Occurrence of Cleft-Palate and Alteration of <i>Tgf-</i>β_<i>3</i> Expression and the Mechanisms Leading to Palatal Fusion in Mice following Dietary Folic-Acid Deficiency

Abstract

Folic acid (FA) is essential for numerous bodily functions. Its decrease during pregnancy has been associated with an increased risk of congenital malformations in the progeny. The relationship between FA deficiency and the appearance of cleft palate (CP) is controversial, and little information exists on a possible effect of FA on palate development. We investigated the effect of a 2–8 weeks’ induced FA deficiency in female mice on the development of CP in their progeny as well as the mechanisms leading to palatal fusion, i.e. cell proliferation, cell death, and palatal-shelf adhesion and fusion. We showed that an 8 weeks’ maternal FA deficiency caused complete CP in the fetuses although a 2 weeks’ maternal FA deficiency was enough to alter all the mechanisms analyzed. Since transforming growth factor-β₃ (TGF-β₃) is crucial for palatal fusion and since most of the mechanisms impaired by FA deficiency were also observed in the palates of Tgf-β₃null mutant mice, we investigated the presence of TGF-β₃ mRNA, its protein and phospho-SMAD2 in FA-deficient (FAD) mouse palates. Our results evidenced a large reduction in Tgf-β₃ expression in palates of embryos of dams fed an FAD diet for 8 weeks; Tgf-β₃ expression was less reduced in palates of embryos of dams fed an FAD diet for 2 weeks. Addition of TGF-β₃ to palatal-shelf cultures of embryos of dams fed an FAD diet for 2 weeks normalized all the altered mechanisms. Thus, an insufficient folate status may be a risk factor for the development of CP in mice, and exogenous TGF-β₃ compensates this deficit in vitro.

Maternal folic acid–deficient diet causes congenital malformations in the mouse eye

“…This was also observed in a previous study by our group on the effects of a FAD on palate development (Maldonado et al, 2011). This was also observed in a previous study by our group on the effects of a FAD on palate development (Maldonado et al, 2011).…”

“…We have found many eyes from FAD animals with a thicker retina, which was clearly detached from the underlying pigment epithelium, small vitreous body with hypercellularity, and fusion of the lens epithelium to the corneal stroma, which are defects that have been described in Tgf-b2 (Sanford et al, 1997;D€ unker et al, 2003) and Tgf-bRII (Ittner et al, 2005) null mice. A reduced expression of TGF-bs has been demonstrated in other systems under a FAD (Santoso and Rohman, 2006;Maldonado et al, 2011), whereas FA supplements have proven to induce the expression of TGF-b2 (Guay et al, 2004), TGF-bRII (Yao et al, 2011), and other TGF-bs (Maldonado et al, 2011). A reduced expression of TGF-bs has been demonstrated in other systems under a FAD (Santoso and Rohman, 2006;Maldonado et al, 2011), whereas FA supplements have proven to induce the expression of TGF-b2 (Guay et al, 2004), TGF-bRII (Yao et al, 2011), and other TGF-bs (Maldonado et al, 2011).…”

“…The diets were adjusted to mice requirements, and were based on a pure amino acid diet (Harlan Laboratories, Inc., Indianapolis, IN) (Walzem and Clifford, 1988), only modified in its FA content, as follows: FA-deficient diet (FAD: 0 mg FA/kg diet, Harlan Laboratories, TD 02490; n 5 52) and control diet (2 mg FA/kg diet, n 5 9). These diets have been already used successfully in previous studies by our research group (Partearroyo et al, 2010(Partearroyo et al, , 2013Maldonado et al, 2011). Mice were fed their respective diets ad libitum for 2, 4, 6, 8, 10, 12, 14, or 16 weeks.…”

Folic acid deficiency induces premature hearing loss through mechanisms involving cochlear oxidative stress and impairment of homocysteine metabolism

“…Altogether, human epidemiology and mouse genetic data reinforce the hypothesis that folic acid deficiency and Hcy metabolism play an important role in hearing disorders, although the mechanisms by which cochlear function is affected remain poorly understood. In this study, we used a rodent model for folic acid deficiency (26, 27) to show that reduced intake of this essential vitamin causes cochlear impairment of Hcy metabolism, oxidative stress, severe cellular damage, and apoptotic cell death, leading to accelerated hearing loss.…”

Folic Acid in Obstetric Practice: A Review

“…16,17 However, a recent Cochrane review concluded that folic acid, alone or in combination with vitamins and minerals decreases NTD risk but did not have a clear effect on the occurrence of other birth defects. 1…”