**2. Food restriction organ crosstalk in obese/diabetic "mice and men"**

The enhancement in chronic diseases, such as obesity and diabetes (including early neurodegenerative diseases), is speculated to multiply by a factor of 5 by the year 2050, and will be linked to various organ diseases in the global population [1]. In overweight individuals, the increased adiposity is thought to be associated with epigenetic modifications, encompassing chromatin alterations induced by the environment and/or unhealthy diets. Genetic modifications inducing abnormal metabolic turnover in white adipose tissue (WAT) consolidate the defective nuclear mitochondrial interplay, leading to decrements in their energy expenditure. Several hypotheses predicting the induction of obesity encompass the telomere-induction of cellular senescence associate a decline in telomeres with mitochondrial functioning [2, 3]. This phenomenon haunts humans in particular (in comparison to other mammals) and indicates that the human genes exhibit malfunctions in early childhood, like mitochondrial apoptosis associated with an enhanced probability of incurring nonalcoholic fatty hepatic disease

Furthermore, the theoretical aspects of age-related mutations and senescence [6, 7] have proven essential to describe the enhanced insulin resistance and the severity of weight gain and diabetes, which may be linked to xenobiotic ingestion in general [7, 8]. Adaptation model systems allude to theories of aging, postulating genetic alterations, like mutational patterns, which could be induced through excessive ingestion of dietary fats and sugars, which may lead to patterns of age-related mortality in general. Hereditary and/or evolutionary senescence mechanisms encompass known genetic approaches, which may yield information related to age-specific patterns of segregating genetic traits in various populations. Modern genetic analyses, such as DNA or RNA microarray analyses, are now available to aid in pinpointing age-related changes in the genetic "interplay." This has unraveled a solid identification of novel, age-dependent genetic pathways of metabolism, which are associated with disturbances in the steady state of the appearance of new mutations within single genes

Various lifestyles in a global population could decrease, or event prevent, senescence as well as mutations, associated with the telomere shortening theory, thus improving in adaptation of man to his environment. A single gene, like Sirt1 (Sirtuin-1), being involved in longevity, may govern the expression of a plethora of genes being of relevance to the triggering of organ diseases in obesity and diabetes. Sirt1 may be of relevance to both (a) the telomere hypothesis

In different, closed habitats, the phenotypical transformation of a "versatile," i.e., beige adipocyte phenotype, to the traditional white, triglyceride-storing, adipocytes, has been linked to a poor glucose homeostasis. This is now associated to diabetes and hepatic malfunctioning and a defective Sirt1, leading to insulin resistance. Sirt1-mediated malfunctioning with concomitant loss of appetite control and NAFLD development in experimental animals seems to involve other genes, such as the obese (ob), leptin, fat, and agouti genes [8]. Sirt1 dysregulation and insulin resistance are linked to diabetes and encompass genes like the "mature-onset diabetes of the young genes," as well as others [9]. In obesity and diabetes, changes in Sirt1 expression is linked to the transcription factor p53, which enables the transformation the "normal" white

(NAFLD), as well as degenerative, detrimental diseases [4, 5].

4 Adiposity - Omics and Molecular Understanding

involved in diseases like NAFLD, as well as obesity worldwide [8].

adipose into an adipokine secreting tissue type, linked to NAFLD [6].

[2] and (b) the mitochondrial theories of aging [3, 4].

NAFLD may involve up to some 40% of individuals in the world population [7, 8]. Lipoprotein and glucose metabolism is disturbed in obese individuals [10] with increased lipid accumulation and excess lipids stored in adipose tissue. In obese individuals, obesity manifests when the body mass index (BMI) reaches 30.0 kg/m2 [8]. However, nutrigenomic diets have shown good results in the treatment of NAFLD in both lean and obese individuals with BMI-values around 25 kg/m2 ) [11], resulting in a back-transformation of adipose tissue transformation (to a more white (WAT) phenotype), which is consequently linked to improved glucose turnover and less conspicuous NAFLD.

Abnormal lipid turnover in the liver may increase adiposity in obese individuals. Food restriction studies have shown to normalize hepatic lipid metabolism, as well as adipose tissue type transformation associated with an altered immune response in obese individuals [12–16]. The observed gene-environment interactions pinpoints Sirt1 as the major defective gene involved in global obesity and NAFLD epidemics. Sirt1 dysregulation is therefore considered as the more prominent facilitators in the development of obesity, affecting the cell epigenetics (i.e., DNA sequence, methylation, and histone modifications). Like for the hepatic nucleoceptors [7], the adipose tissue counterparts are subjected to histone deacetylation by Sirt1, targeting transcription factors (TFs) like PGC-1α, p53, the pregnane X receptor (PXR), where the latter is known to bind vitamin K2 (i.e., MK-4 or MK-7) in order to modulate gene expression, adapting metabolic activity, insulin resistance, as well as the level of cellular and body inflammation [7, 8, 10]. It is well known that Sirt1 is linked to appetite regulation through obesityrelated and diabetic genes [8], as well as the DNA repair system.

Transcriptional regulation of metabolic processes depends upon isoforms of PPARγ, interacting with nuclear and mitochondrial genes via influence AMPK (5′-AMP activated protein kinase, AMPK) activation regulated by nutrient availability. Furthermore, Sirt1 deacetylation of Forkhead box protein O1 (FOXO1) controls apoptosis with regulation of xenobiotic metabolism and inflammation, as well as vitamin K2 (MK-4/MK-7). The specific effect of vitamin K2 is described in detail in a separate book on vitamin K2, edited by Gordeladze, to be published in early 2017 by InTech Publishing Company. Suffice to mention here is that the involvement of Sirt1 in adipose tissue transformation is mediated by p53 transcriptional dysregulation, which causes repression of PPARγ and FOXO1, both being instrumental in the lipid metabolism of adipocytes [17–20]. Finally, Sirt1/p53 interactions may modulate the adipocytes' levels of adipocytokines, as well as immune responses, being important to maintain an abnormal adipose tissue-liver cross-talk leading to NAFLD in obesity [21–29].

In animal models of both obesity and diabetes, the disturbed adipogenesis being coupled to NAFLD [6, 30] is probably a result of the enhanced release of adipocytokines (i.e., apelin, leptin, adiponectin, and A-II =angiotensin-II), which is seen with the appearance of hepatic fibrogenesis, NAFLD, as well as neurodegenerative diseases [31, 32]. It is well known that food restriction, activating both Sirt1 and PGC-1α in tissues of transgenic (fat/NZO) mice, normalized adipose tissue-liver cross-talk being associated with improved body weights, as well as hepatic lipid metabolism, reflecting the usefulness of this model system to adapt successful treatments of NAFLD in obese patients. As expected, food restriction enhanced hepatic fatty acid oxidation in obese and/or diabetic mice; however, adipose tissue mass (body weights) was not altered in transgenic (i.e., ob, db, and Ay mice) expressing leptin resistance [30], which normally is linked to low activation levels of PGC1α by leptin.

The enhanced hepatic lipid turnover was not associated with improved adipocyte metabolism in obese, diabetic, and/or agouti mice after prolonged food restriction. However, we have shown that treatment by vitamin K2 of both human stem cells and mouse preadipocytes, with gene-manipulated G<sup>s</sup> - and Gi2-alpha type G-proteins altered their phenotype from white (WAT) to "beige" (BAT-like), reducing the expression of white adipose tissue genes, while those of brown adipose tissue counterparts were enhanced [33].

The brain-liver-based metabolic pathway for the Alzheimer's disease-related peptide β-amyloid also involves Sirt1 [9]. In these patients, the adipose tissue loses its capability to process the β-amyloid in a normal fashion, now bringing about adipose tissue transformation [12, 31, 32], which leads to leptin resistance and NAFLD. Interestingly, food restriction fully restores the Sirt1/PGC-1α regulation of adipose tissue and liver lipid/β-amyloid turnover [32], thus involving the immune response with support for a mandatory role of the immune system in the progression of Alzheimer's disease in both the developing and developed world [32, 33]. Furthermore, aberrant posttranscriptional modulation of p53 determines liver affection and adipose tissue type transition in obesity.

Hence, abnormal gene regulation of the adipocytes' metabolism seems to be closely linked to the hepatic lipid turnover, which in turn leads to failure to adapt to the environment, causing senescence and obesity. In obesity, the response to stress signals, which involve both Sirt1 and the tumor suppressor protein p53, which are closely linked to insulin resistance [34] and metabolic processes, but also to cancer and DNA damage. Deficiency of p53 is linked to cancer and is interpreted as if a poor regulation of Sirt1 is involved, predisposing for cancer. An interest in the nutritional modulation of obesity, with or without concomitant diabetes, has increased due to the effects of feeding patterns on Sirt1 and p53, being involved in the reciprocal nuclear-mitochondrial interactions, emerging mutations, as well as apoptosis (cell death) and/or responses encompassing permanent cellular senescence [35–41]. Sirt1 and its posttranscriptional impact on p53 [42, 43] is heavily involved in the differentiation of adipocytes, as well as lipid metabolism in general [44–48], with their implications for abnormal Sirt1 deacetylation of p53, linked to lipid metabolism with its characteristic transformation of adipocytes and ensuing liver disease. Interestingly, both Sirt1 and p53 knockout mice develop NAFLD [49–52], which alludes to a close connections between adipocyte phenotype "switch" involving Sirt 1 and/or p53 impact on mitochondrial functioning [53–56].

The leptin gene is but one of a plethora of genes determining food intake and body weight preservation where the transformation of adipose tissue is closely linked to p53-induced events, overriding the intrinsic control function of leptin or Sirt1 [57] in adipose tissuebased metabolism of both glucose and lipids β-amyloid. Additionally, leptin from adipocytes, with its augmented egress in obese subjects, is linked to inflammatory [58] or immune responses characterized by augmented circulatory levels of inflammatory derived cytokines [12, 16, 20]. The condition known as "hyperleptinemia" is paralleled with enhanced levels p53 and NAFLD, where there is a significant link between peripheral leptin levels, inflammation markers, and Kupffer cell activation [59]. Studies on food restriction in obese/ diabetic animals clearly demonstrated a lack of change in body weight, construed as abnormally enhanced adipogenesis with concomitant and leptin disorders, which be relevant to obesity in humans in general [60]. Both in obese animals, as well as in human, a parallel occurrence of NAFLD with hyperleptinemia are construed as being linked to a lack of hepatoprotective ability of the fat cells to secrete adiponectin [61–63], as well as diminished ability to prevent or dampen hepatic inflammation.

treatments of NAFLD in obese patients. As expected, food restriction enhanced hepatic fatty acid oxidation in obese and/or diabetic mice; however, adipose tissue mass (body weights) was not altered in transgenic (i.e., ob, db, and Ay mice) expressing leptin resistance [30],

The enhanced hepatic lipid turnover was not associated with improved adipocyte metabolism in obese, diabetic, and/or agouti mice after prolonged food restriction. However, we have shown that treatment by vitamin K2 of both human stem cells and mouse preadipocytes,

(WAT) to "beige" (BAT-like), reducing the expression of white adipose tissue genes, while

The brain-liver-based metabolic pathway for the Alzheimer's disease-related peptide β-amyloid also involves Sirt1 [9]. In these patients, the adipose tissue loses its capability to process the β-amyloid in a normal fashion, now bringing about adipose tissue transformation [12, 31, 32], which leads to leptin resistance and NAFLD. Interestingly, food restriction fully restores the Sirt1/PGC-1α regulation of adipose tissue and liver lipid/β-amyloid turnover [32], thus involving the immune response with support for a mandatory role of the immune system in the progression of Alzheimer's disease in both the developing and developed world [32, 33]. Furthermore, aberrant posttranscriptional modulation of p53 determines liver affection and adipose tissue

Hence, abnormal gene regulation of the adipocytes' metabolism seems to be closely linked to the hepatic lipid turnover, which in turn leads to failure to adapt to the environment, causing senescence and obesity. In obesity, the response to stress signals, which involve both Sirt1 and the tumor suppressor protein p53, which are closely linked to insulin resistance [34] and metabolic processes, but also to cancer and DNA damage. Deficiency of p53 is linked to cancer and is interpreted as if a poor regulation of Sirt1 is involved, predisposing for cancer. An interest in the nutritional modulation of obesity, with or without concomitant diabetes, has increased due to the effects of feeding patterns on Sirt1 and p53, being involved in the reciprocal nuclear-mitochondrial interactions, emerging mutations, as well as apoptosis (cell death) and/or responses encompassing permanent cellular senescence [35–41]. Sirt1 and its posttranscriptional impact on p53 [42, 43] is heavily involved in the differentiation of adipocytes, as well as lipid metabolism in general [44–48], with their implications for abnormal Sirt1 deacetylation of p53, linked to lipid metabolism with its characteristic transformation of adipocytes and ensuing liver disease. Interestingly, both Sirt1 and p53 knockout mice develop NAFLD [49–52], which alludes to a close connections between adipocyte phenotype "switch"

The leptin gene is but one of a plethora of genes determining food intake and body weight preservation where the transformation of adipose tissue is closely linked to p53-induced events, overriding the intrinsic control function of leptin or Sirt1 [57] in adipose tissuebased metabolism of both glucose and lipids β-amyloid. Additionally, leptin from adipocytes, with its augmented egress in obese subjects, is linked to inflammatory [58] or immune responses characterized by augmented circulatory levels of inflammatory derived cytokines [12, 16, 20]. The condition known as "hyperleptinemia" is paralleled with enhanced

involving Sirt 1 and/or p53 impact on mitochondrial functioning [53–56].


which normally is linked to low activation levels of PGC1α by leptin.

those of brown adipose tissue counterparts were enhanced [33].

with gene-manipulated G<sup>s</sup>

6 Adiposity - Omics and Molecular Understanding

type transition in obesity.

A plethora of p53-mediated interactions with the innate immune defense system [64–67] points to a function of p53 leading to immune homeostasis and/or inflammatory disease, which both are associated with hepatocyte senescence, lipid turnover, as well as a recruitment/attraction of natural killer (NK) cells [68, 69]. This persistence of "senescence" characterizing the cross-talk between white adipose tissue (WAT) and the liver does not facilitate the elimination/removal of the senescent cells; however, the p53-related promotion of adipose tissue adipogenesis with the development of NAFLD is allowed to take place. p53 is known to activate and suppress target genes like Sirt1, being associated with the innate immune response [70, 71], as well as and SREBP-1 (sterol regulatory element-binding protein-1) [45, 52], which serves as a key transcriptional regulator of the synthesis of lipids (triglycerides) in adipocytes. Sirt1, with its major role in lipid turnover in adipose tissue, is also metabolically "associated" to adiponectin release via the Sirt1/FOXO1 transcriptional complex [72, 73], known to maintain basic hepatic functions. The regulation of the liver and adipose tissue metabolism becomes evident as the p53 is released from the nucleus, implicating p53 itself and microRNA (miRNA) species in the aberrant regulation of fatty acid turnover in the mitochondria.

The impact of p53 on gene regulators encompasses miRNAs [74], where their function in the induction of obesity [75] hints to altered expression of multiple miRNA species in metabolic tissues [76, 77]. This also lends an important role to be played by an "abnormal" immune system [78–80]. Hitherto, the following findings pertaining to miRNAs involved are: MiR-103 and -143 have been shown to be important in the "kick-off" and maintenance of adipogenesis [81], where miRNAs, e.g., miR-27 and miR-519d [82] serve as regulators of PPARγ [83], which accounts for the differentiation, as well as the overall number of fat cells. PPARγ is heavily expressed in adipocytes, i.e., especially in WAT, and plays a mandatory role in the Sirt1-mediated transcriptional stimulation of adiponectin and leptin. The PPARα-mediated activation of Sirt1 yields an increase in lipid turnover through a general enhancement of β-oxidation. Furthermore, p53-associated miRNA dysregulation seems to be of importance, characterizing the aberrant metabolism of adipocyte-derived lipids, linked to the inactivation of nuclearmitochondrial crosstalk. Angiotensin II (AII, from the adipocytokine Apelin) [31] effectuates PPARγ-Sirt1 expression in the adipose tissue [32, 84, 85], playing a pivotal role in the production and release of adiponectin [31, 32]. Furthermore, miRNA species such as miR-34a [86], miR-122, and miR-132 [87, 88], which directly obliterate the Sirt1-mediated biochemical processes, bring about adiponectin release, to be construed as a poor activation of hepatic genes governing both glucose and lipid turnover [62]. Furthermore, the CCAAT/enhancer-binding protein alpha (C/EBPα) stimulates Sirt1 expression, which is coupled to adipogenesis through modulation of PPARγ [63], involving miR-34a.

Underneath, a high-stringency emulation (using the Mir@nt@n algorithm), and based on the most recent scientific articles [86–90], the links between microRNA species and genes shown to be implicated in the development of the "fat liver syndrome" are shown in **Figures 1** and **2**, respectively.

Suffice to say, SIRT1, seems to be modulated by hsa-mir-30c, while, ABCA1-levels are determined by the integrated input of signals emanating from micro-RNA species like hsa-MiRs 144, 148a, 145, and 33b. Future studies of these MiRs will show whether they might be targets or markers for gene manipulations normalizing liver metabolism, and thus combatting adiposity, in patients with aberrant lipid metabolism and/or adiposity.

**Figure 1.** High stringency emulation of gene-microRNA interactions, showing the impact of microRNA species on some "master" genes involved in the development of supersized adipocytes with the WAT (white adipocyte tissue-phenotype) alongside a fatty liver in patients developing nonalcoholic fatty liver disease (NAFLD).

**Figure 2.** High stringency emulation of gene-microRNA interactions, showing the impact of microRNA species on some "master" genes involved in the development of a fatty liver in patients developing nonalcoholic fatty liver disease (NAFLD).
