Essential role of Ahnak in adipocyte differentiation leading to the transcriptional regulation of Bmpr1α expression

Abstract

The role of Ahnak in obesity has been reported previously. Loss of Ahnak leads to decreased Bmp4/Smad1 signaling, resulting in the downregulation of adipocyte differentiation. However, the biological significance of Ahnak remains largely unknown. In this study, we demonstrate that Ahnak-mediated impaired adipogenesis results in decreased Bmpr1α transcriptional expression. To confirm this, Ahnak siRNA was used to knock-down Ahnak in C3H10T1/2 and primary stromal vascular fraction cells. Ahnak siRNA transfected cells showed suppression of Bmpr1α expression and decreased BMP4/ Bmpr1α signaling. The differential adipogenesis was further confirmed by knock-down of Bmpr1α in C3H10T1/2 cells, which resulted in reduced adipogenesis. Moreover, stable Ahnak knock-out C3H10T1/2 cells stably transfected with Ahnak CRISPR/Cas9 plasmid suppressed expression of Bmpr1α and prevented differentiation into adipocytes. Furthermore, we developed immortalized pre-adipocytes from wild-type or Ahnak Knock-out mice’s stromal vascular fraction (SVF) to confirm the function of Ahnak in pre-adipocyte transition. Immortalized Ahnak knock-out SVF cells showed lower level of Bmpr1α expression, evidence by their impaired BMP4/Bmpr1α signaling. Upon adipogenic induction, immortalized Ahnak knock-out SVF cells exhibited a marked decrease in adipocyte differentiation compared with immortalized wild-type pre-adipocytes. Furthermore, over-expression of Bmpr1α restored the adipogenic activity of Ahnak knock-out C3H10T1/2 cells and immortalized Ahnak knock-out SVF cells. Our data reveal the missing link in Ahnak-mediated adipose tissue remodeling and suggest that precise regulation of Ahnak in adipose tissue might have a therapeutic advantage for metabolic disease treatment.

Plakoglobin regulates adipocyte differentiation independently of the Wnt/β-catenin signalling pathway

“…2C). Consistent with prior studies, depletion of known regulators of adipogenesis, such as CAST and AHNAK, impaired 3T3-L1 differentiation (32,33) (Fig. 2A,C).…”

“…1E,F). Among proteins that were significantly increased in abundance in the HFD-14-3-3ζ interactome, known regulators of adipogenesis, such as Calpastatin (CAST) (30,31) and AHNAK were detected (32,33) (Fig. 1B).…”

Ahnak-knockout mice show susceptibility toBartonella henselaeinfection because of CD4+ T cell inactivation and decreased cytokine secretion

“…AHNAK is the largest protein on our body and involved in the formation of cytoskeletal structure, muscular regeneration, and calcium homeostasis (9) and is involved in several biological processes. We previously reported that AHNAK is involved in obesity and cellular adipogenesis (10–12). Moreover, AHNAK functions as a tumor suppressor protein to prevent the development of breast and lung cancers by inhibiting cancer cell growth through the potentiation of transforming growth factor-β (TGF-β) signaling pathway (13, 14).…”

The S100B Protein and Partners in Adipocyte Response to Cold Stress and Adaptive Thermogenesis: Facts, Hypotheses, and Perspectives

“…The giant protein AHNAK1 (M.W. 700 kDa) is a downstream effector in β-adrenergic signaling [ 73 , 74 ] and has central functions in adiposity regulations [ 53 , 75 , 76 , 77 ]. The AHNAK1 protein has three main functional domains: a short NH2-terminal domain, followed by a large central domain made of repeated amino acid sequences, and a COOH-terminal domain [ 78 ].…”