RNA modifications

Non-coding RNAs are small nucleolar RNAs, ribosomal RNAs, long regulatory non-coding RNAs(IncRNAs), microRNAs, small interfering RNAs(siRNAs) and piwi-interacting(piRNAs) RNAs and other regulatory RNAs involved in functional tissue specificity that are nucleic transcriptional and intergenerational signaling for inheritable phenotype. The microRNAs are transcribed and folded into a hairpin structure and cleaved via a DROSHA complex the resultant hairpin precursor pre-miRNA is transported from the nucleus to the cytoplasm via exportin-5 and unites with a Dicer complex to become a mature microRNA. A negative regulatory RNA-inducing silencing complex (RISC) results with degradation of the mRNA sequence, thus regulating protein synthesis; also important in post transcriptional regulation of many diseases. MicroRNAs can be utilized as epigenetic biomarkers for various cancer types (Earl R, Thomas PR (1994), Duygu B et al - 2013, Wong NW et al-2017, Chatterjee et al - 2013).

Environmental factors can remodel epigenomic somatic tissues and sperm of which is dynamic and vulnerable to internal and external environmental changes. During spermatogenesis DNA modifications are erased, reconstructed and the histones are replaced via arginine-rich protamine in the sperm. The fundamental question of how parental diet and lifestyle alter epigenetic phenotype and perhaps behavior, other mechanistic signals transfer environmental and epigenetic fluctuations.

Table 10 shows the types, and Characteristics, and Major Functions of RNA.

RNA

Abundance

Size (nt)

Stability

Function

mRNA

2%-5%    of

total

1000

1500

Unstable to very stable

Carries the genetic information

NON-CODING RNAS (NCRNAS)

Short ncRNAs

miRNAs

<1% of total

19-031

Stable to

very

stable

Regulation of proliferation, differentiation, and apoptosis

siRNAs

<1% of total

Post-transcriptional gene silencing

RNAs

<1% of total

mRNA splicing

tRNAs

15% of total

Decode a mRNA sequence into a protein

circRNAs

5%-10% of total

>50

Protein production and transporting miRNAs inside the cell/Regulation of mRNA splicing - Chen (2016)

Long ncRNAs

rRNA

80.00%

>200

Very

stable

Essential    for    protein

synthesis

Mitochondrial DNA methylation

Mitochondria is the control center for lipid (fat) metabolism, the Mitochondria DNA (mtDNA) is a 16,569 base-pair though mtDNA is absent of histones and comprised of a H (heavy) and L (light) DNA strand that encodes for 37 genes: 13 oxidative phosphorylation related protein-encoding genes, 22 transfer RNAs and 2 ribosomal RNAs mtDNA is said to modify 5-mC and 5-hmC though these epigenetic modifications are still debatable, these are regulative of skeletal and heart muscles, more non-CpG (than CpG) is methylated in the Dloop region of the circular mrDNA leading to activation of ND1 and repression of ND6, mtDNA has dependence of: mitochondrial transcription factor 2, mitochondrial transcription factor A and mitochondrial RNA polymerase. The rate of lipid or fat metabolism is regulated via mtDNA that is encoded on the X chromosome inherited on the maternal side, if the maternal is showing obesity, the slow metabolic biomarkers are not always expressed if the recipient is in acknowledgement of functional foods and participates in regular physical exercise. (Also see future of epigenetics and Bio-functional-foods)