CABS1 is a novel calcium-binding protein specifically expressed in elongate spermatids of mice

CABS1 Is Essential for Progressive Motility and the Integrity of Fibrous Sheath in Mouse Epididymal Spermatozoa

The calcium-binding protein spermatid-associated 1 (CABS1) localizes to the principal piece of mature sperm flagella. Deletion of CABS1 results in subfertility in male mice, possibly due to an impaired annulus in the sperm flagella. However, it is unknown whether there are other mechanisms by which CABS1 affects male fertility. Our current investigation has uncovered that CABS1 is located in the midsection of the flagellum in testicular sperm and the principal piece in epididymal sperm. Moreover, male mice lacking CABS1 exhibit a defect in the progressive motility of sperm. Furthermore, the regulation of calcium levels, which has been reported to have a significant impact on sperm motility, capacitation, and the acrosome reaction, is also affected when sperm are exposed to alkalized high-salt buffer (pH 8.0) and progesterone (100 μM) in Cabs1-null spermatozoa. This alteration in calcium response may contribute to changes in the phosphorylation of PKA substrates and subsequent phosphorylation of tyrosine residues. Additionally, the absence of CABS1 leads to a defective fibrous sheath and abnormal configuration of doublet microtubules in post-testicular sperm. These findings indicate that the absence of CABS1 also disrupts the structural integrity of the fibrous sheath, resulting in male subfertility. The highly conserved nature of CABS1 in humans suggests that it could potentially be a contributing factor to asthenozoospermia in men.

The metabolomics changes in epididymal lumen fluid of CABS1 deficient male mice potentially contribute to sperm deformity

Introduction

Epididymal lumen fluids provides a stable microenvironment for sperm maturation. Ca2+ binding protein CABS1 is known to maintain structural integrity of mouse sperm flagella during epididymal transit of sperm. Besides, CABS1 was reported to contain anti-inflammatory peptide sequences and be present in both human saliva and plasma. However, little is known about the role of CABS1 in regulation of the microenvironment of epididymal lumen fluids.

Methods

To further confirm the role of CABS1 in epididymis, we identified the expression of CABS1 in epididymal lumen fluids. Moreover, high performance liquid chromatography, coupled with tandem mass spectrometry technique was used to analyze the metabolic profiles and in vivo microperfusion of the cauda epididymis and inductively coupled plasma mass spectrometry (ICP-MS) assays was used to detect the concentration of metal ion of mouse cauda epididymal lumen fluids in CABS1 deficient and normal mice.

Results

The results showed that CABS1 is present in epididymal lumen fluids, and the concentration of calcium in epididymal lumen fluids is not changed in Cabs1-/- male mice. Among 34 differential metabolites identified in cauda epididymis, 21 were significantly upregulated while 13 were significantly downregulated in KO cauda epididymis. Pathway analysis identified pyrimidine metabolism, inositol phosphate metabolism, arachidonic acid metabolism, purine metabolism and histidine metabolism as relevant pathways in cauda epididymis.

Discussion

The perturbations of mitochondrial dysfunction and inflammation may be the crucial reason for the poor performance of Cabs1-/- sperm.

Santos J, Puttagunta L, Lewis SJ, Watanabe M, Gonshor A, Buck R, Befus AD, Marcet-Palacios M. Identification and characterization of calcium binding protein, spermatid-associated 1 (CABS1)# in selected human tissues and fluids

Calcium binding protein, spermatid associated 1 (CABS1) is a protein most widely studied in spermatogenesis. However, mRNA for CABS1 has been found in numerous tissues, albeit with little information about the protein. Previously, we identified CABS1 mRNA and protein in human salivary glands and provided evidence that in humans CABS1 contains a heptapeptide near its carboxyl terminus that has anti-inflammatory activities. Moreover, levels of an immunoreactive form of CABS1 were elevated in psychological stress. To more fully characterize human CABS1 we developed additional polyclonal and monoclonal antibodies to different sections of the protein and used these antibodies to characterize CABS1 in an overexpression cell lysate, human salivary glands, saliva, serum and testes using western blot, immunohistochemistry and bioinformatics approaches exploiting the Gene Expression Omnibus (GEO) database. CABS1 appears to have multiple molecular weight forms, consistent with its recognition as a structurally disordered protein, a protein with structural plasticity. Interestingly, in human testes, its cellular distribution differs from that in rodents and pigs, and includes Leydig cells, primary spermatogonia, Sertoli cells and developing spermatocytes and spermatids, Geodata suggests that CABS1 is much more widely distributed than previously recognized, including in the urogenital, gastrointestinal and respiratory tracts, as well as in the nervous system, immune system and other tissues. Much remains to be learned about this intriguing protein.

Sperm long non-coding RNAs as markers for ram fertility

It is critical in sheep farming to accurately estimate ram fertility for maintaining reproductive effectiveness and for production profitability. However, there is currently a lack of reliable biomarkers to estimate semen quality and ram fertility, which is hindering advances in animal science and technology. The objective of this study was to uncover long non-coding RNAs (lncRNAs) in sperm from rams with distinct fertility phenotypes. Mature rams were allocated into two groups: high and low fertility (HF; n = 31; 94.5 ± 2.8%, LF; n = 25; 83.1 ± 5.73%; P = 0.028) according to the pregnancy rates sired by the rams (average pregnancy rate; 89.4 ± 7.2%). Total RNAs were isolated from sperm of the highest- and lowest-fertility rams (n = 4, pregnancy rate; 99.2 ± 1.6%, and 73.6 ± 4.4%, respectively) followed by next-generation sequencing of the transcripts. We uncovered 11,209 lncRNAs from the sperm of rams with HF and LF. In comparison to each other, there were 93 differentially expressed (DE) lncRNAs in sperm from the two distinct fertility phenotypes. Of these, 141 mRNAs were upregulated and 134 were downregulated between HF and LF, respectively. Genes commonly enriched for 9 + 2 motile cilium and sperm flagellum were ABHD2, AK1, CABS1, ROPN1, SEPTIN2, SLIRP, and TEKT3. Moreover, CABS1, CCDC39, CFAP97D1, ROPN1, SLIRP, TEKT3, and TTC12 were commonly enriched in flagellated sperm motility and sperm motility. Differentially expressed mRNAs were enriched in the top 16 KEGG pathways. Targets of the differentially expressed lncRNAs elucidate functions in cis and trans manner using the genetic context of the lncRNA locus, and lncRNA sequences revealed 471 mRNAs targets of 10 lncRNAs. This study illustrates the existence of potential lncRNA biomarkers that can be implemented in analyzing the quality of ram sperm and determining the sperm fertility and is used in breeding soundness exams for precision livestock farming to ensure food security on a global scale.

Risk of Sperm Disorders and Impaired Fertility in Frozen-Thawed Bull Semen: A Genome-Wide Association Study

Cryopreservation is a widely used method of semen conservation in animal breeding programs. This process, however, can have a detrimental effect on sperm quality, especially in terms of its morphology. The resultant sperm disorders raise the risk of reduced sperm fertilizing ability, which poses a serious threat to the long-term efficacy of livestock reproduction and breeding. Understanding the genetic factors underlying these effects is critical for maintaining sperm quality during cryopreservation, and for animal fertility in general. In this regard, we performed a genome-wide association study to identify genomic regions associated with various cryopreservation sperm abnormalities in Holstein cattle, using single nucleotide polymorphism (SNP) markers via a high-density genotyping assay. Our analysis revealed a significant association of specific SNPs and candidate genes with absence of acrosomes, damaged cell necks and tails, as well as wrinkled acrosomes and decreased motility of cryopreserved sperm. As a result, we identified candidate genes such as POU6F2, LPCAT4, DPYD, SLC39A12 and CACNB2, as well as microRNAs (bta-mir-137 and bta-mir-2420) that may play a critical role in sperm morphology and disorders. These findings provide crucial information on the molecular mechanisms underlying acrosome integrity, motility, head abnormalities and damaged cell necks and tails of sperm after cryopreservation. Further studies with larger sample sizes, genome-wide coverage and functional validation are needed to explore causal variants in more detail, thereby elucidating the mechanisms mediating these effects. Overall, our results contribute to the understanding of genetic architecture in cryopreserved semen quality and disorders in bulls, laying the foundation for improved animal reproduction and breeding.

The interplay of arsenic, silymarin, and NF-ĸB pathway in male reproductive toxicity: A review

Arsenic toxicity is one of the most trending reasons for several malfunctions, particularly reproductive toxicity. The exact mechanism of arsenic poisoning is a big question mark. Exposure to arsenic reduces sperm count, impairs fertilization, and causes inflammation and genotoxicity through interfering with autophagy, epigenetics, ROS generation, downregulation of essential protein expression, metabolite changes, and hampering several signaling cascades, particularly by the alteration of NF-ĸB pathway. This work tries to give a clear idea about the different aspects of arsenic resulting in male reproductive complications, often leading to infertility. The first part of this article explains the implications of arsenic poisoning and the crosstalk of the NF-ĸB pathway in male reproductive toxicity. Silymarin is a bioactive compound that exerts anti-cancer and anti-inflammatory properties and has demonstrated hopeful outcomes in several cancers, including colon cancer, breast cancer, and skin cancer, by downregulating the hyperactive NF-ĸB pathway. The next half of this article thus sheds light on silymarin's therapeutic potential in inhibiting the NF-ĸB signaling cascade, thus offering protection against arsenic-induced male reproductive toxicity.

Differential protein expression of GABA A receptor alpha 1 subunit and calbindin in rat spermatozoa associated with proteomic analysis in testis following methamphetamine administration

Methamphetamine (METH) can induce spermatogenesis impairment, testicular apoptosis, and abnormal sperm quality. It also promotes changes in the expression of receptors for sex hormones and neurotransmitters, including GABA receptors in the testis. Proteomic assessment focusing on proteins involved in the calcium signalling pathway in the testis can facilitate diagnostic factors contributing to testicular and sperm functions, especially those related to spermatogenesis and fertilisation. In this study, we proposed to determine the localisation and differential expression of GABA A receptor alpha 1 subunit (GABA A-α1) in the spermatozoa of METH-administered rats. The differential proteomic profile of the testis was also observed by focusing on proteins in the KEGG pathways belonging to the calcium signalling pathway. There were 212 differentially expressed proteins in the rat testis, based on the cut-off value of 1.2-fold change. Most of those proteins, 13 proteins, were classified in the calcium signalling pathway, including 4 down-regulated and 9 up-regulated proteins. An immunolocalisation study of the GABA A-α1 receptor and calbindin revealed their localisation in the equatorial segment of the head in the rat spermatozoa. The expression of calbindin is also found in the middle piece of sperm. An increase in GABA A-α1 receptor in rat spermatozoa was correlated with an increase in abnormal sperm motility and morphology after methamphetamine exposure. Moreover, calbindin expression in sperm decreased in METH-administered rats. All our findings demonstrate that METH influences intracellular calcium homeostasis by acting through the calcium signalling pathway-associated proteins. Moreover, it might disrupt ion homeostasis in sperm through the GABA A-α1 receptor and calbindin, triggering a change in intracellular calcium and chloride ions. These changes may cause abnormalities in spermatogenesis, testicular apoptosis, and sperm quality impairment.

Assessing Population Structure and Signatures of Selection in Wanbei Pigs Using Whole Genome Resequencing Data

Wanbei pig (WBP) is one of the indigenous pig resources in China and has many germplasm characteristics. However, research on its genome is lacking. To assess the genomic variation, population structure, and selection signatures, we resequenced 18 WBP for the first time and performed a comprehensive analysis with resequenced data of 10 Asian wild boars. In total, 590.03 Gb of data and approximately 41 million variants were obtained. Polymorphism level (θπ) ratio and genetic differentiation (fixation index)-based cross approaches were applied, and 539 regions, which harbored 176 genes, were selected. Functional analysis of the selected genes revealed that they were associated with lipid metabolism (SCP2, APOA1, APOA4, APOC3, CD36, BCL6, ADCY8), backfat thickness (PLAG1, CACNA2D1), muscle (MYOG), and reproduction (CABS1). Overall, our results provide a valuable resource for characterizing the uniqueness of WBP and a basis for future breeding.

Using publicly available transcriptomic data to identify mechanistic and diagnostic biomarkers in azoospermia and overall male infertility

Azoospermia, which is the absence of spermatozoa in an ejaculate occurring due to defects in sperm production, or the obstruction of the reproductive tract, affects about 1% of all men and is prevalent in up to 10–15% of infertile males. Conventional semen analysis remains the gold standard for diagnosing and treating male infertility; however, advances in molecular biology and bioinformatics now highlight the insufficiency thereof. Hence, the need to widen the scope of investigating the aetiology of male infertility stands pertinent. The current study aimed to identify common differentially expressed genes (DEGs) that might serve as potential biomarkers for non-obstructive azoospermia (NOA) and overall male infertility. DEGs across different datasets of transcriptomic profiling of testis from human patients with different causes of infertility/ impaired spermatogenesis and/or azoospermia were explored using the gene expression omnibus (GEO) database. Following the search using the GEOquery, 30 datasets were available, with 5 meeting the inclusion criteria. The DEGs for datasets were identified using limma R packages through the GEO2R tool. The annotated genes of the probes in each dataset were intersected with DEGs from all other datasets. Enriched Ontology Clustering for the identified genes was performed using Metascape to explore the possible connection or interaction between the genes. Twenty-five DEGs were shared between most of the datasets, which might indicate their role in the pathogenesis of male infertility. Of the 25 DEGs, eight genes (THEG, SPATA20, ROPN1L, GSTF1, TSSK1B, CABS1, ADAD1, RIMBP3) are either involved in the overall spermatogenic processes or at specific phases of spermatogenesis. We hypothesize that alteration in the expression of these genes leads to impaired spermatogenesis and, ultimately, male infertility. Thus, these genes can be used as potential biomarkers for the early detection of NOA.

Cabs1 Maintains Structural Integrity of Mouse Sperm Flagella during Epididymal Transit of Sperm

The calcium-binding protein spermatid-associated 1 (Cabs1) is a novel spermatid-specific protein. However, its function remains largely unknown. In this study, we found that a long noncoding RNA (lncRNA) transcripted from the Cabs1 gene antisense, AntiCabs1, was also exclusively expressed in spermatids. Cabs1 and AntiCabs1 knockout mice were generated separately (using Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-Cas9 methods) to investigate their functions in spermatogenesis. The genetic loss of Cabs1 did not affect testicular and epididymal development; however, male mice exhibited significantly impaired sperm tail structure and subfertility. Ultrastructural analysis revealed defects in sperm flagellar differentiation leading to an abnormal annulus and disorganization of the midpiece-principal piece junction, which may explain the high proportion of sperm with a bent tail. Interestingly, the proportion of sperm with a bent tail increased during transit in the epididymis. Furthermore, Western blot and immunofluorescence analyses showed that a genetic loss of Cabs1 decreased Septin 4 and Krt1 and increased cyclin Y-like 1 (Ccnyl1) levels compared with the wild type, suggesting that Cabs1 deficiency disturbed the expression of cytoskeleton-related proteins. By contrast, AntiCabs1^-/- mice were indistinguishable from the wild type regarding testicular and epididymal development, sperm morphology, concentration and motility, and male fertility. This study demonstrates that Cabs1 is an important component of the sperm annulus essential for proper sperm tail assembly and motility.

Structural and posttranslational analysis of human calcium-binding protein, spermatid-associated 1

Recently, we detected a novel biomarker in human saliva called calcium-binding protein, spermatid-associated 1 (CABS1). CABS1 protein had previously been described only in testis, and little was known of its characteristics other than it was considered a structurally disordered protein. Levels of human CABS1 (hCABS1) in saliva correlate with stress, whereas smaller sized forms of hCABS1 in saliva are associated with resilience to stress. Interestingly, hCABS1 also has an anti-inflammatory peptide sequence near its carboxyl terminus, similar to that of a rat prohormone, submandibular rat 1. We performed phylogenetic and sequence analysis of hCABS1. We found that from 72 CABS1 sequences currently annotated in the National Center for Biotechnology Information protein database, only 14 contain the anti-inflammatory domain "TxIFELL," all of which are primates. We performed structural unfoldability analysis using PONDER and FoldIndex and discovered three domains that are highly disordered. Predictions of three-dimensional structure of hCABS1 using RaptorX, IonCom, and I-TASSER software agreed with these findings. Predicted neutrophil elastase cleavage density also correlated with hCABS1 regions of high structural disorder. Ligand binding prediction identified Ca2+ , Mg2+ , Zn2+ , leucine, and thiamine pyrophosphate, a pattern observed in enzymes associated with energy metabolism and mitochondrial localization. These new observations on hCABS1 raise intriguing questions about the interconnection between the autonomic nervous system, stress, and the immune system. However, the precise molecular mechanisms involved in the complex biology of hCABS1 remain unclear. We provide a detailed in silico analysis of relevant aspects of the structure and function of hCABS1 and postulate extracellular and intracellular roles.

Identification of Signatures of Selection by Whole-Genome Resequencing of a Chinese Native Pig

Identification of genomic signatures of selection that help reveal genetic mechanisms underlying traits in domesticated pigs is of importance. Anqing six-end-white pig (ASP), a representative of the native breeds in China, has many distinguishing phenotypic characteristics. To identify the genomic signatures of selection of the ASP, whole-genome sequencing of 20 ASPs produced 469.01 Gb of sequence data and more than 26 million single-nucleotide polymorphisms. Combining these data with the available whole genomes of 13 Chinese wild boars, 157 selected regions harboring 48 protein-coding genes were identified by applying the polymorphism levels (θπ) and genetic differentiation (F_ST) based cross approaches. The genes found to be positively selected in ASP are involved in crucial biological processes such as coat color (MC1R), salivary secretion (STATH), reproduction (SPIRE2, OSBP2, LIMK2, FANCA, and CABS1), olfactory transduction (OR5K4), and growth (NPY1R, NPY5R, and SELENOM). Our research increased the knowledge of ASP phenotype-related genes and help to improve our understanding of the underlying biological mechanisms and provide valuable genetic resources that enable effective use of pigs in agricultural production.

CRISPR/Cas9-based genome editing in mice uncovers 13 testis- or epididymis-enriched genes individually dispensable for male reproduction†

Developing a safe and effective male contraceptive remains a challenge in the field of medical science. Molecules that selectively target the male reproductive tract and whose targets are indispensable for male reproductive function serve among the best candidates for a novel non-hormonal male contraceptive method. To determine the function of these genes in vivo, mutant mice carrying disrupted testis- or epididymis-enriched genes were generated by zygote microinjection or electroporation of the CRISPR/Cas9 components. Male fecundity was determined by consecutively pairing knockout males with wild-type females and comparing the fecundity of wild-type controls. Phenotypic analyses of testis appearance and weight, testis and epididymis histology, and sperm movement were further carried out to examine any potential spermatogenic or sperm maturation defect in mutant males. In this study, we uncovered 13 testis- or epididymis-enriched evolutionarily conserved genes that are individually dispensable for male fertility in mice. Owing to their dispensable nature, it is not feasible to use these targets for the development of a male contraceptive.

A method to study protein biomarkers in saliva using an automated capillary nano-immunoassay platform (Wes™)

Traditional immunoprobing techniques like Western blot continue to play a crucial role in the discovery and validation of biomarkers. This technique suffers from several limitations that affect reproducibility and feasibility for large-scale studies. Modern immunoprobing techniques have addressed several of these limitations. Here we contrast the use of Western blot and an automated capillary nano-immunoassay (CNIA), Wes™. We provide evidence highlighting the methodological advantages of Wes™ over Western blot in the validation of a novel biomarker, Calcium-binding protein and spermatid-associated 1 (hCABS1). While Wes™ offers a faster, more consistent approach with lower requirements for sample and antibody volumes, variations in expected molecular weights and computational algorithms used to analyze the data must receive careful consideration and assessment. Our data suggests that CNIA approaches are likely to positively impact biomarker discovery and validation.

EFCAB2 is a novel calcium-binding protein in mouse testis and sperm

Calcium-binding proteins regulate ion metabolism and the necessary signaling pathways for the maturational events of sperm. Our aim is to identify the novel calcium-binding proteins in testis. The gene EFCAB2 (GenBank NM_026626.3, NP_080902.1) was not previously examined, and its properties and exact mechanisms of action are unknown. In this study, we performed phylogenetic and structure prediction analyses of EFCAB2, which displays definitive structural features. Additionally, the distribution, localization, and calcium binding ability of mouse EFCAB2 were investigated. Results revealed extensive conservation of EFCAB2 among different eukaryotic orthologs. The constructed 3D model predicted that mouse EFCAB2 contains seven α-helices and two EF-hand motifs. The first EF-hand motif is located in N-terminal, while the second is located in C-terminal. By aligning the 3D structure of Ca2+-binding loops from EFCAB2 with calmodulin, we predicted six residues that might be involved in Ca2+ binding. The distribution of the Efcab2 mRNA, as determined by northern blotting, was detected only in the testis among mouse tissues. Native and recombinant EFCAB2 protein were detected by western blotting as one band at 20 kDa. In situ hybridization and immunohistochemical analyses showed its localization specifically in spermatogenic cells from primary spermatocytes to elongate spermatids within the seminiferous epithelium, but neither spermatogonia nor somatic cells were expressed. Moreover, EFCAB2 was specifically localized to the principal piece of cauda epididymal sperm flagellum. Furthermore, the analyses of purified recombinant EFCAB2 by Stains-all, ruthenium red staining, and by applying in vitro autoradiography assay showed that the physiological function of this protein is Ca2+ binding. These results suggested that EFCAB2 might be involved in the control of sperm flagellar movement. Altogether, here we describe about EFCAB2 as a novel calcium-binding protein in mouse testis and sperm.

A novel biomarker associated with distress in humans: calcium-binding protein, spermatid-specific 1 (CABS1)

Calcium-binding protein spermatid-specific 1 (CABS1) is expressed in the human submandibular gland and has an anti-inflammatory motif similar to that in submandibular rat 1 in rats. Here, we investigate CABS1 in human saliva and its association with psychological and physiological distress and inflammation in humans. Volunteers participated across three studies: 1) weekly baseline measures; 2) a psychosocial speech and mental arithmetic stressor under evaluative threat; and 3) during academic exam stress. Salivary samples were analyzed for CABS1 and cortisol. Additional measures included questionnaires of perceived stress and negative affect; exhaled nitric oxide; respiration and cardiac activity; lung function; and salivary and nasal inflammatory markers. We identified a CABS1 immunoreactive band at 27 kDa in all participants and additional molecular mass forms in some participants. One week temporal stability of the 27-kDa band was satisfactory (test-retest reliability estimate = 0.62-0.86). Acute stress increased intensity of 18, 27, and 55 kDa bands; 27-kDa increases were associated with more negative affect and lower heart rate, sympathetic activity, respiration rate, and minute ventilation. In both acute and academic stress, changes in 27 kDa were positively associated with salivary cortisol. The 27-kDa band was also positively associated with VEGF and salivary leukotriene B4 levels. Participants with low molecular weight CABS1 bands showed reduced habitual stress and negative affect in response to acute stress. CABS1 is readily detected in human saliva and is associated with psychological and physiological indicators of stress. The role of CABS1 in inflammatory processes, stress, and stress resilience requires careful study.

Integrated proteomics and metabolomics analysis of rat testis: Mechanism of arsenic-induced male reproductive toxicity

Arsenic is a widespread metalloid in environment, whose exposure has been associated with a broad spectrum of toxic effects. However, a global view of arsenic-induced male reproductive toxicity is still lack, and the underlying mechanisms remain largely unclear. Our results revealed that arsenic exposure decreased testosterone level and reduced sperm quality in rats. By conducting an integrated proteomics and metabolomics analysis, the present study aims to investigate the global influence of arsenic exposure on the proteome and metabolome in rat testis. The abundance of 70 proteins (36 up-regulated and 34 down-regulated) and 13 metabolites (8 increased and 5 decreased) were found to be significantly altered by arsenic treatment. Among these, 19 proteins and 2 metabolites were specifically related to male reproductive system development and function, including spermatogenesis, sperm function and fertilization, fertility, internal genitalia development, and mating behavior. It is further proposed that arsenic mainly impaired spermatogenesis and fertilization via aberrant modulation of these male reproduction-related proteins and metabolites, which may be mediated by the ERK/AKT/NF-κB-dependent signaling pathway. Overall, these findings will aid our understanding of the mechanisms responsible for arsenic-induced male reproductive toxicity, and from such studies useful biomarkers indicative of arsenic exposure could be discovered.

Spermatogenesis-associated proteins at different developmental stages of buffalo testicular seminiferous tubules identified by comparative proteomic analysis

The testicular seminiferous tubules contain Sertoli cells and different types of spermatogenic cells. They provide the microenvironment for spermatogenesis, but the precise molecular mechanism of spermatogenesis is still not well known. Here, we have employed tandem mass tag coupled to LC-MS/MS with the high-throughput quantitative proteomics technology to explore the protein expression from buffalo testicular seminiferous tubules at three different developmental stages (prepuberty, puberty, and postpuberty). The results show 304 differentially expressed proteins with a ≥2-fold change, and bioinformatics analysis indicates that 27 of these may be associated with spermatogenesis. Expression patterns of seven selected proteins were verified via Western blot and quantitative RT-PCR analysis, and further cellular localizations of these proteins by immunohistochemical or immunofluorescence analysis. Taken together, the results provide potential molecular markers of spermatogenesis and provide a rich resource for further studies on male reproduction regulation.

CABCOCO1, a novel coiled-coil protein With calcium-binding activity, is localized in the sperm flagellum

The gene 1700040L02Rik (GenBank accession number NM_028491, NP_082767.1) was selected by in silico screening as candidate that encodes a calcium-binding protein in sperm from a database of predicted mouse cilia-related genes. The predicted amino acid sequence revealed the presence of coiled-coil domain at the C-terminus and a CLAMP motif containing a leucine zipper domain in the middle of the protein. Assessment of a recombinant version of this protein by Stains-all and ruthenium red staining and by direct measurement of terbium binding revealed its calcium-binding activities. We therefore named this protein CABCOCO1 for calcium-binding coiled-coil protein-1. Immunohistochemical analyses showed its localization in spermatogenic cells of mouse testis. CABCOCO1 was first observed in the cytoplasm of murine spermatocytes, concentrated around centrioles of spermatids and co-localized with the centrosomal protein pericentrin. During the stage when centrosome number is reduced, CABCOCO1 relocalized to the murine sperm flagellum. On the other hand, in porcine sperm, whose proximal centriole remains intact while the distal centriole degenerates during spermiogenesis, CABCOCO1 localized both in the basal body and the flagellum. These results suggested that CABCOCO1 is involved in the control of sperm flagellar movement. Mol. Reprod. Dev. 83: 912-926, 2016 © 2016 Wiley Periodicals, Inc.

Identification, localization, and functional analysis of the homologues of mouse CABS1 protein in porcine testis

Previously, we have identified a calcium-binding protein that is specifically expressed in spermatids and localized to the flagella of the mature sperm in mouse, so-called mCABS1. However, the physiological roles of CABS1 in the male reproductive system have not been fully elucidated yet. In the current study, we aimed to localize and clarify the role of CABS1 in porcine (pCABS1). We determined for the first time the full nucleotides sequence of pCABS1 mRNA. pCABS1 protein was detected on SDS-PAGE gel as two bands at 75 kDa and 70 kDa in adult porcine testis, whereas one band at 70 kDa in epididymal sperm. pCABS1 immunoreactivity in seminiferous tubules was detected in the elongated spermatids, and that in the epididymal sperm was found in the acrosome as well as flagellum. The immunoreactivity of pCABS1 in the acrosomai region disappeared during acrosome reaction. We also identified that pCABS1 has a transmembrane domain using computational prediction of the amino acids sequence. The treatment of porcine capacitated sperm with anti-pCABS1 antiserum significantly decreased acrosome reactions. These results suggest that pCABS1 plays an important role in controlling calcium ion signaling during the acrosome reaction.

Calcium-binding protein, spermatid-specific 1 is expressed in human salivary glands and contains an anti-inflammatory motif

Salivary glands are involved in the production and exocrine and endocrine secretion of biologically active proteins, polypeptides, and hormones involved in growth and differentiation, homeostasis, and digestion. We have previously studied the prohormone submandibular rat 1 (SMR1), product of the Vcsa1 gene, which is highly expressed in the testes and salivary glands of rats, and can be cleaved to produce polypeptides with analgesic, erectile function, and anti-inflammatory activities. Humans lack the Vcsa1 gene, but homologous sequences and functions for analgesia and erectile function exist in the human genes Prol1, SMR3a, and SMR3b located on the human chromosomal region close to where Vcsa1 lies in the rat. Here we show the human protein calcium-binding protein spermatid-specific 1 (CABS1) contains a similar sequence to the anti-inflammatory sequence in rat SMR1, thus CABS1 may be another human gene with homologous function to Vcsa1. Using Western blot and PCR, we discovered that the human protein CABS1, previously thought to only be expressed in the testes, is also expressed in the salivary glands and lung, in a tissue-specific manner. Peptides derived from CABS1 were tested in an in vivo mouse model of lipopolysaccharide (LPS)-induced neutrophilia and an ex vivo rat model of antigen-induced intestinal anaphylaxis and significantly reduced both neutrophil accumulation in bronchoalveolar lavage fluid and antigen-induced ileal contractions, respectively. Thus human CABS1 has a peptide motif homologous to the anti-inflammatory peptide sequence of rat SMR1. Whether this similarity of CABS1 extends to the neuroendocrine regulation of the anti-inflammatory activity seen for SMR1 remains to be determined.

Porcine sperm capacitation involves tyrosine phosphorylation and activation of aldose reductase

Mammalian sperm must be activated in the tubal isthmus through capacitation to induce the acrosome reaction and subsequent fertilization. Although the molecular mechanisms involved in capacitation have yet to be fully elucidated, increased concentrations of reactive oxygen species (ROS) and the extent of tyrosine phosphorylation of proteins have been suggested to play central roles in the completion of capacitation. In this study, aldose reductase was for the first time identified as one of the tyrosine-phosphorylated proteins involved in the capacitation of porcine cauda epididymal sperm. Both tyrosine phosphorylation and activity of aldose reductase associated with the particulate fraction of sperm cells were significantly enhanced during capacitation. Alrestatin, a membrane-permeable and specific inhibitor of aldose reductase, plays a role in the inhibition of aldose reductase activity, elevation of intracellular levels of ROS, and induction of hyperactivated motility, all at similar dose dependencies. Alrestatin canceled both the increase in the tyrosine phosphorylation of aldose reductase and the decrease in the glutathione levels in sperm-induced during capacitation. The hyperactivated motility was induced to a higher extent in the presence of glucose than in the presence of fructose. These results indicate that aldose reductase plays an important role in induction of hyperactivation and capacitation of sperm through the elevation of ROS in sperm cells. Furthermore, aldose reductase was shown to be added to sperm during transit through the epididymis, suggesting that aldose reductase is one of the key proteins that support the functional maturation of sperm.

Ruthenium red colorimetric and birefringent staining of amyloid-β aggregates in vitro and in Tg2576 mice

Alzheimer's disease (AD) is a devastating neurodegenerative disease most notably characterized by the misfolding of amyloid-β (Aβ) into fibrils and its accumulation into plaques. In this Article, we utilize the affinity of Aβ fibrils to bind metal cations and subsequently imprint their chirality to bound molecules to develop novel imaging compounds for staining Aβ aggregates. Here, we investigate the cationic dye ruthenium red (ammoniated ruthenium oxychloride) that binds calcium-binding proteins, as a labeling agent for Aβ deposits. Ruthenium red stained amyloid plaques red under light microscopy, and exhibited birefringence under crossed polarizers when bound to Aβ plaques in brain tissue sections from the Tg2576 mouse model of AD. Staining of Aβ plaques was confirmed via staining of the same sections with the fluorescent amyloid binding dye Thioflavin S. In addition, it was confirmed that divalent cations such as calcium displace ruthenium red, consistent with a mechanism of binding by electrostatic interaction. We further characterized the interaction of ruthenium red with synthetic Aβ fibrils using independent biophysical techniques. Ruthenium red exhibited birefringence and induced circular dichroic bands at 540 nm upon binding to Aβ fibrils due to induced chirality. Thus, the chirality and cation binding properties of Aβ aggregates could be capitalized for the development of novel amyloid labeling methods, adding to the arsenal of AD imaging techniques and diagnostic tools.