barrier (48); or 2) a possible reduction in cell proliferation and cell survival together with a simultaneous increase in germ cell apoptosis (49), as shown in men after local heating (43 C in a water bath for 30 minutes for 6 consecutive days). Damage to the seminiferous epithelium 2 weeks after the end of this heat treatment and impaired expression of several proteins mainly expressed during germ cell proliferation, survival, as well as in apoptosis, was observed (49). Yet, ejaculates at D34 contained spermatozoa ($15% of control value), which suggests that some, but not all, germ cells were more specifically affected by heat; this was reflected in the increased sperm DFI at D20 during hyperthermia without a drop in sperm output.…”

The Hypoxic Testicle: Physiology and Pathophysiology

“…Another study in mice with a heat stress protocol of 35°C for 24 h showed that 225 genes were differentially expressed between fertility-related heat-susceptible and heat-resistant animals [97]. On the other hand, in humans, it was shown that 31 and 36 known proteins were differentially expressed two and nine weeks after heat treatment, respectively [98]. Although the range of functions that the genes upregulated or downregulated by heat is broad, many of these genes are associated with heat stress, cell signaling, and apoptosis.…”