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Gene & Protein in Disease Placenta, FASD, and soy

Table 2. Ethanol and dietary soy effects on placental However, the reduction in Igf1r mRNA level observed with
expression of ASPH, Notch1, and HES1 ethanol exposure does not align with immunoreactivity
results, which indicated no significant modulation
Variable F‑ratio P‑value by ethanol. There are no prior data on the impact of
mRNA chronic ethanol exposure on IGF-2R immunoreactivity.
Asph 2.431* 0.0726* Dietary soy differentially impacted insulin/IGF receptor
Notch1 5.692 0.0013 expression, suppressing insulin receptor mRNA levels in
Hes1 8.342 <0.0001 control groups while elevating Igf1r and Igf2r levels in
Protein ethanol-exposed groups. The reduced insulin receptor
ASPH 21.63 <0.0001 mRNA levels in both control and ethanol soy groups,
Notes: The mRNA transcripts were measured in CC, CS, EC, and compared to casein controls, are consistent with multiplex
ELISA findings. However, the comparable levels of Insr
ES placental tissue homogenates through qRT-polymerase chain
reaction analysis. Results were normalized to 18S rRNA measured and Igf1r mRNA in the CS and ES groups contrast sharply
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in the same samples. ASPH protein was measured using ELISA, with the significantly lower protein levels in the ES group.
with results normalized to protein content. Inter-group comparisons Altogether, these findings suggest that the expression
(n=8/group) were conducted using one-way ANOVA. The F-ratios of placental insulin and IGF receptors is regulated at the
and P-values are tabulated. *Marks P-values with a statistical trend mRNA level. However, in the setting of chronic ethanol
(0.05≤ P ≤ 0.10). See Figure 4 for graphed data and post hoc Tukey
multiple comparisons test results. exposure, post-transcriptional mechanisms, such as
translation regulation or protein stability, negatively
ethanol in other FASD studies, we examined ASPH’s impact receptor protein expression.
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mRNA and protein expression to corroborate the ethanol- The concurrent reductions in insulin polypeptide and
induced alterations in insulin/IGF signaling and further receptor levels in the EC group indicate that ethanol impairs
evaluate the insulin-sensitizing effects of dietary soy in our placental insulin signaling, consistent with previous
model. reports in other cell types and tissues. 26,31 In contrast,

Previous studies of rat placental tissue demonstrated the IGF-1 pathway appears to be moderately resistant to
the expression of insulin, Igf1, and Igf2 trophic factors. The ethanol’s inhibitory effects; despite reductions in the Igf1r
higher level of Igf2 compared with Igf1 mRNA is consistent mRNA level, Igf1 mRNA and IGF-1R protein expressions
with the concept that IGF-2 plays more important were preserved. Similarly, the absence of effects on Igf2
and Igf2r mRNA expression reflects the preservation
metabolic and mitogenic signaling roles during early of related pathways vis-à-vis chronic ethanol exposure.
development, whereas IGF-1 regulates similar functions A puzzling observation was that despite dietary soy-
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later in development and life. The current work suggests associated reductions in INSR and IGF-1R proteins, and
that ethanol-associated impairments in placental insulin a lack of Insr mRNA stimulation, placentation normalized,
signaling could be mediated by reduced insulin mRNA and the phenotypic effects of FASD were abolished.
1
expression, akin to trophic factor withdrawal. The selective Therefore, while it is reasonable to attribute the ethanol
absence of an ethanol inhibitory effect on IGF-2 suggests effects to impairments in insulin signaling, the rescue
that IGF networks may be less vulnerable than insulin effects of dietary soy were not mediated by the restoration
pathways to the adverse effects of ethanol. The significant of insulin pathway mediators. Similarly, the findings that
soy-mediated increases in both insulin and IGF-2 in Igf1 mRNA level was unaffected, Igf1r was normalized, but
ethanol-exposed placentas suggest that the insulin- IGF-1R protein was inhibited do not strongly support the
sensitizing, anti-inflammatory, and antioxidant effects of notion that IGF-1 signaling was restored by dietary soy.
soy enhance the availability of trophic factors and ligand Instead, the dominant positive responses were observed
regulation of pathways utilized for growth, metabolism, with respect to IGF-2, as both ligand and receptor mRNA
and placentation in the setting of chronic ethanol exposure. levels were significantly increased by dietary soy in the
In addition, there is supportive evidence that plant-based ES group. IGF-2 can compensate for impaired insulin
phytonutrients in soy positively impact metabolism and pathways by supporting mitogenesis and metabolic
cellular functions by influencing gene expression. 30 functions during development. 32,33 This study provides
The expression of insulin, IGF-1, and IGF-2 receptors the first demonstration that the positive rescue effects of
in placental tissue has been previously reported. The dietary soy during development are mediated, at least in
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ethanol-associated inhibition of Insr mRNA is consistent part, through IGF-2-activated networks.
with previous findings from ELISA analyses, suggesting The present study included measurements of Irs1, Irs2,
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that its expression is regulated at the transcriptional level. and Irs4, whereas the multiplex ELISAs evaluated in the

Volume 3 Issue 2 (2024) 8 doi: 10.36922/gpd.3113