Ghosh Ilora, Chattopadhaya Ratna, Kumar Vinod, Chakravarty B N, Datta Kasturi
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, India.
Soc Reprod Fertil Suppl. 2007;63:539-43.
Hyaluronan (HA), a complex glycosaminoglycan, is an important component in reproductive fluids and regulates several reproductive processes. It is thought that the multifaceted biological function of HA is mediated through hyaladherin family protein that binds with HA. We have reported a novel glycoprotein from human that has specific affinity towards hyaluronan, referred to as Hyaluronan Binding Protein-1 (HABP1, Ac. No. NP-001203) and is localized on human chromosome 17 p13.3. Sequence analysis of this gene has further revealed that HABP1 is synthesized as a precursor protein of 282 amino acids which undergoes a post-translational modification to give rise to the mature form of 209 amino acids by proteolytic cleavage of 73 amino acids at the N-terminal. The localization of mature HABP1 in several organs including the sperm surface and its involvement in fertilization have already been demonstrated. Enhanced phosphorylation of HABP1 in motile spermatozoa suggests its involvement in cellular signalling. Though only the mature form of HABP1 is detected in somatic tissues, the precursor form of HABP1 was detected in testicular tubules in a stage-specific manner in pachytene and round spermatids. To study the role of HABP1 in the fertilization process, we have shown the absence of mature HABP1 in cryptorchidic rats testes and an accumulation of the precursor form of HABP1 in giant cells, generated in infertile cryptorchidic rats. The loss of HABP1 from the sperm surface of a patient with very low sperm motility and the absence of the proprotein form of HABP1 in pachytene and round spermatids from testicular biopsy material with spermatogenic arrest, suggests that male infertility may be associated with the level of HABP1 on spermatozoa. In order to examine the role of HABP1 in sperm-oocyte interaction, we found that the number of spermatozoa bound to an oocyte was reduced significantly in the presence of D-mannosylated albumin, the universal blocker of sperm-oocyte interaction, and that this effect could be reversed by the addition of purified recombinant HABP1. In continuation, we have used spermatozoa of a patient, who had failed in IVF: the spermatozoa were incubated with HABP1 containing IVF medium for 2 hrs, then washed and allowed them to interact with the oocyte. The fertilized egg thus devloped up to the 16 cell stage, suggesting that HABP1 can modulate the sperm-oocyte interaction, even when sub-fertile spermatozoa are used.
透明质酸（HA）是一种复合糖胺聚糖，是生殖液中的重要成分，可调节多种生殖过程。人们认为，HA的多方面生物学功能是通过与HA结合的透明质酸黏附素家族蛋白介导的。我们报道了一种来自人类的新型糖蛋白，它对透明质酸具有特异性亲和力，称为透明质酸结合蛋白-1（HABP1，登录号NP-001203），定位于人类染色体17 p13.3。对该基因的序列分析进一步表明，HABP1最初合成的是一个由282个氨基酸组成的前体蛋白，该前体蛋白经过翻译后修饰，通过在N端切割73个氨基酸，产生了由209个氨基酸组成的成熟形式。成熟的HABP1在包括精子表面在内的多个器官中的定位及其在受精过程中的作用已经得到证实。运动精子中HABP1磷酸化增强表明其参与细胞信号传导。虽然在体细胞组织中仅检测到成熟形式的HABP1，但在粗线期和圆形精子细胞中，以阶段特异性方式在睾丸小管中检测到HABP1的前体形式。为了研究HABP1在受精过程中的作用，我们发现隐睾大鼠睾丸中不存在成熟的HABP1，而在不育隐睾大鼠产生的巨细胞中积累了HABP1的前体形式。精子活力极低的患者精子表面HABP1缺失，以及生精停滞的睾丸活检材料中粗线期和圆形精子细胞中不存在HABP1的前体蛋白形式，这表明男性不育可能与精子上HABP1的水平有关。为了研究HABP1在精卵相互作用中的作用，我们发现，在存在D-甘露糖基化白蛋白（精卵相互作用的通用阻断剂）的情况下，与卵母细胞结合的精子数量显著减少，而添加纯化的重组HABP1可以逆转这种作用。接下来，我们使用了一位体外受精失败患者的精子：将精子与含有HABP1的体外受精培养基孵育2小时，然后洗涤，使其与卵母细胞相互作用。由此产生的受精卵发育到了16细胞阶段，这表明即使使用生育能力低下的精子，HABP1也可以调节精卵相互作用。
