Na,K-ATPase alpha4 isoform in male germ cell physiology

男性生殖细胞生理学中的 Na,K-ATP 酶 α4 亚型

• 批准号: 7075390
• 负责人: V GUSTAVO BLANCO
• 金额: $ 23.15万
• 依托单位: UNIVERSITY OF KANSAS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7075390
• 关键词: SDS polyacrylamide gel electrophoresis; Sertoli cells; acrosome; clinical research; enzyme activity; enzyme inhibitors; enzyme mechanism; epididymis; fertility; gametogenesis; germ cells; human subject; immunocytochemistry; isozymes; laboratory rat; male; male reproductive system; membrane potentials; ouabain; posttranslational modifications; protein localization; reproductive development; sedimentation velocity; sodium potassium exchanging ATPase; sperm capacitation; sperm motility

DESCRIPTION (provided by applicant): The Na,K-ATPase comprises a group of isozymes responsible for maintaining the Na+ and K+ gradients across the plasma membrane of most cells. Isozyme diversity for the Na,K-ATPase results from the association of different molecular forms of the catalytic alpha, alpha1, alpha2, alpha3 and alpha4 and glycosylated beta (beta1,beta2 and beta3) subunits that constitute the enzyme. The various Na,K-ATPase isozymes are expressed in a highly regulated manner, depending on cell type, developmental stage, hormonal stimulation and pathological state of the tissue. In addition, Na,K-ATPase isoforms have enzymatic properties that are unique. The a4 isoform exhibits the most restricted pattern of expression, and it is selectively expressed in rat testes, where it is abundant in germ cells. Its function comprises approximately two thirds of the total Na,K-ATPase activity of spermatozoa, the rest corresponding to the ubiquitously expressed ctl isoform. Functionally, the alpha4 polypeptide has enzymatic properties different from those of the other Na,K-ATPase isoforms. This suggests a physiological role for the isoform, and (4 may be adapted to fulfill the ionic requirements of the male germ cells. It is well known that the Na+ and K+ gradients are key factors for sperm motility. Also, for spermatozoa capacitation and acrosomal reaction, which are required steps for the biogenesis of fertile spermatozoa. At present, the precise role of (4 in these processes remains unknown. The main objective of the present proposal is to elucidate the biological importance of the Na,K-ATPase alpha4 isoform in male germ cell function and its relevance to male fertility. Specifically the aims are: 1) to investigate expression and cell localization of the Na,K-ATPase (4 polypeptide in male germ cells during development, and in Sertoli cells, 2) to study the function of (4 in male germ cells during gametogenesis, epididymal maturation and acrosomal reaction, 3) to study the role of the Na,K-ATPase (4 isoform in sperm physiology, and 4) to determine the enzymatic properties and function of Na,K-ATPase (4 isoform from humans. This study will be important to understand the biological relevance of the testes specific isoform of the Na,K-ATPase in male fertility and contraception.

描述（由申请人提供）：Na，K-ATPase包括一组负责在大多数细胞的质膜上维持Na+和K+梯度的同工酶。 Na，K-ATPase的同工酶多样性是由催化α，alpha1，alpha2，alpha2，alpha3和alpha4以及糖基化β（beta1，beta2和beta3）亚基的不同分子形式的关联。各种Na，K-ATPase同工酶以高度调节的方式表达，具体取决于细胞类型，发育阶段，激素刺激和组织的病理状态。另外，Na，K-ATPase同工型具有独特的酶促性能。 A4同工型表现出最受限制的表达模式，并且在大鼠睾丸中有选择地表达，在大鼠睾丸中它在生殖细胞中很丰富。它的功能包括精子的总Na，K-ATPase活性的大约三分之二，其余的对应于泛表达的CTL同工型。在功能上，α4多肽具有与其他Na，K-ATPase同工型不同的酶促性能。这表明了同工型的生理作用，并且（4可以适应于满足男性生殖细胞的离子要求。众所周知，Na+和K+梯度是精子运动的关键因素。对于精子电容和Arosomal反应，这是对目前的精子的生物作用的必需步骤。目前的建议是阐明Na，K-ATPase Alpha4同工型在男性生殖细胞功能中的生物学重要性及其与男性生育的相关性。 AROSOMAL反应，3）研究Na，K-ATPase（4同工型在精子生理学中和4）的作用，以确定Na，K-ATPase的酶特性和功能（4来自人类的同工型。这项研究对于了解睾丸，k-ATPase在男性生育和避孕方面的睾丸特异性同工型的生物学相关性将很重要。