Expression of the human antigen SPAG2 in the testis and localization to the outer dense fibers in spermatozoa

Diekman, Alan B.; Olson, Gary E.; Goldberg, Erwin

doi:10.1002/(sici)1098-2795(199807)50:3<284::aid-mrd4>3.0.co;2-f

Cited by 18 publications

(10 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During the induction of self-tolerance during the neonatal period, such neo-antigens are probably not recognized by the immune system [53], while after meiosis the later stages of male germ cells are sequestered from the immune system by the blood-testis barrier and the blood-epididymis barrier [54,55]. Although several human sperm-specific auto-and iso-antigens are recognized by infertile patient sera (e.g., SAGA-1, SPAG2, SP17, FA1) [32,[56][57][58], only a very few have been found on the spermatozoal surface (e.g., SAGA-1) [32]-a critical criterion for the selection of a potential contraceptive immunogen [59]. Evaluation of FSP95 localization using sperm immobilization assay, immunofluorescence on live cells, and immunoelectron microscopic localization, along with lack of a putative eukaryotic secretory signal sequence and no apparent transmembrane domains in the FSP95 deduced amino acid sequence, all suggest that the molecule is not present on the sperm plasma membrane.…”

Section: Discussionmentioning

confidence: 99%

FSP95, A Testis-Specific 95-Kilodalton Fibrous Sheath Antigen That Undergoes Tyrosine Phosphorylation in Capacitated Human Spermatozoa1

Mandal

Naaby-Hansen

Wolkowicz

et al. 1999

Biology of Reproduction

158

120

View full text Add to dashboard Cite

Protein tyrosine phosphorylation has been associated with both capacitation and motility of mammalian sperm. During capacitation, human spermatozoa undergo tyrosine phosphorylation of a characteristic set of proteins, only one of which has thus far been cloned and localized. We report here the sequence of a fibrous sheath protein of 95 kDa (FSP95) that undergoes tyrosine phosphorylation during capacitation of human spermatozoa and has similarity to sperm A-kinase anchor proteins (AKAPs). FSP95 is both auto- and iso-antigenic in humans as it is recognized by sera containing antisperm antibodies from infertile men and women. The 853-residue protein has a calculated molecular weight of 94.6 kDa and an isoelectric point (pI) of 6.0, and it contains multiple potential phosphorylation sites for protein kinase C and casein kinase II as well as one potential tyrosine kinase phosphorylation site at amino acid 435. The sequence has amino acid homology to mouse sperm fibrous sheath AKAP82 (pro-mAKAP82, 34% identity) and to human sperm fibrous sheath AKAP82 (pro-hAKAP82, 32% identity). The gene encoding FSP95 has 5 exons separated by 4 introns and is located on chromosome 12 at locus p13.3. Northern analysis detected a single transcript of approximately 3.0 kilobases, and Northern dot blot analysis of 50 human tissues revealed FSP95 mRNA expression only in testis. By employing sperm immobilization, indirect immunofluorescence, and immunoelectron microscopy with antisera to purified recombinant FSP95, the protein was localized to the ribs of the fibrous sheath in the principal piece of the sperm tail. FSP95 is the second fibrous sheath protein to be cloned, sequenced and localized in human spermatozoa.

show abstract

Section: Discussionmentioning

confidence: 99%

FSP95, A Testis-Specific 95-Kilodalton Fibrous Sheath Antigen That Undergoes Tyrosine Phosphorylation in Capacitated Human Spermatozoa1

Mandal

Naaby-Hansen

Wolkowicz

et al. 1999

Biology of Reproduction

158

120

View full text Add to dashboard Cite

show abstract

“…However, irrespective of the potential of the recombinant protein as a diagnostic tool for ASA, it is difficult to envisage how antibodies to RSP44 cause infertility in patients due to the likely inaccessibility of the antigen deep within the axonemal complex. Although several human sperm auto-and iso-antigens are recognized by infertile patient sera containing ASA (e.g., SAGA-1, SPAG2, SP17, FA1, AKAP3) (Diekman et al, 1997(Diekman et al, , 1998Lea et al, 1997;Naz et al, 1984;Mandal et al, 1999) only a very few have been found on the spermatozoal surface (e.g., SAGA-1) (Diekman et al, 1997) a critical criterion for considering its potential involvement in fertility. RSP44 belongs to the group of internal alloantigens which is probably not involved in antibody-mediated infertility based on the current understanding of the physiology of fertilization.…”

Section: Discussionmentioning

confidence: 99%

Radial spoke protein 44 (human meichroacidin) is an axonemal alloantigen of sperm and cilia

Shetty

Klotz

Wolkowicz

et al. 2007

Gene

View full text Add to dashboard Cite

To identify novel sperm alloantigens relevant to immune infertility, sera from infertile men containing antisperm antibodies (ASA) were employed on 2-D immunoblots of human sperm proteins. An immunoreactive protein spot (MW: 44 k Da, pI: 4.5) was microsequenced and the related cDNA was cloned yielding a 309 amino acid sequence corresponding to a gene currently annotated in Genbank as TSGA2 homolog (mouse) to signify 'testis specific gene A2'. In Genbank the protein deduced from this gene is currently named human meichroacidin, an orthologue of meichroacidin previously identified in mouse spermatocytes. Human TSGA2 mapped to chromosome 21q22.3. Human meichroacidin (hMCA) contained a single potential tyrosine phosphorylation site and five casein kinase phosporylation motifs. The N-terminus contained a Membrane Occupation Recognition Nexus (MORN) motif found in the lipid kinase-phosphatidylinositol 4-phosphate 5-kinase (PIP5K) family and junctophilins. However hMCA lacked the characteristic kinase homology domain of PIP5K. Northern blot analysis revealed 1.5 kb hMCA transcripts in testis and trachea with lower levels in thyroid and spinal cord. A semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) analysis demonstrated occurrence of the mRNA messages in all the ciliated tissues tested with highest levels of messages in testis and trachea. Western blot analysis showed the presence of hMCA protein in brain, thyroid and trachea at the identical mass, 44 k Da, as in human testis. However, this immunoreactive pattern differed from that of sperm in which a 38 k Da form was also evident suggesting that hMCA undergoes proteolytic processing. In human testis, hMCA localized to the tails of developing spermatids and did not localize to the nucleus of either spermatocytes or spermatids. EM immunocytochemistry localized hMCA within the radial spokes of the axonemal complex of the sperm flagellum, and immunofluorescence studies revealed hmeichroacidin in the cilia of epithelial cells in the trachea and ependyma. Bioinformatic identification of orthologues of meichroacidin in several lower organisms including ciliates and flagellates suggest the protein plays a role in flagellar motility across phyla. We propose the term radial spoke protein 44 as an accurate designation, preferable to human meichroacidin because it denotes the restricted localization of the protein to the radial spokes of the axonemes of both sperm and cilia. Further, since the human gene is expressed in brain, thyroid, trachea and lung in addition to testis, we suggest that the gene name be changed from TSGA2 [testis specific gene A2] to radial spoke protein 44 [RSP44].

show abstract

“…To determine whether ASA can cause infertility, several target sperm antigens were isolated and characterized, and their encoding genes determined [17]. However, it is generally agreed that antibodies to surface antigens of spermatozoa correlate best with infertility.…”

Section: Introductionmentioning

confidence: 99%

A Novel Tissue Engineering‐based Assay for Immunological Infertility

et al. 2008

View full text Add to dashboard Cite

Antisperm antibodies (ASA) are present in 9–36% of infertile couples, a condition called immunological infertility. The variability of ASA in terms of antigenic specificity and biological effects has made it difficult to design a test able to distinguish reliably between ASA that contribute to infertility and those that do not. To develop a reliable and reproducible method able to detect sperm antibodies, we took advantage of recent progress made in tissue engineering techniques. We used collagen gel as a bio‐scaffold for the production of engineered sperm analogues. The advantages of using collagen gels include biocompatibility, ease of fabrication and low cost. We found that this tissue engineering‐based assay is more specific and more sensitive than a conventional test routinely used for ASA detection. In addition, it exhibited low intra‐ and inter‐variations. We envision the use of this novel approach for the detection of a variety of autoantibodies in autoimmune diseases. In addition to diagnostic purposes, tissue‐engineering based tests could be useful in monitoring treatments with bio‐drugs.

show abstract

Expression of the human antigen SPAG2 in the testis and localization to the outer dense fibers in spermatozoa

Cited by 18 publications

References 54 publications

FSP95, A Testis-Specific 95-Kilodalton Fibrous Sheath Antigen That Undergoes Tyrosine Phosphorylation in Capacitated Human Spermatozoa1

FSP95, A Testis-Specific 95-Kilodalton Fibrous Sheath Antigen That Undergoes Tyrosine Phosphorylation in Capacitated Human Spermatozoa1

Radial spoke protein 44 (human meichroacidin) is an axonemal alloantigen of sperm and cilia

A Novel Tissue Engineering‐based Assay for Immunological Infertility

Contact Info

Product

Resources

About