Latent transforming growth factor β binding protein 3 controls adipogenesis

Area of Science:

• Biochemistry
• Cell Biology
• Stem Cell Research

Background:

• Transforming growth factor-beta (TGFβ) is crucial for various cellular functions, including stem cell differentiation.
• Latent TGFβ binding proteins (LTBPs) are key components of the latent TGFβ complex, influencing its bioavailability and function.
• The specific role of LTBPs, particularly LTBP3, in adipogenesis (fat cell formation) has not been previously investigated.

Purpose of the Study:

• To investigate the role of LTBP3 in the process of adipogenesis.
• To determine if LTBP3 expression influences stem cell differentiation into adipocytes.
• To elucidate the underlying mechanisms of LTBP3's function in adipogenesis, including its dependence on TGFβ signaling.

Main Methods:

• Analyzing LTBP gene expression during adipogenesis in vitro.
• Utilizing siRNA-mediated knockdown of LTBP3 in various cell lines (C3H/10T1/2, 3T3-L1, M2, BMSC).
• Assessing adipogenesis by measuring lipid vesicle formation and PPARγ expression.
• Generating and analyzing LTBP3 knockout (Ltbp3-/-) mice.
• Employing TGFβ neutralizing antibodies and receptor I kinase inhibitors to investigate TGFβ dependency.

Main Results:

• LTBP3 expression remained constant during adipogenesis, while other LTBP family members decreased.
• LTBP3 knockdown significantly reduced adipogenesis in multiple cell types, evidenced by fewer lipid vesicles and lower PPARγ levels.
• LTBP3 knockout mice exhibited significantly reduced white adipose tissue mass.
• The inhibitory effect of LTBP3 loss on adipogenesis was rescued by TGFβ pathway inhibition, indicating a TGFβ-dependent mechanism.

Conclusions:

• LTBP3 plays a critical, TGFβ-dependent role in promoting adipogenesis both in vitro and in vivo.
• These findings reveal a novel function for LTBP3 in regulating fat cell differentiation.
• Understanding LTBP3's role is significant for potential applications in regenerative medicine involving mesenchymal stem cell fate control.