Regulation of the transcriptional activation of CTRP3 in chondrocytes by c-Jun

New Insights Into Implications of CTRP3 in Obesity, Metabolic Dysfunction, and Cardiovascular Diseases: Potential of Therapeutic Interventions

Adipose tissue, as the largest endocrine organ, secretes many biologically active molecules circulating in the bloodstream, collectively termed adipocytokines, which not only regulate the metabolism but also play a role in pathophysiological processes. C1q tumor necrosis factor (TNF)-related protein 3 (CTRP3) is a member of C1q tumor necrosis factor-related proteins (CTRPs), which is a paralog of adiponectin. CTRP3 has a wide range of effects on glucose/lipid metabolism, inflammation, and contributes to cardiovascular protection. In this review, we comprehensively discussed the latest research on CTRP3 in obesity, diabetes, metabolic syndrome, and cardiovascular diseases.

Possible association between circulating CTRP3 and knee osteoarthritis in postmenopausal women

BACKGROUND

Osteoarthritis (OA) is considered as one of the most common cause of chronic pain and functional disabilities in the elderly.

AIM

To examine serum levels of complement-C1q TNF-related protein 3 (CTRP3) in postmenopausal women with knee OA.

METHODS

A population-based cross-sectional study was performed in women who complained of chronic knee pain. All subjects were followed by clinical and weight-bearing bilateral anteroposterior radiographical examinations. The Kellgren and Lawrence (K&L) score was used for knee OA classification. Two groups of postmenopausal women were chosen to investigate CTRP3 as an OA marker who had the K&L score ≥ 3 as a case group and K&L ≤ 1 as a control group. Serum levels of CTRP3 were measured in two groups.

RESULTS

According to K&L classification, 36 subjects with knee OA and 54 age-matched without or mild OA were selected. After adjusting the obtained data for taking NSAID drugs, the concentration of Ln CTRP3 in serum of patients with OA was lower compared to control group [mean ± SE, (0.39 ± 0.05 ng/ml vs. 0.48 ± 0.03 ng/ml, respectively, p = 0.04)].

DISCUSSION

There is a possible role for CTRP3 as an anti-inflammatory mediator in knee OA in postmenopausal women.

CONCLUSIONS

Our results indicate an association between CTRP3 and knee OA. However, a much more robust study is required to draw that circulating CTRP3 could be a clinical marker for osteoarthritis.

C1q/TNF-related protein-3 and glucose homeostasis

Adipokines are cytokines produced by adipocytes that may mediate inflammatory processes, whilst adipocyte-derived proteins may have the converse effect. C1q/TNF-related protein-3 or CTRP3 is a novel adipokine that is expressed and released by most types of human tissues including adipose tissue. This adipokine, considered as an adiponectin, can normalize blood glucose by several mechanisms. In addition, it can modulate the expression/secretion of other cytokine and adipokines leading to lower insulin resistance in peripheral tissues. Beneficial effects of CTRP3 against hyperglycemia-induced complications in the kidney and eye have been reported. In this review, we have presented the latest findings on the in vitro and in vivo hypoglycemic effects of CTRP3, followed by the findings on the preventive/therapeutic effects of CTRP3 adipokines against diabetes related complications.

C1q/TNF-Related Protein 3 (CTRP3) Function and Regulation

As the largest endocrine organ, adipose tissue secretes many bioactive molecules that circulate in blood, collectively termed adipokines. Efforts to identify such metabolic regulators have led to the discovery of a family of secreted proteins, designated as C1q tumor necrosis factor (TNF)-related proteins (CTRPs). The CTRP proteins, adiponectin, TNF-alpha, as well as other proteins with the distinct C1q domain are collectively grouped together as the C1q/TNF superfamily. Reflecting profound biological potency, the initial characterization of these adipose tissue-derived CTRP factors finds wide-ranging effects upon metabolism, inflammation, and survival-signaling in multiple tissue types. CTRP3 (also known as CORS26, cartducin, or cartonectin) is a unique member of this adipokine family. In this review we provide a comprehensive overview of the research concerning the expression, regulation, and physiological function of CTRP3. © 2017 American Physiological Society. Compr Physiol 7:863-878, 2017.