One-carbon metabolism, spermatogenesis, and male infertility

Balanced diet is the natural source of micronutrients, such as folate and vitamins, vital for proper functioning of the body. One-carbon metabolic pathway along with folate and other vitamins plays an important role in DNA synthesis and in the establishment of epigenetic modifications like DNA/histone methylation. Spermatogenesis involves distinct cellular, genetic, and chromatin changes during the course of production of male gamete sperm. Folate and normal activity of 1-carbon metabolic pathway enzymes are central to nucleotide synthesis, methylation, and maintenance of genomic integrity as well as protection from DNA damage. As a result, polymorphisms in 1-carbon metabolic pathway genes affecting several physiological processes also have an impact on spermatogenesis and may affect directly or indirectly quality of sperm. Alterations in these processes may be a consequence of additive effect resulting from altered expression of 1-carbon metabolic pathway genes and/or inadequate folate/micronutrients supplementation. The present review provides an overview of different cellular and molecular events regulated by 1-carbon metabolic pathway enzymes and their impact on male reproductive health. It also summarizes the different studies where polymorphisms in the enzymes of 1-carbon metabolic pathway or folate deficiency are associated with male infertility and future prospects.