Table 1.

Transgenic mouse models used to study heritable L1 retrotransposition events

Study	L1 element used	Promoter driving L1 transgene	Reporter cassette	Transgene copy number	Developmental origin of identified insertions	Insertions transmitted?
Ostertag et al.59	Human L1RP	Native L1RP 5′UTR	pAC‐EGFP	n/d	Male germline	n/d
		pPolII + native L1RP 5′UTR	pAC‐EGFP	n/d	Male germline	Yes
Prak et al.60	Human L1RP	pPolII + native L1RP 5′UTR	pCMV‐EGFP	n/d	Early embryonic in founder mouse	Yes
Babushok et al.62	Human LRE3	pHSP70‐2 + native LRE3 5′UTR	Markerless cassette	n/d	Early embryonic	No
An et al.63	Mouse synthetic ORFeus_Mm	pCAG	pRSV LTR‐EGFP	31064	n/d	Yes
An et al.64	Mouse synthetic ORFeus_Mm	pCAG; conditionally activated by Cre‐mediated recombination	pRSV LTR‐EGFP	Single‐copy	n/d	n/d
Kano et al.65	Human LRE3 flanked by chicken β‐globin insulators	Native LRE3 5′UTR	γ‐globin intron in 3′UTR	n/d	Early embryonic	No
	Human L1RP 61	Native L1RP 5′UTR	pCMV‐EGFP	n/d
	Human L1RP (tested in rat)	Native L1RP 5′UTR	Markerless cassette	n/d
	Mouse TGF21	Native TGF21 5′UTR	pCMV‐EGFP	n/d
Newkirk et al.66	Mouse synthetic ORFeus_Mm	Native L1spa 5′UTR	pCMV‐EGFP	Single‐copy	Male germline	n/d

From left to right, columns indicate the study cited, the species of origin and name of the L1 element, the promoter(s) driving L1 transgene expression, the promoter driving reporter cassette expression, the developmental origins of insertions examined by each study, and whether germline transmission of insertions to subsequent generations was observed. pPolII, mouse RNA polymerase II promoter; pHSP70‐2, mouse heat shock protein 70‐2 promoter; pAC, preproacrosin promoter; pCMV, human cytomegalovirus immediate‐early enhancer and promoter; pCAG, CMV immediate‐early enhancer/modified chicken β‐actin promoter; pRSV LTR, Rous sarcoma virus LTR promoter. n/d; not determined. In Kano et al.,65 the L1_RP element was used in both transgenic mouse and transgenic rat models; the L1_RP transgenic mice were first reported by Muotri et al.61