This research is being presented at the American Heart Association’s Scientific Sessions in Chicago Nov. 16.
Tapan Chatterjee, PhD, and researchers in the division of cardiovascular diseases found that action by the enzyme histone deacetylase 9 (HDAC9) can lead to obesity-induced body fat dysfunction and that HDAC9-regulated pathways could be targets for potential treatment options in obesity-related diseases.
"Failure of fat cells to differentiate and properly store excess calories in obesity is associated with adipose tissue (fat) inflammation, fatty liver disease, insulin resistance, diabetes and increased cardiovascular diseases,” Chatterjee says. "We know that dysfunctional fat tissue is the underlying culprit in obesity-related diseases; however, we do not know why fat tissue becomes dysfunctional when a person becomes obese.”
Chatterjee says researchers in this study first identified HDAC9 regulator of fat cell differentiation within the living organism.
"Caloric intake promotes HDAC9 down-regulation to allow the conversion of precursor fat cells to ‘functional’ fat cells, capable of efficiently storing excess calories for future use and also maintaining whole body lipid and glucose stability,” he says. "Ideally, fat cells should function as a reversible storage site of excess calories and as an endocrine organ to maintain systemic lipid and glucose stability.
"Unfortunately, during chronic over-feeding, we find HDAC9 level is up-regulated in fat tissue, thereby blocking the conversion which leads to adipose tissue dysfunction and the onset of diseases such as diabetes, liver disease, high blood pressure and heart disease—the nation’s No. 1 killer.”
Researchers examined various members of the HDAC family of proteins and found that only HDAC9 showed a direct correlation to differentiation of precursor fat cells, both from human and mouse fat tissues.
"HDAC9 down-regulation is necessary for the differentiation of precursor fat cells to mature fat cells; forced up-regulation of HDAC9 by genetic manipulation blocks the differentiation of the precursor fat cells,” Chatterjee says. "On the other hand, precursor fat cells from HDAC9 genetic knockout mice showed accelerated differentiation.
"We believe that HDAC9 keeps precursor fat cells in the undifferentiated state; metabolic cues trigger HDAC9 down-regulation allowing conversion of the precursor cells to mature fat cells. We are exploring the cellular signaling mechanism that promotes such down-regulation of this enzyme during the normal fat cell differentiation process.”
Chatterjee says researchers were really interested in the tie between increased HDAC9 levels in fat tissue of mice and the caloric overload.
"Fat tissues from these obese mice showed dysfunction, with increased expression of pro-inflammatory agents and decreased expression of hormones responsible for maintaining whole body lipid and glucose stability,” he says. "The fat tissues of these mice are not capable of efficiently storing excess calories and are not able to perform proper endocrine functions.
"The adaptive response fails for some reason during chronic caloric overload, leading to the generation of fat tissue mass that is dysfunctional.”
Chatterjee says the HDAC9 level in fat cells is the underlying molecular culprit for dysfunctional fat tissue during obesity.
"We are currently examining HDAC9 knockout mice subjected to chronic high-fat feeding and think that HDAC9 gene removal will protect mice from obesity-linked adipose tissue dysfunction and associated metabolic disorders,” he says.
"Identification of HDAC9 as a novel regulator of fat cell differentiation and the finding that elevated HDAC9 levels are associated with adipose tissue dysfunction in obesity are extremely interesting and novel findings,” he continues.
Chatterjee’s team is pursuing studies to understand how diet regulates HDAC9 levels in fat tissue and how HDAC9 up-regulation can be prevented during diet-induced obesity through pharmacological means.
"Our findings may help lead researchers to targeted therapies that may prevent the development of obesity-related disorders in humans.”
This study was funded by a grant from the National Institutes of Health.
Katie Pence | EurekAlert!
One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie
The dark side of cichlid fish: from cannibal to caregiver
20.04.2018 | Veterinärmedizinische Universität Wien
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy