scholarly journals Mitochondria in Sex Hormone-Induced Disorder of Energy Metabolism in Males and Females

2021 ◽  
Vol 12 ◽  
Author(s):  
Lijun Yin ◽  
Man Luo ◽  
Ru Wang ◽  
Jianping Ye ◽  
Xiaohui Wang
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Mitochondrial Dysfunction ◽  
Polycystic Ovary ◽  
Β Cells ◽  
Androgen Excess ◽  
Brown Adipocytes ◽  
Peripheral Insulin Resistance ◽  
Male Subjects

Androgens have a complex role in the regulation of insulin sensitivity in the pathogenesis of type 2 diabetes. In male subjects, a reduction in androgens increases the risk for insulin resistance, which is improved by androgen injections. However, in female subjects with polycystic ovary syndrome (PCOS), androgen excess becomes a risk factor for insulin resistance. The exact mechanism underlying the complex activities of androgens remains unknown. In this review, a hormone synergy-based view is proposed for understanding this complexity. Mitochondrial overactivation by substrate influx is a mechanism of insulin resistance in obesity. This concept may apply to the androgen-induced insulin resistance in PCOS. Androgens and estrogens both exhibit activities in the induction of mitochondrial oxidative phosphorylation. The two hormones may synergize in mitochondria to induce overproduction of ATP. ATP surplus in the pancreatic β-cells and α-cells causes excess secretion of insulin and glucagon, respectively, leading to peripheral insulin resistance in the early phase of type 2 diabetes. In the skeletal muscle and liver, the ATP surplus contributes to insulin resistance through suppression of AMPK and activation of mTOR. Consistent ATP surplus leads to mitochondrial dysfunction as a consequence of mitophagy inhibition, which provides a potential mechanism for mitochondrial dysfunction in β-cells and brown adipocytes in PCOS. The hormone synergy-based view provides a basis for the overactivation and dysfunction of mitochondria in PCOS-associated type 2 diabetes. The molecular mechanism for the synergy is discussed in this review with a focus on transcriptional regulation. This view suggests a unifying mechanism for the distinct metabolic roles of androgens in the control of insulin action in men with hypogonadism and women with PCOS.

scholarly journals Relationship Between Oxidative Stress, ER Stress, and Inflammation in Type 2 Diabetes: The Battle Continues

2019 ◽  
Vol 8 (9) ◽  
pp. 1385 ◽  
Author(s):  
Burgos-Morón ◽  
Abad-Jiménez ◽  
Marañón ◽  
Iannantuoni ◽  
Escribano-López ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Er Stress ◽  
Mitochondrial Dysfunction ◽  
Current Knowledge ◽  
Β Cells ◽  
The Relationship ◽  
And Oxidative Stress

Type 2 diabetes (T2D) is a metabolic disorder characterized by hyperglycemia and insulin resistance in which oxidative stress is thought to be a primary cause. Considering that mitochondria are the main source of ROS, we have set out to provide a general overview on how oxidative stress is generated and related to T2D. Enhanced generation of reactive oxygen species (ROS) and oxidative stress occurs in mitochondria as a consequence of an overload of glucose and oxidative phosphorylation. Endoplasmic reticulum (ER) stress plays an important role in oxidative stress, as it is also a source of ROS. The tight interconnection between both organelles through mitochondrial-associated membranes (MAMs) means that the ROS generated in mitochondria promote ER stress. Therefore, a state of stress and mitochondrial dysfunction are consequences of this vicious cycle. The implication of mitochondria in insulin release and the exposure of pancreatic β-cells to hyperglycemia make them especially susceptible to oxidative stress and mitochondrial dysfunction. In fact, crosstalk between both mechanisms is related with alterations in glucose homeostasis and can lead to the diabetes-associated insulin-resistance status. In the present review, we discuss the current knowledge of the relationship between oxidative stress, mitochondria, ER stress, inflammation, and lipotoxicity in T2D.

scholarly journals Insulin: The Friend and the Foe in the Development of Type 2 Diabetes Mellitus

2020 ◽  
Vol 21 (5) ◽  
pp. 1770
Author(s):  
Nadia Rachdaoui
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Insulin Secretion ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell ◽  
Peripheral Insulin Resistance

Insulin, a hormone produced by pancreatic β-cells, has a primary function of maintaining glucose homeostasis. Deficiencies in β-cell insulin secretion result in the development of type 1 and type 2 diabetes, metabolic disorders characterized by high levels of blood glucose. Type 2 diabetes mellitus (T2DM) is characterized by the presence of peripheral insulin resistance in tissues such as skeletal muscle, adipose tissue and liver and develops when β-cells fail to compensate for the peripheral insulin resistance. Insulin resistance triggers a rise in insulin demand and leads to β-cell compensation by increasing both β-cell mass and insulin secretion and leads to the development of hyperinsulinemia. In a vicious cycle, hyperinsulinemia exacerbates the metabolic dysregulations that lead to β-cell failure and the development of T2DM. Insulin and IGF-1 signaling pathways play critical roles in maintaining the differentiated phenotype of β-cells. The autocrine actions of secreted insulin on β-cells is still controversial; work by us and others has shown positive and negative actions by insulin on β-cells. We discuss findings that support the concept of an autocrine action of secreted insulin on β-cells. The hypothesis of whether, during the development of T2DM, secreted insulin initially acts as a friend and contributes to β-cell compensation and then, at a later stage, becomes a foe and contributes to β-cell decompensation will be discussed.

scholarly journals Androgen excess in pancreatic β cells and neurons predisposes female mice to type 2 diabetes

JCI Insight ◽  
2018 ◽  
Vol 3 (12) ◽  
Author(s):  
Guadalupe Navarro ◽  
Camille Allard ◽  
Jamie J. Morford ◽  
Weiwei Xu ◽  
Suhuan Liu ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Androgen Excess ◽  
Female Mice

scholarly journals Selenoprotein P as a significant regulator of pancreatic β cell function

2019 ◽  
Author(s):  
Yoshiro Saito
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Molecular Mechanisms ◽  
Cell Function ◽  
Insulin Signalling ◽  
Selenoprotein P ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Β Cell Function

Abstract Selenoprotein P (SeP; encoded by SELENOP) is selenium (Se)-rich plasma protein that is mainly produced in the liver. SeP functions as a Se-transport protein to deliver Se from the liver to other tissues, such as the brain and testis. The protein plays a pivotal role in Se metabolism and antioxidative defense, and it has been identified as a ‘hepatokine’ that causes insulin resistance in type 2 diabetes. SeP levels are increased in type 2 diabetes patients, and excess SeP impairs insulin signalling, promoting insulin resistance. Furthermore, increased levels of SeP disturb the functioning of pancreatic β cells and inhibit insulin secretion. This review focuses on the biological function of SeP and the molecular mechanisms associated with the adverse effects of excess SeP on pancreatic β cells’ function, particularly with respect to redox reactions. Interactions between the liver and pancreas are also discussed.

scholarly journals Dual Mechanism for Type-2 Diabetes Resolution after Roux-en-Y Gastric Bypass

2009 ◽  
Vol 75 (6) ◽  
pp. 498-503 ◽  
Author(s):  
Edward Lin ◽  
S. Scott Davis ◽  
Jahnavi Srinivasan ◽  
John F. Sweeney ◽  
Thomas R. Ziegler ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Weight Loss ◽  
Gastric Bypass ◽  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Cell Function ◽  
Β Cell ◽  
Peripheral Insulin Resistance

Resolution of Type-2 diabetes mellitus (DM) after weight loss surgery is well documented, but the mechanism is elusive. We evaluated the glucose-insulin metabolism of patients undergoing a Roux-en-Y gastric bypass (RYGB) using the intravenous glucose tolerance test (IVGTT) and compared it with patients who underwent laparoscopic adjustable gastric band (AB) placement. Thirty-one female patients (age range, 20 to 50 years; body mass index, 47.2 kg/m2) underwent RYGB. Nine female patients underwent AB placement and served as control subjects. All patients underwent IVGTT at baseline and 1 month and 6 months after surgery. Thirteen patients undergoing RYGB and one patient undergoing AB exhibited impaired glucose tolerance or DM defined by the American Diabetes Association. By 6 months post surgery, diabetes was resolved in all but one patient undergoing RYGB but not in the patient undergoing AB. Patients with diabetes undergoing RYGB demonstrated increased insulin secretion and β-cell responsiveness 1 month after surgery and continued this trend up to 6 months, whereas none of the patients undergoing AB had changes in β-cell function. Both patients undergoing RYGB and those undergoing AB demonstrated significant weight loss (34.6 and 35.0 kg/m2, respectively) and improved insulin sensitivity at 6 months. RYGB ameliorates DM resolution in two phases: 1) early augmentation of beta cell function at 1 month; and 2) attenuation of peripheral insulin resistance at 6 months. Patients undergoing AB only exhibited reduction in peripheral insulin resistance at 6 months but no changes in insulin secretion.

scholarly journals Mitochondrial Dysfunction andβ-Cell Failure in Type 2 Diabetes Mellitus

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Zhongmin Alex Ma ◽  
Zhengshan Zhao ◽  
John Turk
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Mitochondrial Dysfunction ◽  
Membrane Integrity ◽  
Metabolic Stress ◽  
Atp Synthesis ◽  
Peripheral Insulin Resistance ◽  
Glucose Stimulated Insulin Secretion

Type 2 diabetes mellitus (T2DM) is the most common human endocrine disease and is characterized by peripheral insulin resistance and pancreatic isletβ-cell failure. Accumulating evidence indicates that mitochondrial dysfunction is a central contributor toβ-cell failure in the evolution of T2DM. As reviewed elsewhere, reactive oxygen species (ROS) produced byβ-cell mitochondria as a result of metabolic stress activate several stress-response pathways. This paper focuses on mechanisms whereby ROS affect mitochondrial structure and function and lead toβ-cell failure. ROS activate UCP2, which results in proton leak across the mitochondrial inner membrane, and this leads to reducedβ-cell ATP synthesis and content, which is a critical parameter in regulating glucose-stimulated insulin secretion. In addition, ROS oxidize polyunsaturated fatty acids in mitochondrial cardiolipin and other phospholipids, and this impairs membrane integrity and leads to cytochromecrelease into cytosol and apoptosis. Group VIA phospholipase A2(iPLA2β) appears to be a component of a mechanism for repairing mitochondrial phospholipids that contain oxidized fatty acid substituents, and genetic or acquired iPLA2β-deficiency increasesβ-cell mitochondrial susceptibility to injury from ROS and predisposes to developing T2DM. Interventions that attenuate ROS effects onβ-cell mitochondrial phospholipids might prevent or retard development of T2DM.

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