Proteins as the Molecular Markers of Male Fertility

Non-canonical G protein signaling

The original paradigm of classical - also referred to as canonical - cellular signal transduction of heterotrimeric G proteins (G protein) is defined by a hierarchical, orthograde interaction of three players: the agonist-activated G protein-coupled receptor (GPCR), which activates the transducing G protein, that in turn regulates its intracellular effectors. This receptor-transducer-effector concept was extended by the identification of regulators and adapters such as the regulators of G protein signaling (RGS), receptor kinases like βARK, or GPCR-interacting arrestin adapters that are integrated into this canonical signaling process at different levels to enable fine-tuning. Finally, the identification of atypical signaling mechanisms of classical regulators, together with the discovery of novel modulators, added a new and fascinating dimension to the cellular G protein signal transduction. This heterogeneous group of accessory G protein modulators was coined "activators of G protein signaling" (AGS) proteins and plays distinct roles in canonical and non-canonical G protein signaling pathways. AGS proteins contribute to the control of essential cellular functions such as cell development and division, intracellular transport processes, secretion, autophagy or cell movements. As such, they are involved in numerous biological processes that are crucial for diseases, like diabetes mellitus, cancer, and stroke, which represent major health burdens. Although the identification of a large number of non-canonical G protein signaling pathways has broadened the spectrum of this cellular communication system, their underlying mechanisms, functions, and biological effects are poorly understood. In this review, we highlight and discuss atypical G protein-dependent signaling mechanisms with a focus on inhibitory G proteins (Gi) involved in canonical and non-canonical signal transduction, review recent developments and open questions, address the potential of new approaches for targeted pharmacological interventions.

Molecular Markers: A New Paradigm in the Prediction of Sperm Freezability

For decades now, sperm cryopreservation has been a pillar of assisted reproduction in animals as well as humans. Nevertheless, the success of cryopreservation varies across species, seasons, and latitudes and even within the same individual. With the dawn of progressive analytical techniques in the field of genomics, proteomics, and metabolomics, new options for a more accurate semen quality assessment have become available. This review summarizes currently available information on specific molecular characteristics of spermatozoa that could predict their cryotolerance before the freezing process. Understanding the changes in sperm biology as a result of their exposure to low temperatures may contribute to the development and implementation of appropriate measures to assure high post-thaw sperm quality. Furthermore, an early prediction of cryotolerance or cryosensitivity may lead to the establishment of customized protocols interconnecting adequate sperm processing procedures, freezing techniques, and cryosupplements that are most feasible for the individual needs of the ejaculate.

Alterations in seminal plasma proteomic profile in men with primary and secondary infertility

Proteome of seminal plasma provides profound information related to the male reproductive health. This pilot study was conducted to characterize proteomic profile of seminal plasma from men with primary, or secondary infertility and compare it with proven fertile men. Study participants (n = 59) were recruited at the Cleveland Clinic and divided according to their fertility status: proven fertile (n = 39); primary infertility (n = 11) and secondary infertility (n = 9). Proteomic shotgun analysis revealed a total of 515 peptides common to primary infertility and control group; whereas 523 peptides were common to secondary infertility and control group. Bioinformatic analysis revealed dysregulation of biological processes such as cell secretion and vesicle mediated transport in primary infertility, whereas immune system response, regulation of proteolysis and iron homeostasis were dysregulated in secondary infertility. Western blot validation showed overexpression of ANXA2 and CDC42, and underexpression of SEMG2 proteins in primary infertility; and overexpression of ANXA2 and APP proteins in secondary infertility. This study elucidates the potential role of differentially expressed proteins in the seminal plasma as diagnostic biomarker for primary and secondary infertility. Furthermore, our results suggest maturation failure and immune reaction response as the main cause of infertility in men with primary and secondary infertility, respectively. Additional validation of the proteins involved in the above pathways is warranted.

Showing NAFLD, as a key connector disease between Alzheimer's disease and diabetes via analysis of systems biology

AIM

This study was designed to perform network analysis of Alzheimers҆ disease and diabetes and to find their correlation with each other and other diseases/pathways.

BACKGROUND

Alzheimer's disease (AD) as a neurodegenerative disease and diabetes as a metabolic disease are two major health problems in the recent years. The recent studies have reported their correlation and same spreading pathways of these two diseases together, but details of this relation are not well known yet at molecular level..

METHODS

In thermal proteome profiling (TPP) technique, after treatment of the extracted proteins by heat and drug concentration, the resulting proteins were analyzed by mass spectrometry. Enrichment analysis of these proteins led to development of AD and diabetes. First, corresponding genes for each disease were extracted from DisGeNET database and then, protein-protein interaction network was constructed for each of them using the search tool for retrieval of interacting genes and proteins (STRING). After analyzing these networks, hub-bottleneck nodes of networks were evaluated. Also, common nodes between two networks were extracted and used for further analysis.

RESULTS

High correlation was found between AD and diabetes based on the existence of 40 common genes. Results of analyses revealed 14 genes in AD and 12 genes in diabetes as hub-bottleneck 7 of which were common including caspase 3 (CASP3), insulin-like growth factor 1 (IGF1), catalase (CAT), tumor necrosis factor (TNF), leptin (LEP), vascular endothelial growth factor A (VEGFA), and interleukin 6 ( IL-6).

CONCLUSION

Our results revealed a direct correlation between AD and diabetes and also a correlation between these two diseases and non-alcoholic fatty liver disease (NAFLD), suggesting that a small change in each of these three diseases can lead to development of any other diseases in the patients. Also, the enrichments exhibited the existence of common pathways between AD, diabetes, NAFLD, and male infertility.