TLDR Too much Smad7 changes skin and hair development by breaking down a protein called β-catenin, leading to more oil glands and fewer hair follicles.
The study from 2006 explored how Smad7 affects skin development, particularly hair follicle formation and sebaceous gland development, in transgenic mice. It was found that Smad7 overexpression disrupted hair follicle morphogenesis and differentiation, while accelerating sebaceous gland development. This was due to Smad7 binding to β-catenin and inducing its degradation by recruiting the E3 ligase Smurf2, which suppressed Wnt/β-catenin signaling. The abnormalities in hair follicles and sebaceous glands were exacerbated when Smurf2 and Smad7 were co-expressed. Conversely, reducing Smad7 levels in keratinocytes increased β-catenin protein and Wnt signaling. The study concluded that Smad7 antagonizes Wnt/β-catenin signaling, which alters the skin differentiation program, favoring sebaceous gland formation over hair follicles. The number of mice used in the study was not specified.
384 citations,
June 2005 in “Genes & development” β-catenin is essential for stem cell activation and proliferation in hair follicles.
142 citations,
June 2003 in “The journal of investigative dermatology. Symposium proceedings/The Journal of investigative dermatology symposium proceedings” Hair follicle stem cells can generate all hair cell types, skin, and sebaceous glands.
111 citations,
June 2002 in “The EMBO Journal” Too much Smad7 can cause serious changes in skin tissues, including problems with hair growth, thymus shrinkage, and eye development issues.
338 citations,
April 2001 in “Current Biology” 
109 citations,
December 1998 in “The Journal of Dermatology” Manipulating the catagen and telogen phases of hair growth could lead to treatments for hair disorders.
59 citations,
March 2008 in “The journal of investigative dermatology/Journal of investigative dermatology” Smad-4 and Smad-7 are key in hair follicle development, with other Smads being less important.
143 citations,
September 2008 in “Experimental gerontology” Skin aging is due to impaired stem cell mobilization or fewer responsive stem cells.
1 citations,
April 2022 in “BMC Genomics” Researchers found genes linked to hair loss in male giant pandas.
11 citations,
October 2021 in “Frontiers in Cell and Developmental Biology” Non-coding RNAs are important for hair growth and could lead to new hair loss treatments, but more research is needed.
5 citations,
April 2022 in “Frontiers in Medicine” Hair and skin healing involve complex cell interactions controlled by specific molecules and pathways, and hair follicle cells can help repair skin wounds.
