title: SEPT12/SPAG4/LAMINB1 complexes are required for maintaining the integrity of the nuclear envelope in postmeiotic male germ cells.
abstract: Male infertility affects approximately 50% of all infertile couples. The male-related causes of intracytoplasmic sperm injection failure include the absence of sperm, immotile or immature sperm, and sperm with structural defects such as those caused by premature chromosomal condensation and DNA damage. Our previous studies based on a knockout mice model indicated that SEPT12 proteins are critical for the terminal morphological formation of sperm. SEPT12 mutations in men result in teratozospermia and oligozospermia. In addition, the spermatozoa exhibit morphological defects of the head and tail, premature chromosomal condensation, and nuclear damage. However, the molecular functions of SEPT12 during spermatogenesis remain unclear. To determine the molecular functions of SEPT12, we applied a yeast 2-hybrid system to identify SEPT12 interactors. Seven proteins that interact with SEPT12 were identified: SEPT family proteins (SEPT4 and SEPT6), nuclear or nuclear membrane proteins (protamine 2, sperm-associated antigen 4, and NDC1 transmembrane nucleoproine), and sperm-related structural proteins (pericentriolar material 1 and obscurin-like 1). Sperm-associated antigen 4 (SPAG4; also known as SUN4) belongs to the SUN family of proteins and acts as a linker protein between nucleoskeleton and cytoskeleton proteins and localizes in the nuclear membrane. We determined that SEPT12 interacts with SPAG4 in a male germ cell line through coimmunoprecipitation. During human spermiogenesis, SEPT12 is colocalized with SPAG4 near the nuclear periphery in round spermatids and in the centrosome region in elongating spermatids. Furthermore, we observed that SEPT12/SPAG4/LAMINB1 formed complexes and were coexpressed in the nuclear periphery of round spermatids. In addition, mutated SEPT12, which was screened from an infertile man, affected the integration of these nuclear envelope complexes through coimmunoprecipitation. This was the first study that suggested that SEPT proteins link to the SUN/LAMIN complexes during the formation of nuclear envelopes and are involved in the development of postmeiotic germ cells.
authors.affiliation: Division of Urology, Department of Surgery, Shin-Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan; School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.
authors.forename: Chung-Hsin
authors.initials: CH
authors.lastname: Yeh
authors.affiliation: Department of Obstetrics & Gynecology, National Cheng Kung University, College of Medicine, Tainan, Taiwan.
authors.forename: Pao-Lin
authors.initials: PL
authors.lastname: Kuo
authors.affiliation: Department of Obstetrics & Gynecology, National Cheng Kung University, College of Medicine, Tainan, Taiwan.
authors.forename: Ya-Yun
authors.initials: YY
authors.lastname: Wang
authors.affiliation: Graduate Institute of Basic Medicine, Fu Jen Catholic University, College of Medicine, New Taipei City, Taiwan.
authors.forename: Ying-Yu
authors.initials: YY
authors.lastname: Wu
authors.affiliation: Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Tao-Yuan, Taiwan.
authors.forename: Mei-Feng
authors.initials: MF
authors.lastname: Chen
authors.affiliation: Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Ding-Yen
authors.initials: DY
authors.lastname: Lin
authors.affiliation: School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan; Department of Obstetrics and Gynecology, Cathay General Hospital, Taipei City, Taiwan; Institute of Systems Biology and Bioinformatics, National Central University, Zhongli City, Taoyuan County, Taiwan.
authors.forename: Tsung-Hsuan
authors.initials: TH
authors.lastname: Lai
authors.affiliation: School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan; Graduate Institute of Basic Medicine, Fu Jen Catholic University, College of Medicine, New Taipei City, Taiwan.
authors.forename: Han-Sun
authors.initials: HS
authors.lastname: Chiang
authors.affiliation: Graduate Institute of Basic Medicine, Fu Jen Catholic University, College of Medicine, New Taipei City, Taiwan.
authors.forename: Ying-Hung
authors.initials: YH
authors.lastname: Lin
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism*; D006801:Humans; D034921:Lamin Type B / Q000378:metabolism*; D008297:Male; D008540:Meiosis; D009685:Nuclear Envelope / Q000378:metabolism*; D011485:Protein Binding; D058112:Septins / Q000378:metabolism*; D013091:Spermatogenesis; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D034921:Lamin Type B; C114799:SPAG4 protein, human; C502729:SEPTIN12 protein, human; D058112:Septins