Vitamin B12 Metabolism during Pregnancy and in Embryonic Mouse Models

Abstract

Vitamin B12 (cobalamin, Cbl) is required for cellular metabolism. It is an essential coenzyme in mammals for two reactions: the conversion of homocysteine to methionine by the enzyme methionine synthase and the conversion of methylmalonyl-CoA to succinyl-CoA by the enzyme methylmalonyl-CoA mutase. Symptoms of Cbl deficiency are hematological, neurological and cognitive, including megaloblastic anaemia, tingling and numbness of the extremities, gait abnormalities, visual disturbances, memory loss and dementia. During pregnancy Cbl is essential, presumably because of its role in DNA synthesis and methionine synthesis; however, there are conflicting studies regarding an association between early pregnancy loss and Cbl deficiency. We here review the literature about the requirement for Cbl during pregnancy, and summarized what is known of the expression pattern and function of genes required for Cbl metabolism in embryonic mouse models.

C. elegans MRP-5 Exports Vitamin B12 from Mother to Offspring to Support Embryonic Development

“…For instance, the intake of folate supplements by pregnant women reduces the occurrence of neural tube defects in newborns ( Czeizel and Dudás, 1992 ; Viswanathan et al, 2017 ). Folate functions together with vitamin B12, or cobalamin, in the one carbon cycle to recycle methionine from homocysteine ( Moreno-Garcia et al, 2013 ) ( Figure 1A ). One of the main functions of the one-carbon cycle is to produce S-adenosylmethionine (SAM), a major methyl donor required to synthesize phosphatidylcholine, an important component of cellular membranes, and to modify histones and DNA to ensure proper genomic functions ( Rosenblatt and Whitehead, 1999 ).…”

Experimental immunology The influence of vitamin B 12 supplementation on the level of white blood cells and lymphocytes phenotype in rats fed a low-protein diet

“…It also plays a very important role in the formation of red blood cells. Symptoms of B 12 deficiency include hematological, neurological and cognitive disorders, including megaloblastic anemia, visual disturbances and memory loss [ 11 , 12 ]. Therefore, we decided to investigate the effect of vitamin B 12 on immunological parameters in rats fed a standard and low-protein diet.…”

Antivitamins B12—A Structure‐ and Reactivity‐Based Concept

“…Hence, they induce 'functional' B 12 -deficiency,a nd may still simulatep ossible regulatory roles of B 12 -cofactors. [62] Furthermore, B 12 -deficiency has still largely unresolved roles in cell proliferation and differentiation. [36b, 59] In fact, neurological effects of Cbls (and of their deficiency) in mammals still appear to be particularly puzzling, [60] and B 12 was called a 'moonlighting' vitamin recently.…”