Identification of SALL4 Expressing Islet-1+ Cardiovascular Progenitor Cell Clones

Emerging Insights into Sall4's Role in Cardiac Regenerative Medicine

Sall4 as a pivotal transcription factor has been extensively studied across diverse biological processes, including stem cell biology, embryonic development, hematopoiesis, tissue stem/progenitor maintenance, and the progression of various cancers. Recent research highlights Sall4's emerging roles in modulating cardiac progenitors and cellular reprogramming, linking its functions to early heart development and regenerative medicine. These findings provide new insights into the critical functions of Sall4 in cardiobiology. This review explores Sall4's complex molecular mechanisms and their implications for advancing cardiac regenerative medicine.

SALL4 mediates SHP2 inhibition in myocardial fibroblasts through the DOT1L/H3K79me2 signaling pathway to promote the progression of myocardial infarction

OBJECTIVE

To explore the influence of SALL4 in cardiac fibroblasts on the progression of myocardial infarction.

METHODS

Analysis of genes specifically expressed in myocardial infarction by bioinformatics methods; The impact of SALL4 on myocardial infarction was assessed using mouse ultrasound experiments and Masson staining; The effect of SALL4 on the expression levels of collagen-I and collagen-III in myocardial tissue was examined by immunohistochemical staining; The migration ability of cardiac fibroblasts was evaluated using a Transwell assay; The proliferative ability of cardiac fibroblasts was tested using a CCK-8 assay; The relative fluorescence intensity of α-SMA and CTGF in cardiac fibroblasts were checked through immunofluorescence staining experiment; The expression of SALL4, DOT1L, H3K79me2, P53, SHP2, YAP, nucleus-YAP, collagen-I, α-SMA, CTGF, and PAI-1 in myocardial tissues or cardiac fibroblasts was detected using western blot analysis.

RESULTS

SALL4-specific high expression in myocardial infarction; SALL4 intensified the alterations in the heart structure of mice with myocardial infarction and worsened the fibrosis of myocardial infarction; SALL4 also promoted the expression of SALL4, DOT1L, H3K79me2, P53, SHP2, YAP, nucleus-YAP, collagen-I, collagen-III, α-SMA, CTGF, and PAI-1 in myocardial infarction tissues and cardiac fibroblasts; Subsequently, SALL4 could enhance the immunofluorescence intensity of α-SMA and CTGF; Moreover, SALL4 could promote the proliferation and migration of cardiac fibroblasts.

CONCLUSION

In cardiac fibroblasts, SALL4 mediates the DOT1L/H3K79me2 signaling pathway to inhibit SHP2, which then promotes the YAP/TAZ signaling pathway, thereby facilitating the progression of myocardial infarction.

Sall4 and Gata4 induce cardiac fibroblast transition towards a partially multipotent state with cardiogenic potential

Cardiac cellular fate transition holds remarkable promise for the treatment of ischemic heart disease. We report that overexpressing two transcription factors, Sall4 and Gata4, which play distinct and overlapping roles in both pluripotent stem cell reprogramming and embryonic heart development, induces a fraction of stem-like cells in rodent cardiac fibroblasts that exhibit unlimited ex vivo expandability with clonogenicity. Transcriptomic and phenotypic analyses reveal that around 32 ± 6.4% of the expanding cells express Nkx2.5, while 13 ± 3.6% express Oct4. Activated signaling pathways like PI3K/Akt, Hippo, Wnt, and multiple epigenetic modification enzymes are also detected. Under suitable conditions, these cells demonstrate a high susceptibility to differentiating into cardiomyocyte, endothelial cell, and extracardiac neuron-like cells. The presence of partially pluripotent-like cells is characterized by alkaline phosphatase staining, germ layer marker expression, and tumor formation in injected mice (n = 5). Additionally, significant stem-like fate transitions and cardiogenic abilities are induced in human cardiac fibroblasts, but not in rat or human skin fibroblasts. Molecularly, we identify that SALL4 and GATA4 physically interact and synergistically stimulate the promoters of pluripotency genes but repress fibrogenic gene, which correlates with a primitive transition process. Together, this study uncovers a new cardiac regenerative mechanism that could potentially advance therapeutic endeavors and tissue engineering.

SALL4 deletion and kidney and cardiac defects associated with VACTERL association

Congenital anomalies of the kidney and urinary tract (CAKUT) can be a part of the VACTERL association, which represents the non-random combination of the following congenital anomalies: vertebral anomalies, anal anomalies, cardiac anomalies, tracheal-esophageal anomalies, kidney anomalies, and limb anomalies. VACTERL association is generally considered to be a non-genetic condition. Exceptions include a patient with a heterozygous nonsense SALL4 variant and anal stenosis, tetralogy of Fallot, sacro-vertebral fusion, and radial and thumb anomalies. SALL4 encodes a transcription factor that plays a critical role in kidney morphogenesis. Here, we report a patient with VACTERL association and a heterozygous 128-kb deletion spanning SALL4 who presented with renal hypoplasia, radial and atrio-septal defects, and patent ductus arteriosus. The present report of SALL4 deletion, in addition to a previously reported patient with VACTERL association phenotype and SALL4 nonsense mutation, further supports the notion that SALL4 haploinsufficiency can lead to VACTERL association.