Odorant Receptor OR2C1 Is an Essential Modulator of Boar Sperm Capacitation by Binding with Heparin

High-resolution LC-MS/MS combined with TMT quantitative proteomic analysis reveals regulatory mechanism of sperm capacitation by heparin, Ca2+ and BSA

Heparin, BSA, and CaCl2 have been demonstrated to induce sperm capacitation in vitro; however, the specific molecular mechanisms by which different chemokines regulate sperm capacitation remain incompletely elucidated. In previous studies, our laboratory utilized various chemokines to induce capacitation in porcine sperm in vitro and classified these chemokines into three categories based on changes in olfactory receptors. Therefore, this study aims to systematically investigate the molecular pathways and regulatory mechanisms underlying heparin, CaCl2, and BSA induced porcine sperm capacitation. Porcine sperm were treated with heparin, CaCl2, or BSA for 1-4 h, and capacitation was assessed by measuring mitochondrial membrane potential (MMP), intracellular Ca2+ concentration, and capacitation rate. Differential protein expression among the three groups was analyzed using TMT-based quantitative proteomics. The results demonstrated that heparin, CaCl2, and BSA significantly increased intracellular Ca2+ concentration in a time-dependent manner, reduced MMP, and successfully induced sperm capacitation. Proteomic analysis revealed that differentially expressed proteins between the heparin and BSA groups were primarily enriched in lipid metabolism-related signaling pathways, such as PPAR and AMPK, while differentially expressed proteins in the CaCl2 group were significantly enriched in B vitamin metabolic pathways, including riboflavin and nicotinic acid metabolism. Furthermore, olfactory receptors OR1J4 and OR4C13 were found to specifically bind chemokines and participate in the regulation of sperm capacitation. In conclusion, this study elucidates the distinct molecular mechanisms by which heparin, CaCl2, and BSA induce porcine sperm capacitation and provides the first evidence of the critical role of olfactory receptors OR1J4 and OR4C13 in regulating sperm capacitation, offering new theoretical insights into the molecular mechanisms underlying sperm capacitation.

Deciphering olfactory receptor binding mechanisms: a structural and dynamic perspective on olfactory receptors

Olfactory receptors, classified as G-protein coupled receptors (GPCRs), have been a subject of scientific inquiry since the early 1950s. Historically, investigations into the sensory mechanisms of olfactory receptors were often confined to behavioral characteristics in model organisms or the expression of related proteins and genes. However, with the development of cryo-electron microscopy techniques, it has gradually become possible to decipher the specific structures of olfactory receptors in insects and humans. This has provided new insights into the binding mechanisms between odor molecules and olfactory receptors. Furthermore, due to the rapid advancements in related fields such as computer simulations, the prediction and exploration of odor molecule binding to olfactory receptors have been progressively achieved through molecular dynamics simulations. Through this comprehensive review, we aim to provide a thorough analysis of research related to the binding mechanisms between odor molecules and olfactory receptors from the perspectives of structural biology and molecular dynamics simulations. Finally, we will provide an outlook on the future of research in the field of olfactory receptor sensory mechanisms.

Putting Nose into Reproduction: Influence of Nasal and Reproductive Odourant Signaling on Male Reproduction

Odourant receptors (ORs) are not restricted only to the nose, but also occur in many other organs and tissues, including the reproductive system. In fact, ORs are the most heavily expressed in testis than in any other extra-nasal tissue. Accumulating evidence suggests that olfactory and reproductive systems are both structurally and functionally linked and that these interconnections can influence various aspects of reproduction. In this article, we first review our current understanding of these interconnections and then collate accumulated evidence on the presence of ORs in the male reproductive system and sperm cells. We then investigate the potential role of female reproductive tract odourants in sperm chemotaxis and selection. Finally, since the existing evidence especially for sperm odor sensing capability and its physiological function are controversial, we also review potential reasons for the controversy and propose some ways to resolve the debate. Collectively, we conclude that reproductive odourant signaling may play an important, although currently largely unclear role in many key processes directly related to male fertility. However, since we lack holistic understanding of the functional significance of ORs and odor sensing pathways of the male reproductive system, more empirical research is warranted.

The Olfactory Trail of Neurodegenerative Diseases

Alterations in olfactory functions are proposed as possible early biomarkers of neurodegenerative diseases. Parkinson's and Alzheimer's diseases manifest olfactory dysfunction as a symptom, which is worth mentioning. The alterations do not occur in all patients, but they can serve to rule out neurodegenerative pathologies that are not associated with small deficits. Several prevalent neurodegenerative conditions, including impaired smell, arise in the early stages of Parkinson's and Alzheimer's diseases, presenting an attractive prospect as a snitch for early diagnosis. This review covers the current knowledge on the link between olfactory deficits and Parkinson's and Alzheimer's diseases. The review also covers the emergence of olfactory receptors as actors in the pathophysiology of these diseases. Olfactory receptors are not exclusively expressed in olfactory sensory neurons. Olfactory receptors are widespread in the human body; they are expressed, among others, in the testicles, lungs, intestines, kidneys, skin, heart, and blood cells. Although information on these ectopically expressed olfactory receptors is limited, they appear to be involved in cell recognition, migration, proliferation, wound healing, apoptosis, and exocytosis. Regarding expression in non-chemosensory regions of the central nervous system (CNS), future research should address the role, in both the glia and neurons, of olfactory receptors. Here, we review the limited but relevant information on the altered expression of olfactory receptor genes in Parkinson's and Alzheimer's diseases. By unraveling how olfactory receptor activation is involved in neurodegeneration and identifying links between olfactory structures and neuronal death, valuable information could be gained for early diagnosis and intervention strategies in neurodegenerative diseases.

Phenylbutyrate and Dichloroacetate Enhance the Liquid-Stored Boar Sperm Quality via PDK1 and PDK3

Artificial insemination (AI) with liquid-stored semen is the most prevalent and efficient assisted reproduction technique in the modern pork industry. Pyruvate dehydrogenase complex component X (PDHX) was demonstrated to be associated with sperm metabolism and affected the boar sperm viability, motility, and fertility. Pyruvate Dehydrogenase Kinases (PDKs) are the key metabolic enzymes that regulate pyruvate dehydrogenase complex (PDHC) activity and also the conversion from glycolysis to oxidative phosphorylation. In the present study, two PDK inhibitors, Dichloroacetate (DCA) and Phenylbutyrate (4-PBA), were added to an extender and investigated to determine their regulatory roles in liquid-stored boar sperm at 17 °C. The results indicated that PDK1 and PDK3 were predominantly located at the head and flagella of the boar sperm. The addition of 2 mM DCA and 0.5 mM 4-PBA significantly enhanced the sperm motility, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), and ATP content. In addition, DCA and 4-PBA exerted their effects by inhibiting PDK1 and PDK3, respectively. In conclusion, DCA and 4-PBA were found to regulate the boar sperm metabolic activities via PDK1 and PDK3. These both can improve the quality parameters of liquid-stored boar sperm, which will help to improve and optimize liquid-stored boar semen after their addition in the extender.

Recent Developments in Ion Channel and Ion-Related Signaling

Ion channels play an important role in the cellular functions of various organ systems, such as the nervous, cardiovascular, immune, and endocrine systems, and are potential therapeutic targets for treatments of their dysfunctions, via 'channelopathy' [...].