A deletion of a novel heat shock gene on the Y chromosome associated with azoospermia

Deletions of the Y chromosome are a significant cause of spermatogenic failure. Three major deletion intervals have been defined and termed AZFa, AZFb and AZFc. Here, we report an unusual case of a proximal AZFb deletion that includes the Y chromosome palindromic sequence P4 and a novel heat shock factor (HSFY). This deletion neither include the genes EIF1AY, RPS4Y2 nor copies of the RBMY1 genes. The individual presented with idiopathic azoospermia. We propose that deletions of the testis-specific HSFY gene family may be a cause of unexplained cases of idiopathic male infertility. This deletion would not have been detected using current protocols for Y chromosome microdeletion screens, therefore we recommend that current screening protocols be extended to include this region and other palindrome sequences that contain genes expressed specifically in the testis.     

Characterization of the genomic organization, localization and expression of four PRY genes (PRY1, PRY2, PRY3 and PRY4).

PRY (PTP-BL related on the Y chromosome) has been proposed as a candidate spermatogenesis gene. We report the characterization of the genomic structure, the number of copies on the Y chromosome and the expression of the gene. By comparison of the cDNA sequence with the genomic sequence, five exons were identified. Analysis of GenBank-derived clones on the Y chromosome revealed the presence of two full-length copies in azoospermia factor region b (AZFb) (PRY1 and PRY2) and two shorter versions of the PRY gene containing exons 3, 4 and 5 in AZFc (PRY3 and PRY4). A clone containing sequences homologous to exons 3, 4 and 5 is located in area 5L (between AZFa and AZFb), a clone containing a sequence homologous to exon 5 is located in area 5M (in AZFb) and a clone containing a fragment homologous to exon 3 is located in 6F. A repeat structure of exons 1 and 2 is present on the short arm of the Y chromosome as well as on the long arm. PRY1 and PRY2, two gene copies that are located in AZFb, a region often deleted in patients with severe male infertility, were shown to be expressed in the testis. PRY may therefore play an important role in spermatogenesis.     

无精子和严重少精子患者Y染色体AZF微缺失的PCR筛查

目的：探讨Y染色体上AZF微缺失与精子生成的遗传效应关系,建立对无精子症和严重少精子患者Y染色体微缺失的筛查方法。方法;本文应用聚合酶链反应（PCR）技术对无精子症和严重少精子患者进行Y染色体上AZFa,AZFb,AZFc等5个基因片段的微缺失检测。结果：在64例无精子患者中,AZFb,AZFc,RBM人率分别为4．69％、17．19％、4．69％、未发现AZFa缺失。在53例严重少精子患者中,除1例同时伴有RBM缺失外,均为AZFc缺失,未发现AZFa和AZFb缺失,缺失率为18．87％。30例正常对照组未发现5个区域缺失。结论：精子发生与Y染色体上的多个基因有关,AZFb,AZFc的微缺失是导致无精子和严重少精子的重要原因,AZFc区微缺失可作病因筛查主要候选基因。     

The origin and evolution of human ampliconic gene families and ampliconic structure

Out of the nine male-specific gene families in the human Y chromosome amplicons, we investigate the origin and evolution of seven families for which gametologous and orthologous sequences are available. Proto-X/Y gene pairs in the original mammalian sex chromosomes played major roles in origins and gave rise to five gene families: XKRY, VCY, HSFY, RBMY, and TSPY. The divergence times between gametologous X- and Y-linked copies in these families are well correlated with the former X-chromosomal locations. The CDY and DAZ families originated exceptionally by retroposition and transposition of autosomal copies, respectively, but CDY possesses an X-linked copy of enigmatic origin. We also investigate the evolutionary relatedness among Y-linked copies of a gene family in light of their ampliconic locations (palindromes, inverted repeats, and the TSPY array). Although any pair of copies located at the same arm positions within a palindrome is identical or nearly so by frequent gene conversion, copies located at different arm positions are distinctively different. Since these and other distinct copies in various gene families were amplified almost simultaneously in the stem lineage of Catarrhini, we take these simultaneous amplifications as evidence for the elaborate formation of Y ampliconic structure. Curiously, some copies in a gene family located at different palindromes exhibit high sequence similarity, and in most cases, such similarity greatly extends to repeat units that harbor these copies. It appears that such palindromic repeat units have evolved by and large en bloc, but they have undergone frequent exchanges between palindromes.     

Expression pattern of the Y-linked PRY gene suggests a function in apoptosis but not in spermatogenesis

In this study, we aimed at analysing the expression of the PRY (PTPN-13 like on the Y chromosome) gene, located on the Y chromosome, in order to define the function of this gene. Active copies of the PRY gene (PRY1 and PRY2) are located in the AZFb region. PCR amplification of PRY cDNA indicated that the PRY gene is expressed in testicular tissue and ejaculated sperm, but not in Percoll-treated sperm. Furthermore, immunocytochemistry on testicular tissue showed the expression of the PRY gene in a small number of spermatozoa and spermatids. In the ejaculate of the male partner of 18 infertile couples, the PRY protein was found in 1.5-51.2% of spermatozoa and in most of the sperm precursor cells. The percentage of spermatozoa showing DNA fragmentation was also determined in 13 of these samples, by using the TdT (terminal deoxynucleotidyl transferase)-mediated dUDP nick-end labelling (TUNEL) reaction. These data correlated with the percentage of PRY-positive cells. When double labelling for PRY and DNA fragmentation was performed to assess whether PRY-positive cells also show DNA fragmentation, we saw that 27-48% of the PRY-positive spermatozoa were also positive for the TUNEL reaction. The overall data of RNA analysis, immunocytochemistry and the TUNEL reaction indicate that the role of the PRY gene in spermatogenesis can be questioned, but suggest its involvement in apoptosis of spermatids and spermatozoa.     

人Y染色体类热休克蛋白因子编码特征和男性生精障碍

精子生成障碍是男性不育的主要原因之一，而无精症和少精症在男性不育症患者中，90％是由于生精功能障碍引起，其中特发性生精障碍占60％。近年来通过人类基因组计划的实施，发现不少Y染色体上诱发不育症的候选基因，包括类热休克蛋白因子HSFY、LW-1和mHSFYL。本文通过HSFY、LW-1和mHSFYL的编码特征，阐述它们在精子生成过程中的作用和诱发生精障碍、导致无精症和少精症的遗传学机理。     

The prognostic role of the extent of Y microdeletion on spermatogenesis and maturity of Sertoli cells

Substantial involvement of the Y chromosome in sexual development and spermatogenesis has been demonstrated. Over the last decade, varying extent of Y chromosome microdeletions have been identified among infertile patients with azoospermia or oligozoospermia. These microdeletions were clustered in three main regions named AZFa, AZFb, and AZFc. Analysis of the Y chromosome microdeletion was found to be of prognostic value in cases of infertility, both in terms of clinical management as well as for understanding the aetiology of the spermatogenesis impairment. However, the accumulated data are difficult to analyse, due to the variable extent of these deletions, the different sequence-tagged sites (STS) used to detect the microdeletions, and the non-uniformity of the histological terminology used by different investigators. This debate discusses the chances of finding testicular spermatozoa in men with a varying extent of Y chromosome microdeletions. The genotype and germ cell findings in men with AZFa microdeletions as well as those that include more than a single AZF region are reviewed, as is the effect of Y chromosome AZF microdeletions on the maturity of the Sertoli cells.     

热休克因子1与恶性肿瘤

热休克因子1 (heat shock factor 1,HSF1) 是调控真核生物热休克反应的主要转录因子。HSF1的作用远不止诱导热休克蛋白（heat shock protein, HSP）表达, 也是肿瘤发生的一个有力调节因子,对肿瘤的起始和维持是必需的。HSF1在肿瘤发生中的可能机制是：作为转录因子诱导HSP90和抑制雌激素反应元件调节的基因和XAF1基因的表达;HSF1作为非转录因子诱导细胞有丝分裂停止和基因组不稳定性。     

AZF deletions and Y chromosomal haplogroups: history and update based on sequence

AZF deletions are genomic deletions in the euchromatic part of the long arm of the human Y chromosome (Yq11) associated with azoospermia or severe oligozoospermia. Consequently, it can be assumed that these deletions remove Y chromosomal genes required for spermatogenesis. However, these 'classical' or 'complete' AZF deletions, AZFa, AZFb and AZFc, represent only a subset of rearrangements in Yq11. With the benefit of the Y chromosome sequence, more rearrangements (deletions, duplications, inversions) inside and outside the classical AZF deletion intervals have been elucidated and intra-chromosomal non-allelic homologous recombinations (NAHRs) of repetitive sequence blocks have been identified as their major cause. These include duplications in AZFa, AZFb and AZFc and the partial AZFb and AZFc deletions of which some were summarized under the pseudonym 'gr/gr' deletions. At least some of these rearrangements are associated with distinct Y chromosomal haplogroups and are present with similar frequencies in fertile and infertile men. This suggests a functional redundancy of the AZFb/AZFc multi-copy genes. Alternatively, the functional contribution(s) of these genes to human spermatogenesis might be different in men of different Y haplogroups. That raises the question whether, the frequency of Y haplogroups with different AZF gene contents in distinct human populations leads to a male fertility status that varies between populations or whether, the presence of the multiple Y haplogroups implies a balancing selection via genomic deletion/amplification mechanisms.     

Evolution of the DAZ gene family suggests that Y-linked DAZ plays little, or a limited, role in spermatogenesis but underlines a recent African origin for human populations

The recent transposition to the Y chromosome of the autosomal DAZL1 gene, potentially involved in germ cell development, created a unique opportunity to study the rate of Y chromosome evolution and assess the selective forces that may act upon such genes, and provided a new estimate of the male-to-female mutation rate (alpham). Two different Y- located DAZ sequences were observed in all Old World monkeys, apes and humans. Different DAZ copies originate from independent amplification events in each primate lineage. A comparison of autosomal DAZL1 and Y- linked DAZ intron sequences gave a new figure for male-to-female mutation rates of alpham = 4. It was found that human DAZ exons and introns are evolving at the same rate, implying neutral genetic drift and the absence of any functional selective pressures. We therefore hypothesize that Y-linked DAZ plays little, or a limited, role in human spermatogenesis. The two copies of DAZ in man appear to be due to a relatively recent duplication event (55 000-200 000 years). A worldwide survey of 67 men from five continents representing 19 distinct populations showed that most males have both DAZ variants. This implies a common origin for the Y chromosome consistent with a recent 'out of Africa' origin of the human race.      

特发性无精子症及少弱精子症患者Y染色体AZF微缺失筛查分析

目的探讨特发性无精子症及少弱精子症不育男性与Y染色体AZF微缺失的关系.方法用双重PCR技术对63例患者(无精于症41例,少弱精子症14例,严重少精子症8例)进行Y染色体AZFa、AZFb、AZFc、SRY的微缺失筛查.同时对26例无精于症患者行睾丸活检、组织学评估.结果63例中AZF微缺失7例,缺失率为11.1%.其中无精子症5例,严重少精子症2例.AZFc缺失4例,AZFb缺失2例,AZFb AZFc缺失1例,未发现AZFa区缺失.63例及对照组30例SRY基因扩增均阳性.26例无精子症患者行睾丸活检、组织学检查,无1例精子发生正常.结论Y染色体微缺失,特别是AZFc区DAZ基因的微缺失,是引起无精子和严重少弱精子等生精障碍而致男性不育较为重要的遗传学因素.     

男子不育症相关的Y染色体基因组学

由于Y染色体存在性别决定基因和精子发生相关基因,男子不育相关的Y染色体基因组学逐步形成,对男子不育症有了全新的诠释。研究发现:缺乏基因重组的Y染色体不但不会逐渐丢失其重要基因,更不会逐渐消亡,而且也处于不断进化中;人类Y染色体有独特的短串重复序列-微卫星DNA和中度Alu家族重复序列,可能与男子不育症的发生有关;Y染色体上约有107个基因列在基因库,在MSY区域约有156个转录单位,其中78个编码蛋白质有27个蛋白质家族已被确认,11个蛋白质仅在睾丸组织中表达,与调节精子的发生相关;Y染色体所特有的基因不但调节着睾丸的生精功能,可能对前列腺、大脑等人体组织器官也有重要作用。     

Klinefelter综合征患者Y染色体AZF微缺失分析

目的观察Klinefelter综合征患者Y染色体AZF微缺失发生情况。方法12例Klinefelter综合征患者ICSI/IVF等辅助受孕前进行睾丸细针穿刺吸液细胞学检查及Y染色体AZF微缺失分析。确定8个实验用序列标签位点（STS）,分别是：sY84、sY86、sY127、sY134、sY152、sY153、sY254、sY255,并以X/Y连锁锌指蛋白基因（ZFX/Y）为内对照进行多重PCR筛查AZF微缺失。结果睾丸细针穿刺吸液细胞学检查显示,3例（25.0%,3/12）可见到极少量形态较完整的精子及各级生精细胞、精子细胞,7例（58.3%,7/12）仅见少量生精细胞及精子细胞,2例（16.7%,2/12）仅见支持细胞,未见生精细胞及精子。12例Klinefelter综合征患者共检测出AZF微缺失2例分别为AZFa＋AZFc区缺失和AZFb＋AZFc区缺失;对照组32例样本未检出AZF基因微缺失。KS患者AZF微缺失检出率与对照组比较有显著差异（χ^2=5.587,P=0.018）。结论Klinefelter综合征患者存在Y染色体长臂AZF微缺失,缺失率为16.7%。