Biology subjects

Jarvi, K.

Publications and source records attributed to Jarvi, K..

3 recordsLinked to original sources

bioRxiv2018

Discovery of a human testis-specific protein complex TEX101-DPEP3 and selection of its disrupting antibodies

TEX101 is a testis-specific protein expressed exclusively in male germ cells and is a validated biomarker of male infertility. Studies in mice suggest that TEX101 is a cell-surface chaperone which regulates, through protein-protein interactions, the maturation of proteins involved in spermatozoa transit and oocyte binding. Male TEX101-null mice are sterile. Here, we identified by co-immunoprecipitation-mass spectrometry the interactome of human TEX101 in testicular tissues and spermatozoa. The testis-specific cell-surface dipeptidase 3 (DPEP3) emerged as the top hit. We further validated the TEX101-DPEP3 complex by using hybrid immunoassays. Combinations of antibodies recognizing different epitopes of TEX101 and DPEP3 facilitated development of a simple immunoassay to screen for disruptors of TEX101-DPEP3 complex. As a proof-of-a-concept, we demonstrated that anti-TEX101 antibody T4 disrupted the native TEX101-DPEP3 complex. Disrupting antibodies may be used to study the human TEX101-DPEP3 complex, and to develop modulators for male fertility.\n\nNon-standard abbreviations

molecular biology↗

bioRxiv2018

Identification of TEX101 functional interactome through proteomic measurement of human spermatozoa homozygous for the missense variant rs35033974

TEX101 is a testis-specific cell-surface protein expressed exclusively in the male germ cells and a validated biomarker of male infertility. Mouse TEX101 was found essential for male fertility, and was suggested to function as a cell surface chaperone involved in maturation of proteins required for sperm migration and sperm-oocyte interaction. However, the precise functional role of human TEX101 is not known and cannot be studied in vitro due to the lack of human germ cell lines. Here, we genotyped 386 healthy fertile men and sub-fertile patients for a common and potentially deleterious missense variant rs35033974 of TEX101, and identified 52 heterozygous and 4 homozygous patients. We then discovered by targeted proteomics that the variant allele rs35033974 was associated with near-complete degradation (>97%) of the corresponding G99V TEX101 form, and suggested that spermatozoa of homozygous patients could serve as a knockdown model to study TEX101 function in humans. Differential proteomic profiling with label-free quantification measured 8,046 proteins in spermatozoa of eight men and identified 8 cell-surface and 9 secreted testis-specific proteins significantly down-regulated in four patients homozygous for rs35033974. Substantially reduced levels of testis-specific cell-surface proteins potentially involved in sperm migration and sperm-oocyte fusion (including LY6K and ADAM29) were confirmed by targeted proteomics and western blotting assays. Since recent population-scale genomic data revealed homozygous fathers with biological children, rs35033974 is not a single pathogenic factor of male infertility in humans. However, median TEX101 levels in seminal plasma were found 5-fold lower (P=0.0005) in heterozygous than in wild-type men of European ancestry. We conclude that spermatozoa of rs35033974 homozygous men have substantially reduced levels of TEX101 and could be used as a model to elucidate the precise TEX101 function, which will advance biology of human reproduction.\n\nNon-standard abbreviations

molecular biology↗

bioRxiv2017

Multi-omics Biomarker Pipeline Reveals Elevated Levels Of Protein-Glutamine Gamma-Glutamyltransferase 4 In Seminal Plasma Of Patients With Prostate Cancer

PurposeProstate-specific antigen, a blood serum biomarker of prostate cancer, lacks specificity and prognostic significance, so considerable efforts are devoted to developing novel biomarkers. Seminal plasma, due to its proximity to prostate, is a promising fluid for biomarker discovery and non-invasive diagnostics. In this study, we investigated if seminal plasma proteins could increase specificity of detecting primary prostate cancer and discriminate between high- and low-grade cancers.\n\nExperimental DesignTo select 148 most promising biomarker candidates, we combined proteins identified through five independent data mining or experimental approaches: tissue transcriptomics, seminal plasma proteomics, cell secretomics, tissue specificity and androgen regulation. A rigorous biomarker development pipeline based on targeted proteomics assays was designed to evaluate the most promising candidates.\n\nResultsWe qualified 77 and verified 19 proteins in seminal plasma of 67 negative biopsy and 155 prostate cancer patients. Verification revealed a prostate-specific, secreted and androgen-regulated protein-glutamine gamma-glutamyltransferase 4 (TGM4), which could predict prostate cancer on biopsy and outperformed age and serum PSA. Machine-learning approaches also revealed improved multi-marker combinations for diagnosis and prognosis. In the independent verification set measured by an inhouse ELISA, TGM4 was up-regulated 3.7-fold (P=0.006) and revealed AUC 0.66 for detecting prostate cancer on biopsy for patients with serum PSA[≥]4 ng/mL and age[≥]50. Low levels of TGM4 (median 120 pg/mL) were detected in blood serum, but could not differentiate between negative biopsy, prostate cancer or prostate inflammation.\n\nConclusionsPerformance of TGM4 warrants its further investigation within the distinct genomic subtypes and evaluation for the inclusion into emerging multi-biomarker panels.

cancer biology↗