Table 1. Known and predicted functions of androgen-responsive proteins in enriched meiotic cell preparations†.
| Gene | Protein name (alias) | SpotNo. | Normalised spot volume | Known functions a | Role in meioticcells? b | |||
| C | TE | TE+Flut | TE+T24 | |||||
| Acrbp | Acrosin-binding protein | 95 | 0.99 | 0.69 | 0.66 | 1.04 | May be involved in packaging and condensation of the acrosin zymogen in the acrosome | |
| Actg1 | Actin, cytoplasmic 2 (Gamma-actin) | 63b, 86 | 1.34 | 1.08 | 0.97 | 1.72 | Role in cytoskeleton, scaffolding, cell movement, cell cycle | Meiotic division, cell structure |
| Actr1a | Alpha-centractin(Arp1, Ctrn1) | 187 | 1.09 | 0.90 | 0.77 | 1.06 | Key component of the dynactin complex involved in microtubule-based motility. Associated with centrosome and likely involved in chromosome organisation and spindle dynamics | Meiotic division |
| Akr1b1 | Aldose reductase (Alr) | 9a, 145 | 1.57 | 0.81 | 0.68 | 1.05 | Oxidoreductase, activates stress signalling pathways | Response to oxidative stress |
| Aldh2 | Aldehyde dehydrogenase, mitochondrial precursor | 113a | 1.13 | 0.91 | 0.73 | 0.91 | Metabolic enzyme present in mitochondrial matrix, protector of oxidative stress | Response to oxidative stress |
| Atp5a1 | ATP synthase subunit alpha, mitochondrial precursor (Chain A, Rat Liver F1-Atpase) | 113b | 1.13 | 0.91 | 0.73 | 0.91 | Component of ATPase machinery in mitochondria | Response to oxidative stress |
| Atp5b | ATP synthase subunit beta, mitochondrial precursor, OR ATP synthase beta subunit c | 162a | 1.08 | 0.74 | 0.90 | 0.97 | A component of ATPase machinery in mitochondria | Response to oxidative stress |
| Capza1 | F-actin capping protein alpha-1 subunit (CapZa1) | 242b | 1.23 | 1.10 | 0.92 | 1.19 | Subunit of Capz F-actin capping protein which regulates actin filament assembly and disassembly | Meiotic division, cell structure |
| Capza2 | F-actin-capping protein subunit alpha-2 (CapZa2) | 242a | 1.23 | 1.10 | 0.92 | 1.19 | Subunit of Capz F-actin capping protein which regulates actin filament assembly and disassembly | Meiotic division, cell structure |
| Cops4/Csn4 | COP9 signalosome complex subunit 4 | 352 | 1.00 | 1.08 | 1.06 | 0.88 | Component of COP9 signalosome complex (CSN), involved in various cellular and developmental processes. CSN is an essential regulator of ubiquitin conjugation pathway and has known roles in cell cycle and in meiosis. Other COP subunits are highly expressed in PSC | Meiosis |
| Crym | Mu-chrystallin homolog | 192 | 0.86 | 0.96 | 1.00 | 1.22 | Binds thyroid hormone and NADPH. Multiple alternatively spliced transcript variants have been found for this gene | |
| Ddx4 | Probable ATP-dependent RNA helicase DDX4 (Mvh) | 160b, 311 | 0.89 | 0.95 | 1.14 | 0.78 | Germ cell specific RNA helicase DEAD box proteins, null mutation in mice causes arrest at zygotene spermatocytes. Involved in miRNA processing and germ cell specification in chromatoid body. Localises to site of microtubule assembly | Meiosis, RNA processing |
| Diablo | Diablo homolog (Drosophila) (larger C-terminal fragment) (Smac/Diablo) | 68 | 1.76 | 1.43 | 1.08 | 1.88 | Mitochondrial protein involved in apoptosis; upon apoptotic stimulus binds to inhibitors of apoptosis and prevents their interaction with caspases | Apoptosis |
| Eno1 | Alpha-enolase (Eno1) | 4, 23, 41, 74 | 1.49 | 0.95 | 0.59 | 0.83 | Subunit of a multifunctional enzyme with roles in glycolysis, hypoxia tolerance, allergic responses | Indicator of metabolic stress |
| Fabp9 | Fatty acid binding protein 9, testis | 297 | 0.81 | 0.99 | 1.04 | 0.93 | Testis specific fatty acid binding protein, is increased during germ cell apoptosis [90] | Apoptosis |
| Fth1 | Ferritin heavy chain (Fth1) | 87, 104 | 0.85 | 1.37 | 1.26 | 0.97 | Component of ferritin complex, involved in iron storage and delivery | Response to oxidative stress |
| Ftl1 | Ferritin light chain 1 (Ftl1) | 30, 64, 148 | 0.59 | 0.93 | 1.21 | 1.05 | Component of ferritin complex, involved in iron storage and delivery | Response to oxidative stress |
| Galk1 | Galactokinase 1 | 63c | 1.34 | 1.08 | 0.97 | 1.72 | Galactose/carbohdryate metabolism | Cell metabolism |
| Gstm5 | Glutathione S-transferase Mu 5 | 62 | 1.49 | 1.05 | 0.98 | 0.84 | Subunit of glutathione S-transferase (GST) enzymes. This subunit likely functionally distinct from other mu class subunits, is primarily expressed in testis. GSTs have antioxidant properties and are involved in oxidative stress response | Response to oxidative stress |
| Hnrnpk | Heterogeneous nuclear ribo-nucleoprotein K (hnRNP K) | 201b | 0.83 | 1.05 | 1.16 | 0.93 | Multifunctional protein with roles in splicing, transcription, translation, chromatin remodeling and apoptosis | Apoptosis, RNA splicing |
| Hnrph3 | Heterogeneous nuclear ribo-nucleoprotein H3 (HnRNP H) OR mCG11326, isoform CRA_b [Mus musculus] | 16b, 46a, 46b | 1.25 | 0.74 | 0.56 | 1.05 | Heterogeneous nuclear ribonucleoprotein, role in RNA splicing, component of spliceosome | RNA splicing |
| Hspa2 | Heat shock-related 70 kDa protein 2 (Hsp70-2) | 108b | 1.14 | 0.96 | 1.06 | 0.74 | Molecular chaperone with known role in meiosis: present in the synaptonemal complex and is necessary for activation of CDC2 and entry into meiotic division. Null mice are infertile due to pachytene spermatocyte arrest and apoptosis [91] | Meiotic division |
| Hspa9 | Stress-70 protein, mitochondrial precursor (Grp75, mortalin) | 96, 313 | 1.35 | 1.07 | 0.85 | 1.20 | Multifunctional chaperone and mitochondrial protein involved in cell proliferation, stress response and cellular aging | Response to cell stress, meiosis |
| Hspd1 | Heat shock protein 1 (chaperonin, Hsp60) | 320 | 0.81 | 0.96 | 1.02 | 0.94 | Mitochondrial protein import and protein folding. Known roles in apoptosis and response to cellular stress | Apoptosis, response to cell stress |
| Iah1 | Isoamyl acetate-hydrolyzing esterase 1 homolog | 379b | 1.18 | 1.20 | 1.13 | 1.34 | Probable lipase | |
| Idi1 | Isopentenyl-diphosphate Delta-isomerase 1 | 106 | 1.42 | 1.08 | 0.91 | 1.33 | Ubiquitously expressed isomerase | |
| Immt | Inner membrane protein, mitochondrial (Mitofilin) | 342 | 0.94 | 1.08 | 1.16 | 0.98 | Mitochondrial protein involved in maintenance of mitochondrial morphology, shown to be changed during apoptosis, oxidative stress & various disease states | Response to oxidative stress, apoptosis |
| Immt | Inner membrane protein, mitochondrial, isoform CRA_a (Mitofilin) | 57, 103 | 0.76 | 1.03 | 1.23 | 0.68 | Mitochondrial protein involved in maintenance of mitochondrial morphology, shown to be changed during apoptosis, oxidative stress & various disease states | Response to oxidative stress, apoptosis |
| Ipo5 | predicted: Importin 5 (Putative uncharacterized protein Ipo5) (Imp5, Ranbp5) | 167 | 1.00 | 1.14 | 1.26 | 0.87 | Functions in nuclear protein import as nuclear transport receptor | |
| Itpa | Inosine triphosphatase [Rattus norvegicus] | 70b, 269c | 1.72 | 1.43 | 1.20 | 1.00 | Hydrolyzes inosine and deoxyinosine triphosphate | |
| Lap3 | Leucine aminopeptidase 3 (Cytosol aminopeptidase) | 350a | 1.10 | 0.92 | 0.90 | 0.95 | Catalyzes removal of unsubstituted N-terminal amino acids from various peptides, presumably involved in processing and turnover of intracellular proteins | |
| Ldhb | L-lactate dehydrogenase B (Ldh-B) | 48, 72 | 1.74 | 1.28 | 1.06 | 0.95 | Cytoplasmic oxidoreductase involved in glycolysis | Cell metabolism, response to oxidative stress |
| Ldhc | L-lactate dehydrogenase C chain (Ldh3, LDH testis subunit) | 9c | 1.57 | 0.81 | 0.68 | 1.05 | Cytoplasmic oxidoreductase involved in glycolysis, sperm motility | Cell metabolism |
| Lztfl1 | Leucine zipper transcription factor-like protein 1 | 63a | 1.34 | 1.08 | 0.97 | 1.72 | Tumour suppressive activity, role in ciliary protein trafficking | |
| Mapre1 | Microtubule-associated protein RP/EB family member 1 (EB1) | 170b, 302 | 1.38 | 1.10 | 0.96 | 1.38 | Role in microtubule polymerization and spindle function during cell division. Associates with centrosomes, Anaphase Promoting Complex and dynactin complex | Meiotic division |
| Nasp | Nuclear autoantigenic sperm protein (Nasp) | 83 | 0.74 | 0.98 | 1.21 | 0.76 | Linker histone chaperone required for DNA replication, normal cell cycle progression and cell proliferation. Interacts with Hspa2 in spermatocytes, involved in meiotic checkpoint | Meiotic division |
| Ndufs1 | NADH dehydrogenase (ubiquinone) Fe-S protein 1, 75 kDa | 338 | 1.21 | 0.97 | 0.99 | 1.19 | Core subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I). Roles in oxidative metabolism. Cleaved by caspases during initial apoptotic response | Response to oxidative stress, apoptosis |
| P4hb/ Pdia1/ | Protein disulfide-isomerase precursor | 180,307, 351 | 0.92 | 0.91 | 0.90 | 1.14 | Multifunctional protein catalyzes the formation, breakage and rearrangement of disulfide bonds. Involved in ER stress response | Response to cell stress |
| Pafah-1b2 | Platelet-activating factor acetylhydrolase 1B subunit beta (Pafahb) | 379a | 1.18 | 1.20 | 1.13 | 1.34 | Subunit of the enzyme that metabolizes Platelet Activating Factor (PAF), a biologically active phospholipid with diverse biologic effects. Mice with a null mutation infertile due pachytene arrest [92] | Meiosis, apoptosis |
| Park7 /Cap1 | Protein DJ-1, Contraception-associated protein 1 (DJ1, SP22, Cap1) | 54, 110, 375b | 1.53 | 1.13 | 0.85 | 0.96 | Multifunctional molecular chaperone with roles in oxidative stress, apoptosis, fertilization, androgen-receptor dependent transcription, cancer | Apoptosis, response to oxidative stress |
| Pcna | Proliferating cell nuclear antigen (PCNA) | 188 | 0.93 | 1.22 | 1.23 | 1.32 | Auxiliary protein of DNA polymerase delta involved in DNA replication and post-replicative DNA repair pathways. Mice expressing PCNA that cannot be mono-ubiquitylated are infertile due to spermatocyte arrest [81] | DNA repair |
| Pdhb | Pyruvate dehydrogenase E1 component subunit beta, mitochondrial precursor | 381 | 1.22 | 1.12 | 1.04 | 1.10 | Component of pyruvate dehydrogenase, located in the mitochondrial matrix. Role in oxidation reduction. | Cell metabolism, response to oxidative stress |
| Pdia3 | Protein disulfide-isomerase A3 precursor | 124 | 1.18 | 0.79 | 0.81 | 1.21 | Isomerase with roles in cell (and ER) stress and apoptosis | Apoptosis, response to cell stress |
| Pdia6 | Protein disulfide-isomerase A6 precursor (CaBP1)c | 142a | 1.23 | 1.10 | 0.93 | 1.38 | Isomerase present in the ER and on cell surface. Identified in various proteomic screens of cells under stress | Response to cell stress |
| Pebp1 | Phosphatidyl-ethanolamine-binding protein 1 (Pebp1/Rkip) | 1, 269a | 1.85 | 0.62 | 0.64 | 1.64 | Inhibits signalling pathways (MAPK, NFKB and GCPR), various roles including apoptosis and cell cycle. Component of sperm plasma membrane | Apoptosis, cell cycle |
| Pgls | 6- phospho-gluconolactonase (6PGL) | 339 | 1.09 | 0.98 | 0.88 | 0.99 | Enzyme involved in carbohydrate metabolism | Cell metabolism |
| Ppt1 | Palmitoyl-protein thioesterase 1 (Ppt1) | 9b | 1.57 | 0.81 | 0.68 | 1.05 | Lysosomal protein, involved in apoptosis, cell stress | Apoptosis, response to cell stress |
| Prdx6 | Peroxiredoxin-6 | 132 | 1.39 | 0.95 | 1.03 | 0.93 | Cytosolic member of peroxiredoxin family of antioxidant proteins, protects cells from oxidative damage | Response to oxidative stress |
| Prmt5 | Protein arginine N-methyl-transferase 5 (Prmt5) | 108a | 1.14 | 0.96 | 1.06 | 0.74 | Methyltransferase that dimethylates arginine residues in proteins including components of the spliceosome and Piwi proteins in meiotic nuage and chromatoid body. Null mutation of Drosophila homolog causes spermatocyte arrest [66] | RNA splicing, meiosis |
| Prpf19 | Pre-mRNA-processing factor 19 (Nuclear matrix protein SNEV [Mus musculus]) (Prp19, SNEV) | 350b | 1.10 | 0.92 | 0.90 | 0.95 | Roles in DNA double-strand break repair, spliceosome assembly, localized to mitotic spindle during anaphase, participates in protein degradation in the proteosome | DNA repair, RNA splicing, meiotic division |
| Psma6 | Proteasome subunit alpha type 6 | 360 | 1.12 | 1.02 | 0.93 | 0.95 | Component of the proteosome | Protein degradation |
| Psmb4 | Proteasome subunit beta type 4 precursor (Psmb4) | 91 | 1.44 | 1.11 | 0.98 | 0.91 | Beta7 subunit of 20 S proteasome, binds to other proteins including Prp19, role in targeted protein degradation | Meiosis, cell signalling, protein degradation |
| Rab2a | Ras-related protein Rab-2A (Rab2) | 375a | 1.03 | 1.19 | 1.14 | 1.22 | Required for protein transport from the endoplasmic reticulum to the Golgi complex. Component of acrosome | |
| Rab6a | Ras-related protein Rab-6A [Mus musculus] (Rab6) | 70a, 269a | 1.72 | 1.20 | 1.00 | 1.43 | Regulator of membrane traffic from the Golgi apparatus towards the endoplasmic reticulum | |
| Ropn1l | Ropporin-like protein (AKAP-associated sperm protein) [Mus musculus] (Asp) | 70c | 1.72 | 1.43 | 1.20 | 1.00 | Testis specific protein. Predicted to interact with AKAP3 which is present in round spermatid acrosome | |
| Ruvbl1 | RuvB-like 1 | 154 | 1.26 | 1.03 | 0.86 | 0.93 | DNA helicase. Component of the NuA4 histone acetyltransferase complex which is involved in transcriptional activation of select genes. Associates with tubulins in the mitotic spindle and centrosome | Meiotic division, apoptosis |
| Sae1 | SUMO-activating enzyme subunit 1 | 330 | 1.20 | 1.21 | 0.97 | 1.12 | Subunit of sumo activating enzyme, participates in post-translational sumoylation of target proteins. SUMO modification regulates activity of numerous transcription factors with roles in cell-cycle, apoptosis and development | Meiosis, general cell function |
| Sdha | Succinate dehydrogenase [ubiquinone] flavoprotein subunit, mitochondrial precursor (Fp) | 213 | 0.93 | 0.91 | 1.02 | 0.74 | Flavoprotein (FP) subunit of succinate dehydrogenase involved in mitochondrial electron transport chain. Known to be changed in response to cellular stress | Response to cell stress |
| Sept2 | Septin-2 | 174 | 1.19 | 1.02 | 0.96 | 0.83 | Required for normal cell division | Meiotic division |
| Sf3a1 | Splicing factor 3a, subunit 1 (SAP114) | 356 | 0.91 | 1.07 | 1.10 | 0.94 | Component of splicing factor SF3A, functions early during pre-mRNA splicing | RNA splicing |
| Sf3a3 | Splicing factor 3a, subunit 3 [Mus musculus] (SAP61) | 201a | 0.83 | 1.05 | 1.16 | 0.93 | Component of splicing factor SF3A, functions early during pre-mRNA splicing | RNA splicing |
| Sfrs7 | Splicing factor, arginine/serine-rich 7 (9G8) | 150b | 0.79 | 0.92 | 1.00 | 1.16 | Well known component of human spliceosome and is required for pre-mRNA splicing | RNA splicing |
| Tbca | Tubulin cofactor a | 286 | 1.03 | 1.19 | 1.16 | 1.34 | Involved in tubulin folding, acts as a molecular chaperone for tubulins | Meiotic division, general cell function |
| Thop1 | Thimet oligopeptidase | 160a | 0.89 | 0.95 | 1.14 | 0.78 | Involved in small peptide metabolism, broad substrate specificity | |
| Tpm3 | Tropomyosin alpha-3 chain | 290 | 1.22 | 1.03 | 0.95 | 1.18 | Binds and stabilises actin filaments, required for cell division in some cells | Meiotic division |
| Tsta3 | Tissue specific transplantation antigen P35B | 285 | 1.14 | 1.03 | 0.88 | 0.97 | An NADP(H)-binding protein that catalyses reactions in GDP-D-mannose metabolism, converting GDP-4-keto-6-D-deoxymannose to GDP-L-fucose | |
| Tuba1c | Tubulin alpha-1C chain d | 93a | 1.39 | 1.03 | 0.87 | 0.89 | Constituent of microtubules, roles in meiotic division | Meiotic division, general cell function |
| Tuba3a | Tubulin alpha-3 chain d | 344a | 1.18 | 1.04 | 0.96 | 0.98 | Constituent of microtubules, roles in meiotic division | Meiotic division, general cell function |
| Tubb2c | Tubulin beta-2C chain d | 47a | 1.34 | 0.93 | 0.90 | 0.73 | Constituent of microtubules, roles in meiotic division | Meiotic division, general cell function |
| Ube2N | Ubiquitin-conjugating enzyme E2N (Ubc13) | 141 | 0.59 | 0.83 | 0.85 | 0.88 | Role in poly-ubiquitination that mediates transcriptional activation. Roles in cell cycle and survival, DNA repair. Participates in polyubiquitination of PCNA which is required for DNA repair | DNA repair |
| Ywhab | 14-3-3 protein beta/alpha | 137a | 1.58 | 1.15 | 1.06 | 1.25 | Participate in protein-protein interactions to control a wide variety of processes. Known to inhibit testis specific kinase 1 (TESK1) which is expressed in pachytene spermatocytes [93] | Meiosis, apoptosis, cell signalling |
| Ywhae | 14-3-3 protein epsilon (14-3-3e) | 29, 130, 240 | 1.32 | 0.84 | 0.64 | 1.30 | Participate in protein-protein interactions to control a wide variety of processes including cell cycle and apoptosis | Meiosis, apoptosis, cell signalling |
| Ywhag | 14-3-3 protein gamma | 218b | 1.44 | 1.04 | 1.05 | 1.22 | Participate in protein-protein interactions to control a wide variety of processes including cell cycle and apoptosis | Meiosis, apoptosis, cell signalling |
| Ywhaz | 14-3-3 protein zeta/delta | 137b, 218a | 1.58 | 1.15 | 1.06 | 1.25 | Participate in protein-protein interactions to control a wide variety of processes including cell cycle and apoptosis | Meiosis, apoptosis, cell signalling |
†
Further information on protein identity, fold changes between treatment groups, false discovery rate, power value, and localisation of mRNA expression in the seminiferous epithelium is given in Table S1 and S2. Information on peptide identification scores, number of peptides identified and % sequence coverage is shown in Table S2. Actual mass spectra for all identified proteins are shown in Table S3. Abbreviations: PSC = pachytene spermatocytes.
a
Summary of likely major functions based on information from UniProt, GO annotations, Entrez Gene ID and PubMed.
b
Brief overview of potential role in meiotic cells based on known functions and/or previously described roles in the testis.