Supplementary Material for: Deficient Expression of Genes Involved in the Endogenous Defense System against Transposons in Cryptorchid Boys with Impaired Mini-Puberty

Mini-puberty is the period between 30 and 80 days after birth when testosterone and gonadotropin surges occur in male infants to induce the transformation of gonocytes into adult/dark spermatogonia. Cryptorchid boys with impaired mini-puberty develop infertility despite timely and successful surgical treatment. The decreased germ cell count found in this group of boys could be the result of uncontrolled transposon activity inducing genomic instability and germ cell death. A genome-wide analysis of 18 cryptorchid and 4 control testes was performed with Affymetrix chips. We found that 5 of 8 genes that are important for transposon silencing were not expressed in the high azoospermia risk group of cryptorchid boys but were expressed in the low azoospermia risk and control groups. Two genes, CBX3 and DNMT1, were equally expressed in all 3 groups. Impaired expression of the DDX4, MAEL,MOV10L1, PIWIL2, PIWIL4, and TDRD9 genes in the group of cryptorchid boys at high risk of infertility indicates that gene instability induced by impaired expression of transposon silencing genes contribute to the development of azoospermia. Intact mini-puberty appears to be essential for the development of the endogenous defense system mediated by transposon silencing.

小青春期（mini-puberty）指出生后30至80天的阶段，此时雄性婴儿体内睾酮与促性腺激素出现骤增，诱导生殖母细胞转化为成年型/深色型精原细胞。小青春期发育异常的隐睾症男童，即便接受及时且成功的手术治疗，仍会罹患不育症。该类男童所出现的生殖细胞数量减少，可能源于转座子活性失控所引发的基因组不稳定性与生殖细胞死亡。本研究采用Affymetrix基因芯片（Affymetrix chips），对18例隐睾症患者与4例对照的睾丸组织开展全基因组分析。研究发现，在8个与转座子沉默相关的关键基因中，有5个在无精子症高风险的隐睾症男童组中未表达，而在无精子症低风险组与对照组中均有表达。CBX3与DNMT1这两个基因在三组样本中均呈同等水平的表达。在不育高风险的隐睾症男童组中，DDX4、MAEL、MOV10L1、PIWIL2、PIWIL4及TDRD9基因均存在表达异常，这表明转座子沉默基因表达异常所引发的基因组不稳定性，促成了无精子症的发生发展。完整的小青春期，对于转座子沉默所介导的内源性防御系统的发育而言，似乎是必不可少的。