[Cell Signaling Technology] Cellular Senescence 연구는 Cell Signaling Technology와 함께하세요!

Cell Signaling Technology Cellular Senescence

Cellular senescence (세포 노화)는 일반적으로 증식하는 세포가 DNA 손상에 대한 반응으로 성장 촉진 자극에 저항성을 갖게 되는 안정적인 세포 주기 정지 상태를 의미합니다. Senescence 는 Leonard Hayflick이 인간의 태아 fibroblast가 결국 분열을 멈추었지만 장기간 배양한 후에도 생존할 수 있고 대사 활성을 유지한다는 것을 관찰함으로써 처음 설명되었습니다. 현재는 줄기세포와 같은 특성을 가진 세포 유형을 제외하고는 변형된 악성 세포만이 무한히 복제되는 반면, 변형되지 않은 세포는 그렇지 않다는 것이 일반적으로 받아들여지고 있습니다. 여기에는 제한적인 in vitro 조건에서 개발된 배아 또는 induced pluripotent stem cell 외에 endogenous germline 및 somatic stem cell가 포함됩니다. 노화 세포는 세포 주기로 재진입할 수 있는 활동 정지 세포 및 최종 분화 세포와 구별됩니다.

아래 Cell Signaling Technology의 Senescence Signaling Pathway handout을 다운로드 해보세요.

Why Is Senescence Research Important?

노화 세포는 나이가 들수록 축적되며 노화 관련 장애와 같은 정상적인 노화 과정에 영향을 줍니다. 암, 신경퇴화, 대사 및 심혈관계 질환을 포함한 노화 및 연령 관련 병리학 간의 연관성은 노화 연구 분야를 크게 촉진시켰습니다. 설치류 모델 연구에 따르면 생체 내에서 선택적으로 노화 세포를 제거하면 염증을 줄이고 면역체계 기능을 강화해 노화 관련 질병의 진행을 늦춰 건강과 수명을 늘릴 수 있습니다. 예를 들어, 일부 화학 요법을 포함하여 노화를 유도하는 약물은 세포 복제 잠재력을 억제함으로써 암에 효과적입니다. 그러나 노화 세포는 DNA 손상으로 인한 것으로 추정되는 화학 요법을 받는 환자에게 축적되며, 원치 않는 부작용, 특히 피로의 원인이 되는 것으로 여겨집니다. 노화 세포는 또한 SASP 성분의 방출을 통해 암의 재발과 전이를 야기할 수 있습니다. 따라서 화학요법 환자에게 노화 세포에 대한 표적 치료제인 세놀리틱스 (senolytics)를 사용하면 암 재발을 예방하고 일부 부작용을 완화하는 데 도움이 될 수 있습니다. 또한 정상 쥐를 이용한 연구에서 수명을 연장하고 노화와 관련된 신체적 감소를 지연시킬 수 있는 것을 관찰했으며, 이는 노화와 관련된 질병을 치료하는데 효과적일 수 있다는 것을 보여줍니다. 현재 관절염과 만성신장질환 치료를 위한 임상시험에서 Senolytic 약물이 인체에서 테스트되고 있습니다.

Biomarkers of Senescence

Cell Signaling Technology Cellular Senescence

Phospho-Histone H2A.X (Ser139), also known as γ-H2A.X is a commonly used marker of cell senescence (green-stained nucleus in the image on the right).

Confocal immunofluorescent analysis of HeLa cells, untreated (left) or UV-treated (right), using Phospho-Histone H2A.X (Ser139) (20E3) Rabbit mAb #9718 (green). Actin filaments have been labeled with DY-554 phalloidin (red).

Senescent cells are characterized by stable cell cycle arrest as well as morphological and metabolic changes, chromatin reorganization, altered gene expression, and acquisition of the senescence-associated secretory phenotype (SASP). It is important to note that not all senescent cells display all biomarkers of senescence. In addition, senescence biomarkers are not necessarily specific to senescent cells, as some markers are observed in apoptotic cells or quiescent cells, for example. Therefore, the identification of senescent cells depends on the observation of several biomarkers, such as those described below:

Only cells with stable cell cycle arrest are considered senescent. Unlike a quiescent cell, a senescent cell will not reenter the cell cycle in response to any known physiological stimuli. Cell cycle arrest is mediated by the p53/p21CIP1 and p16INK4A/pRb tumor suppressor pathways, described in more detail below. Expression of p16INK4A is frequently observed in senescent cells, serving as a useful biomarker. However, p16INK4A is also highly expressed in pRb-negative tumors and cell lines.

Senescent cells typically have an enlarged size and flattened shape compared to their dividing cell counterparts. Senescent cells display extensive vacuolization and are sometimes multi-nucleated. In addition, disrupted nuclear envelope integrity is observed due to a loss of lamin B1 expression. Senescent cells accumulate dysfunctional mitochondria and display increased levels of reactive oxygen species (ROS). Increased lysosomal content and altered lysosomal activity is also observed, which is reflected by increased levels of β-galactosidase activity at pH 6.0, leading this to be widely adopted as a biomarker of cellular senescence.

Lamin B1 IF

Loss of Lamin B1 (shown here in green) is a marker of cellular senescence.

A hallmark feature of senescent cells is extensive chromatin reorganization, most notably the formation of senescence-associated heterochromatin foci (SAHF). These sites of facultative heterochromatin play a role in silencing genes that promote proliferation including E2F target genes like cyclin A. Senescent cells typically contain 30-50 SAHF which are characterized by bright DAPI staining and macroH2A, heterochromatin protein 1 (HP1), and lysine 9 di-or-tri-methylated histone H3 (H3K9Me2/3) immunoreactivity. Although SAHF is frequently observed during senescence, some cells undergo senescence without forming SAHF.


HP1 is a commonly used marker of cellular senescence. Immunohistochemical analysis of HP1 expression in paraffin-embedded human breast carcinoma using HP1 alpha antibody.

DNA damage, such as DNA double strand breaks, is a prominent feature of senescence. Senescent cells display a persistent DNA damage response (DDR) which ultimately triggers cell cycle arrest. Senescent cells contain nuclear foci called DNA segments with chromatin alterations reinforcing senescence (DNA-SCARS), which associate with PML nuclear bodies and accumulate DDR proteins such as activated p53, ATR, and ATM. DNA-SCARS that occur at uncapped telomeres are called telomere dysfunction-induced foci (TIF). Another indicator of DNA damage is γ-H2A.X, which is the phosphorylated form of H2A.X, a variant histone required for checkpoint-mediated cell cycle arrest and DNA repair following double-stranded DNA breaks. DNA damage, caused by ionizing radiation, UV-light, or radiomimetic agents, results in rapid phosphorylation of H2A.X at Ser139.

Phospho-Histone H2A.X IF

H2A.X is a commonly used marker of cell senescence. Confocal immunofluorescent analysis of HeLa cells, untreated (left), treated with UV (100 mJ/cm2) using Phospho-Histone H2A.X (Ser139) Mouse mAb (green). Actin filaments were labeled with DyLight™ 554 Phalloidin (red).

Many senescent cells acquire a pro-inflammatory senescence-associated secretory phenotype (SASP) that mediates non-cell autonomous effects of senescence, both beneficial and deleterious. The SASP is comprised of a highly complex mixture of secreted cytokines, chemokines, growth factors, and proteases, with the precise composition varying markedly by cell and tissue context and the senescence-inducing stimulus. These secreted factors facilitate communication with neighboring cells and the immune system, which ultimately influences the fate of the senescent cell. For example, the SASP recruits immune cells to senescent cells, thereby facilitating their elimination, which serves a tumor suppressor function. Paradoxically, however, the SASP has been shown to promote tumor cell progression through secretion of factors that promote angiogenesis, extracellular matrix remodeling, or epithelial-mesenchymal transition (EMT). Additionally, chronic senescence-induced inflammation can induce systemic immunosuppression, potentially leading to the onset of diseases including cancer. This chronic inflammation may also drive tissue damage and degeneration associated with aging.

Most Common Proteins in Senescence

Antibodies and detection reagents for identifying senescent cells are available from Cell Signaling Technologies:

Protein or Marker Role in Senescence
Senescence-associated β-galactosidase Increased activity at pH 6.0 in senescent cells
p53 Activation can trigger cell cycle arrest
Rb (Retinoblastoma tumor suppressor protein) Inhibition triggers cell cycle arrest
p21CIP1 Inhibits cyclin dependent kinases; downstream of p53
p16INK4A Inhibits phosphorylation and inactivation of pRb
Bcl-2 Increased expression in senescent cells, inhibits apoptosis
macroH2A1.1 macroH2A1 isoform; marker of SAHF
macroH2A1.2 macroH2A1 isoform; marker of SAHF
H3K9Me2/3 (lysine 9 di-or-tri-methylated histone H3) Marker of SAHF
HP1 (heterochromatin protein 1) Marker of SAHF
Phospho-Histone H2A.X (Ser139) Marker of DNA damage
Lamin B1 Expression reduced in senescent cells leading to disruption of nuclear envelope
HMGB1 (High mobility group protein B1) SASP component
IL-6 (Interleukin 6) SASP component
TNF-α (Tumor necrosis factor α) SASP component
MMP3 (Matrix metalloproteinase-3) SASP component

Related Products

Antibody Sampler Kit for Senescence Research

Senescence 관련 연구를 위한 Cell Signaling Technology의 Antibody Sampler Kit 제품 입니다. Antibody Sampler Kit는 각 연구분야에 필요한 key target protein들에 대한 primary antibody의 trial size (20ul)와 host에 맞는 HRP-conjugated secondary antibody (100ul)을 함께 제공하는 제품으로 연구자들에게 편리를 제공합니다.

Senescence Assay Kit

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