Related Experiment Video

Updated: Aug 25, 2026

Generation and Culturing of Primary Human Keratinocytes from Adult Skin
10:42

Generation and Culturing of Primary Human Keratinocytes from Adult Skin

Published on: December 22, 2017

Modulation of proliferation-specific and differentiation-specific markers in human keratinocytes by SMAD7

Louise Smith1, Alison L Dahler, Lois L Cavanagh

  • 1Epithelial Pathobiology Group, Cancer Biology Programme, Centre for Immunology and Cancer Research, University of Queensland, Princess Alexandra Hospital, Brisbane, Queensland, Australia.

Experimental Cell Research
|March 17, 2004
PubMed

Insights

SMAD7 plays a dual role in keratinocyte differentiation, inhibiting proliferation in normal cells but promoting differentiation in response to TGF-beta. This suggests SMAD7 modulates squamous differentiation through TGF-beta-dependent and -independent pathways.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Dermatology

Background:

  • Human epidermal keratinocyte differentiation is a complex process regulated by various signaling pathways.
  • SMAD7 is known to inhibit TGF-beta signaling, a key regulator of keratinocyte differentiation.

Purpose of the Study:

  • To investigate the role of SMAD7 in human epidermal keratinocyte differentiation.
  • To elucidate the specific mechanisms and signaling pathways involved in SMAD7's function.

Main Methods:

  • Overexpression of SMAD7 in human epidermal keratinocytes.
  • Analysis of proliferation-specific and differentiation-specific gene expression and promoter activity.
  • Examination of various signaling pathway reporters (AP1, NFkappaB, E2F, etc.).

Main Results:

  • SMAD7 inhibited proliferation-specific gene promoters (keratin 14, cdc2) and mRNA expression (cdc2, E2F1) in proliferating keratinocytes.
  • This inhibitory effect on proliferation was mediated by a novel domain outside the TGF-beta inhibitory region and was lost in transformed cells.
  • SMAD7 suppressed E2F-responsive reporters and modestly increased AP1 activity in proliferating cells.
  • In differentiated keratinocytes, SMAD7 acted as an inhibitor of TGF-beta, superinducing differentiation markers.

Conclusions:

  • SMAD7 exhibits distinct functions in proliferating versus differentiated keratinocytes.
  • SMAD7 participates in TGF-beta-independent signaling pathways regulating keratinocyte proliferation.
  • SMAD7 modulates squamous differentiation by opposing TGF-beta's suppressive effects.

More Related Videos

Characterization of In Vitro Differentiation of Human Primary Keratinocytes by RNA-Seq Analysis07:29

Characterization of In Vitro Differentiation of Human Primary Keratinocytes by RNA-Seq Analysis

Published on: May 16, 2020

Establishing a High Throughput Epidermal Spheroid Culture System to Model Keratinocyte Stem Cell Plasticity10:03

Establishing a High Throughput Epidermal Spheroid Culture System to Model Keratinocyte Stem Cell Plasticity

Published on: January 30, 2021

Related Concept Videos

TGF - β Signaling Pathway01:16

TGF - β Signaling Pathway

The TGF-β signaling pathway regulates cell growth, differentiation, adhesion, motility, and development. TGF-β ligands that induce TGF-β signaling are synthesized in their latent form. Several proteases or cell surface receptors such as integrins act upon the latent form, releasing the active ligand. There are three types of mammalian TGF-βs: (TGF-β1, TGF-β2, and TGF-β3) that bind as homodimers or heterodimers to TGF-β receptors. The TGF-β receptors are of three kinds RI, RII, and RIII. The RI...
Renewal of Skin Epidermal Stem Cells01:12

Renewal of Skin Epidermal Stem Cells

The skin is divided into epidermis, dermis, and hypodermis, the skin's outermost, middle, and inner layers. The human epidermal layer regularly undergoes renewal, where old, dead cells are replaced by new cells. Epidermal stem cells or EpiSCs divide and differentiate to restore the lost cells. For the renewal process, some EpiSCs continuously self-renew. In contrast, few others differentiate into transit-amplifying cells, which later form prickle or spinous cells, followed by granular cells,...
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Somatic to iPS Cell Reprogramming01:29

Somatic to iPS Cell Reprogramming

Reprogramming alters the gene expression in somatic cells, transforming them into induced pluripotent stem (iPS) cells over several generations. Scientists can reprogram cells by introducing genes for four transcription factors—Oct4, Sox2, Klf4, and c-Myc (OSKM) by viral or non-viral methods. These factors are also known as Yamanaka factors after Shinya Yamanaka, who first generated iPS cells using mouse skin cells. Yamanaka was awarded the Nobel Prize in Physiology or Medicine in 2012 for this...